--- /dev/null
+<?php
+
+/*
+ * This file is part of the JsonSchema package.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JsonSchema\Uri;
+
+use JsonSchema\Exception\InvalidSchemaMediaTypeException;
+use JsonSchema\Exception\JsonDecodingException;
+use JsonSchema\Exception\ResourceNotFoundException;
+use JsonSchema\Uri\Retrievers\FileGetContents;
+use JsonSchema\Uri\Retrievers\UriRetrieverInterface;
+use JsonSchema\UriRetrieverInterface as BaseUriRetrieverInterface;
+use JsonSchema\Validator;
+
+/**
+ * Retrieves JSON Schema URIs
+ *
+ * @author Tyler Akins <fidian@rumkin.com>
+ */
+class UriRetriever implements BaseUriRetrieverInterface
+{
+ /**
+ * @var array Map of URL translations
+ */
+ protected $translationMap = array(
+ // use local copies of the spec schemas
+ '|^https?://json-schema.org/draft-(0[34])/schema#?|' => 'package://dist/schema/json-schema-draft-$1.json'
+ );
+
+ /**
+ * @var null|UriRetrieverInterface
+ */
+ protected $uriRetriever = null;
+
+ /**
+ * @var array|object[]
+ *
+ * @see loadSchema
+ */
+ private $schemaCache = array();
+
+ /**
+ * Guarantee the correct media type was encountered
+ *
+ * @param UriRetrieverInterface $uriRetriever
+ * @param string $uri
+ *
+ * @return bool|void
+ */
+ public function confirmMediaType($uriRetriever, $uri)
+ {
+ $contentType = $uriRetriever->getContentType();
+
+ if (is_null($contentType)) {
+ // Well, we didn't get an invalid one
+ return;
+ }
+
+ if (in_array($contentType, array(Validator::SCHEMA_MEDIA_TYPE, 'application/json'))) {
+ return;
+ }
+
+ if (substr($uri, 0, 23) == 'http://json-schema.org/') {
+ //HACK; they deliver broken content types
+ return true;
+ }
+
+ throw new InvalidSchemaMediaTypeException(sprintf('Media type %s expected', Validator::SCHEMA_MEDIA_TYPE));
+ }
+
+ /**
+ * Get a URI Retriever
+ *
+ * If none is specified, sets a default FileGetContents retriever and
+ * returns that object.
+ *
+ * @return UriRetrieverInterface
+ */
+ public function getUriRetriever()
+ {
+ if (is_null($this->uriRetriever)) {
+ $this->setUriRetriever(new FileGetContents());
+ }
+
+ return $this->uriRetriever;
+ }
+
+ /**
+ * Resolve a schema based on pointer
+ *
+ * URIs can have a fragment at the end in the format of
+ * #/path/to/object and we are to look up the 'path' property of
+ * the first object then the 'to' and 'object' properties.
+ *
+ * @param object $jsonSchema JSON Schema contents
+ * @param string $uri JSON Schema URI
+ *
+ * @throws ResourceNotFoundException
+ *
+ * @return object JSON Schema after walking down the fragment pieces
+ */
+ public function resolvePointer($jsonSchema, $uri)
+ {
+ $resolver = new UriResolver();
+ $parsed = $resolver->parse($uri);
+ if (empty($parsed['fragment'])) {
+ return $jsonSchema;
+ }
+
+ $path = explode('/', $parsed['fragment']);
+ while ($path) {
+ $pathElement = array_shift($path);
+ if (!empty($pathElement)) {
+ $pathElement = str_replace('~1', '/', $pathElement);
+ $pathElement = str_replace('~0', '~', $pathElement);
+ if (!empty($jsonSchema->$pathElement)) {
+ $jsonSchema = $jsonSchema->$pathElement;
+ } else {
+ throw new ResourceNotFoundException(
+ 'Fragment "' . $parsed['fragment'] . '" not found'
+ . ' in ' . $uri
+ );
+ }
+
+ if (!is_object($jsonSchema)) {
+ throw new ResourceNotFoundException(
+ 'Fragment part "' . $pathElement . '" is no object '
+ . ' in ' . $uri
+ );
+ }
+ }
+ }
+
+ return $jsonSchema;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function retrieve($uri, $baseUri = null, $translate = true)
+ {
+ $resolver = new UriResolver();
+ $resolvedUri = $fetchUri = $resolver->resolve($uri, $baseUri);
+
+ //fetch URL without #fragment
+ $arParts = $resolver->parse($resolvedUri);
+ if (isset($arParts['fragment'])) {
+ unset($arParts['fragment']);
+ $fetchUri = $resolver->generate($arParts);
+ }
+
+ // apply URI translations
+ if ($translate) {
+ $fetchUri = $this->translate($fetchUri);
+ }
+
+ $jsonSchema = $this->loadSchema($fetchUri);
+
+ // Use the JSON pointer if specified
+ $jsonSchema = $this->resolvePointer($jsonSchema, $resolvedUri);
+
+ if ($jsonSchema instanceof \stdClass) {
+ $jsonSchema->id = $resolvedUri;
+ }
+
+ return $jsonSchema;
+ }
+
+ /**
+ * Fetch a schema from the given URI, json-decode it and return it.
