]> scripts.mit.edu Git - autoinstallsdev/mediawiki.git/blobdiff - includes/api/ApiBase.php
MediaWiki 1.30.2
[autoinstallsdev/mediawiki.git] / includes / api / ApiBase.php
index bc25ca61dc4f678a049116ebdf5c45a8a7878d25..bf2b97794ecd3f0550f2a9c3fba9435fe09a03d0 100644 (file)
@@ -1,10 +1,10 @@
 <?php
 /**
- * API for MediaWiki 1.8+
+ *
  *
  * Created on Sep 5, 2006
  *
- * Copyright © 2006, 2010 Yuri Astrakhan <Firstname><Lastname>@gmail.com
+ * Copyright © 2006, 2010 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * @file
  */
 
+use Wikimedia\Rdbms\IDatabase;
+
 /**
  * This abstract class implements many basic API functions, and is the base of
  * all API classes.
  * The class functions are divided into several areas of functionality:
  *
  * Module parameters: Derived classes can define getAllowedParams() to specify
- *     which parameters to expect,h ow to parse and validate them.
- *
- * Profiling: various methods to allow keeping tabs on various tasks and their
- *     time costs
+ *    which parameters to expect, how to parse and validate them.
  *
  * Self-documentation: code to allow the API to document its own state
  *
  * @ingroup API
  */
-abstract class ApiBase {
+abstract class ApiBase extends ContextSource {
+
+       /**
+        * @name Constants for ::getAllowedParams() arrays
+        * These constants are keys in the arrays returned by ::getAllowedParams()
+        * and accepted by ::getParameterFromSettings() that define how the
+        * parameters coming in from the request are to be interpreted.
+        * @{
+        */
 
-       // These constants allow modules to specify exactly how to treat incoming parameters.
+       /** (null|boolean|integer|string) Default value of the parameter. */
+       const PARAM_DFLT = 0;
 
-       const PARAM_DFLT = 0; // Default value of the parameter
-       const PARAM_ISMULTI = 1; // Boolean, do we accept more than one item for this parameter (e.g.: titles)?
-       const PARAM_TYPE = 2; // Can be either a string type (e.g.: 'integer') or an array of allowed values
-       const PARAM_MAX = 3; // Max value allowed for a parameter. Only applies if TYPE='integer'
-       const PARAM_MAX2 = 4; // Max value allowed for a parameter for bots and sysops. Only applies if TYPE='integer'
-       const PARAM_MIN = 5; // Lowest value allowed for a parameter. Only applies if TYPE='integer'
-       const PARAM_ALLOW_DUPLICATES = 6; // Boolean, do we allow the same value to be set more than once when ISMULTI=true
-       const PARAM_DEPRECATED = 7; // Boolean, is the parameter deprecated (will show a warning)
-       const PARAM_REQUIRED = 8; // Boolean, is the parameter required?
-       const PARAM_RANGE_ENFORCE = 9; // Boolean, if MIN/MAX are set, enforce (die) these? Only applies if TYPE='integer' Use with extreme caution
+       /** (boolean) Accept multiple pipe-separated values for this parameter (e.g. titles)? */
+       const PARAM_ISMULTI = 1;
 
-       const LIMIT_BIG1 = 500; // Fast query, std user limit
-       const LIMIT_BIG2 = 5000; // Fast query, bot/sysop limit
-       const LIMIT_SML1 = 50; // Slow query, std user limit
-       const LIMIT_SML2 = 500; // Slow query, bot/sysop limit
+       /**
+        * (string|string[]) Either an array of allowed value strings, or a string
+        * type as described below. If not specified, will be determined from the
+        * type of PARAM_DFLT.
+        *
+        * Supported string types are:
+        * - boolean: A boolean parameter, returned as false if the parameter is
+        *   omitted and true if present (even with a falsey value, i.e. it works
+        *   like HTML checkboxes). PARAM_DFLT must be boolean false, if specified.
+        *   Cannot be used with PARAM_ISMULTI.
+        * - integer: An integer value. See also PARAM_MIN, PARAM_MAX, and
+        *   PARAM_RANGE_ENFORCE.
+        * - limit: An integer or the string 'max'. Default lower limit is 0 (but
+        *   see PARAM_MIN), and requires that PARAM_MAX and PARAM_MAX2 be
+        *   specified. Cannot be used with PARAM_ISMULTI.
+        * - namespace: An integer representing a MediaWiki namespace. Forces PARAM_ALL = true to
+        *   support easily specifying all namespaces.
+        * - NULL: Any string.
+        * - password: Any non-empty string. Input value is private or sensitive.
+        *   <input type="password"> would be an appropriate HTML form field.
+        * - string: Any non-empty string, not expected to be very long or contain newlines.
+        *   <input type="text"> would be an appropriate HTML form field.
+        * - submodule: The name of a submodule of this module, see PARAM_SUBMODULE_MAP.
+        * - tags: A string naming an existing, explicitly-defined tag. Should usually be
+        *   used with PARAM_ISMULTI.
+        * - text: Any non-empty string, expected to be very long or contain newlines.
+        *   <textarea> would be an appropriate HTML form field.
+        * - timestamp: A timestamp in any format recognized by MWTimestamp, or the
+        *   string 'now' representing the current timestamp. Will be returned in
+        *   TS_MW format.
+        * - user: A MediaWiki username or IP. Will be returned normalized but not canonicalized.
+        * - upload: An uploaded file. Will be returned as a WebRequestUpload object.
+        *   Cannot be used with PARAM_ISMULTI.
+        */
+       const PARAM_TYPE = 2;
 
-       private $mMainModule, $mModuleName, $mModulePrefix;
-       private $mParamCache = array();
+       /** (integer) Max value allowed for the parameter, for PARAM_TYPE 'integer' and 'limit'. */
+       const PARAM_MAX = 3;
 
        /**
-        * Constructor
-        * @param $mainModule ApiMain object
-        * @param $moduleName string Name of this module
-        * @param $modulePrefix string Prefix to use for parameter names
+        * (integer) Max value allowed for the parameter for users with the
+        * apihighlimits right, for PARAM_TYPE 'limit'.
         */
-       public function __construct( $mainModule, $moduleName, $modulePrefix = '' ) {
-               $this->mMainModule = $mainModule;
-               $this->mModuleName = $moduleName;
-               $this->mModulePrefix = $modulePrefix;
-       }
+       const PARAM_MAX2 = 4;
+
+       /** (integer) Lowest value allowed for the parameter, for PARAM_TYPE 'integer' and 'limit'. */
+       const PARAM_MIN = 5;
 
-       /*****************************************************************************
-        * ABSTRACT METHODS                                                          *
-        *****************************************************************************/
+       /** (boolean) Allow the same value to be set more than once when PARAM_ISMULTI is true? */
+       const PARAM_ALLOW_DUPLICATES = 6;
+
+       /** (boolean) Is the parameter deprecated (will show a warning)? */
+       const PARAM_DEPRECATED = 7;
 
        /**
-        * Evaluates the parameters, performs the requested query, and sets up
-        * the result. Concrete implementations of ApiBase must override this
-        * method to provide whatever functionality their module offers.
-        * Implementations must not produce any output on their own and are not
-        * expected to handle any errors.
-        *
-        * The execute() method will be invoked directly by ApiMain immediately
-        * before the result of the module is output. Aside from the
-        * constructor, implementations should assume that no other methods
-        * will be called externally on the module before the result is
-        * processed.
-        *
-        * The result data should be stored in the ApiResult object available
-        * through getResult().
+        * (boolean) Is the parameter required?
+        * @since 1.17
         */
-       public abstract function execute();
+       const PARAM_REQUIRED = 8;
 
        /**
-        * Returns a string that identifies the version of the extending class.
-        * Typically includes the class name, the svn revision, timestamp, and
-        * last author. Usually done with SVN's Id keyword
-        * @return string
+        * (boolean) For PARAM_TYPE 'integer', enforce PARAM_MIN and PARAM_MAX?
+        * @since 1.17
         */
-       public abstract function getVersion();
+       const PARAM_RANGE_ENFORCE = 9;
 
        /**
-        * Get the name of the module being executed by this instance
-        * @return string
+        * (string|array|Message) Specify an alternative i18n documentation message
+        * for this parameter. Default is apihelp-{$path}-param-{$param}.
+        * @since 1.25
         */
-       public function getModuleName() {
-               return $this->mModuleName;
-       }
+       const PARAM_HELP_MSG = 10;
 
        /**
-        * Get parameter prefix (usually two letters or an empty string).
-        * @return string
+        * ((string|array|Message)[]) Specify additional i18n messages to append to
+        * the normal message for this parameter.
+        * @since 1.25
         */
-       public function getModulePrefix() {
-               return $this->mModulePrefix;
-       }
+       const PARAM_HELP_MSG_APPEND = 11;
 
        /**
-        * Get the name of the module as shown in the profiler log
-        * @return string
+        * (array) Specify additional information tags for the parameter. Value is
+        * an array of arrays, with the first member being the 'tag' for the info
+        * and the remaining members being the values. In the help, this is
+        * formatted using apihelp-{$path}-paraminfo-{$tag}, which is passed
+        * $1 = count, $2 = comma-joined list of values, $3 = module prefix.
+        * @since 1.25
         */
-       public function getModuleProfileName( $db = false ) {
-               if ( $db ) {
-                       return 'API:' . $this->mModuleName . '-DB';
-               } else {
-                       return 'API:' . $this->mModuleName;
-               }
-       }
+       const PARAM_HELP_MSG_INFO = 12;
 
        /**
-        * Get the main module
-        * @return ApiMain object
+        * (string[]) When PARAM_TYPE is an array, this may be an array mapping
+        * those values to page titles which will be linked in the help.
+        * @since 1.25
         */
-       public function getMain() {
-               return $this->mMainModule;
-       }
+       const PARAM_VALUE_LINKS = 13;
 
        /**
-        * Returns true if this module is the main module ($this === $this->mMainModule),
-        * false otherwise.
-        * @return bool
+        * ((string|array|Message)[]) When PARAM_TYPE is an array, this is an array
+        * mapping those values to $msg for ApiBase::makeMessage(). Any value not
+        * having a mapping will use apihelp-{$path}-paramvalue-{$param}-{$value}.
+        * @since 1.25
         */
-       public function isMain() {
-               return $this === $this->mMainModule;
-       }
+       const PARAM_HELP_MSG_PER_VALUE = 14;
 
        /**
-        * Get the result object
-        * @return ApiResult
+        * (string[]) When PARAM_TYPE is 'submodule', map parameter values to
+        * submodule paths. Default is to use all modules in
+        * $this->getModuleManager() in the group matching the parameter name.
+        * @since 1.26
         */
-       public function getResult() {
-               // Main module has getResult() method overriden
-               // Safety - avoid infinite loop:
-               if ( $this->isMain() ) {
-                       ApiBase::dieDebug( __METHOD__, 'base method was called on main module. ' );
-               }
-               return $this->getMain()->getResult();
-       }
+       const PARAM_SUBMODULE_MAP = 15;
 
        /**
-        * Get the result data array (read-only)
-        * @return array
+        * (string) When PARAM_TYPE is 'submodule', used to indicate the 'g' prefix
+        * added by ApiQueryGeneratorBase (and similar if anything else ever does that).
+        * @since 1.26
         */
-       public function getResultData() {
-               return $this->getResult()->getData();
-       }
+       const PARAM_SUBMODULE_PARAM_PREFIX = 16;
 
        /**
-        * Set warning section for this module. Users should monitor this
-        * section to notice any changes in API. Multiple calls to this
-        * function will result in the warning messages being separated by
-        * newlines
-        * @param $warning string Warning message
+        * (boolean|string) When PARAM_TYPE has a defined set of values and PARAM_ISMULTI is true,
+        * this allows for an asterisk ('*') to be passed in place of a pipe-separated list of
+        * every possible value. If a string is set, it will be used in place of the asterisk.
+        * @since 1.29
         */
-       public function setWarning( $warning ) {
-               $data = $this->getResult()->getData();
-               if ( isset( $data['warnings'][$this->getModuleName()] ) ) {
-                       // Don't add duplicate warnings
-                       $warn_regex = preg_quote( $warning, '/' );
-                       if ( preg_match( "/{$warn_regex}(\\n|$)/", $data['warnings'][$this->getModuleName()]['*'] ) ) {
-                               return;
-                       }
-                       $oldwarning = $data['warnings'][$this->getModuleName()]['*'];
-                       // If there is a warning already, append it to the existing one
-                       $warning = "$oldwarning\n$warning";
-                       $this->getResult()->unsetValue( 'warnings', $this->getModuleName() );
-               }
-               $msg = array();
-               ApiResult::setContent( $msg, $warning );
-               $this->getResult()->disableSizeCheck();
-               $this->getResult()->addValue( 'warnings', $this->getModuleName(), $msg );
-               $this->getResult()->enableSizeCheck();
-       }
+       const PARAM_ALL = 17;
 
        /**
-        * If the module may only be used with a certain format module,
-        * it should override this method to return an instance of that formatter.
-        * A value of null means the default format will be used.
-        * @return mixed instance of a derived class of ApiFormatBase, or null
+        * (int[]) When PARAM_TYPE is 'namespace', include these as additional possible values.
+        * @since 1.29
         */
-       public function getCustomPrinter() {
-               return null;
-       }
+       const PARAM_EXTRA_NAMESPACES = 18;
 
        /**
-        * Generates help message for this module, or false if there is no description
-        * @return mixed string or false
+        * (boolean) Is the parameter sensitive? Note 'password'-type fields are
+        * always sensitive regardless of the value of this field.
+        * @since 1.29
         */
-       public function makeHelpMsg() {
-               static $lnPrfx = "\n  ";
+       const PARAM_SENSITIVE = 19;
 
-               $msg = $this->getDescription();
+       /**
+        * (array) When PARAM_TYPE is an array, this indicates which of the values are deprecated.
+        * Keys are the deprecated parameter values, values define the warning
+        * message to emit: either boolean true (to use a default message) or a
+        * $msg for ApiBase::makeMessage().
+        * @since 1.30
+        */
+       const PARAM_DEPRECATED_VALUES = 20;
 
-               if ( $msg !== false ) {
+       /**
+        * (integer) Maximum number of values, for normal users. Must be used with PARAM_ISMULTI.
+        * @since 1.30
+        */
+       const PARAM_ISMULTI_LIMIT1 = 21;
 
-                       if ( !is_array( $msg ) ) {
-                               $msg = array(
-                                       $msg
-                               );
-                       }
-                       $msg = $lnPrfx . implode( $lnPrfx, $msg ) . "\n";
+       /**
+        * (integer) Maximum number of values, for users with the apihighimits right.
+        * Must be used with PARAM_ISMULTI.
+        * @since 1.30
+        */
+       const PARAM_ISMULTI_LIMIT2 = 22;
 
-                       if ( $this->isReadMode() ) {
-                               $msg .= "\nThis module requires read rights";
-                       }
-                       if ( $this->isWriteMode() ) {
-                               $msg .= "\nThis module requires write rights";
-                       }
-                       if ( $this->mustBePosted() ) {
-                               $msg .= "\nThis module only accepts POST requests";
-                       }
-                       if ( $this->isReadMode() || $this->isWriteMode() ||
-                                       $this->mustBePosted() )
-                       {
-                               $msg .= "\n";
-                       }
+       /**@}*/
 
-                       // Parameters
-                       $paramsMsg = $this->makeHelpMsgParameters();
-                       if ( $paramsMsg !== false ) {
-                               $msg .= "Parameters:\n$paramsMsg";
-                       }
+       const ALL_DEFAULT_STRING = '*';
 
-                       // Examples
-                       $examples = $this->getExamples();
-                       if ( $examples !== false ) {
-                               if ( !is_array( $examples ) ) {
-                                       $examples = array(
-                                               $examples
-                                       );
-                               }
+       /** Fast query, standard limit. */
+       const LIMIT_BIG1 = 500;
+       /** Fast query, apihighlimits limit. */
+       const LIMIT_BIG2 = 5000;
+       /** Slow query, standard limit. */
+       const LIMIT_SML1 = 50;
+       /** Slow query, apihighlimits limit. */
+       const LIMIT_SML2 = 500;
 
-                               if ( count( $examples ) > 0 ) {
-                                       $msg .= 'Example' . ( count( $examples ) > 1 ? 's' : '' ) . ":\n  ";
-                                       $msg .= implode( $lnPrfx, $examples ) . "\n";
-                               }
-                       }
+       /**
+        * getAllowedParams() flag: When set, the result could take longer to generate,
+        * but should be more thorough. E.g. get the list of generators for ApiSandBox extension
+        * @since 1.21
+        */
+       const GET_VALUES_FOR_HELP = 1;
 
-                       if ( $this->getMain()->getShowVersions() ) {
-                               $versions = $this->getVersion();
-                               $pattern = '/(\$.*) ([0-9a-z_]+\.php) (.*\$)/i';
-                               $callback = array( $this, 'makeHelpMsg_callback' );
+       /** @var array Maps extension paths to info arrays */
+       private static $extensionInfo = null;
 
-                               if ( is_array( $versions ) ) {
-                                       foreach ( $versions as &$v ) {
-                                               $v = preg_replace_callback( $pattern, $callback, $v );
-                                       }
-                                       $versions = implode( "\n  ", $versions );
-                               } else {
-                                       $versions = preg_replace_callback( $pattern, $callback, $versions );
-                               }
+       /** @var ApiMain */
+       private $mMainModule;
+       /** @var string */
+       private $mModuleName, $mModulePrefix;
+       private $mSlaveDB = null;
+       private $mParamCache = [];
+       /** @var array|null|bool */
+       private $mModuleSource = false;
 
-                               $msg .= "Version:\n  $versions\n";
-                       }
-               }
+       /**
+        * @param ApiMain $mainModule
+        * @param string $moduleName Name of this module
+        * @param string $modulePrefix Prefix to use for parameter names
+        */
+       public function __construct( ApiMain $mainModule, $moduleName, $modulePrefix = '' ) {
+               $this->mMainModule = $mainModule;
+               $this->mModuleName = $moduleName;
+               $this->mModulePrefix = $modulePrefix;
 
-               return $msg;
+               if ( !$this->isMain() ) {
+                       $this->setContext( $mainModule->getContext() );
+               }
        }
 
-       /**
-        * Generates the parameter descriptions for this module, to be displayed in the
-        * module's help.
-        * @return string
+       /************************************************************************//**
+        * @name   Methods to implement
+        * @{
         */
-       public function makeHelpMsgParameters() {
-               $params = $this->getFinalParams();
-               if ( $params ) {
 
-                       $paramsDescription = $this->getFinalParamDescription();
-                       $msg = '';
-                       $paramPrefix = "\n" . str_repeat( ' ', 19 );
-                       foreach ( $params as $paramName => $paramSettings ) {
-                               $desc = isset( $paramsDescription[$paramName] ) ? $paramsDescription[$paramName] : '';
-                               if ( is_array( $desc ) ) {
-                                       $desc = implode( $paramPrefix, $desc );
-                               }
+       /**
+        * Evaluates the parameters, performs the requested query, and sets up
+        * the result. Concrete implementations of ApiBase must override this
+        * method to provide whatever functionality their module offers.
+        * Implementations must not produce any output on their own and are not
+        * expected to handle any errors.
+        *
+        * The execute() method will be invoked directly by ApiMain immediately
+        * before the result of the module is output. Aside from the
+        * constructor, implementations should assume that no other methods
+        * will be called externally on the module before the result is
+        * processed.
+        *
+        * The result data should be stored in the ApiResult object available
+        * through getResult().
+        */
+       abstract public function execute();
 
-                               if ( !is_array( $paramSettings ) ) {
-                                       $paramSettings = array(
-                                               self::PARAM_DFLT => $paramSettings,
-                                       );
-                               }
+       /**
+        * Get the module manager, or null if this module has no sub-modules
+        * @since 1.21
+        * @return ApiModuleManager
+        */
+       public function getModuleManager() {
+               return null;
+       }
 
