<?php
/**
 * See deferred.txt
 * @package MediaWiki
 */

/**
 * @todo document
 * @package MediaWiki
 */
class LinksUpdate {

	/**#@+
	 * @access private
	 */
	var $mId, $mTitle;
	/**#@-*/

	/**
	 * Constructor
	 * Initialize private variables
	 * @param integer $id
	 * @param string $title
	 */
	function LinksUpdate( $id, $title ) {
		$this->mId = $id;
		$this->mTitle = $title;
	}

	/**
	 * Update link tables with outgoing links from an updated article
	 * Relies on the 'link cache' to be filled out.
	 */
	
	function doUpdate() {
		global $wgUseDumbLinkUpdate, $wgLinkCache, $wgDBtransactions;
		global $wgUseCategoryMagic;

		if ( $wgUseDumbLinkUpdate ) {
			$this->doDumbUpdate();
			return;
		}

		$fname = 'LinksUpdate::doUpdate';
		wfProfileIn( $fname );

		$del = array();
		$add = array();

		$dbw =& wfGetDB( DB_MASTER );
		$pagelinks = $dbw->tableName( 'pagelinks' );
		$imagelinks = $dbw->tableName( 'imagelinks' );
		$categorylinks = $dbw->tableName( 'categorylinks' );
		
		#------------------------------------------------------------------------------
		# Good links

		if ( $wgLinkCache->incrementalSetup( LINKCACHE_PAGE, $del, $add ) ) {
			# Delete where necessary
			if ( count( $del ) ) {
				$batch = new LinkBatch( $del );
				$set = $batch->constructSet( 'pl', $dbw );
				if ( $set ) {
					$sql = "DELETE FROM $pagelinks WHERE pl_from={$this->mId} AND ($set)";
					$dbw->query( $sql, $fname );
				}
			}
		} else {
			# Delete everything
			$dbw->delete( 'pagelinks', array( 'pl_from' => $this->mId ), $fname );
						
			# Get the addition list
			$add = $wgLinkCache->getPageLinks();
		}

		# Do the insertion
		if( 0 != count( $add ) ) {
			$arr = array();
			foreach( $add as $lt => $target ) {
				array_push( $arr, array(
							'pl_from' => $this->mId,
							'pl_namespace' => $target->getNamespace(),
							'pl_title'     => $target->getDbKey() ) );
			}
			
			# The link cache was constructed without FOR UPDATE, so there may be collisions
			# Ignoring for now, I'm not sure if that causes problems or not, but I'm fairly
			# sure it's better than without IGNORE
			$dbw->insert( 'pagelinks', $arr, $fname, array( 'IGNORE' ) );
		}

		#------------------------------------------------------------------------------
		# Image links
		$dbw->delete('imagelinks',array('il_from'=>$this->mId),$fname);
		
		# Get addition list
		$add = $wgLinkCache->getImageLinks();
		
		# Do the insertion
		$sql = '';
		$image = NS_IMAGE;
		if ( 0 != count ( $add ) ) {
			$arr = array();
			foreach ($add as $iname => $val ) {
				$nt = Title::makeTitle( $image, $iname );
				if( !$nt ) continue;
				$nt->invalidateCache();
				array_push( $arr, array(
					'il_from' => $this->mId,
					'il_to'   => $iname ) );
			}
			$dbw->insert('imagelinks', $arr, $fname, array('IGNORE'));
		}

		#------------------------------------------------------------------------------
		# Category links
		if( $wgUseCategoryMagic ) {
			global $messageMemc, $wgDBname;
			
			# Get addition list
			$add = $wgLinkCache->getCategoryLinks();
			
			# select existing catlinks for this page
			$res = $dbw->select( 'categorylinks',
				array( 'cl_to', 'cl_sortkey' ),
				array( 'cl_from' => $this->mId ), 
				$fname,
				'FOR UPDATE' );

			$del = array();
			if( 0 != $dbw->numRows( $res ) ) {
				while( $row = $dbw->fetchObject( $res ) ) {
					if( !isset( $add[$row->cl_to] ) || $add[$row->cl_to] != $row->cl_sortkey ) {
						// in the db, but no longer in the page
						// or sortkey has changed -> delete
						$del[] = $row->cl_to;
					} else {
						// remove already existing category memberships
						// from the add array
						unset( $add[$row->cl_to] );
					}
				}
			}
			