+ * Caches schema objects.
+ *
+ * @param string $fetchUri Absolute URI
+ *
+ * @return object JSON schema object
+ */
+ protected function loadSchema($fetchUri)
+ {
+ if (isset($this->schemaCache[$fetchUri])) {
+ return $this->schemaCache[$fetchUri];
+ }
+
+ $uriRetriever = $this->getUriRetriever();
+ $contents = $this->uriRetriever->retrieve($fetchUri);
+ $this->confirmMediaType($uriRetriever, $fetchUri);
+ $jsonSchema = json_decode($contents);
+
+ if (JSON_ERROR_NONE < $error = json_last_error()) {
+ throw new JsonDecodingException($error);
+ }
+
+ $this->schemaCache[$fetchUri] = $jsonSchema;
+
+ return $jsonSchema;
+ }
+
+ /**
+ * Set the URI Retriever
+ *
+ * @param UriRetrieverInterface $uriRetriever
+ *
+ * @return $this for chaining
+ */
+ public function setUriRetriever(UriRetrieverInterface $uriRetriever)
+ {
+ $this->uriRetriever = $uriRetriever;
+
+ return $this;
+ }
+
+ /**
+ * Parses a URI into five main components
+ *
+ * @param string $uri
+ *
+ * @return array
+ */
+ public function parse($uri)
+ {
+ preg_match('|^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?|', $uri, $match);
+
+ $components = array();
+ if (5 < count($match)) {
+ $components = array(
+ 'scheme' => $match[2],
+ 'authority' => $match[4],
+ 'path' => $match[5]
+ );
+ }
+
+ if (7 < count($match)) {
+ $components['query'] = $match[7];
+ }
+
+ if (9 < count($match)) {
+ $components['fragment'] = $match[9];
+ }
+
+ return $components;
+ }
+
+ /**
+ * Builds a URI based on n array with the main components
+ *
+ * @param array $components
+ *
+ * @return string
+ */
+ public function generate(array $components)
+ {
+ $uri = $components['scheme'] . '://'
+ . $components['authority']
+ . $components['path'];
+
+ if (array_key_exists('query', $components)) {
+ $uri .= $components['query'];
+ }
+
+ if (array_key_exists('fragment', $components)) {
+ $uri .= $components['fragment'];
+ }
+
+ return $uri;
+ }
+
+ /**
+ * Resolves a URI
+ *
+ * @param string $uri Absolute or relative
+ * @param string $baseUri Optional base URI
+ *
+ * @return string
+ */
+ public function resolve($uri, $baseUri = null)
+ {
+ $components = $this->parse($uri);
+ $path = $components['path'];
+
+ if ((array_key_exists('scheme', $components)) && ('http' === $components['scheme'])) {
+ return $uri;
+ }
+
+ $baseComponents = $this->parse($baseUri);
+ $basePath = $baseComponents['path'];
+
+ $baseComponents['path'] = UriResolver::combineRelativePathWithBasePath($path, $basePath);
+
+ return $this->generate($baseComponents);
+ }
+
+ /**
+ * @param string $uri
+ *
+ * @return bool
+ */
+ public function isValid($uri)
+ {
+ $components = $this->parse($uri);
+
+ return !empty($components);
+ }
+
+ /**
+ * Set a URL translation rule
+ */
+ public function setTranslation($from, $to)
+ {
+ $this->translationMap[$from] = $to;
+ }
+
+ /**
+ * Apply URI translation rules
+ */
+ public function translate($uri)
+ {
+ foreach ($this->translationMap as $from => $to) {
+ $uri = preg_replace($from, $to, $uri);
+ }
+
+ // translate references to local files within the json-schema package
+ $uri = preg_replace('|^package://|', sprintf('file://%s/', realpath(__DIR__ . '/../../..')), $uri);
+
+ return $uri;
+ }
+}