-                               $deprecated = isset( $paramSettings[self::PARAM_DEPRECATED] ) ?
-                                       $paramSettings[self::PARAM_DEPRECATED] : false;
-                               if ( $deprecated ) {
-                                       $desc = "DEPRECATED! $desc";
-                               }
+       /**
+        * If the module may only be used with a certain format module,
+        * it should override this method to return an instance of that formatter.
+        * A value of null means the default format will be used.
+        * @note Do not use this just because you don't want to support non-json
+        * formats. This should be used only when there is a fundamental
+        * requirement for a specific format.
+        * @return mixed Instance of a derived class of ApiFormatBase, or null
+        */
+       public function getCustomPrinter() {
+               return null;
+       }
 
-                               $required = isset( $paramSettings[self::PARAM_REQUIRED] ) ?
-                                       $paramSettings[self::PARAM_REQUIRED] : false;
-                               if ( $required ) {
-                                       $desc .= $paramPrefix . "This parameter is required";
+       /**
+        * Returns usage examples for this module.
+        *
+        * Return value has query strings as keys, with values being either strings
+        * (message key), arrays (message key + parameter), or Message objects.
+        *
+        * Do not call this base class implementation when overriding this method.
+        *
+        * @since 1.25
+        * @return array
+        */
+       protected function getExamplesMessages() {
+               // Fall back to old non-localised method
+               $ret = [];
+
+               $examples = $this->getExamples();
+               if ( $examples ) {
+                       if ( !is_array( $examples ) ) {
+                               $examples = [ $examples ];
+                       } elseif ( $examples && ( count( $examples ) & 1 ) == 0 &&
+                               array_keys( $examples ) === range( 0, count( $examples ) - 1 ) &&
+                               !preg_match( '/^\s*api\.php\?/', $examples[0] )
+                       ) {
+                               // Fix up the ugly "even numbered elements are description, odd
+                               // numbered elemts are the link" format (see doc for self::getExamples)
+                               $tmp = [];
+                               $examplesCount = count( $examples );
+                               for ( $i = 0; $i < $examplesCount; $i += 2 ) {
+                                       $tmp[$examples[$i + 1]] = $examples[$i];
                                }
+                               $examples = $tmp;
+                       }
 
-                               $type = isset( $paramSettings[self::PARAM_TYPE] ) ? $paramSettings[self::PARAM_TYPE] : null;
-                               if ( isset( $type ) ) {
-                                       if ( isset( $paramSettings[self::PARAM_ISMULTI] ) ) {
-                                               $prompt = 'Values (separate with \'|\'): ';
-                                       } else {
-                                               $prompt = 'One value: ';
-                                       }
-
-                                       if ( is_array( $type ) ) {
-                                               $choices = array();
-                                               $nothingPrompt = false;
-                                               foreach ( $type as $t ) {
-                                                       if ( $t === '' ) {
-                                                               $nothingPrompt = 'Can be empty, or ';
-                                                       } else {
-                                                               $choices[] =  $t;
-                                                       }
-                                               }
-                                               $desc .= $paramPrefix . $nothingPrompt . $prompt . implode( ', ', $choices );
-                                       } else {
-                                               switch ( $type ) {
-                                                       case 'namespace':
-                                                               // Special handling because namespaces are type-limited, yet they are not given
-                                                               $desc .= $paramPrefix . $prompt . implode( ', ', MWNamespace::getValidNamespaces() );
-                                                               break;
-                                                       case 'limit':
-                                                               $desc .= $paramPrefix . "No more than {$paramSettings[self :: PARAM_MAX]}";
-                                                               if ( isset( $paramSettings[self::PARAM_MAX2] ) ) {
-                                                                       $desc .= " ({$paramSettings[self::PARAM_MAX2]} for bots)";
-                                                               }
-                                                               $desc .= ' allowed';
-                                                               break;
-                                                       case 'integer':
-                                                               $hasMin = isset( $paramSettings[self::PARAM_MIN] );
-                                                               $hasMax = isset( $paramSettings[self::PARAM_MAX] );
-                                                               if ( $hasMin || $hasMax ) {
-                                                                       if ( !$hasMax ) {
-                                                                               $intRangeStr = "The value must be no less than {$paramSettings[self::PARAM_MIN]}";
-                                                                       } elseif ( !$hasMin ) {
-                                                                               $intRangeStr = "The value must be no more than {$paramSettings[self::PARAM_MAX]}";
-                                                                       } else {
-                                                                               $intRangeStr = "The value must be between {$paramSettings[self::PARAM_MIN]} and {$paramSettings[self::PARAM_MAX]}";
-                                                                       }
-
-                                                                       $desc .= $paramPrefix . $intRangeStr;
-                                                               }
-                                                               break;
-                                               }
-
-                                               if ( isset( $paramSettings[self::PARAM_ISMULTI] ) ) {
-                                                       $isArray = is_array( $paramSettings[self::PARAM_TYPE] );
-
-                                                       if ( !$isArray
-                                                                       || $isArray && count( $paramSettings[self::PARAM_TYPE] ) > self::LIMIT_SML1) {
-                                                               $desc .= $paramPrefix . "Maximum number of values " .
-                                                                       self::LIMIT_SML1 . " (" . self::LIMIT_SML2 . " for bots)";
-                                                       }
-                                               }
+                       foreach ( $examples as $k => $v ) {
+                               if ( is_numeric( $k ) ) {
+                                       $qs = $v;
+                                       $msg = '';
+                               } else {
+                                       $qs = $k;
+                                       $msg = self::escapeWikiText( $v );
+                                       if ( is_array( $msg ) ) {
+                                               $msg = implode( ' ', $msg );
                                        }
                                }
 
-                               $default = is_array( $paramSettings )
-                                               ? ( isset( $paramSettings[self::PARAM_DFLT] ) ? $paramSettings[self::PARAM_DFLT] : null )
-                                               : $paramSettings;
-                               if ( !is_null( $default ) && $default !== false ) {
-                                       $desc .= $paramPrefix . "Default: $default";
-                               }
-
-                               $msg .= sprintf( "  %-14s - %s\n", $this->encodeParamName( $paramName ), $desc );
+                               $qs = preg_replace( '/^\s*api\.php\?/', '', $qs );
+                               $ret[$qs] = $this->msg( 'api-help-fallback-example', [ $msg ] );
                        }
-                       return $msg;
-
-               } else {
-                       return false;
-               }
-       }
-
-       /**
-        * Callback for preg_replace_callback() call in makeHelpMsg().
-        * Replaces a source file name with a link to ViewVC
-        */
-       public function makeHelpMsg_callback( $matches ) {
-               global $wgAutoloadClasses, $wgAutoloadLocalClasses;
-               if ( isset( $wgAutoloadLocalClasses[get_class( $this )] ) ) {
-                       $file = $wgAutoloadLocalClasses[get_class( $this )];
-               } elseif ( isset( $wgAutoloadClasses[get_class( $this )] ) ) {
-                       $file = $wgAutoloadClasses[get_class( $this )];
-               }
-
-               // Do some guesswork here
-               $path = strstr( $file, 'includes/api/' );
-               if ( $path === false ) {
-                       $path = strstr( $file, 'extensions/' );
-               } else {
-                       $path = 'phase3/' . $path;
-               }
-
-               // Get the filename from $matches[2] instead of $file
-               // If they're not the same file, they're assumed to be in the
-               // same directory
-               // This is necessary to make stuff like ApiMain::getVersion()
-               // returning the version string for ApiBase work
-               if ( $path ) {
-                       return "{$matches[0]}\n   http://svn.wikimedia.org/" .
-                               "viewvc/mediawiki/trunk/" . dirname( $path ) .
-                               "/{$matches[2]}";
                }
-               return $matches[0];
-       }
 
-       /**
-        * Returns the description string for this module
-        * @return mixed string or array of strings
-        */
-       protected function getDescription() {
-               return false;
+               return $ret;
        }
 
        /**
-        * Returns usage examples for this module. Return null if no examples are available.
-        * @return mixed string or array of strings
+        * Return links to more detailed help pages about the module.
+        * @since 1.25, returning boolean false is deprecated
+        * @return string|array
         */
-       protected function getExamples() {
-               return false;
+       public function getHelpUrls() {
+               return [];
        }
 
        /**
@@ -449,114 +376,527 @@ abstract class ApiBase {
         * value) or (parameter name) => (array with PARAM_* constants as keys)
         * Don't call this function directly: use getFinalParams() to allow
         * hooks to modify parameters as needed.
+        *
+        * Some derived classes may choose to handle an integer $flags parameter
+        * in the overriding methods. Callers of this method can pass zero or
+        * more OR-ed flags like GET_VALUES_FOR_HELP.
+        *
         * @return array
         */
-       protected function getAllowedParams() {
-               return false;
+       protected function getAllowedParams( /* $flags = 0 */ ) {
+               // int $flags is not declared because it causes "Strict standards"
+               // warning. Most derived classes do not implement it.
+               return [];
        }
 
        /**
-        * Returns an array of parameter descriptions.
-        * Don't call this functon directly: use getFinalParamDescription() to
-        * allow hooks to modify descriptions as needed.
-        * @return array
+        * Indicates if this module needs maxlag to be checked
+        * @return bool
         */
-       protected function getParamDescription() {
-               return false;
+       public function shouldCheckMaxlag() {
+               return true;
        }
 
        /**
-        * Get final list of parameters, after hooks have had a chance to
-        * tweak it as needed.
-        * @return array
+        * Indicates whether this module requires read rights
+        * @return bool
         */
-       public function getFinalParams() {
-               $params = $this->getAllowedParams();
-               wfRunHooks( 'APIGetAllowedParams', array( &$this, &$params ) );
-               return $params;
+       public function isReadMode() {
+               return true;
        }
 
        /**
-        * Get final description, after hooks have had a chance to tweak it as
-        * needed.
-        * @return array
+        * Indicates whether this module requires write mode
+        *
+        * This should return true for modules that may require synchronous database writes.
+        * Modules that do not need such writes should also not rely on master database access,
+        * since only read queries are needed and each master DB is a single point of failure.
+        * Additionally, requests that only need replica DBs can be efficiently routed to any
+        * datacenter via the Promise-Non-Write-API-Action header.
+        *
+        * @return bool
         */
-       public function getFinalParamDescription() {
-               $desc = $this->getParamDescription();
-               wfRunHooks( 'APIGetParamDescription', array( &$this, &$desc ) );
-               return $desc;
+       public function isWriteMode() {
+               return false;
        }
 
        /**
-        * This method mangles parameter name based on the prefix supplied to the constructor.
-        * Override this method to change parameter name during runtime
-        * @param $paramName string Parameter name
-        * @return string Prefixed parameter name
+        * Indicates whether this module must be called with a POST request
+        * @return bool
         */
-       public function encodeParamName( $paramName ) {
-               return $this->mModulePrefix . $paramName;
+       public function mustBePosted() {
+               return $this->needsToken() !== false;
        }
 
        /**
-        * Using getAllowedParams(), this function makes an array of the values
-        * provided by the user, with key being the name of the variable, and
-        * value - validated value from user or default. limits will not be
-        * parsed if $parseLimit is set to false; use this when the max
-        * limit is not definitive yet, e.g. when getting revisions.
-        * @param $parseLimit Boolean: true by default
-        * @return array
+        * Indicates whether this module is deprecated
+        * @since 1.25
+        * @return bool
         */
-       public function extractRequestParams( $parseLimit = true ) {
-               // Cache parameters, for performance and to avoid bug 24564.
-               if ( !isset( $this->mParamCache[$parseLimit] ) ) {
-                       $params = $this->getFinalParams();
-                       $results = array();
-
-                       if ( $params ) { // getFinalParams() can return false
-                               foreach ( $params as $paramName => $paramSettings ) {
-                                       $results[$paramName] = $this->getParameterFromSettings(
-                                               $paramName, $paramSettings, $parseLimit );
-                               }
-                       }
-                       $this->mParamCache[$parseLimit] = $results;
-               }
-               return $this->mParamCache[$parseLimit];
+       public function isDeprecated() {
+               return false;
        }
 
        /**
-        * Get a value for the given parameter
-        * @param $paramName string Parameter name
-        * @param $parseLimit bool see extractRequestParams()
-        * @return mixed Parameter value
+        * Indicates whether this module is "internal"
+        * Internal API modules are not (yet) intended for 3rd party use and may be unstable.
+        * @since 1.25
+        * @return bool
         */
-       protected function getParameter( $paramName, $parseLimit = true ) {
-               $params = $this->getFinalParams();
-               $paramSettings = $params[$paramName];
-               return $this->getParameterFromSettings( $paramName, $paramSettings, $parseLimit );
+       public function isInternal() {
+               return false;
        }
 
        /**
-        * Die if none or more than one of a certain set of parameters is set and not false.
-        * @param $params array of parameter names
+        * Returns the token type this module requires in order to execute.
+        *
+        * Modules are strongly encouraged to use the core 'csrf' type unless they
+        * have specialized security needs. If the token type is not one of the
+        * core types, you must use the ApiQueryTokensRegisterTypes hook to
+        * register it.
+        *
+        * Returning a non-falsey value here will force the addition of an
+        * appropriate 'token' parameter in self::getFinalParams(). Also,
+        * self::mustBePosted() must return true when tokens are used.
+        *
+        * In previous versions of MediaWiki, true was a valid return value.
+        * Returning true will generate errors indicating that the API module needs
+        * updating.
+        *
+        * @return string|false
         */
-       public function requireOnlyOneParameter( $params ) {
-               $required = func_get_args();
-               array_shift( $required );
-
-               $intersection = array_intersect( array_keys( array_filter( $params,
-                               array( $this, "parameterNotEmpty" ) ) ), $required );
+       public function needsToken() {
+               return false;
+       }
+
+       /**
+        * Fetch the salt used in the Web UI corresponding to this module.
+        *
+        * Only override this if the Web UI uses a token with a non-constant salt.
+        *
+        * @since 1.24
+        * @param array $params All supplied parameters for the module
+        * @return string|array|null
+        */
+       protected function getWebUITokenSalt( array $params ) {
+               return null;
+       }
+
+       /**
+        * Returns data for HTTP conditional request mechanisms.
+        *
+        * @since 1.26
+        * @param string $condition Condition being queried:
+        *  - last-modified: Return a timestamp representing the maximum of the
+        *    last-modified dates for all resources involved in the request. See
+        *    RFC 7232 § 2.2 for semantics.
+        *  - etag: Return an entity-tag representing the state of all resources involved
+        *    in the request. Quotes must be included. See RFC 7232 § 2.3 for semantics.
+        * @return string|bool|null As described above, or null if no value is available.
+        */
+       public function getConditionalRequestData( $condition ) {
+               return null;
+       }
+
+       /**@}*/
+
+       /************************************************************************//**
+        * @name   Data access methods
+        * @{
+        */
+
+       /**
+        * Get the name of the module being executed by this instance
+        * @return string
+        */
+       public function getModuleName() {
+               return $this->mModuleName;
+       }
+
+       /**
+        * Get parameter prefix (usually two letters or an empty string).
+        * @return string
+        */
+       public function getModulePrefix() {
+               return $this->mModulePrefix;
+       }
+
+       /**
+        * Get the main module
+        * @return ApiMain
+        */
+       public function getMain() {
+               return $this->mMainModule;
+       }
+
+       /**
+        * Returns true if this module is the main module ($this === $this->mMainModule),
+        * false otherwise.
+        * @return bool
+        */
+       public function isMain() {
+               return $this === $this->mMainModule;
+       }
+
+       /**
+        * Get the parent of this module
+        * @since 1.25
+        * @return ApiBase|null
+        */
+       public function getParent() {
+               return $this->isMain() ? null : $this->getMain();
+       }
+
+       /**
+        * Returns true if the current request breaks the same-origin policy.
+        *
+        * For example, json with callbacks.
+        *
+        * https://en.wikipedia.org/wiki/Same-origin_policy
+        *
+        * @since 1.25
+        * @return bool
+        */
+       public function lacksSameOriginSecurity() {
+               // Main module has this method overridden
+               // Safety - avoid infinite loop:
+               if ( $this->isMain() ) {
+                       self::dieDebug( __METHOD__, 'base method was called on main module.' );
+               }
+
+               return $this->getMain()->lacksSameOriginSecurity();
+       }
+
+       /**
+        * Get the path to this module
+        *
+        * @since 1.25
+        * @return string
+        */
+       public function getModulePath() {
+               if ( $this->isMain() ) {
+                       return 'main';
+               } elseif ( $this->getParent()->isMain() ) {
+                       return $this->getModuleName();
+               } else {
+                       return $this->getParent()->getModulePath() . '+' . $this->getModuleName();
+               }
+       }
+
+       /**
+        * Get a module from its module path
+        *
+        * @since 1.25
+        * @param string $path
+        * @return ApiBase|null
+        * @throws ApiUsageException
+        */
+       public function getModuleFromPath( $path ) {
+               $module = $this->getMain();
+               if ( $path === 'main' ) {
+                       return $module;
+               }
+
+               $parts = explode( '+', $path );
+               if ( count( $parts ) === 1 ) {
+                       // In case the '+' was typed into URL, it resolves as a space
+                       $parts = explode( ' ', $path );
+               }
+
+               $count = count( $parts );
+               for ( $i = 0; $i < $count; $i++ ) {
+                       $parent = $module;
+                       $manager = $parent->getModuleManager();
+                       if ( $manager === null ) {
+                               $errorPath = implode( '+', array_slice( $parts, 0, $i ) );
+                               $this->dieWithError( [ 'apierror-badmodule-nosubmodules', $errorPath ], 'badmodule' );
+                       }
+                       $module = $manager->getModule( $parts[$i] );
+
+                       if ( $module === null ) {
+                               $errorPath = $i ? implode( '+', array_slice( $parts, 0, $i ) ) : $parent->getModuleName();
+                               $this->dieWithError(
+                                       [ 'apierror-badmodule-badsubmodule', $errorPath, wfEscapeWikiText( $parts[$i] ) ],
+                                       'badmodule'
+                               );
+                       }
+               }
+
+               return $module;
+       }
+
+       /**
+        * Get the result object
+        * @return ApiResult
+        */
+       public function getResult() {
+               // Main module has getResult() method overridden
+               // Safety - avoid infinite loop:
+               if ( $this->isMain() ) {
+                       self::dieDebug( __METHOD__, 'base method was called on main module. ' );
+               }
+
+               return $this->getMain()->getResult();
+       }
+
+       /**
+        * Get the error formatter
+        * @return ApiErrorFormatter
+        */
+       public function getErrorFormatter() {
+               // Main module has getErrorFormatter() method overridden
+               // Safety - avoid infinite loop:
+               if ( $this->isMain() ) {
+                       self::dieDebug( __METHOD__, 'base method was called on main module. ' );
+               }
+
+               return $this->getMain()->getErrorFormatter();
+       }
+
+       /**
+        * Gets a default replica DB connection object
+        * @return IDatabase
+        */
+       protected function getDB() {
+               if ( !isset( $this->mSlaveDB ) ) {
+                       $this->mSlaveDB = wfGetDB( DB_REPLICA, 'api' );
+               }
+
+               return $this->mSlaveDB;
+       }
+
+       /**
+        * Get the continuation manager
+        * @return ApiContinuationManager|null
+        */
+       public function getContinuationManager() {
+               // Main module has getContinuationManager() method overridden
+               // Safety - avoid infinite loop:
+               if ( $this->isMain() ) {
+                       self::dieDebug( __METHOD__, 'base method was called on main module. ' );
+               }
+
+               return $this->getMain()->getContinuationManager();
+       }
+
+       /**
+        * Set the continuation manager
+        * @param ApiContinuationManager|null $manager
+        */
+       public function setContinuationManager( $manager ) {
+               // Main module has setContinuationManager() method overridden
+               // Safety - avoid infinite loop:
+               if ( $this->isMain() ) {
+                       self::dieDebug( __METHOD__, 'base method was called on main module. ' );
+               }
+
+               $this->getMain()->setContinuationManager( $manager );
+       }
+
+       /**@}*/
+
+       /************************************************************************//**
+        * @name   Parameter handling
+        * @{
+        */
+
+       /**
+        * Indicate if the module supports dynamically-determined parameters that
+        * cannot be included in self::getAllowedParams().
+        * @return string|array|Message|null Return null if the module does not
+        *  support additional dynamic parameters, otherwise return a message
+        *  describing them.
+        */
+       public function dynamicParameterDocumentation() {
+               return null;
+       }
+
+       /**
+        * This method mangles parameter name based on the prefix supplied to the constructor.
+        * Override this method to change parameter name during runtime
+        * @param string|string[] $paramName Parameter name
+        * @return string|string[] Prefixed parameter name
+        * @since 1.29 accepts an array of strings
+        */
+       public function encodeParamName( $paramName ) {
+               if ( is_array( $paramName ) ) {
+                       return array_map( function ( $name ) {
+                               return $this->mModulePrefix . $name;
+                       }, $paramName );
+               } else {
+                       return $this->mModulePrefix . $paramName;
+               }
+       }
+
+       /**
+        * Using getAllowedParams(), this function makes an array of the values
+        * provided by the user, with key being the name of the variable, and
+        * value - validated value from user or default. limits will not be
+        * parsed if $parseLimit is set to false; use this when the max
+        * limit is not definitive yet, e.g. when getting revisions.
+        * @param bool $parseLimit True by default
+        * @return array
+        */
+       public function extractRequestParams( $parseLimit = true ) {
+               // Cache parameters, for performance and to avoid T26564.
+               if ( !isset( $this->mParamCache[$parseLimit] ) ) {
+                       $params = $this->getFinalParams();
+                       $results = [];
+
+                       if ( $params ) { // getFinalParams() can return false
+                               foreach ( $params as $paramName => $paramSettings ) {
+                                       $results[$paramName] = $this->getParameterFromSettings(
+                                               $paramName, $paramSettings, $parseLimit );
+                               }
+                       }
+                       $this->mParamCache[$parseLimit] = $results;
+               }
+
+               return $this->mParamCache[$parseLimit];
+       }
+
+       /**
+        * Get a value for the given parameter
+        * @param string $paramName Parameter name
+        * @param bool $parseLimit See extractRequestParams()
+        * @return mixed Parameter value
+        */
+       protected function getParameter( $paramName, $parseLimit = true ) {
+               $paramSettings = $this->getFinalParams()[$paramName];
+
+               return $this->getParameterFromSettings( $paramName, $paramSettings, $parseLimit );
+       }
+
+       /**
+        * Die if none or more than one of a certain set of parameters is set and not false.
+        *
+        * @param array $params User provided set of parameters, as from $this->extractRequestParams()
+        * @param string $required,... Names of parameters of which exactly one must be set
+        */
+       public function requireOnlyOneParameter( $params, $required /*...*/ ) {
+               $required = func_get_args();
+               array_shift( $required );
+
+               $intersection = array_intersect( array_keys( array_filter( $params,
+                       [ $this, 'parameterNotEmpty' ] ) ), $required );
 