			// delete any removed categorylinks
			if( count( $del ) > 0) {
				// delete old ones
				$dbw->delete( 'categorylinks',
					array(
						'cl_from' => $this->mId,
						'cl_to'   => $del ),
					$fname );
				foreach( $del as $cname ){
					$nt = Title::makeTitle( NS_CATEGORY, $cname );
					$nt->invalidateCache();
					// update the timestamp which indicates when the last article
					// was added or removed to/from this article
					$key = $wgDBname . ':Category:' . md5( $nt->getDBkey() ) . ':adddeltimestamp';
					$messageMemc->set( $key , wfTimestamp( TS_MW ), 24*3600 );
				}
			}
			
			// add any new category memberships
			if( count( $add ) > 0 ) {
				$arr = array();
				foreach( $add as $cname => $sortkey ) {
					$nt = Title::makeTitle( NS_CATEGORY, $cname );
					$nt->invalidateCache();
					// update the timestamp which indicates when the last article
					// was added or removed to/from this article
					$key = $wgDBname . ':Category:' . md5( $nt->getDBkey() ) . ':adddeltimestamp';
					$messageMemc->set( $key , wfTimestamp( TS_MW ), 24*3600 );
					array_push( $arr, array(
						'cl_from'    => $this->mId,
						'cl_to'      => $cname,
						'cl_sortkey' => $sortkey ) );
				}
				// do the actual sql insertion
				$dbw->insert( 'categorylinks', $arr, $fname, array( 'IGNORE' ) );
			}
		}
		
		wfProfileOut( $fname );
	}

	/**
	  * Link update which clears the previous entries and inserts new ones
	  * May be slower or faster depending on level of lock contention and write speed of DB
	  * Also useful where link table corruption needs to be repaired, e.g. in refreshLinks.php
	 */
	function doDumbUpdate() {
		global $wgLinkCache, $wgDBtransactions, $wgUseCategoryMagic;
		$fname = 'LinksUpdate::doDumbUpdate';
		wfProfileIn( $fname );
		
		
		$dbw =& wfGetDB( DB_MASTER );
		$pagelinks = $dbw->tableName( 'pagelinks' );
		$imagelinks = $dbw->tableName( 'imagelinks' );
		$categorylinks = $dbw->tableName( 'categorylinks' );
		
		$dbw->delete('pagelinks', array('pl_from'=>$this->mId),$fname);

		$a = $wgLinkCache->getPageLinks();
		if ( 0 != count( $a ) ) {
			$arr = array();
			foreach( $a as $lt => $target ) {
				array_push( $arr, array(
					'pl_from'      => $this->mId,
					'pl_namespace' => $target->getNamespace(),
					'pl_title'     => $target->getDBkey() ) );
			}
			$dbw->insert( 'pagelinks', $arr, $fname, array( 'IGNORE' ) );
		}

		$dbw->delete('imagelinks', array('il_from'=>$this->mId),$fname);

		$a = $wgLinkCache->getImageLinks();
		$sql = '';
		if ( 0 != count ( $a ) ) {
			$arr = array();
			foreach( $a as $iname => $val )
				array_push( $arr, array(
					'il_from' => $this->mId,
					'il_to'   => $iname ) );
			$dbw->insert( 'imagelinks', $arr, $fname, array( 'IGNORE' ) );
		}

		if( $wgUseCategoryMagic ) {
			$dbw->delete('categorylinks', array('cl_from'=>$this->mId),$fname);
			
			# Get addition list
			$add = $wgLinkCache->getCategoryLinks();
			
			# Do the insertion
			$sql = '';
			if ( 0 != count ( $add ) ) {
				$arr = array();
				foreach( $add as $cname => $sortkey ) {
					# FIXME: Change all this to avoid unnecessary duplication
					$nt = Title::makeTitle( NS_CATEGORY, $cname );
                                        if( !$nt ) continue;
                                        $nt->invalidateCache();
					array_push( $arr, array(
						'cl_from'    => $this->mId,
						'cl_to'      => $cname,
						'cl_sortkey' => $sortkey ) );
				}
				$dbw->insert( 'categorylinks', $arr, $fname, array( 'IGNORE' ) );
			}
		}
		wfProfileOut( $fname );
	}
}
?>