                if ( count( $intersection ) > 1 ) {
-                       $this->dieUsage( 'The parameters ' . implode( ', ', $intersection ) . ' can not be used together', 'invalidparammix' );
+                       $this->dieWithError( [
+                               'apierror-invalidparammix',
+                               Message::listParam( array_map(
+                                       function ( $p ) {
+                                               return '<var>' . $this->encodeParamName( $p ) . '</var>';
+                                       },
+                                       array_values( $intersection )
+                               ) ),
+                               count( $intersection ),
+                       ] );
                } elseif ( count( $intersection ) == 0 ) {
-                       $this->dieUsage( 'One of the parameters ' . implode( ', ', $required ) . ' is required', 'missingparam' );
+                       $this->dieWithError( [
+                               'apierror-missingparam-one-of',
+                               Message::listParam( array_map(
+                                       function ( $p ) {
+                                               return '<var>' . $this->encodeParamName( $p ) . '</var>';
+                                       },
+                                       array_values( $required )
+                               ) ),
+                               count( $required ),
+                       ], 'missingparam' );
                }
        }
 
        /**
-        * Callback function used in requireOnlyOneParameter to check whether reequired parameters are set
+        * Die if more than one of a certain set of parameters is set and not false.
         *
-        * @param  $x object Parameter to check is not null/false
+        * @param array $params User provided set of parameters, as from $this->extractRequestParams()
+        * @param string $required,... Names of parameters of which at most one must be set
+        */
+       public function requireMaxOneParameter( $params, $required /*...*/ ) {
+               $required = func_get_args();
+               array_shift( $required );
+
+               $intersection = array_intersect( array_keys( array_filter( $params,
+                       [ $this, 'parameterNotEmpty' ] ) ), $required );
+
+               if ( count( $intersection ) > 1 ) {
+                       $this->dieWithError( [
+                               'apierror-invalidparammix',
+                               Message::listParam( array_map(
+                                       function ( $p ) {
+                                               return '<var>' . $this->encodeParamName( $p ) . '</var>';
+                                       },
+                                       array_values( $intersection )
+                               ) ),
+                               count( $intersection ),
+                       ] );
+               }
+       }
+
+       /**
+        * Die if none of a certain set of parameters is set and not false.
+        *
+        * @since 1.23
+        * @param array $params User provided set of parameters, as from $this->extractRequestParams()
+        * @param string $required,... Names of parameters of which at least one must be set
+        */
+       public function requireAtLeastOneParameter( $params, $required /*...*/ ) {
+               $required = func_get_args();
+               array_shift( $required );
+
+               $intersection = array_intersect(
+                       array_keys( array_filter( $params, [ $this, 'parameterNotEmpty' ] ) ),
+                       $required
+               );
+
+               if ( count( $intersection ) == 0 ) {
+                       $this->dieWithError( [
+                               'apierror-missingparam-at-least-one-of',
+                               Message::listParam( array_map(
+                                       function ( $p ) {
+                                               return '<var>' . $this->encodeParamName( $p ) . '</var>';
+                                       },
+                                       array_values( $required )
+                               ) ),
+                               count( $required ),
+                       ], 'missingparam' );
+               }
+       }
+
+       /**
+        * Die if any of the specified parameters were found in the query part of
+        * the URL rather than the post body.
+        * @since 1.28
+        * @param string[] $params Parameters to check
+        * @param string $prefix Set to 'noprefix' to skip calling $this->encodeParamName()
+        */
+       public function requirePostedParameters( $params, $prefix = 'prefix' ) {
+               // Skip if $wgDebugAPI is set or we're in internal mode
+               if ( $this->getConfig()->get( 'DebugAPI' ) || $this->getMain()->isInternalMode() ) {
+                       return;
+               }
+
+               $queryValues = $this->getRequest()->getQueryValues();
+               $badParams = [];
+               foreach ( $params as $param ) {
+                       if ( $prefix !== 'noprefix' ) {
+                               $param = $this->encodeParamName( $param );
+                       }
+                       if ( array_key_exists( $param, $queryValues ) ) {
+                               $badParams[] = $param;
+                       }
+               }
+
+               if ( $badParams ) {
+                       $this->dieWithError(
+                               [ 'apierror-mustpostparams', join( ', ', $badParams ), count( $badParams ) ]
+                       );
+               }
+       }
+
+       /**
+        * Callback function used in requireOnlyOneParameter to check whether required parameters are set
+        *
+        * @param object $x Parameter to check is not null/false
         * @return bool
         */
        private function parameterNotEmpty( $x ) {
@@ -564,25 +904,84 @@ abstract class ApiBase {
        }
 
        /**
-        * @deprecated use MWNamespace::getValidNamespaces()
+        * Get a WikiPage object from a title or pageid param, if possible.
+        * Can die, if no param is set or if the title or page id is not valid.
+        *
+        * @param array $params User provided set of parameters, as from $this->extractRequestParams()
+        * @param bool|string $load Whether load the object's state from the database:
+        *        - false: don't load (if the pageid is given, it will still be loaded)
+        *        - 'fromdb': load from a replica DB
+        *        - 'fromdbmaster': load from the master database
+        * @return WikiPage
         */
-       public static function getValidNamespaces() {
-               return MWNamespace::getValidNamespaces();
+       public function getTitleOrPageId( $params, $load = false ) {
+               $this->requireOnlyOneParameter( $params, 'title', 'pageid' );
+
+               $pageObj = null;
+               if ( isset( $params['title'] ) ) {
+                       $titleObj = Title::newFromText( $params['title'] );
+                       if ( !$titleObj || $titleObj->isExternal() ) {
+                               $this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $params['title'] ) ] );
+                       }
+                       if ( !$titleObj->canExist() ) {
+                               $this->dieWithError( 'apierror-pagecannotexist' );
+                       }
+                       $pageObj = WikiPage::factory( $titleObj );
+                       if ( $load !== false ) {
+                               $pageObj->loadPageData( $load );
+                       }
+               } elseif ( isset( $params['pageid'] ) ) {
+                       if ( $load === false ) {
+                               $load = 'fromdb';
+                       }
+                       $pageObj = WikiPage::newFromID( $params['pageid'], $load );
+                       if ( !$pageObj ) {
+                               $this->dieWithError( [ 'apierror-nosuchpageid', $params['pageid'] ] );
+                       }
+               }
+
+               return $pageObj;
        }
 
        /**
-        * Return true if we're to watch the page, false if not, null if no change.
-        * @param $watchlist String Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
-        * @param $titleObj Title the page under consideration
-        * @param $userOption String The user option to consider when $watchlist=preferences.
-        *      If not set will magically default to either watchdefault or watchcreations
-        * @returns Boolean
+        * Get a Title object from a title or pageid param, if possible.
+        * Can die, if no param is set or if the title or page id is not valid.
+        *
+        * @since 1.29
+        * @param array $params User provided set of parameters, as from $this->extractRequestParams()
+        * @return Title
         */
-       protected function getWatchlistValue ( $watchlist, $titleObj, $userOption = null ) {
+       public function getTitleFromTitleOrPageId( $params ) {
+               $this->requireOnlyOneParameter( $params, 'title', 'pageid' );
+
+               $titleObj = null;
+               if ( isset( $params['title'] ) ) {
+                       $titleObj = Title::newFromText( $params['title'] );
+                       if ( !$titleObj || $titleObj->isExternal() ) {
+                               $this->dieWithError( [ 'apierror-invalidtitle', wfEscapeWikiText( $params['title'] ) ] );
+                       }
+                       return $titleObj;
+               } elseif ( isset( $params['pageid'] ) ) {
+                       $titleObj = Title::newFromID( $params['pageid'] );
+                       if ( !$titleObj ) {
+                               $this->dieWithError( [ 'apierror-nosuchpageid', $params['pageid'] ] );
+                       }
+               }
+
+               return $titleObj;
+       }
 
-               $userWatching = $titleObj->userIsWatching();
+       /**
+        * Return true if we're to watch the page, false if not, null if no change.
+        * @param string $watchlist Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
+        * @param Title $titleObj The page under consideration
+        * @param string $userOption The user option to consider when $watchlist=preferences.
+        *    If not set will use watchdefault always and watchcreations if $titleObj doesn't exist.
+        * @return bool
+        */
+       protected function getWatchlistValue( $watchlist, $titleObj, $userOption = null ) {
+               $userWatching = $this->getUser()->isWatched( $titleObj, User::IGNORE_USER_RIGHTS );
 
-               global $wgUser;
                switch ( $watchlist ) {
                        case 'watch':
                                return true;
@@ -595,13 +994,14 @@ abstract class ApiBase {
                                if ( $userWatching ) {
                                        return true;
                                }
-                               # If no user option was passed, use watchdefault or watchcreation
+                               # If no user option was passed, use watchdefault and watchcreations
                                if ( is_null( $userOption ) ) {
-                                       $userOption = $titleObj->exists()
-                                               ? 'watchdefault' : 'watchcreations';
+                                       return $this->getUser()->getBoolOption( 'watchdefault' ) ||
+                                               $this->getUser()->getBoolOption( 'watchcreations' ) && !$titleObj->exists();
                                }
+
                                # Watch the article based on the user preference
-                               return (bool)$wgUser->getOption( $userOption );
+                               return $this->getUser()->getBoolOption( $userOption );
 
                        case 'nochange':
                                return $userWatching;
@@ -612,80 +1012,165 @@ abstract class ApiBase {
        }
 
        /**
-        * Set a watch (or unwatch) based the based on a watchlist parameter.
-        * @param $watch String Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
-        * @param $titleObj Title the article's title to change
-        * @param $userOption String The user option to consider when $watch=preferences
-        */
-       protected function setWatch ( $watch, $titleObj, $userOption = null ) {
-               $value = $this->getWatchlistValue( $watch, $titleObj, $userOption );
-               if ( $value === null ) {
-                       return;
-               }
-
-               $articleObj = new Article( $titleObj );
-               if ( $value ) {
-                       $articleObj->doWatch();
-               } else {
-                       $articleObj->doUnwatch();
-               }
-       }
-
-       /**
-        * Using the settings determine the value for the given parameter
-        *
-        * @param $paramName String: parameter name
-        * @param $paramSettings Mixed: default value or an array of settings
-        *  using PARAM_* constants.
-        * @param $parseLimit Boolean: parse limit?
-        * @return mixed Parameter value
+        * Using the settings determine the value for the given parameter
+        *
+        * @param string $paramName Parameter name
+        * @param array|mixed $paramSettings Default value or an array of settings
+        *  using PARAM_* constants.
+        * @param bool $parseLimit Parse limit?
+        * @return mixed Parameter value
         */
        protected function getParameterFromSettings( $paramName, $paramSettings, $parseLimit ) {
                // Some classes may decide to change parameter names
                $encParamName = $this->encodeParamName( $paramName );
 
+               // Shorthand
                if ( !is_array( $paramSettings ) ) {
-                       $default = $paramSettings;
-                       $multi = false;
-                       $type = gettype( $paramSettings );
-                       $dupes = false;
-                       $deprecated = false;
-                       $required = false;
-               } else {
-                       $default = isset( $paramSettings[self::PARAM_DFLT] ) ? $paramSettings[self::PARAM_DFLT] : null;
-                       $multi = isset( $paramSettings[self::PARAM_ISMULTI] ) ? $paramSettings[self::PARAM_ISMULTI] : false;
-                       $type = isset( $paramSettings[self::PARAM_TYPE] ) ? $paramSettings[self::PARAM_TYPE] : null;
-                       $dupes = isset( $paramSettings[self::PARAM_ALLOW_DUPLICATES] ) ? $paramSettings[self::PARAM_ALLOW_DUPLICATES] : false;
-                       $deprecated = isset( $paramSettings[self::PARAM_DEPRECATED] ) ? $paramSettings[self::PARAM_DEPRECATED] : false;
-                       $required = isset( $paramSettings[self::PARAM_REQUIRED] ) ? $paramSettings[self::PARAM_REQUIRED] : false;
-
-                       // When type is not given, and no choices, the type is the same as $default
-                       if ( !isset( $type ) ) {
-                               if ( isset( $default ) ) {
-                                       $type = gettype( $default );
-                               } else {
-                                       $type = 'NULL'; // allow everything
-                               }
+                       $paramSettings = [
+                               self::PARAM_DFLT => $paramSettings,
+                       ];
+               }
+
+               $default = isset( $paramSettings[self::PARAM_DFLT] )
+                       ? $paramSettings[self::PARAM_DFLT]
+                       : null;
+               $multi = isset( $paramSettings[self::PARAM_ISMULTI] )
+                       ? $paramSettings[self::PARAM_ISMULTI]
+                       : false;
+               $multiLimit1 = isset( $paramSettings[self::PARAM_ISMULTI_LIMIT1] )
+                       ? $paramSettings[self::PARAM_ISMULTI_LIMIT1]
+                       : null;
+               $multiLimit2 = isset( $paramSettings[self::PARAM_ISMULTI_LIMIT2] )
+                       ? $paramSettings[self::PARAM_ISMULTI_LIMIT2]
+                       : null;
+               $type = isset( $paramSettings[self::PARAM_TYPE] )
+                       ? $paramSettings[self::PARAM_TYPE]
+                       : null;
+               $dupes = isset( $paramSettings[self::PARAM_ALLOW_DUPLICATES] )
+                       ? $paramSettings[self::PARAM_ALLOW_DUPLICATES]
+                       : false;
+               $deprecated = isset( $paramSettings[self::PARAM_DEPRECATED] )
+                       ? $paramSettings[self::PARAM_DEPRECATED]
+                       : false;
+               $deprecatedValues = isset( $paramSettings[self::PARAM_DEPRECATED_VALUES] )
+                       ? $paramSettings[self::PARAM_DEPRECATED_VALUES]
+                       : [];
+               $required = isset( $paramSettings[self::PARAM_REQUIRED] )
+                       ? $paramSettings[self::PARAM_REQUIRED]
+                       : false;
+               $allowAll = isset( $paramSettings[self::PARAM_ALL] )
+                       ? $paramSettings[self::PARAM_ALL]
+                       : false;
+
+               // When type is not given, and no choices, the type is the same as $default
+               if ( !isset( $type ) ) {
+                       if ( isset( $default ) ) {
+                               $type = gettype( $default );
+                       } else {
+                               $type = 'NULL'; // allow everything
                        }
                }
 
+               if ( $type == 'password' || !empty( $paramSettings[self::PARAM_SENSITIVE] ) ) {
+                       $this->getMain()->markParamsSensitive( $encParamName );
+               }
+
                if ( $type == 'boolean' ) {
                        if ( isset( $default ) && $default !== false ) {
-                               // Having a default value of anything other than 'false' is pointless
-                               ApiBase::dieDebug( __METHOD__, "Boolean param $encParamName's default is set to '$default'" );
+                               // Having a default value of anything other than 'false' is not allowed
+                               self::dieDebug(
+                                       __METHOD__,
+                                       "Boolean param $encParamName's default is set to '$default'. " .
+                                               'Boolean parameters must default to false.'
+                               );
                        }
 
-                       $value = $this->getMain()->getRequest()->getCheck( $encParamName );
+                       $value = $this->getMain()->getCheck( $encParamName );
+               } elseif ( $type == 'upload' ) {
+                       if ( isset( $default ) ) {
+                               // Having a default value is not allowed
+                               self::dieDebug(
+                                       __METHOD__,
+                                       "File upload param $encParamName's default is set to " .
+                                               "'$default'. File upload parameters may not have a default." );
+                       }
+                       if ( $multi ) {
+                               self::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
+                       }
+                       $value = $this->getMain()->getUpload( $encParamName );
+                       if ( !$value->exists() ) {
+                               // This will get the value without trying to normalize it
+                               // (because trying to normalize a large binary file
+                               // accidentally uploaded as a field fails spectacularly)
+                               $value = $this->getMain()->getRequest()->unsetVal( $encParamName );
+                               if ( $value !== null ) {
+                                       $this->dieWithError(
+                                               [ 'apierror-badupload', $encParamName ],
+                                               "badupload_{$encParamName}"
+                                       );
+                               }
+                       }
                } else {
-                       $value = $this->getMain()->getRequest()->getVal( $encParamName, $default );
+                       $value = $this->getMain()->getVal( $encParamName, $default );
 
                        if ( isset( $value ) && $type == 'namespace' ) {
                                $type = MWNamespace::getValidNamespaces();
+                               if ( isset( $paramSettings[self::PARAM_EXTRA_NAMESPACES] ) &&
+                                       is_array( $paramSettings[self::PARAM_EXTRA_NAMESPACES] )
+                               ) {
+                                       $type = array_merge( $type, $paramSettings[self::PARAM_EXTRA_NAMESPACES] );
+                               }
+                               // By default, namespace parameters allow ALL_DEFAULT_STRING to be used to specify
+                               // all namespaces.
+                               $allowAll = true;
+                       }
+                       if ( isset( $value ) && $type == 'submodule' ) {
+                               if ( isset( $paramSettings[self::PARAM_SUBMODULE_MAP] ) ) {
+                                       $type = array_keys( $paramSettings[self::PARAM_SUBMODULE_MAP] );
+                               } else {
+                                       $type = $this->getModuleManager()->getNames( $paramName );
+                               }
+                       }
+
+                       $request = $this->getMain()->getRequest();
+                       $rawValue = $request->getRawVal( $encParamName );
+                       if ( $rawValue === null ) {
+                               $rawValue = $default;
+                       }
+
+                       // Preserve U+001F for self::parseMultiValue(), or error out if that won't be called
+                       if ( isset( $value ) && substr( $rawValue, 0, 1 ) === "\x1f" ) {
+                               if ( $multi ) {
+                                       // This loses the potential $wgContLang->checkTitleEncoding() transformation
+                                       // done by WebRequest for $_GET. Let's call that a feature.
+                                       $value = join( "\x1f", $request->normalizeUnicode( explode( "\x1f", $rawValue ) ) );
+                               } else {
+                                       $this->dieWithError( 'apierror-badvalue-notmultivalue', 'badvalue_notmultivalue' );
+                               }
+                       }
+
+                       // Check for NFC normalization, and warn
+                       if ( $rawValue !== $value ) {
+                               $this->handleParamNormalization( $paramName, $value, $rawValue );
                        }
                }
 
+               $allSpecifier = ( is_string( $allowAll ) ? $allowAll : self::ALL_DEFAULT_STRING );
+               if ( $allowAll && $multi && is_array( $type ) && in_array( $allSpecifier, $type, true ) ) {
+                       self::dieDebug(
+                               __METHOD__,
+                               "For param $encParamName, PARAM_ALL collides with a possible value" );
+               }
                if ( isset( $value ) && ( $multi || is_array( $type ) ) ) {
-                       $value = $this->parseMultiValue( $encParamName, $value, $multi, is_array( $type ) ? $type : null );
+                       $value = $this->parseMultiValue(
+                               $encParamName,
+                               $value,
+                               $multi,
+                               is_array( $type ) ? $type : null,
+                               $allowAll ? $allSpecifier : null,
+                               $multiLimit1,
+                               $multiLimit2
+                       );
                }
 
                // More validation only when choices were not given
@@ -696,27 +1181,30 @@ abstract class ApiBase {
                                        case 'NULL': // nothing to do
                                                break;
                                        case 'string':
+                                       case 'text':
+                                       case 'password':
                                                if ( $required && $value === '' ) {
-                                                       $this->dieUsageMsg( array( 'missingparam', $paramName ) );
+                                                       $this->dieWithError( [ 'apierror-missingparam', $paramName ] );
                                                }
-
                                                break;
                                        case 'integer': // Force everything using intval() and optionally validate limits
-                                               $min = isset ( $paramSettings[self::PARAM_MIN] ) ? $paramSettings[self::PARAM_MIN] : null;
-                                               $max = isset ( $paramSettings[self::PARAM_MAX] ) ? $paramSettings[self::PARAM_MAX] : null;
-                                               $enforceLimits = isset ( $paramSettings[self::PARAM_RANGE_ENFORCE] )
-                                                               ? $paramSettings[self::PARAM_RANGE_ENFORCE] : false;
-
-                                               if ( !is_null( $min ) || !is_null( $max ) ) {
-                                                   if ( is_array( $value ) ) {
-                                                           $value = array_map( 'intval', $value );
-                                                           foreach ( $value as &$v ) {
+                                               $min = isset( $paramSettings[self::PARAM_MIN] ) ? $paramSettings[self::PARAM_MIN] : null;
+                                               $max = isset( $paramSettings[self::PARAM_MAX] ) ? $paramSettings[self::PARAM_MAX] : null;
+                                               $enforceLimits = isset( $paramSettings[self::PARAM_RANGE_ENFORCE] )
+                                                       ? $paramSettings[self::PARAM_RANGE_ENFORCE] : false;
+
+                                               if ( is_array( $value ) ) {
+                                                       $value = array_map( 'intval', $value );
+                                                       if ( !is_null( $min ) || !is_null( $max ) ) {
+                                                               foreach ( $value as &$v ) {
                                                                        $this->validateLimit( $paramName, $v, $min, $max, null, $enforceLimits );
                                                                }
-                                                   } else {
-                                                           $value = intval( $value );
-                                                           $this->validateLimit( $paramName, $value, $min, $max, null, $enforceLimits );
-                                                   }
+                                                       }
+                                               } else {
+                                                       $value = intval( $value );
+                                                       if ( !is_null( $min ) || !is_null( $max ) ) {
+                                                               $this->validateLimit( $paramName, $value, $min, $max, null, $enforceLimits );
+                                                       }
                                                }
                                                break;
                                        case 'limit':
@@ -724,645 +1212,1748 @@ abstract class ApiBase {
                                                        // Don't do any validation whatsoever
                                                        break;
                                                }
-                                               if ( !isset( $paramSettings[self::PARAM_MAX] ) || !isset( $paramSettings[self::PARAM_MAX2] ) ) {
-                                                       ApiBase::dieDebug( __METHOD__, "MAX1 or MAX2 are not defined for the limit $encParamName" );
+                                               if ( !isset( $paramSettings[self::PARAM_MAX] )
+                                                       || !isset( $paramSettings[self::PARAM_MAX2] )
+                                               ) {
+                                                       self::dieDebug(
+                                                               __METHOD__,
+                                                               "MAX1 or MAX2 are not defined for the limit $encParamName"
+                                                       );
                                                }
                                                if ( $multi ) {
-                                                       ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
+                                                       self::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
                                                }
                                                $min = isset( $paramSettings[self::PARAM_MIN] ) ? $paramSettings[self::PARAM_MIN] : 0;
                                                if ( $value == 'max' ) {
-                                                       $value = $this->getMain()->canApiHighLimits() ? $paramSettings[self::PARAM_MAX2] : $paramSettings[self::PARAM_MAX];
-                                                       $this->getResult()->setParsedLimit( $this->getModuleName(), $value );
+                                                       $value = $this->getMain()->canApiHighLimits()
+                                                               ? $paramSettings[self::PARAM_MAX2]
+                                                               : $paramSettings[self::PARAM_MAX];
+                                                       $this->getResult()->addParsedLimit( $this->getModuleName(), $value );
                                                } else {
                                                        $value = intval( $value );
-                                                       $this->validateLimit( $paramName, $value, $min, $paramSettings[self::PARAM_MAX], $paramSettings[self::PARAM_MAX2] );
+                                                       $this->validateLimit(
+                                                               $paramName,
+                                                               $value,
+                                                               $min,
+                                                               $paramSettings[self::PARAM_MAX],
+                                                               $paramSettings[self::PARAM_MAX2]
+                                                       );
                                                }
                                                break;
                                        case 'boolean':
                                                if ( $multi ) {
-                                                       ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
+                                                       self::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
                                                }
                                                break;
                                        case 'timestamp':
-                                               if ( $multi ) {
-                                                       ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
-                                               }
-                                               $value = wfTimestamp( TS_UNIX, $value );
-                                               if ( $value === 0 ) {
-                                                       $this->dieUsage( "Invalid value '$value' for timestamp parameter $encParamName", "badtimestamp_{$encParamName}" );
+                                               if ( is_array( $value ) ) {
+                                                       foreach ( $value as $key => $val ) {
+                                                               $value[$key] = $this->validateTimestamp( $val, $encParamName );
+                                                       }
+                                               } else {
+                                                       $value = $this->validateTimestamp( $value, $encParamName );
                                                }
-                                               $value = wfTimestamp( TS_MW, $value );
                                                break;
                                        case 'user':
-                                               if ( !is_array( $value ) ) {
-                                                       $value = array( $value );
+                                               if ( is_array( $value ) ) {
+                                                       foreach ( $value as $key => $val ) {
+                                                               $value[$key] = $this->validateUser( $val, $encParamName );
+                                                       }
+                                               } else {
+                                                       $value = $this->validateUser( $value, $encParamName );
                                                }
+                                               break;
+                                       case 'upload': // nothing to do
+                                               break;
+                                       case 'tags':
+                                               // If change tagging was requested, check that the tags are valid.
+                                               if ( !is_array( $value ) && !$multi ) {
+                                                       $value = [ $value ];
+                                               }
+                                               $tagsStatus = ChangeTags::canAddTagsAccompanyingChange( $value );
+                                               if ( !$tagsStatus->isGood() ) {
+                                                       $this->dieStatus( $tagsStatus );
+                                               }
+                                               break;
+                                       default:
+                                               self::dieDebug( __METHOD__, "Param $encParamName's type is unknown - $type" );
+                               }
+                       }
+
+                       // Throw out duplicates if requested
+                       if ( !$dupes && is_array( $value ) ) {
+                               $value = array_unique( $value );
+                       }
+
+                       // Set a warning if a deprecated parameter has been passed
+                       if ( $deprecated && $value !== false ) {
+                               $feature = $encParamName;
+                               $m = $this;
+                               while ( !$m->isMain() ) {
+                                       $p = $m->getParent();
+                                       $name = $m->getModuleName();
+                                       $param = $p->encodeParamName( $p->getModuleManager()->getModuleGroup( $name ) );
+                                       $feature = "{$param}={$name}&{$feature}";
+                                       $m = $p;
+                               }
+                               $this->addDeprecation( [ 'apiwarn-deprecation-parameter', $encParamName ], $feature );
+                       }
+
+                       // Set a warning if a deprecated parameter value has been passed
+                       $usedDeprecatedValues = $deprecatedValues && $value !== false
+                               ? array_intersect( array_keys( $deprecatedValues ), (array)$value )
+                               : [];
+                       if ( $usedDeprecatedValues ) {
+                               $feature = "$encParamName=";
+                               $m = $this;
+                               while ( !$m->isMain() ) {
+                                       $p = $m->getParent();
+                                       $name = $m->getModuleName();
+                                       $param = $p->encodeParamName( $p->getModuleManager()->getModuleGroup( $name ) );
+                                       $feature = "{$param}={$name}&{$feature}";
+                                       $m = $p;
+                               }
+                               foreach ( $usedDeprecatedValues as $v ) {
+                                       $msg = $deprecatedValues[$v];
+                                       if ( $msg === true ) {
+                                               $msg = [ 'apiwarn-deprecation-parameter', "$encParamName=$v" ];
+                                       }
+                                       $this->addDeprecation( $msg, "$feature$v" );
+                               }
+                       }
+               } elseif ( $required ) {
+                       $this->dieWithError( [ 'apierror-missingparam', $paramName ] );
+               }
+
+               return $value;
+       }
+
+       /**
+        * Handle when a parameter was Unicode-normalized
+        * @since 1.28
+        * @param string $paramName Unprefixed parameter name
+        * @param string $value Input that will be used.
+        * @param string $rawValue Input before normalization.
+        */
+       protected function handleParamNormalization( $paramName, $value, $rawValue ) {
+               $encParamName = $this->encodeParamName( $paramName );
+               $this->addWarning( [ 'apiwarn-badutf8', $encParamName ] );
+       }
+
+       /**
+        * Split a multi-valued parameter string, like explode()
+        * @since 1.28
+        * @param string $value
+        * @param int $limit
+        * @return string[]
+        */
+       protected function explodeMultiValue( $value, $limit ) {
+               if ( substr( $value, 0, 1 ) === "\x1f" ) {
+                       $sep = "\x1f";
+                       $value = substr( $value, 1 );
+               } else {
+                       $sep = '|';
+               }
+
+               return explode( $sep, $value, $limit );
+       }
+
+       /**
+        * Return an array of values that were given in a 'a|b|c' notation,
+        * after it optionally validates them against the list allowed values.
+        *
+        * @param string $valueName The name of the parameter (for error
+        *  reporting)
+        * @param mixed $value The value being parsed
+        * @param bool $allowMultiple Can $value contain more than one value
+        *  separated by '|'?
+        * @param string[]|null $allowedValues An array of values to check against. If
+        *  null, all values are accepted.
+        * @param string|null $allSpecifier String to use to specify all allowed values, or null
+        *  if this behavior should not be allowed
+        * @param int|null $limit1 Maximum number of values, for normal users.
+        * @param int|null $limit2 Maximum number of values, for users with the apihighlimits right.
+        * @return string|string[] (allowMultiple ? an_array_of_values : a_single_value)
+        */
+       protected function parseMultiValue( $valueName, $value, $allowMultiple, $allowedValues,
+               $allSpecifier = null, $limit1 = null, $limit2 = null
+       ) {
+               if ( ( trim( $value ) === '' || trim( $value ) === "\x1f" ) && $allowMultiple ) {
+                       return [];
+               }
+               $limit1 = $limit1 ?: self::LIMIT_SML1;
+               $limit2 = $limit2 ?: self::LIMIT_SML2;
+
+               // This is a bit awkward, but we want to avoid calling canApiHighLimits()
+               // because it unstubs $wgUser
+               $valuesList = $this->explodeMultiValue( $value, $limit2 + 1 );
+               $sizeLimit = count( $valuesList ) > $limit1 && $this->mMainModule->canApiHighLimits()
+                       ? $limit2
+                       : $limit1;
+
+               if ( $allowMultiple && is_array( $allowedValues ) && $allSpecifier &&
+                       count( $valuesList ) === 1 && $valuesList[0] === $allSpecifier
+               ) {
+                       return $allowedValues;
+               }
+
+               if ( self::truncateArray( $valuesList, $sizeLimit ) ) {
+                       $this->addDeprecation(
+                               [ 'apiwarn-toomanyvalues', $valueName, $sizeLimit ],
+                               "too-many-$valueName-for-{$this->getModulePath()}"
+                       );
+               }
+
+               if ( !$allowMultiple && count( $valuesList ) != 1 ) {
+                       // T35482 - Allow entries with | in them for non-multiple values
+                       if ( in_array( $value, $allowedValues, true ) ) {
+                               return $value;
+                       }
+
+                       if ( is_array( $allowedValues ) ) {
+                               $values = array_map( function ( $v ) {
+                                       return '<kbd>' . wfEscapeWikiText( $v ) . '</kbd>';
+                               }, $allowedValues );
+                               $this->dieWithError( [
+                                       'apierror-multival-only-one-of',
+                                       $valueName,
+                                       Message::listParam( $values ),
+                                       count( $values ),
+                               ], "multival_$valueName" );
+                       } else {
+                               $this->dieWithError( [
+                                       'apierror-multival-only-one',
+                                       $valueName,
+                               ], "multival_$valueName" );
+                       }
+               }
+
+               if ( is_array( $allowedValues ) ) {
+                       // Check for unknown values
+                       $unknown = array_map( 'wfEscapeWikiText', array_diff( $valuesList, $allowedValues ) );
+                       if ( count( $unknown ) ) {
+                               if ( $allowMultiple ) {
+                                       $this->addWarning( [
+                                               'apiwarn-unrecognizedvalues',
+                                               $valueName,
+                                               Message::listParam( $unknown, 'comma' ),
+                                               count( $unknown ),
+                                       ] );
+                               } else {
+                                       $this->dieWithError(
+                                               [ 'apierror-unrecognizedvalue', $valueName, wfEscapeWikiText( $valuesList[0] ) ],
+                                               "unknown_$valueName"
+                                       );
+                               }
+                       }
+                       // Now throw them out
+                       $valuesList = array_intersect( $valuesList, $allowedValues );
+               }
+
+               return $allowMultiple ? $valuesList : $valuesList[0];
+       }
+
+       /**
+        * Validate the value against the minimum and user/bot maximum limits.
+        * Prints usage info on failure.
+        * @param string $paramName Parameter name
+        * @param int &$value Parameter value
+        * @param int|null $min Minimum value
+        * @param int|null $max Maximum value for users
+        * @param int $botMax Maximum value for sysops/bots
+        * @param bool $enforceLimits Whether to enforce (die) if value is outside limits
+        */
+       protected function validateLimit( $paramName, &$value, $min, $max, $botMax = null,
+               $enforceLimits = false
+       ) {
+               if ( !is_null( $min ) && $value < $min ) {
+                       $msg = ApiMessage::create(
+                               [ 'apierror-integeroutofrange-belowminimum',
+                                       $this->encodeParamName( $paramName ), $min, $value ],
+                               'integeroutofrange',
+                               [ 'min' => $min, 'max' => $max, 'botMax' => $botMax ?: $max ]
+                       );
+                       $this->warnOrDie( $msg, $enforceLimits );
+                       $value = $min;
+               }
+
+               // Minimum is always validated, whereas maximum is checked only if not
+               // running in internal call mode
+               if ( $this->getMain()->isInternalMode() ) {
+                       return;
+               }
+
+               // Optimization: do not check user's bot status unless really needed -- skips db query
+               // assumes $botMax >= $max
+               if ( !is_null( $max ) && $value > $max ) {
+                       if ( !is_null( $botMax ) && $this->getMain()->canApiHighLimits() ) {
+                               if ( $value > $botMax ) {
+                                       $msg = ApiMessage::create(
+                                               [ 'apierror-integeroutofrange-abovebotmax',
+                                                       $this->encodeParamName( $paramName ), $botMax, $value ],
+                                               'integeroutofrange',
+                                               [ 'min' => $min, 'max' => $max, 'botMax' => $botMax ?: $max ]
+                                       );
+                                       $this->warnOrDie( $msg, $enforceLimits );
+                                       $value = $botMax;
+                               }
+                       } else {
+                               $msg = ApiMessage::create(
+                                       [ 'apierror-integeroutofrange-abovemax',
+                                               $this->encodeParamName( $paramName ), $max, $value ],
+                                       'integeroutofrange',
+                                       [ 'min' => $min, 'max' => $max, 'botMax' => $botMax ?: $max ]
+                               );
+                               $this->warnOrDie( $msg, $enforceLimits );
+                               $value = $max;
+                       }
+               }
+       }
+
+       /**
+        * Validate and normalize of parameters of type 'timestamp'
+        * @param string $value Parameter value
+        * @param string $encParamName Parameter name
+        * @return string Validated and normalized parameter
+        */
+       protected function validateTimestamp( $value, $encParamName ) {
+               // Confusing synonyms for the current time accepted by wfTimestamp()
+               // (wfTimestamp() also accepts various non-strings and the string of 14
+               // ASCII NUL bytes, but those can't get here)
+               if ( !$value ) {
+                       $this->addDeprecation(
+                               [ 'apiwarn-unclearnowtimestamp', $encParamName, wfEscapeWikiText( $value ) ],
+                               'unclear-"now"-timestamp'
+                       );
+                       return wfTimestamp( TS_MW );
+               }
+
+               // Explicit synonym for the current time
+               if ( $value === 'now' ) {
+                       return wfTimestamp( TS_MW );
+               }
+
+               $unixTimestamp = wfTimestamp( TS_UNIX, $value );
+               if ( $unixTimestamp === false ) {
+                       $this->dieWithError(
+                               [ 'apierror-badtimestamp', $encParamName, wfEscapeWikiText( $value ) ],
+                               "badtimestamp_{$encParamName}"
+                       );
+               }
+
+               return wfTimestamp( TS_MW, $unixTimestamp );
+       }
+
+       /**
+        * Validate the supplied token.
+        *
+        * @since 1.24
+        * @param string $token Supplied token
+        * @param array $params All supplied parameters for the module
+        * @return bool
+        * @throws MWException
+        */
+       final public function validateToken( $token, array $params ) {
+               $tokenType = $this->needsToken();
+               $salts = ApiQueryTokens::getTokenTypeSalts();
+               if ( !isset( $salts[$tokenType] ) ) {
+                       throw new MWException(
+                               "Module '{$this->getModuleName()}' tried to use token type '$tokenType' " .
+                                       'without registering it'
+                       );
+               }
+
+               $tokenObj = ApiQueryTokens::getToken(
+                       $this->getUser(), $this->getRequest()->getSession(), $salts[$tokenType]
+               );
+               if ( $tokenObj->match( $token ) ) {
+                       return true;
+               }
+
+               $webUiSalt = $this->getWebUITokenSalt( $params );
+               if ( $webUiSalt !== null && $this->getUser()->matchEditToken(
+                       $token,
+                       $webUiSalt,
+                       $this->getRequest()
+               ) ) {
+                       return true;
+               }
+
+               return false;
+       }
+
+       /**
+        * Validate and normalize of parameters of type 'user'
+        * @param string $value Parameter value
+        * @param string $encParamName Parameter name
+        * @return string Validated and normalized parameter
+        */
+       private function validateUser( $value, $encParamName ) {
+               $title = Title::makeTitleSafe( NS_USER, $value );
+               if ( $title === null || $title->hasFragment() ) {
+                       $this->dieWithError(
+                               [ 'apierror-baduser', $encParamName, wfEscapeWikiText( $value ) ],
+                               "baduser_{$encParamName}"
+                       );
+               }
+
+               return $title->getText();
+       }
+
+       /**@}*/
+
+       /************************************************************************//**
+        * @name   Utility methods
+        * @{
+        */
+
+       /**
+        * Set a watch (or unwatch) based the based on a watchlist parameter.
+        * @param string $watch Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
+        * @param Title $titleObj The article's title to change
+        * @param string $userOption The user option to consider when $watch=preferences
+        */
+       protected function setWatch( $watch, $titleObj, $userOption = null ) {
+               $value = $this->getWatchlistValue( $watch, $titleObj, $userOption );
+               if ( $value === null ) {
+                       return;
+               }
+
+               WatchAction::doWatchOrUnwatch( $value, $titleObj, $this->getUser() );
+       }
+
+       /**
+        * Truncate an array to a certain length.
+        * @param array &$arr Array to truncate
+        * @param int $limit Maximum length
+        * @return bool True if the array was truncated, false otherwise
+        */
+       public static function truncateArray( &$arr, $limit ) {
+               $modified = false;
+               while ( count( $arr ) > $limit ) {
+                       array_pop( $arr );
+                       $modified = true;
+               }
+
+               return $modified;
+       }
+
+       /**
+        * Gets the user for whom to get the watchlist
+        *
+        * @param array $params
+        * @return User
+        */
+       public function getWatchlistUser( $params ) {
+               if ( !is_null( $params['owner'] ) && !is_null( $params['token'] ) ) {
+                       $user = User::newFromName( $params['owner'], false );
+                       if ( !( $user && $user->getId() ) ) {
+                               $this->dieWithError(
+                                       [ 'nosuchusershort', wfEscapeWikiText( $params['owner'] ) ], 'bad_wlowner'
+                               );
+                       }
+                       $token = $user->getOption( 'watchlisttoken' );
+                       if ( $token == '' || !hash_equals( $token, $params['token'] ) ) {
+                               $this->dieWithError( 'apierror-bad-watchlist-token', 'bad_wltoken' );
+                       }
+               } else {
+                       if ( !$this->getUser()->isLoggedIn() ) {
+                               $this->dieWithError( 'watchlistanontext', 'notloggedin' );
+                       }
+                       $this->checkUserRightsAny( 'viewmywatchlist' );
+                       $user = $this->getUser();
+               }
+
+               return $user;
+       }
+
+       /**
+        * A subset of wfEscapeWikiText for BC texts
+        *
+        * @since 1.25
+        * @param string|array $v
+        * @return string|array
+        */
+       private static function escapeWikiText( $v ) {
+               if ( is_array( $v ) ) {
+                       return array_map( 'self::escapeWikiText', $v );
+               } else {
+                       return strtr( $v, [
+                               '__' => '_&#95;', '{' => '&#123;', '}' => '&#125;',
+                               '[[Category:' => '[[:Category:',
+                               '[[File:' => '[[:File:', '[[Image:' => '[[:Image:',
+                       ] );
+               }
+       }
+
+       /**
+        * Create a Message from a string or array
+        *
+        * A string is used as a message key. An array has the message key as the
+        * first value and message parameters as subsequent values.
+        *
+        * @since 1.25
+        * @param string|array|Message $msg
+        * @param IContextSource $context
+        * @param array $params
+        * @return Message|null
+        */
+       public static function makeMessage( $msg, IContextSource $context, array $params = null ) {
+               if ( is_string( $msg ) ) {
+                       $msg = wfMessage( $msg );
+               } elseif ( is_array( $msg ) ) {
+                       $msg = call_user_func_array( 'wfMessage', $msg );
+               }
+               if ( !$msg instanceof Message ) {
+                       return null;
+               }
+
+               $msg->setContext( $context );
+               if ( $params ) {
+                       $msg->params( $params );
+               }
+
+               return $msg;
+       }
+
+       /**
+        * Turn an array of message keys or key+param arrays into a Status
+        * @since 1.29
+        * @param array $errors
+        * @param User|null $user
+        * @return Status
+        */
+       public function errorArrayToStatus( array $errors, User $user = null ) {
+               if ( $user === null ) {
+                       $user = $this->getUser();
+               }
+
+               $status = Status::newGood();
+               foreach ( $errors as $error ) {
+                       if ( is_array( $error ) && $error[0] === 'blockedtext' && $user->getBlock() ) {
+                               $status->fatal( ApiMessage::create(
+                                       'apierror-blocked',
+                                       'blocked',
+                                       [ 'blockinfo' => ApiQueryUserInfo::getBlockInfo( $user->getBlock() ) ]
+                               ) );
+                       } elseif ( is_array( $error ) && $error[0] === 'autoblockedtext' && $user->getBlock() ) {
+                               $status->fatal( ApiMessage::create(
+                                       'apierror-autoblocked',
+                                       'autoblocked',
+                                       [ 'blockinfo' => ApiQueryUserInfo::getBlockInfo( $user->getBlock() ) ]
+                               ) );
+                       } elseif ( is_array( $error ) && $error[0] === 'systemblockedtext' && $user->getBlock() ) {
+                               $status->fatal( ApiMessage::create(
+                                       'apierror-systemblocked',
+                                       'blocked',
+                                       [ 'blockinfo' => ApiQueryUserInfo::getBlockInfo( $user->getBlock() ) ]
+                               ) );
+                       } else {
+                               call_user_func_array( [ $status, 'fatal' ], (array)$error );
+                       }
+               }
+               return $status;
+       }
+
+       /**@}*/
+
+       /************************************************************************//**
+        * @name   Warning and error reporting
+        * @{
+        */
+
+       /**
+        * Add a warning for this module.
+        *
+        * Users should monitor this section to notice any changes in API. Multiple
+        * calls to this function will result in multiple warning messages.
+        *
+        * If $msg is not an ApiMessage, the message code will be derived from the
+        * message key by stripping any "apiwarn-" or "apierror-" prefix.
+        *
+        * @since 1.29
+        * @param string|array|Message $msg See ApiErrorFormatter::addWarning()
+        * @param string|null $code See ApiErrorFormatter::addWarning()
+        * @param array|null $data See ApiErrorFormatter::addWarning()
+        */
+       public function addWarning( $msg, $code = null, $data = null ) {
+               $this->getErrorFormatter()->addWarning( $this->getModulePath(), $msg, $code, $data );
+       }
+
+       /**
+        * Add a deprecation warning for this module.
+        *
+        * A combination of $this->addWarning() and $this->logFeatureUsage()
+        *
+        * @since 1.29
+        * @param string|array|Message $msg See ApiErrorFormatter::addWarning()
+        * @param string|null $feature See ApiBase::logFeatureUsage()
+        * @param array|null $data See ApiErrorFormatter::addWarning()
+        */
+       public function addDeprecation( $msg, $feature, $data = [] ) {
+               $data = (array)$data;
+               if ( $feature !== null ) {
+                       $data['feature'] = $feature;
+                       $this->logFeatureUsage( $feature );
+               }
+               $this->addWarning( $msg, 'deprecation', $data );
+
+               // No real need to deduplicate here, ApiErrorFormatter does that for
+               // us (assuming the hook is deterministic).
+               $msgs = [ $this->msg( 'api-usage-mailinglist-ref' ) ];
+               Hooks::run( 'ApiDeprecationHelp', [ &$msgs ] );
+               if ( count( $msgs ) > 1 ) {
+                       $key = '$' . join( ' $', range( 1, count( $msgs ) ) );
+                       $msg = ( new RawMessage( $key ) )->params( $msgs );
+               } else {
+                       $msg = reset( $msgs );
+               }
+               $this->getMain()->addWarning( $msg, 'deprecation-help' );
+       }
+
+       /**
+        * Add an error for this module without aborting
+        *
+        * If $msg is not an ApiMessage, the message code will be derived from the
+        * message key by stripping any "apiwarn-" or "apierror-" prefix.
+        *
+        * @note If you want to abort processing, use self::dieWithError() instead.
+        * @since 1.29
+        * @param string|array|Message $msg See ApiErrorFormatter::addError()
+        * @param string|null $code See ApiErrorFormatter::addError()
+        * @param array|null $data See ApiErrorFormatter::addError()
+        */
+       public function addError( $msg, $code = null, $data = null ) {
+               $this->getErrorFormatter()->addError( $this->getModulePath(), $msg, $code, $data );
+       }
+
+       /**
+        * Add warnings and/or errors from a Status
+        *
+        * @note If you want to abort processing, use self::dieStatus() instead.
+        * @since 1.29
+        * @param StatusValue $status
+        * @param string[] $types 'warning' and/or 'error'
+        */
+       public function addMessagesFromStatus( StatusValue $status, $types = [ 'warning', 'error' ] ) {
+               $this->getErrorFormatter()->addMessagesFromStatus( $this->getModulePath(), $status, $types );
+       }
+
+       /**
+        * Abort execution with an error
+        *
+        * If $msg is not an ApiMessage, the message code will be derived from the
+        * message key by stripping any "apiwarn-" or "apierror-" prefix.
+        *
+        * @since 1.29
+        * @param string|array|Message $msg See ApiErrorFormatter::addError()
+        * @param string|null $code See ApiErrorFormatter::addError()
+        * @param array|null $data See ApiErrorFormatter::addError()
+        * @param int|null $httpCode HTTP error code to use
+        * @throws ApiUsageException always
+        */
+       public function dieWithError( $msg, $code = null, $data = null, $httpCode = null ) {
+               throw ApiUsageException::newWithMessage( $this, $msg, $code, $data, $httpCode );
+       }
+
+       /**
+        * Abort execution with an error derived from an exception
+        *
+        * @since 1.29
+        * @param Exception|Throwable $exception See ApiErrorFormatter::getMessageFromException()
+        * @param array $options See ApiErrorFormatter::getMessageFromException()
+        * @throws ApiUsageException always
+        */
+       public function dieWithException( $exception, array $options = [] ) {
+               $this->dieWithError(
+                       $this->getErrorFormatter()->getMessageFromException( $exception, $options )
+               );
+       }
+
+       /**
+        * Adds a warning to the output, else dies
+        *
+        * @param ApiMessage $msg Message to show as a warning, or error message if dying
+        * @param bool $enforceLimits Whether this is an enforce (die)
+        */
+       private function warnOrDie( ApiMessage $msg, $enforceLimits = false ) {
+               if ( $enforceLimits ) {
+                       $this->dieWithError( $msg );
+               } else {
+                       $this->addWarning( $msg );
+               }
+       }
+
+       /**
+        * Throw an ApiUsageException, which will (if uncaught) call the main module's
+        * error handler and die with an error message including block info.
+        *
+        * @since 1.27
+        * @param Block $block The block used to generate the ApiUsageException
+        * @throws ApiUsageException always
+        */
+       public function dieBlocked( Block $block ) {
+               // Die using the appropriate message depending on block type
+               if ( $block->getType() == Block::TYPE_AUTO ) {
+                       $this->dieWithError(
+                               'apierror-autoblocked',
+                               'autoblocked',
+                               [ 'blockinfo' => ApiQueryUserInfo::getBlockInfo( $block ) ]
+                       );
+               } else {
+                       $this->dieWithError(
+                               'apierror-blocked',
+                               'blocked',
+                               [ 'blockinfo' => ApiQueryUserInfo::getBlockInfo( $block ) ]
+                       );
+               }
+       }
+
+       /**
+        * Throw an ApiUsageException based on the Status object.
+        *
+        * @since 1.22
+        * @since 1.29 Accepts a StatusValue
+        * @param StatusValue $status
+        * @throws ApiUsageException always
+        */
+       public function dieStatus( StatusValue $status ) {
+               if ( $status->isGood() ) {
+                       throw new MWException( 'Successful status passed to ApiBase::dieStatus' );
+               }
+
+               // ApiUsageException needs a fatal status, but this method has
+               // historically accepted any non-good status. Convert it if necessary.
+               $status->setOK( false );
+               if ( !$status->getErrorsByType( 'error' ) ) {
+                       $newStatus = Status::newGood();
+                       foreach ( $status->getErrorsByType( 'warning' ) as $err ) {
+                               call_user_func_array(
+                                       [ $newStatus, 'fatal' ],
+                                       array_merge( [ $err['message'] ], $err['params'] )
+                               );
+                       }
+                       if ( !$newStatus->getErrorsByType( 'error' ) ) {
+                               $newStatus->fatal( 'unknownerror-nocode' );
+                       }
+                       $status = $newStatus;
+               }
+
+               throw new ApiUsageException( $this, $status );
+       }
+
+       /**
+        * Helper function for readonly errors
+        *
+        * @throws ApiUsageException always
+        */
+       public function dieReadOnly() {
+               $this->dieWithError(
+                       'apierror-readonly',
+                       'readonly',
+                       [ 'readonlyreason' => wfReadOnlyReason() ]
+               );
+       }
+
+       /**
+        * Helper function for permission-denied errors
+        * @since 1.29
+        * @param string|string[] $rights
+        * @param User|null $user
+        * @throws ApiUsageException if the user doesn't have any of the rights.
+        *  The error message is based on $rights[0].
+        */
+       public function checkUserRightsAny( $rights, $user = null ) {
+               if ( !$user ) {
+                       $user = $this->getUser();
+               }
+               $rights = (array)$rights;
+               if ( !call_user_func_array( [ $user, 'isAllowedAny' ], $rights ) ) {
+                       $this->dieWithError( [ 'apierror-permissiondenied', $this->msg( "action-{$rights[0]}" ) ] );
+               }
+       }
+
+       /**
+        * Helper function for permission-denied errors
+        * @since 1.29
+        * @param Title $title
+        * @param string|string[] $actions
+        * @param User|null $user
+        * @throws ApiUsageException if the user doesn't have all of the rights.
+        */
+       public function checkTitleUserPermissions( Title $title, $actions, $user = null ) {
+               if ( !$user ) {
+                       $user = $this->getUser();
+               }
+
+               $errors = [];
+               foreach ( (array)$actions as $action ) {
+                       $errors = array_merge( $errors, $title->getUserPermissionsErrors( $action, $user ) );
+               }
+               if ( $errors ) {
+                       $this->dieStatus( $this->errorArrayToStatus( $errors, $user ) );
+               }
+       }
+
+       /**
+        * Will only set a warning instead of failing if the global $wgDebugAPI
+        * is set to true. Otherwise behaves exactly as self::dieWithError().
+        *
+        * @since 1.29
+        * @param string|array|Message $msg
+        * @param string|null $code
+        * @param array|null $data
+        * @param int|null $httpCode
+        * @throws ApiUsageException
+        */
+       public function dieWithErrorOrDebug( $msg, $code = null, $data = null, $httpCode = null ) {
+               if ( $this->getConfig()->get( 'DebugAPI' ) !== true ) {
+                       $this->dieWithError( $msg, $code, $data, $httpCode );
+               } else {
+                       $this->addWarning( $msg, $code, $data );
+               }
+       }
+
+       /**
+        * Die with the 'badcontinue' error.
+        *
+        * This call is common enough to make it into the base method.
+        *
+        * @param bool $condition Will only die if this value is true
+        * @throws ApiUsageException
+        * @since 1.21
+        */
+       protected function dieContinueUsageIf( $condition ) {
+               if ( $condition ) {
+                       $this->dieWithError( 'apierror-badcontinue' );
+               }
+       }
+
+       /**
+        * Internal code errors should be reported with this method
+        * @param string $method Method or function name
+        * @param string $message Error message
+        * @throws MWException always
+        */
+       protected static function dieDebug( $method, $message ) {
+               throw new MWException( "Internal error in $method: $message" );
+       }
+
+       /**
+        * Write logging information for API features to a debug log, for usage
+        * analysis.
+        * @note Consider using $this->addDeprecation() instead to both warn and log.
+        * @param string $feature Feature being used.
+        */
+       public function logFeatureUsage( $feature ) {
+               $request = $this->getRequest();
+               $s = '"' . addslashes( $feature ) . '"' .
+                       ' "' . wfUrlencode( str_replace( ' ', '_', $this->getUser()->getName() ) ) . '"' .
+                       ' "' . $request->getIP() . '"' .
+                       ' "' . addslashes( $request->getHeader( 'Referer' ) ) . '"' .
+                       ' "' . addslashes( $this->getMain()->getUserAgent() ) . '"';
+               wfDebugLog( 'api-feature-usage', $s, 'private' );
+       }
+
+       /**@}*/
+
+       /************************************************************************//**
+        * @name   Help message generation
+        * @{
+        */
+
+       /**
+        * Return the summary message.
+        *
+        * This is a one-line description of the module, suitable for display in a
+        * list of modules.
+        *
+        * @since 1.30
+        * @return string|array|Message
+        */
+       protected function getSummaryMessage() {
+               return "apihelp-{$this->getModulePath()}-summary";
+       }
+
+       /**
+        * Return the extended help text message.
+        *
+        * This is additional text to display at the top of the help section, below
+        * the summary.
+        *
+        * @since 1.30
+        * @return string|array|Message
+        */
+       protected function getExtendedDescription() {
+               return [ [
+                       "apihelp-{$this->getModulePath()}-extended-description",
+                       'api-help-no-extended-description',
+               ] ];
+       }
+
+       /**
+        * Get final module summary
+        *
+        * Ideally this will just be the getSummaryMessage(). However, for
+        * backwards compatibility, if that message does not exist then the first
+        * line of wikitext from the description message will be used instead.
+        *
+        * @since 1.30
+        * @return Message
+        */
+       public function getFinalSummary() {
+               $msg = self::makeMessage( $this->getSummaryMessage(), $this->getContext(), [
+                       $this->getModulePrefix(),
+                       $this->getModuleName(),
+                       $this->getModulePath(),
+               ] );
+               if ( !$msg->exists() ) {
+                       wfDeprecated( 'API help "description" messages', '1.30' );
+                       $msg = self::makeMessage( $this->getDescriptionMessage(), $this->getContext(), [
+                               $this->getModulePrefix(),
+                               $this->getModuleName(),
+                               $this->getModulePath(),
+                       ] );
+                       $msg = self::makeMessage( 'rawmessage', $this->getContext(), [
+                               preg_replace( '/\n.*/s', '', $msg->text() )
+                       ] );
+               }
+               return $msg;
+       }
+
+       /**
+        * Get final module description, after hooks have had a chance to tweak it as
+        * needed.
+        *
+        * @since 1.25, returns Message[] rather than string[]
+        * @return Message[]
+        */
+       public function getFinalDescription() {
+               $desc = $this->getDescription();
+
+               // Avoid PHP 7.1 warning of passing $this by reference
+               $apiModule = $this;
+               Hooks::run( 'APIGetDescription', [ &$apiModule, &$desc ] );
+               $desc = self::escapeWikiText( $desc );
+               if ( is_array( $desc ) ) {
+                       $desc = implode( "\n", $desc );
+               } else {
+                       $desc = (string)$desc;
+               }
+
+               $summary = self::makeMessage( $this->getSummaryMessage(), $this->getContext(), [
+                       $this->getModulePrefix(),
+                       $this->getModuleName(),
+                       $this->getModulePath(),
+               ] );
+               $extendedDescription = self::makeMessage(
+                       $this->getExtendedDescription(), $this->getContext(), [
+                               $this->getModulePrefix(),
+                               $this->getModuleName(),
+                               $this->getModulePath(),
+                       ]
+               );
+
+               if ( $summary->exists() ) {
+                       $msgs = [ $summary, $extendedDescription ];
+               } else {
+                       wfDeprecated( 'API help "description" messages', '1.30' );
+                       $description = self::makeMessage( $this->getDescriptionMessage(), $this->getContext(), [
+                               $this->getModulePrefix(),
+                               $this->getModuleName(),
+                               $this->getModulePath(),
+                       ] );
+                       if ( !$description->exists() ) {
+                               $description = $this->msg( 'api-help-fallback-description', $desc );
+                       }
+                       $msgs = [ $description ];
+               }
+
+               Hooks::run( 'APIGetDescriptionMessages', [ $this, &$msgs ] );
+
+               return $msgs;
+       }
+
+       /**
+        * Get final list of parameters, after hooks have had a chance to
+        * tweak it as needed.
+        *
+        * @param int $flags Zero or more flags like GET_VALUES_FOR_HELP
+        * @return array|bool False on no parameters
+        * @since 1.21 $flags param added
+        */
+       public function getFinalParams( $flags = 0 ) {
+               $params = $this->getAllowedParams( $flags );
+               if ( !$params ) {
+                       $params = [];
+               }
+
+               if ( $this->needsToken() ) {
+                       $params['token'] = [
+                               self::PARAM_TYPE => 'string',
+                               self::PARAM_REQUIRED => true,
+                               self::PARAM_SENSITIVE => true,
+                               self::PARAM_HELP_MSG => [
+                                       'api-help-param-token',
+                                       $this->needsToken(),
+                               ],
+                       ] + ( isset( $params['token'] ) ? $params['token'] : [] );
+               }
+
+               // Avoid PHP 7.1 warning of passing $this by reference
+               $apiModule = $this;
+               Hooks::run( 'APIGetAllowedParams', [ &$apiModule, &$params, $flags ] );
+
+               return $params;
+       }
+
+       /**
+        * Get final parameter descriptions, after hooks have had a chance to tweak it as
+        * needed.
+        *
+        * @since 1.25, returns array of Message[] rather than array of string[]
+        * @return array Keys are parameter names, values are arrays of Message objects
+        */
+       public function getFinalParamDescription() {
+               $prefix = $this->getModulePrefix();
+               $name = $this->getModuleName();
+               $path = $this->getModulePath();
+
+               $desc = $this->getParamDescription();
+
+               // Avoid PHP 7.1 warning of passing $this by reference
+               $apiModule = $this;
+               Hooks::run( 'APIGetParamDescription', [ &$apiModule, &$desc ] );
+
+               if ( !$desc ) {
+                       $desc = [];
+               }
+               $desc = self::escapeWikiText( $desc );
+
+               $params = $this->getFinalParams( self::GET_VALUES_FOR_HELP );
+               $msgs = [];
+               foreach ( $params as $param => $settings ) {
+                       if ( !is_array( $settings ) ) {
+                               $settings = [];
+                       }
 
-                                               foreach ( $value as $key => $val ) {
-                                                       $title = Title::makeTitleSafe( NS_USER, $val );
-                                                       if ( is_null( $title ) ) {
-                                                               $this->dieUsage( "Invalid value for user parameter $encParamName", "baduser_{$encParamName}" );
-                                                       }
-                                                       $value[$key] = $title->getText();
-                                               }
+                       $d = isset( $desc[$param] ) ? $desc[$param] : '';
+                       if ( is_array( $d ) ) {
+                               // Special handling for prop parameters
+                               $d = array_map( function ( $line ) {
+                                       if ( preg_match( '/^\s+(\S+)\s+-\s+(.+)$/', $line, $m ) ) {
+                                               $line = "\n;{$m[1]}:{$m[2]}";
+                                       }
+                                       return $line;
+                               }, $d );
+                               $d = implode( ' ', $d );
+                       }
 
-                                               if ( !$multi ) {
-                                                       $value = $value[0];
-                                               }
-                                               break;
-                                       default:
-                                               ApiBase::dieDebug( __METHOD__, "Param $encParamName's type is unknown - $type" );
+                       if ( isset( $settings[self::PARAM_HELP_MSG] ) ) {
+                               $msg = $settings[self::PARAM_HELP_MSG];
+                       } else {
+                               $msg = $this->msg( "apihelp-{$path}-param-{$param}" );
+                               if ( !$msg->exists() ) {
+                                       $msg = $this->msg( 'api-help-fallback-parameter', $d );
                                }
                        }
+                       $msg = self::makeMessage( $msg, $this->getContext(),
+                               [ $prefix, $param, $name, $path ] );
+                       if ( !$msg ) {
+                               self::dieDebug( __METHOD__,
+                                       'Value in ApiBase::PARAM_HELP_MSG is not valid' );
+                       }
+                       $msgs[$param] = [ $msg ];
 
-                       // Throw out duplicates if requested
-                       if ( is_array( $value ) && !$dupes ) {
-                               $value = array_unique( $value );
+                       if ( isset( $settings[self::PARAM_TYPE] ) &&
+                               $settings[self::PARAM_TYPE] === 'submodule'
+                       ) {
+                               if ( isset( $settings[self::PARAM_SUBMODULE_MAP] ) ) {
+                                       $map = $settings[self::PARAM_SUBMODULE_MAP];
+                               } else {
+                                       $prefix = $this->isMain() ? '' : ( $this->getModulePath() . '+' );
+                                       $map = [];
+                                       foreach ( $this->getModuleManager()->getNames( $param ) as $submoduleName ) {
+                                               $map[$submoduleName] = $prefix . $submoduleName;
+                                       }
+                               }
+                               ksort( $map );
+                               $submodules = [];
+                               $deprecatedSubmodules = [];
+                               foreach ( $map as $v => $m ) {
+                                       $arr = &$submodules;
+                                       $isDeprecated = false;
+                                       $summary = null;
+                                       try {
+                                               $submod = $this->getModuleFromPath( $m );
+                                               if ( $submod ) {
+                                                       $summary = $submod->getFinalSummary();
+                                                       $isDeprecated = $submod->isDeprecated();
+                                                       if ( $isDeprecated ) {
+                                                               $arr = &$deprecatedSubmodules;
+                                                       }
+                                               }
+                                       } catch ( ApiUsageException $ex ) {
+                                               // Ignore
+                                       }
+                                       if ( $summary ) {
+                                               $key = $summary->getKey();
+                                               $params = $summary->getParams();
+                                       } else {
+                                               $key = 'api-help-undocumented-module';
+                                               $params = [ $m ];
+                                       }
+                                       $m = new ApiHelpParamValueMessage( "[[Special:ApiHelp/$m|$v]]", $key, $params, $isDeprecated );
+                                       $arr[] = $m->setContext( $this->getContext() );
+                               }
+                               $msgs[$param] = array_merge( $msgs[$param], $submodules, $deprecatedSubmodules );
+                       } elseif ( isset( $settings[self::PARAM_HELP_MSG_PER_VALUE] ) ) {
+                               if ( !is_array( $settings[self::PARAM_HELP_MSG_PER_VALUE] ) ) {
+                                       self::dieDebug( __METHOD__,
+                                               'ApiBase::PARAM_HELP_MSG_PER_VALUE is not valid' );
+                               }
+                               if ( !is_array( $settings[self::PARAM_TYPE] ) ) {
+                                       self::dieDebug( __METHOD__,
+                                               'ApiBase::PARAM_HELP_MSG_PER_VALUE may only be used when ' .
+                                               'ApiBase::PARAM_TYPE is an array' );
+                               }
+
+                               $valueMsgs = $settings[self::PARAM_HELP_MSG_PER_VALUE];
+                               $deprecatedValues = isset( $settings[self::PARAM_DEPRECATED_VALUES] )
+                                       ? $settings[self::PARAM_DEPRECATED_VALUES]
+                                       : [];
+
+                               foreach ( $settings[self::PARAM_TYPE] as $value ) {
+                                       if ( isset( $valueMsgs[$value] ) ) {
+                                               $msg = $valueMsgs[$value];
+                                       } else {
+                                               $msg = "apihelp-{$path}-paramvalue-{$param}-{$value}";
+                                       }
+                                       $m = self::makeMessage( $msg, $this->getContext(),
+                                               [ $prefix, $param, $name, $path, $value ] );
+                                       if ( $m ) {
+                                               $m = new ApiHelpParamValueMessage(
+                                                       $value,
+                                                       [ $m->getKey(), 'api-help-param-no-description' ],
+                                                       $m->getParams(),
+                                                       isset( $deprecatedValues[$value] )
+                                               );
+                                               $msgs[$param][] = $m->setContext( $this->getContext() );
+                                       } else {
+                                               self::dieDebug( __METHOD__,
+                                                       "Value in ApiBase::PARAM_HELP_MSG_PER_VALUE for $value is not valid" );
+                                       }
+                               }
                        }
 
-                       // Set a warning if a deprecated parameter has been passed
-                       if ( $deprecated && $value !== false ) {
-                               $this->setWarning( "The $encParamName parameter has been deprecated." );
+                       if ( isset( $settings[self::PARAM_HELP_MSG_APPEND] ) ) {
+                               if ( !is_array( $settings[self::PARAM_HELP_MSG_APPEND] ) ) {
+                                       self::dieDebug( __METHOD__,
+                                               'Value for ApiBase::PARAM_HELP_MSG_APPEND is not an array' );
+                               }
+                               foreach ( $settings[self::PARAM_HELP_MSG_APPEND] as $m ) {
+                                       $m = self::makeMessage( $m, $this->getContext(),
+                                               [ $prefix, $param, $name, $path ] );
+                                       if ( $m ) {
+                                               $msgs[$param][] = $m;
+                                       } else {
+                                               self::dieDebug( __METHOD__,
+                                                       'Value in ApiBase::PARAM_HELP_MSG_APPEND is not valid' );
+                                       }
+                               }
                        }
-               } else if ( $required ) {
-                       $this->dieUsageMsg( array( 'missingparam', $paramName ) );
                }
 
-               return $value;
+               Hooks::run( 'APIGetParamDescriptionMessages', [ $this, &$msgs ] );
+
+               return $msgs;
        }
 
        /**
-        * Return an array of values that were given in a 'a|b|c' notation,
-        * after it optionally validates them against the list allowed values.
+        * Generates the list of flags for the help screen and for action=paraminfo
         *
-        * @param $valueName string The name of the parameter (for error
-        *  reporting)
-        * @param $value mixed The value being parsed
-        * @param $allowMultiple bool Can $value contain more than one value
-        *  separated by '|'?
-        * @param $allowedValues mixed An array of values to check against. If
-        *  null, all values are accepted.
-        * @return mixed (allowMultiple ? an_array_of_values : a_single_value)
+        * Corresponding messages: api-help-flag-deprecated,
+        * api-help-flag-internal, api-help-flag-readrights,
+        * api-help-flag-writerights, api-help-flag-mustbeposted
+        *
+        * @return string[]
         */
-       protected function parseMultiValue( $valueName, $value, $allowMultiple, $allowedValues ) {
-               if ( trim( $value ) === '' && $allowMultiple ) {
-                       return array();
-               }
-
-               // This is a bit awkward, but we want to avoid calling canApiHighLimits() because it unstubs $wgUser
-               $valuesList = explode( '|', $value, self::LIMIT_SML2 + 1 );
-               $sizeLimit = count( $valuesList ) > self::LIMIT_SML1 && $this->mMainModule->canApiHighLimits() ?
-                       self::LIMIT_SML2 : self::LIMIT_SML1;
+       protected function getHelpFlags() {
+               $flags = [];
 
-               if ( self::truncateArray( $valuesList, $sizeLimit ) ) {
-                       $this->setWarning( "Too many values supplied for parameter '$valueName': the limit is $sizeLimit" );
+               if ( $this->isDeprecated() ) {
+                       $flags[] = 'deprecated';
                }
-
-               if ( !$allowMultiple && count( $valuesList ) != 1 ) {
-                       $possibleValues = is_array( $allowedValues ) ? "of '" . implode( "', '", $allowedValues ) . "'" : '';
-                       $this->dieUsage( "Only one $possibleValues is allowed for parameter '$valueName'", "multival_$valueName" );
+               if ( $this->isInternal() ) {
+                       $flags[] = 'internal';
                }
-
-               if ( is_array( $allowedValues ) ) {
-                       // Check for unknown values
-                       $unknown = array_diff( $valuesList, $allowedValues );
-                       if ( count( $unknown ) ) {
-                               if ( $allowMultiple ) {
-                                       $s = count( $unknown ) > 1 ? 's' : '';
-                                       $vals = implode( ", ", $unknown );
-                                       $this->setWarning( "Unrecognized value$s for parameter '$valueName': $vals" );
-                               } else {
-                                       $this->dieUsage( "Unrecognized value for parameter '$valueName': {$valuesList[0]}", "unknown_$valueName" );
-                               }
-                       }
-                       // Now throw them out
-                       $valuesList = array_intersect( $valuesList, $allowedValues );
+               if ( $this->isReadMode() ) {
+                       $flags[] = 'readrights';
+               }
+               if ( $this->isWriteMode() ) {
+                       $flags[] = 'writerights';
+               }
+               if ( $this->mustBePosted() ) {
+                       $flags[] = 'mustbeposted';
                }
 
-               return $allowMultiple ? $valuesList : $valuesList[0];
+               return $flags;
        }
 
        /**
-        * Validate the value against the minimum and user/bot maximum limits.
-        * Prints usage info on failure.
-        * @param $paramName string Parameter name
-        * @param $value int Parameter value
-        * @param $min int Minimum value
-        * @param $max int Maximum value for users
-        * @param $botMax int Maximum value for sysops/bots
-        * @param $enforceLimits Boolean Whether to enforce (die) if value is outside limits
-        */
-       function validateLimit( $paramName, &$value, $min, $max, $botMax = null, $enforceLimits = false ) {
-               if ( !is_null( $min ) && $value < $min ) {
+        * Returns information about the source of this module, if known
+        *
+        * Returned array is an array with the following keys:
+        * - path: Install path
+        * - name: Extension name, or "MediaWiki" for core
+        * - namemsg: (optional) i18n message key for a display name
+        * - license-name: (optional) Name of license
+        *
+        * @return array|null
+        */
+       protected function getModuleSourceInfo() {
+               global $IP;
 
-                       $msg = $this->encodeParamName( $paramName ) . " may not be less than $min (set to $value)";
-                       $this->warnOrDie( $msg, $enforceLimits );
-                       $value = $min;
+               if ( $this->mModuleSource !== false ) {
+                       return $this->mModuleSource;
                }
 
-               // Minimum is always validated, whereas maximum is checked only if not running in internal call mode
-               if ( $this->getMain()->isInternalMode() ) {
-                       return;
+               // First, try to find where the module comes from...
+               $rClass = new ReflectionClass( $this );
+               $path = $rClass->getFileName();
+               if ( !$path ) {
+                       // No path known?
+                       $this->mModuleSource = null;
+                       return null;
                }
+               $path = realpath( $path ) ?: $path;
+
+               // Build map of extension directories to extension info
+               if ( self::$extensionInfo === null ) {
+                       $extDir = $this->getConfig()->get( 'ExtensionDirectory' );
+                       self::$extensionInfo = [
+                               realpath( __DIR__ ) ?: __DIR__ => [
+                                       'path' => $IP,
+                                       'name' => 'MediaWiki',
+                                       'license-name' => 'GPL-2.0+',
+                               ],
+                               realpath( "$IP/extensions" ) ?: "$IP/extensions" => null,
+                               realpath( $extDir ) ?: $extDir => null,
+                       ];
+                       $keep = [
+                               'path' => null,
+                               'name' => null,
+                               'namemsg' => null,
+                               'license-name' => null,
+                       ];
+                       foreach ( $this->getConfig()->get( 'ExtensionCredits' ) as $group ) {
+                               foreach ( $group as $ext ) {
+                                       if ( !isset( $ext['path'] ) || !isset( $ext['name'] ) ) {
+                                               // This shouldn't happen, but does anyway.
+                                               continue;
+                                       }
 
-               // Optimization: do not check user's bot status unless really needed -- skips db query
-               // assumes $botMax >= $max
-               if ( !is_null( $max ) && $value > $max ) {
-                       if ( !is_null( $botMax ) && $this->getMain()->canApiHighLimits() ) {
-                               if ( $value > $botMax ) {
-                                       $msg = $this->encodeParamName( $paramName ) . " may not be over $botMax (set to $value) for bots or sysops";
-                                       $this->warnOrDie( $msg, $enforceLimits );
-                                       $value = $botMax;
+                                       $extpath = $ext['path'];
+                                       if ( !is_dir( $extpath ) ) {
+                                               $extpath = dirname( $extpath );
+                                       }
+                                       self::$extensionInfo[realpath( $extpath ) ?: $extpath] =
+                                               array_intersect_key( $ext, $keep );
                                }
-                       } else {
-                               $msg = $this->encodeParamName( $paramName ) . " may not be over $max (set to $value) for users";
-                               $this->warnOrDie( $msg, $enforceLimits );
-                               $value = $max;
+                       }
+                       foreach ( ExtensionRegistry::getInstance()->getAllThings() as $ext ) {
+                               $extpath = $ext['path'];
+                               if ( !is_dir( $extpath ) ) {
+                                       $extpath = dirname( $extpath );
+                               }
+                               self::$extensionInfo[realpath( $extpath ) ?: $extpath] =
+                                       array_intersect_key( $ext, $keep );
                        }
                }
+
+               // Now traverse parent directories until we find a match or run out of
+               // parents.
+               do {
+                       if ( array_key_exists( $path, self::$extensionInfo ) ) {
+                               // Found it!
+                               $this->mModuleSource = self::$extensionInfo[$path];
+                               return $this->mModuleSource;
+                       }
+
+                       $oldpath = $path;
+                       $path = dirname( $path );
+               } while ( $path !== $oldpath );
+
+               // No idea what extension this might be.
+               $this->mModuleSource = null;
+               return null;
        }
 
        /**
-        * Adds a warning to the output, else dies
+        * Called from ApiHelp before the pieces are joined together and returned.
+        *
+        * This exists mainly for ApiMain to add the Permissions and Credits
+        * sections. Other modules probably don't need it.
         *
-        * @param  $msg String Message to show as a warning, or error message if dying
-        * @param  $enforceLimits Boolean Whether this is an enforce (die)
+        * @param string[] &$help Array of help data
+        * @param array $options Options passed to ApiHelp::getHelp
+        * @param array &$tocData If a TOC is being generated, this array has keys
+        *   as anchors in the page and values as for Linker::generateTOC().
         */
-       private function warnOrDie( $msg, $enforceLimits = false ) {
-               if ( $enforceLimits ) {
-                       $this->dieUsage( $msg, 'integeroutofrange' );
-               } else {
-                       $this->setWarning( $msg );
-               }
+       public function modifyHelp( array &$help, array $options, array &$tocData ) {
        }
 
-       /**
-        * Truncate an array to a certain length.
-        * @param $arr array Array to truncate
-        * @param $limit int Maximum length
-        * @return bool True if the array was truncated, false otherwise
-        */
-       public static function truncateArray( &$arr, $limit ) {
-               $modified = false;
-               while ( count( $arr ) > $limit ) {
-                       array_pop( $arr );
-                       $modified = true;
-               }
-               return $modified;
-       }
+       /**@}*/
 
-       /**
-        * Throw a UsageException, which will (if uncaught) call the main module's
-        * error handler and die with an error message.
-        *
-        * @param $description string One-line human-readable description of the
-        *   error condition, e.g., "The API requires a valid action parameter"
-        * @param $errorCode string Brief, arbitrary, stable string to allow easy
-        *   automated identification of the error, e.g., 'unknown_action'
-        * @param $httpRespCode int HTTP response code
-        * @param $extradata array Data to add to the <error> element; array in ApiResult format
+       /************************************************************************//**
+        * @name   Deprecated
+        * @{
         */
-       public function dieUsage( $description, $errorCode, $httpRespCode = 0, $extradata = null ) {
-               wfProfileClose();
-               throw new UsageException( $description, $this->encodeParamName( $errorCode ), $httpRespCode, $extradata );
-       }
-
-       /**
-        * Array that maps message keys to error messages. $1 and friends are replaced.
-        */
-       public static $messageMap = array(
-               // This one MUST be present, or dieUsageMsg() will recurse infinitely
-               'unknownerror' => array( 'code' => 'unknownerror', 'info' => "Unknown error: ``\$1''" ),
-               'unknownerror-nocode' => array( 'code' => 'unknownerror', 'info' => 'Unknown error' ),
-
-               // Messages from Title::getUserPermissionsErrors()
-               'ns-specialprotected' => array( 'code' => 'unsupportednamespace', 'info' => "Pages in the Special namespace can't be edited" ),
-               'protectedinterface' => array( 'code' => 'protectednamespace-interface', 'info' => "You're not allowed to edit interface messages" ),
-               'namespaceprotected' => array( 'code' => 'protectednamespace', 'info' => "You're not allowed to edit pages in the ``\$1'' namespace" ),
-               'customcssjsprotected' => array( 'code' => 'customcssjsprotected', 'info' => "You're not allowed to edit custom CSS and JavaScript pages" ),
-               'cascadeprotected' => array( 'code' => 'cascadeprotected', 'info' => "The page you're trying to edit is protected because it's included in a cascade-protected page" ),
-               'protectedpagetext' => array( 'code' => 'protectedpage', 'info' => "The ``\$1'' right is required to edit this page" ),
-               'protect-cantedit' => array( 'code' => 'cantedit', 'info' => "You can't protect this page because you can't edit it" ),
-               'badaccess-group0' => array( 'code' => 'permissiondenied', 'info' => "Permission denied" ), // Generic permission denied message
-               'badaccess-groups' => array( 'code' => 'permissiondenied', 'info' => "Permission denied" ),
-               'titleprotected' => array( 'code' => 'protectedtitle', 'info' => "This title has been protected from creation" ),
-               'nocreate-loggedin' => array( 'code' => 'cantcreate', 'info' => "You don't have permission to create new pages" ),
-               'nocreatetext' => array( 'code' => 'cantcreate-anon', 'info' => "Anonymous users can't create new pages" ),
-               'movenologintext' => array( 'code' => 'cantmove-anon', 'info' => "Anonymous users can't move pages" ),
-               'movenotallowed' => array( 'code' => 'cantmove', 'info' => "You don't have permission to move pages" ),
-               'confirmedittext' => array( 'code' => 'confirmemail', 'info' => "You must confirm your e-mail address before you can edit" ),
-               'blockedtext' => array( 'code' => 'blocked', 'info' => "You have been blocked from editing" ),
-               'autoblockedtext' => array( 'code' => 'autoblocked', 'info' => "Your IP address has been blocked automatically, because it was used by a blocked user" ),
-
-               // Miscellaneous interface messages
-               'actionthrottledtext' => array( 'code' => 'ratelimited', 'info' => "You've exceeded your rate limit. Please wait some time and try again" ),
-               'alreadyrolled' => array( 'code' => 'alreadyrolled', 'info' => "The page you tried to rollback was already rolled back" ),
-               'cantrollback' => array( 'code' => 'onlyauthor', 'info' => "The page you tried to rollback only has one author" ),
-               'readonlytext' => array( 'code' => 'readonly', 'info' => "The wiki is currently in read-only mode" ),
-               'sessionfailure' => array( 'code' => 'badtoken', 'info' => "Invalid token" ),
-               'cannotdelete' => array( 'code' => 'cantdelete', 'info' => "Couldn't delete ``\$1''. Maybe it was deleted already by someone else" ),
-               'notanarticle' => array( 'code' => 'missingtitle', 'info' => "The page you requested doesn't exist" ),
-               'selfmove' => array( 'code' => 'selfmove', 'info' => "Can't move a page to itself" ),
-               'immobile_namespace' => array( 'code' => 'immobilenamespace', 'info' => "You tried to move pages from or to a namespace that is protected from moving" ),
-               'articleexists' => array( 'code' => 'articleexists', 'info' => "The destination article already exists and is not a redirect to the source article" ),
-               'protectedpage' => array( 'code' => 'protectedpage', 'info' => "You don't have permission to perform this move" ),
-               'hookaborted' => array( 'code' => 'hookaborted', 'info' => "The modification you tried to make was aborted by an extension hook" ),
-               'cantmove-titleprotected' => array( 'code' => 'protectedtitle', 'info' => "The destination article has been protected from creation" ),
-               'imagenocrossnamespace' => array( 'code' => 'nonfilenamespace', 'info' => "Can't move a file to a non-file namespace" ),
-               'imagetypemismatch' => array( 'code' => 'filetypemismatch', 'info' => "The new file extension doesn't match its type" ),
-               // 'badarticleerror' => shouldn't happen
-               // 'badtitletext' => shouldn't happen
-               'ip_range_invalid' => array( 'code' => 'invalidrange', 'info' => "Invalid IP range" ),
-               'range_block_disabled' => array( 'code' => 'rangedisabled', 'info' => "Blocking IP ranges has been disabled" ),
-               'nosuchusershort' => array( 'code' => 'nosuchuser', 'info' => "The user you specified doesn't exist" ),
-               'badipaddress' => array( 'code' => 'invalidip', 'info' => "Invalid IP address specified" ),
-               'ipb_expiry_invalid' => array( 'code' => 'invalidexpiry', 'info' => "Invalid expiry time" ),
-               'ipb_already_blocked' => array( 'code' => 'alreadyblocked', 'info' => "The user you tried to block was already blocked" ),
-               'ipb_blocked_as_range' => array( 'code' => 'blockedasrange', 'info' => "IP address ``\$1'' was blocked as part of range ``\$2''. You can't unblock the IP invidually, but you can unblock the range as a whole." ),
-               'ipb_cant_unblock' => array( 'code' => 'cantunblock', 'info' => "The block you specified was not found. It may have been unblocked already" ),
-               'mailnologin' => array( 'code' => 'cantsend', 'info' => "You are not logged in, you do not have a confirmed e-mail address, or you are not allowed to send e-mail to other users, so you cannot send e-mail" ),
-               'ipbblocked' => array( 'code' => 'ipbblocked', 'info' => 'You cannot block or unblock users while you are yourself blocked' ),
-               'ipbnounblockself' => array( 'code' => 'ipbnounblockself', 'info' => 'You are not allowed to unblock yourself' ),
-               'usermaildisabled' => array( 'code' => 'usermaildisabled', 'info' => "User email has been disabled" ),
-               'blockedemailuser' => array( 'code' => 'blockedfrommail', 'info' => "You have been blocked from sending e-mail" ),
-               'notarget' => array( 'code' => 'notarget', 'info' => "You have not specified a valid target for this action" ),
-               'noemail' => array( 'code' => 'noemail', 'info' => "The user has not specified a valid e-mail address, or has chosen not to receive e-mail from other users" ),
-               'rcpatroldisabled' => array( 'code' => 'patroldisabled', 'info' => "Patrolling is disabled on this wiki" ),
-               'markedaspatrollederror-noautopatrol' => array( 'code' => 'noautopatrol', 'info' => "You don't have permission to patrol your own changes" ),
-               'delete-toobig' => array( 'code' => 'bigdelete', 'info' => "You can't delete this page because it has more than \$1 revisions" ),
-               'movenotallowedfile' => array( 'code' => 'cantmovefile', 'info' => "You don't have permission to move files" ),
-               'userrights-no-interwiki' => array( 'code' => 'nointerwikiuserrights', 'info' => "You don't have permission to change user rights on other wikis" ),
-               'userrights-nodatabase' => array( 'code' => 'nosuchdatabase', 'info' => "Database ``\$1'' does not exist or is not local" ),
-               'nouserspecified' => array( 'code' => 'invaliduser', 'info' => "Invalid username ``\$1''" ),
-               'noname' => array( 'code' => 'invaliduser', 'info' => "Invalid username ``\$1''" ),
-               'summaryrequired' => array( 'code' => 'summaryrequired', 'info' => 'Summary required' ),
-
-               // API-specific messages
-               'readrequired' => array( 'code' => 'readapidenied', 'info' => "You need read permission to use this module" ),
-               'writedisabled' => array( 'code' => 'noapiwrite', 'info' => "Editing of this wiki through the API is disabled. Make sure the \$wgEnableWriteAPI=true; statement is included in the wiki's LocalSettings.php file" ),
-               'writerequired' => array( 'code' => 'writeapidenied', 'info' => "You're not allowed to edit this wiki through the API" ),
-               'missingparam' => array( 'code' => 'no$1', 'info' => "The \$1 parameter must be set" ),
-               'invalidtitle' => array( 'code' => 'invalidtitle', 'info' => "Bad title ``\$1''" ),
-               'nosuchpageid' => array( 'code' => 'nosuchpageid', 'info' => "There is no page with ID \$1" ),
-               'nosuchrevid' => array( 'code' => 'nosuchrevid', 'info' => "There is no revision with ID \$1" ),
-               'nosuchuser' => array( 'code' => 'nosuchuser', 'info' => "User ``\$1'' doesn't exist" ),
-               'invaliduser' => array( 'code' => 'invaliduser', 'info' => "Invalid username ``\$1''" ),
-               'invalidexpiry' => array( 'code' => 'invalidexpiry', 'info' => "Invalid expiry time ``\$1''" ),
-               'pastexpiry' => array( 'code' => 'pastexpiry', 'info' => "Expiry time ``\$1'' is in the past" ),
-               'create-titleexists' => array( 'code' => 'create-titleexists', 'info' => "Existing titles can't be protected with 'create'" ),
-               'missingtitle-createonly' => array( 'code' => 'missingtitle-createonly', 'info' => "Missing titles can only be protected with 'create'" ),
-               'cantblock' => array( 'code' => 'cantblock', 'info' => "You don't have permission to block users" ),
-               'canthide' => array( 'code' => 'canthide', 'info' => "You don't have permission to hide user names from the block log" ),
-               'cantblock-email' => array( 'code' => 'cantblock-email', 'info' => "You don't have permission to block users from sending e-mail through the wiki" ),
-               'unblock-notarget' => array( 'code' => 'notarget', 'info' => "Either the id or the user parameter must be set" ),
-               'unblock-idanduser' => array( 'code' => 'idanduser', 'info' => "The id and user parameters can't be used together" ),
-               'cantunblock' => array( 'code' => 'permissiondenied', 'info' => "You don't have permission to unblock users" ),
-               'cannotundelete' => array( 'code' => 'cantundelete', 'info' => "Couldn't undelete: the requested revisions may not exist, or may have been undeleted already" ),
-               'permdenied-undelete' => array( 'code' => 'permissiondenied', 'info' => "You don't have permission to restore deleted revisions" ),
-               'createonly-exists' => array( 'code' => 'articleexists', 'info' => "The article you tried to create has been created already" ),
-               'nocreate-missing' => array( 'code' => 'missingtitle', 'info' => "The article you tried to edit doesn't exist" ),
-               'nosuchrcid' => array( 'code' => 'nosuchrcid', 'info' => "There is no change with rcid ``\$1''" ),
-               'protect-invalidaction' => array( 'code' => 'protect-invalidaction', 'info' => "Invalid protection type ``\$1''" ),
-               'protect-invalidlevel' => array( 'code' => 'protect-invalidlevel', 'info' => "Invalid protection level ``\$1''" ),
-               'toofewexpiries' => array( 'code' => 'toofewexpiries', 'info' => "\$1 expiry timestamps were provided where \$2 were needed" ),
-               'cantimport' => array( 'code' => 'cantimport', 'info' => "You don't have permission to import pages" ),
-               'cantimport-upload' => array( 'code' => 'cantimport-upload', 'info' => "You don't have permission to import uploaded pages" ),
-               'nouploadmodule' => array( 'code' => 'nomodule', 'info' => 'No upload module set' ),
-               'importnofile' => array( 'code' => 'nofile', 'info' => "You didn't upload a file" ),
-               'importuploaderrorsize' => array( 'code' => 'filetoobig', 'info' => 'The file you uploaded is bigger than the maximum upload size' ),
-               'importuploaderrorpartial' => array( 'code' => 'partialupload', 'info' => 'The file was only partially uploaded' ),
-               'importuploaderrortemp' => array( 'code' => 'notempdir', 'info' => 'The temporary upload directory is missing' ),
-               'importcantopen' => array( 'code' => 'cantopenfile', 'info' => "Couldn't open the uploaded file" ),
-               'import-noarticle' => array( 'code' => 'badinterwiki', 'info' => 'Invalid interwiki title specified' ),
-               'importbadinterwiki' => array( 'code' => 'badinterwiki', 'info' => 'Invalid interwiki title specified' ),
-               'import-unknownerror' => array( 'code' => 'import-unknownerror', 'info' => "Unknown error on import: ``\$1''" ),
-               'cantoverwrite-sharedfile' => array( 'code' => 'cantoverwrite-sharedfile', 'info' => 'The target file exists on a shared repository and you do not have permission to override it' ),
-               'sharedfile-exists' => array( 'code' => 'fileexists-sharedrepo-perm', 'info' => 'The target file exists on a shared repository. Use the ignorewarnings parameter to override it.' ),
-               'mustbeposted' => array( 'code' => 'mustbeposted', 'info' => "The \$1 module requires a POST request" ),
-               'show' => array( 'code' => 'show', 'info' => 'Incorrect parameter - mutually exclusive values may not be supplied' ),
-
-               // ApiEditPage messages
-               'noimageredirect-anon' => array( 'code' => 'noimageredirect-anon', 'info' => "Anonymous users can't create image redirects" ),
-               'noimageredirect-logged' => array( 'code' => 'noimageredirect', 'info' => "You don't have permission to create image redirects" ),
-               'spamdetected' => array( 'code' => 'spamdetected', 'info' => "Your edit was refused because it contained a spam fragment: ``\$1''" ),
-               'filtered' => array( 'code' => 'filtered', 'info' => "The filter callback function refused your edit" ),
-               'contenttoobig' => array( 'code' => 'contenttoobig', 'info' => "The content you supplied exceeds the article size limit of \$1 kilobytes" ),
-               'noedit-anon' => array( 'code' => 'noedit-anon', 'info' => "Anonymous users can't edit pages" ),
-               'noedit' => array( 'code' => 'noedit', 'info' => "You don't have permission to edit pages" ),
-               'wasdeleted' => array( 'code' => 'pagedeleted', 'info' => "The page has been deleted since you fetched its timestamp" ),
-               'blankpage' => array( 'code' => 'emptypage', 'info' => "Creating new, empty pages is not allowed" ),
-               'editconflict' => array( 'code' => 'editconflict', 'info' => "Edit conflict detected" ),
-               'hashcheckfailed' => array( 'code' => 'badmd5', 'info' => "The supplied MD5 hash was incorrect" ),
-               'missingtext' => array( 'code' => 'notext', 'info' => "One of the text, appendtext, prependtext and undo parameters must be set" ),
-               'emptynewsection' => array( 'code' => 'emptynewsection', 'info' => 'Creating empty new sections is not possible.' ),
-               'revwrongpage' => array( 'code' => 'revwrongpage', 'info' => "r\$1 is not a revision of ``\$2''" ),
-               'undo-failure' => array( 'code' => 'undofailure', 'info' => 'Undo failed due to conflicting intermediate edits' ),
-
-               // uploadMsgs
-               'invalid-session-key' => array( 'code' => 'invalid-session-key', 'info' => 'Not a valid session key' ),
-               'nouploadmodule' => array( 'code' => 'nouploadmodule', 'info' => 'No upload module set' ),
-               'uploaddisabled' => array( 'code' => 'uploaddisabled', 'info' => 'Uploads are not enabled.  Make sure $wgEnableUploads is set to true in LocalSettings.php and the PHP ini setting file_uploads is true' ),
-               'copyuploaddisabled' => array( 'code' => 'copyuploaddisabled', 'info' => 'Uploads by URL is not enabled.  Make sure $wgAllowCopyUploads is set to true in LocalSettings.php.' ),
-       );
 
        /**
-        * Helper function for readonly errors
+        * Returns the description string for this module
+        *
+        * Ignored if an i18n message exists for
+        * "apihelp-{$this->getModulePath()}-description".
+        *
+        * @deprecated since 1.25
+        * @return Message|string|array|false
         */
-       public function dieReadOnly() {
-               $parsed = $this->parseMsg( array( 'readonlytext' ) );
-               $this->dieUsage( $parsed['info'], $parsed['code'], /* http error */ 0,
-                       array( 'readonlyreason' => wfReadOnlyReason() ) );
+       protected function getDescription() {
+               return false;
        }
 
        /**
-        * Output the error message related to a certain array
-        * @param $error array Element of a getUserPermissionsErrors()-style array
+        * Returns an array of parameter descriptions.
+        *
+        * For each parameter, ignored if an i18n message exists for the parameter.
+        * By default that message is
+        * "apihelp-{$this->getModulePath()}-param-{$param}", but it may be
+        * overridden using ApiBase::PARAM_HELP_MSG in the data returned by
+        * self::getFinalParams().
+        *
+        * @deprecated since 1.25
+        * @return array|bool False on no parameter descriptions
         */
-       public function dieUsageMsg( $error ) {
-               $parsed = $this->parseMsg( $error );
-               $this->dieUsage( $parsed['info'], $parsed['code'] );
+       protected function getParamDescription() {
+               return [];
        }
 
        /**
-        * Return the error message related to a certain array
-        * @param $error array Element of a getUserPermissionsErrors()-style array
-        * @return array('code' => code, 'info' => info)
+        * Returns usage examples for this module.
+        *
+        * Return value as an array is either:
+        *  - numeric keys with partial URLs ("api.php?" plus a query string) as
+        *    values
+        *  - sequential numeric keys with even-numbered keys being display-text
+        *    and odd-numbered keys being partial urls
+        *  - partial URLs as keys with display-text (string or array-to-be-joined)
+        *    as values
+        * Return value as a string is the same as an array with a numeric key and
+        * that value, and boolean false means "no examples".
+        *
+        * @deprecated since 1.25, use getExamplesMessages() instead
+        * @return bool|string|array
         */
-       public function parseMsg( $error ) {
-               $key = array_shift( $error );
-               if ( isset( self::$messageMap[$key] ) ) {
-                       return array( 'code' =>
-                               wfMsgReplaceArgs( self::$messageMap[$key]['code'], $error ),
-                                       'info' =>
-                               wfMsgReplaceArgs( self::$messageMap[$key]['info'], $error )
-                       );
-               }
-               // If the key isn't present, throw an "unknown error"
-               return $this->parseMsg( array( 'unknownerror', $key ) );
+       protected function getExamples() {
+               return false;
        }
 
        /**
-        * Internal code errors should be reported with this method
-        * @param $method string Method or function name
-        * @param $message string Error message
+        * @deprecated since 1.25, always returns empty string
+        * @param IDatabase|bool $db
+        * @return string
         */
-       protected static function dieDebug( $method, $message ) {
-               wfDebugDieBacktrace( "Internal error in $method: $message" );
+       public function getModuleProfileName( $db = false ) {
+               wfDeprecated( __METHOD__, '1.25' );
+               return '';
        }
 
        /**
-        * Indicates if this module needs maxlag to be checked
-        * @return bool
+        * @deprecated since 1.25
         */
-       public function shouldCheckMaxlag() {
-               return true;
+       public function profileIn() {
+               // No wfDeprecated() yet because extensions call this and might need to
+               // keep doing so for BC.
        }
 
        /**
-        * Indicates whether this module requires read rights
-        * @return bool
+        * @deprecated since 1.25
         */
-       public function isReadMode() {
-               return true;
+       public function profileOut() {
+               // No wfDeprecated() yet because extensions call this and might need to
+               // keep doing so for BC.
        }
+
        /**
-        * Indicates whether this module requires write mode
-        * @return bool
+        * @deprecated since 1.25
         */
-       public function isWriteMode() {
-               return false;
+       public function safeProfileOut() {
+               wfDeprecated( __METHOD__, '1.25' );
        }
 
        /**
-        * Indicates whether this module must be called with a POST request
-        * @return bool
+        * @deprecated since 1.25, always returns 0
+        * @return float
         */
-       public function mustBePosted() {
-               return false;
+       public function getProfileTime() {
+               wfDeprecated( __METHOD__, '1.25' );
+               return 0;
        }
 
        /**
-        * Returns whether this module requires a Token to execute
-        * @returns bool
+        * @deprecated since 1.25
         */
-       public function needsToken() {
-               return false;
+       public function profileDBIn() {
+               wfDeprecated( __METHOD__, '1.25' );
        }
 
        /**
-        * Returns the token salt if there is one, '' if the module doesn't require a salt, else false if the module doesn't need a token
-        * @returns bool
+        * @deprecated since 1.25
         */
-       public function getTokenSalt() {
-               return false;
+       public function profileDBOut() {
+               wfDeprecated( __METHOD__, '1.25' );
        }
 
        /**
-       * Gets the user for whom to get the watchlist
-       *
-       * @returns User
-       */
-       public function getWatchlistUser( $params ) {
-               global $wgUser;
-               if ( !is_null( $params['owner'] ) && !is_null( $params['token'] ) ) {
-                       $user = User::newFromName( $params['owner'], false );
-                       if ( !$user->getId() ) {
-                               $this->dieUsage( 'Specified user does not exist', 'bad_wlowner' );
-                       }
-                       $token = $user->getOption( 'watchlisttoken' );
-                       if ( $token == '' || $token != $params['token'] ) {
-                               $this->dieUsage( 'Incorrect watchlist token provided -- please set a correct token in Special:Preferences', 'bad_wltoken' );
-                       }
-               } else {
-                       if ( !$wgUser->isLoggedIn() ) {
-                               $this->dieUsage( 'You must be logged-in to have a watchlist', 'notloggedin' );
-                       }
-                       $user = $wgUser;
-               }
-               return $user;
+        * @deprecated since 1.25, always returns 0
+        * @return float
+        */
+       public function getProfileDBTime() {
+               wfDeprecated( __METHOD__, '1.25' );
+               return 0;
        }
 
        /**
-        * Returns a list of all possible errors returned by the module
-        * @return array in the format of array( key, param1, param2, ... ) or array( 'code' => ..., 'info' => ... )
+        * Call wfTransactionalTimeLimit() if this request was POSTed
+        * @since 1.26
         */
-       public function getPossibleErrors() {
-               $ret = array();
-
-               $params = $this->getFinalParams();
-               if ( $params ) {
-                       foreach ( $params as $paramName => $paramSettings ) {
-                               if ( isset( $paramSettings[ApiBase::PARAM_REQUIRED] ) ) {
-                                       $ret[] = array( 'missingparam', $paramName );
-                               }
-                       }
-               }
-
-               if ( $this->mustBePosted() ) {
-                       $ret[] = array( 'mustbeposted', $this->getModuleName() );
-               }
-
-               if ( $this->isReadMode() ) {
-                       $ret[] = array( 'readrequired' );
+       protected function useTransactionalTimeLimit() {
+               if ( $this->getRequest()->wasPosted() ) {
+                       wfTransactionalTimeLimit();
                }
-
-               if ( $this->isWriteMode() ) {
-                       $ret[] = array( 'writerequired' );
-                       $ret[] = array( 'writedisabled' );
-               }
-
-               if ( $this->needsToken() ) {
-                       $ret[] = array( 'missingparam', 'token' );
-                       $ret[] = array( 'sessionfailure' );
-               }
-
-               return $ret;
        }
 
        /**
-        * Parses a list of errors into a standardised format
-        * @param $errors array List of errors. Items can be in the for array( key, param1, param2, ... ) or array( 'code' => ..., 'info' => ... )
-        * @return array Parsed list of errors with items in the form array( 'code' => ..., 'info' => ... )
+        * @deprecated since 1.29, use ApiBase::addWarning() instead
+        * @param string $warning Warning message
         */
-       public function parseErrors( $errors ) {
-               $ret = array();
-
-               foreach ( $errors as $row ) {
-                       if ( isset( $row['code'] ) && isset( $row['info'] ) ) {
-                               $ret[] = $row;
-                       } else {
-                               $ret[] = $this->parseMsg( $row );
-                       }
-               }
-               return $ret;
+       public function setWarning( $warning ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               $msg = new ApiRawMessage( $warning, 'warning' );
+               $this->getErrorFormatter()->addWarning( $this->getModulePath(), $msg );
        }
 
        /**
-        * Profiling: total module execution time
+        * Throw an ApiUsageException, which will (if uncaught) call the main module's
+        * error handler and die with an error message.
+        *
+        * @deprecated since 1.29, use self::dieWithError() instead
+        * @param string $description One-line human-readable description of the
+        *   error condition, e.g., "The API requires a valid action parameter"
+        * @param string $errorCode Brief, arbitrary, stable string to allow easy
+        *   automated identification of the error, e.g., 'unknown_action'
+        * @param int $httpRespCode HTTP response code
+        * @param array|null $extradata Data to add to the "<error>" element; array in ApiResult format
+        * @throws ApiUsageException always
         */
-       private $mTimeIn = 0, $mModuleTime = 0;
+       public function dieUsage( $description, $errorCode, $httpRespCode = 0, $extradata = null ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               $this->dieWithError(
+                       new RawMessage( '$1', [ $description ] ),
+                       $errorCode,
+                       $extradata,
+                       $httpRespCode
+               );
+       }
 
        /**
-        * Start module profiling
+        * Get error (as code, string) from a Status object.
+        *
+        * @since 1.23
+        * @deprecated since 1.29, use ApiErrorFormatter::arrayFromStatus instead
+        * @param Status $status
+        * @param array|null &$extraData Set if extra data from IApiMessage is available (since 1.27)
+        * @return array Array of code and error string
+        * @throws MWException
         */
-       public function profileIn() {
-               if ( $this->mTimeIn !== 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called twice without calling profileOut()' );
+       public function getErrorFromStatus( $status, &$extraData = null ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               if ( $status->isGood() ) {
+                       throw new MWException( 'Successful status passed to ApiBase::dieStatus' );
                }
-               $this->mTimeIn = microtime( true );
-               wfProfileIn( $this->getModuleProfileName() );
-       }
 
-       /**
-        * End module profiling
-        */
-       public function profileOut() {
-               if ( $this->mTimeIn === 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called without calling profileIn() first' );
+               $errors = $status->getErrorsByType( 'error' );
+               if ( !$errors ) {
+                       // No errors? Assume the warnings should be treated as errors
+                       $errors = $status->getErrorsByType( 'warning' );
                }
-               if ( $this->mDBTimeIn !== 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'must be called after database profiling is done with profileDBOut()' );
+               if ( !$errors ) {
+                       // Still no errors? Punt
+                       $errors = [ [ 'message' => 'unknownerror-nocode', 'params' => [] ] ];
                }
 
-               $this->mModuleTime += microtime( true ) - $this->mTimeIn;
-               $this->mTimeIn = 0;
-               wfProfileOut( $this->getModuleProfileName() );
-       }
-
-       /**
-        * When modules crash, sometimes it is needed to do a profileOut() regardless
-        * of the profiling state the module was in. This method does such cleanup.
-        */
-       public function safeProfileOut() {
-               if ( $this->mTimeIn !== 0 ) {
-                       if ( $this->mDBTimeIn !== 0 ) {
-                               $this->profileDBOut();
-                       }
-                       $this->profileOut();
+               if ( $errors[0]['message'] instanceof MessageSpecifier ) {
+                       $msg = $errors[0]['message'];
+               } else {
+                       $msg = new Message( $errors[0]['message'], $errors[0]['params'] );
                }
-       }
-
-       /**
-        * Total time the module was executed
-        * @return float
-        */
-       public function getProfileTime() {
-               if ( $this->mTimeIn !== 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called without calling profileOut() first' );
+               if ( !$msg instanceof IApiMessage ) {
+                       $key = $msg->getKey();
+                       $params = $msg->getParams();
+                       array_unshift( $params, isset( self::$messageMap[$key] ) ? self::$messageMap[$key] : $key );
+                       $msg = ApiMessage::create( $params );
                }
-               return $this->mModuleTime;
+
+               return [
+                       $msg->getApiCode(),
+                       ApiErrorFormatter::stripMarkup( $msg->inLanguage( 'en' )->useDatabase( false )->text() )
+               ];
        }
 
        /**
-        * Profiling: database execution time
+        * @deprecated since 1.29. Prior to 1.29, this was a public mapping from
+        *  arbitrary strings (often message keys used elsewhere in MediaWiki) to
+        *  API codes and message texts, and a few interfaces required poking
+        *  something in here. Now we're repurposing it to map those same strings
+        *  to i18n messages, and declaring that any interface that requires poking
+        *  at this is broken and needs replacing ASAP.
         */
-       private $mDBTimeIn = 0, $mDBTime = 0;
+       private static $messageMap = [
+               'unknownerror' => 'apierror-unknownerror',
+               'unknownerror-nocode' => 'apierror-unknownerror-nocode',
+               'ns-specialprotected' => 'ns-specialprotected',
+               'protectedinterface' => 'protectedinterface',
+               'namespaceprotected' => 'namespaceprotected',
+               'customcssprotected' => 'customcssprotected',
+               'customjsprotected' => 'customjsprotected',
+               'cascadeprotected' => 'cascadeprotected',
+               'protectedpagetext' => 'protectedpagetext',
+               'protect-cantedit' => 'protect-cantedit',
+               'deleteprotected' => 'deleteprotected',
+               'badaccess-group0' => 'badaccess-group0',
+               'badaccess-groups' => 'badaccess-groups',
+               'titleprotected' => 'titleprotected',
+               'nocreate-loggedin' => 'nocreate-loggedin',
+               'nocreatetext' => 'nocreatetext',
+               'movenologintext' => 'movenologintext',
+               'movenotallowed' => 'movenotallowed',
+               'confirmedittext' => 'confirmedittext',
+               'blockedtext' => 'apierror-blocked',
+               'autoblockedtext' => 'apierror-autoblocked',
+               'systemblockedtext' => 'apierror-systemblocked',
+               'actionthrottledtext' => 'apierror-ratelimited',
+               'alreadyrolled' => 'alreadyrolled',
+               'cantrollback' => 'cantrollback',
+               'readonlytext' => 'readonlytext',
+               'sessionfailure' => 'sessionfailure',
+               'cannotdelete' => 'cannotdelete',
+               'notanarticle' => 'apierror-missingtitle',
+               'selfmove' => 'selfmove',
+               'immobile_namespace' => 'apierror-immobilenamespace',
+               'articleexists' => 'articleexists',
+               'hookaborted' => 'hookaborted',
+               'cantmove-titleprotected' => 'cantmove-titleprotected',
+               'imagenocrossnamespace' => 'imagenocrossnamespace',
+               'imagetypemismatch' => 'imagetypemismatch',
+               'ip_range_invalid' => 'ip_range_invalid',
+               'range_block_disabled' => 'range_block_disabled',
+               'nosuchusershort' => 'nosuchusershort',
+               'badipaddress' => 'badipaddress',
+               'ipb_expiry_invalid' => 'ipb_expiry_invalid',
+               'ipb_already_blocked' => 'ipb_already_blocked',
+               'ipb_blocked_as_range' => 'ipb_blocked_as_range',
+               'ipb_cant_unblock' => 'ipb_cant_unblock',
+               'mailnologin' => 'apierror-cantsend',
+               'ipbblocked' => 'ipbblocked',
+               'ipbnounblockself' => 'ipbnounblockself',
+               'usermaildisabled' => 'usermaildisabled',
+               'blockedemailuser' => 'apierror-blockedfrommail',
+               'notarget' => 'apierror-notarget',
+               'noemail' => 'noemail',
+               'rcpatroldisabled' => 'rcpatroldisabled',
+               'markedaspatrollederror-noautopatrol' => 'markedaspatrollederror-noautopatrol',
+               'delete-toobig' => 'delete-toobig',
+               'movenotallowedfile' => 'movenotallowedfile',
+               'userrights-no-interwiki' => 'userrights-no-interwiki',
+               'userrights-nodatabase' => 'userrights-nodatabase',
+               'nouserspecified' => 'nouserspecified',
+               'noname' => 'noname',
+               'summaryrequired' => 'apierror-summaryrequired',
+               'import-rootpage-invalid' => 'import-rootpage-invalid',
+               'import-rootpage-nosubpage' => 'import-rootpage-nosubpage',
+               'readrequired' => 'apierror-readapidenied',
+               'writedisabled' => 'apierror-noapiwrite',
+               'writerequired' => 'apierror-writeapidenied',
+               'missingparam' => 'apierror-missingparam',
+               'invalidtitle' => 'apierror-invalidtitle',
+               'nosuchpageid' => 'apierror-nosuchpageid',
+               'nosuchrevid' => 'apierror-nosuchrevid',
+               'nosuchuser' => 'nosuchusershort',
+               'invaliduser' => 'apierror-invaliduser',
+               'invalidexpiry' => 'apierror-invalidexpiry',
+               'pastexpiry' => 'apierror-pastexpiry',
+               'create-titleexists' => 'apierror-create-titleexists',
+               'missingtitle-createonly' => 'apierror-missingtitle-createonly',
+               'cantblock' => 'apierror-cantblock',
+               'canthide' => 'apierror-canthide',
+               'cantblock-email' => 'apierror-cantblock-email',
+               'cantunblock' => 'apierror-permissiondenied-generic',
+               'cannotundelete' => 'cannotundelete',
+               'permdenied-undelete' => 'apierror-permissiondenied-generic',
+               'createonly-exists' => 'apierror-articleexists',
+               'nocreate-missing' => 'apierror-missingtitle',
+               'cantchangecontentmodel' => 'apierror-cantchangecontentmodel',
+               'nosuchrcid' => 'apierror-nosuchrcid',
+               'nosuchlogid' => 'apierror-nosuchlogid',
+               'protect-invalidaction' => 'apierror-protect-invalidaction',
+               'protect-invalidlevel' => 'apierror-protect-invalidlevel',
+               'toofewexpiries' => 'apierror-toofewexpiries',
+               'cantimport' => 'apierror-cantimport',
+               'cantimport-upload' => 'apierror-cantimport-upload',
+               'importnofile' => 'importnofile',
+               'importuploaderrorsize' => 'importuploaderrorsize',
+               'importuploaderrorpartial' => 'importuploaderrorpartial',
+               'importuploaderrortemp' => 'importuploaderrortemp',
+               'importcantopen' => 'importcantopen',
+               'import-noarticle' => 'import-noarticle',
+               'importbadinterwiki' => 'importbadinterwiki',
+               'import-unknownerror' => 'apierror-import-unknownerror',
+               'cantoverwrite-sharedfile' => 'apierror-cantoverwrite-sharedfile',
+               'sharedfile-exists' => 'apierror-fileexists-sharedrepo-perm',
+               'mustbeposted' => 'apierror-mustbeposted',
+               'show' => 'apierror-show',
+               'specialpage-cantexecute' => 'apierror-specialpage-cantexecute',
+               'invalidoldimage' => 'apierror-invalidoldimage',
+               'nodeleteablefile' => 'apierror-nodeleteablefile',
+               'fileexists-forbidden' => 'fileexists-forbidden',
+               'fileexists-shared-forbidden' => 'fileexists-shared-forbidden',
+               'filerevert-badversion' => 'filerevert-badversion',
+               'noimageredirect-anon' => 'apierror-noimageredirect-anon',
+               'noimageredirect-logged' => 'apierror-noimageredirect',
+               'spamdetected' => 'apierror-spamdetected',
+               'contenttoobig' => 'apierror-contenttoobig',
+               'noedit-anon' => 'apierror-noedit-anon',
+               'noedit' => 'apierror-noedit',
+               'wasdeleted' => 'apierror-pagedeleted',
+               'blankpage' => 'apierror-emptypage',
+               'editconflict' => 'editconflict',
+               'hashcheckfailed' => 'apierror-badmd5',
+               'missingtext' => 'apierror-notext',
+               'emptynewsection' => 'apierror-emptynewsection',
+               'revwrongpage' => 'apierror-revwrongpage',
+               'undo-failure' => 'undo-failure',
+               'content-not-allowed-here' => 'content-not-allowed-here',
+               'edit-hook-aborted' => 'edit-hook-aborted',
+               'edit-gone-missing' => 'edit-gone-missing',
+               'edit-conflict' => 'edit-conflict',
+               'edit-already-exists' => 'edit-already-exists',
+               'invalid-file-key' => 'apierror-invalid-file-key',
+               'nouploadmodule' => 'apierror-nouploadmodule',
+               'uploaddisabled' => 'uploaddisabled',
+               'copyuploaddisabled' => 'copyuploaddisabled',
+               'copyuploadbaddomain' => 'apierror-copyuploadbaddomain',
+               'copyuploadbadurl' => 'apierror-copyuploadbadurl',
+               'filename-tooshort' => 'filename-tooshort',
+               'filename-toolong' => 'filename-toolong',
+               'illegal-filename' => 'illegal-filename',
+               'filetype-missing' => 'filetype-missing',
+               'mustbeloggedin' => 'apierror-mustbeloggedin',
+       ];
 
        /**
-        * Start module profiling
+        * @deprecated do not use
+        * @param array|string|MessageSpecifier $error Element of a getUserPermissionsErrors()-style array
+        * @return ApiMessage
         */
-       public function profileDBIn() {
-               if ( $this->mTimeIn === 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'must be called while profiling the entire module with profileIn()' );
-               }
-               if ( $this->mDBTimeIn !== 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called twice without calling profileDBOut()' );
+       private function parseMsgInternal( $error ) {
+               $msg = Message::newFromSpecifier( $error );
+               if ( !$msg instanceof IApiMessage ) {
+                       $key = $msg->getKey();
+                       if ( isset( self::$messageMap[$key] ) ) {
+                               $params = $msg->getParams();
+                               array_unshift( $params, self::$messageMap[$key] );
+                       } else {
+                               $params = [ 'apierror-unknownerror', wfEscapeWikiText( $key ) ];
+                       }
+                       $msg = ApiMessage::create( $params );
                }
-               $this->mDBTimeIn = microtime( true );
-               wfProfileIn( $this->getModuleProfileName( true ) );
+               return $msg;
        }
 
        /**
-        * End database profiling
+        * Return the error message related to a certain array
+        * @deprecated since 1.29
+        * @param array|string|MessageSpecifier $error Element of a getUserPermissionsErrors()-style array
+        * @return array [ 'code' => code, 'info' => info ]
         */
-       public function profileDBOut() {
-               if ( $this->mTimeIn === 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'must be called while profiling the entire module with profileIn()' );
-               }
-               if ( $this->mDBTimeIn === 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called without calling profileDBIn() first' );
+       public function parseMsg( $error ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               // Check whether someone passed the whole array, instead of one element as
+               // documented. This breaks if it's actually an array of fallback keys, but
+               // that's long-standing misbehavior introduced in r87627 to incorrectly
+               // fix T30797.
+               if ( is_array( $error ) ) {
+                       $first = reset( $error );
+                       if ( is_array( $first ) ) {
+                               wfDebug( __METHOD__ . ' was passed an array of arrays. ' . wfGetAllCallers( 5 ) );
+                               $error = $first;
+                       }
                }
 
-               $time = microtime( true ) - $this->mDBTimeIn;
-               $this->mDBTimeIn = 0;
-
-               $this->mDBTime += $time;
-               $this->getMain()->mDBTime += $time;
-               wfProfileOut( $this->getModuleProfileName( true ) );
+               $msg = $this->parseMsgInternal( $error );
+               return [
+                       'code' => $msg->getApiCode(),
+                       'info' => ApiErrorFormatter::stripMarkup(
+                               $msg->inLanguage( 'en' )->useDatabase( false )->text()
+                       ),
+                       'data' => $msg->getApiData()
+               ];
        }
 
        /**
-        * Total time the module used the database
-        * @return float
+        * Output the error message related to a certain array
+        * @deprecated since 1.29, use ApiBase::dieWithError() instead
+        * @param array|string|MessageSpecifier $error Element of a getUserPermissionsErrors()-style array
+        * @throws ApiUsageException always
         */
-       public function getProfileDBTime() {
-               if ( $this->mDBTimeIn !== 0 ) {
-                       ApiBase::dieDebug( __METHOD__, 'called without calling profileDBOut() first' );
-               }
-               return $this->mDBTime;
+       public function dieUsageMsg( $error ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               $this->dieWithError( $this->parseMsgInternal( $error ) );
        }
 
        /**
-        * Debugging function that prints a value and an optional backtrace
-        * @param $value mixed Value to print
-        * @param $name string Description of the printed value
-        * @param $backtrace bool If true, print a backtrace
+        * Will only set a warning instead of failing if the global $wgDebugAPI
+        * is set to true. Otherwise behaves exactly as dieUsageMsg().
+        * @deprecated since 1.29, use ApiBase::dieWithErrorOrDebug() instead
+        * @param array|string|MessageSpecifier $error Element of a getUserPermissionsErrors()-style array
+        * @throws ApiUsageException
+        * @since 1.21
         */
-       public static function debugPrint( $value, $name = 'unknown', $backtrace = false ) {
-               print "\n\n<pre><b>Debugging value '$name':</b>\n\n";
-               var_export( $value );
-               if ( $backtrace ) {
-                       print "\n" . wfBacktrace();
-               }
-               print "\n</pre>\n";
+       public function dieUsageMsgOrDebug( $error ) {
+               wfDeprecated( __METHOD__, '1.29' );
+               $this->dieWithErrorOrDebug( $this->parseMsgInternal( $error ) );
        }
 
        /**
-        * Returns a string that identifies the version of this class.
-        * @return string
+        * Return the description message.
+        *
+        * This is additional text to display on the help page after the summary.
+        *
+        * @deprecated since 1.30
+        * @return string|array|Message
         */
-       public static function getBaseVersion() {
-               return __CLASS__ . ': $Id$';
+       protected function getDescriptionMessage() {
+               return [ [
+                       "apihelp-{$this->getModulePath()}-description",
+                       "apihelp-{$this->getModulePath()}-summary",
+               ] ];
        }
+
+       /**@}*/
 }
+
+/**
+ * For really cool vim folding this needs to be at the end:
+ * vim: foldmarker=@{,@} foldmethod=marker
+ */