<?php
/**
 * Utility class for creating and accessing recent change entries.
 *
 * 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
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * Utility class for creating new RC entries
 *
 * mAttribs:
 *  rc_id           id of the row in the recentchanges table
 *  rc_timestamp    time the entry was made
 *  rc_namespace    namespace #
 *  rc_title        non-prefixed db key
 *  rc_type         is new entry, used to determine whether updating is necessary
 *  rc_source       string representation of change source
 *  rc_minor        is minor
 *  rc_cur_id       page_id of associated page entry
 *  rc_user         user id who made the entry
 *  rc_user_text    user name who made the entry
 *  rc_comment      edit summary
 *  rc_this_oldid   rev_id associated with this entry (or zero)
 *  rc_last_oldid   rev_id associated with the entry before this one (or zero)
 *  rc_bot          is bot, hidden
 *  rc_ip           IP address of the user in dotted quad notation
 *  rc_new          obsolete, use rc_type==RC_NEW
 *  rc_patrolled    boolean whether or not someone has marked this edit as patrolled
 *  rc_old_len      integer byte length of the text before the edit
 *  rc_new_len      the same after the edit
 *  rc_deleted      partial deletion
 *  rc_logid        the log_id value for this log entry (or zero)
 *  rc_log_type     the log type (or null)
 *  rc_log_action   the log action (or null)
 *  rc_params       log params
 *
 * mExtra:
 *  prefixedDBkey   prefixed db key, used by external app via msg queue
 *  lastTimestamp   timestamp of previous entry, used in WHERE clause during update
 *  oldSize         text size before the change
 *  newSize         text size after the change
 *  pageStatus      status of the page: created, deleted, moved, restored, changed
 *
 * temporary:       not stored in the database
 *      notificationtimestamp
 *      numberofWatchingusers
 */
class RecentChange {
	// Constants for the rc_source field.  Extensions may also have
	// their own source constants.
	const SRC_EDIT = 'mw.edit';
	const SRC_NEW = 'mw.new';
	const SRC_LOG = 'mw.log';
	const SRC_EXTERNAL = 'mw.external'; // obsolete

	public $mAttribs = array();
	public $mExtra = array();

	/**
	 * @var Title
	 */
	public $mTitle = false;

	/**
	 * @var User
	 */
	private $mPerformer = false;

	public $numberofWatchingusers = 0; # Dummy to prevent error message in SpecialRecentChangesLinked
	public $notificationtimestamp;

	/**
	 * @var int Line number of recent change. Default -1.
	 */
	public $counter = -1;

	# Factory methods

	/**
	 * @param mixed $row
	 * @return RecentChange
	 */
	public static function newFromRow( $row ) {
		$rc = new RecentChange;
		$rc->loadFromRow( $row );

		return $rc;
	}

	/**
	 * Parsing text to RC_* constants
	 * @since 1.24
	 * @param string|array $type
	 * @throws MWException
	 * @return int|array RC_TYPE
	 */
	public static function parseToRCType( $type ) {
		if ( is_array( $type ) ) {
			$retval = array();
			foreach ( $type as $t ) {
				$retval[] = RecentChange::parseToRCType( $t );
			}

			return $retval;
		}

		switch ( $type ) {
			case 'edit':
				return RC_EDIT;
			case 'new':
				return RC_NEW;
			case 'log':
				return RC_LOG;
			case 'external':
				return RC_EXTERNAL;
			default:
				throw new MWException( "Unknown type '$type'" );
		}
	}

	/**
	 * Parsing RC_* constants to human-readable test
	 * @since 1.24
	 * @param int $rcType
	 * @return string $type
	 */
	public static function parseFromRCType( $rcType ) {
		switch ( $rcType ) {
			case RC_EDIT:
				$type = 'edit';
				break;
			case RC_NEW:
				$type = 'new';
				break;
			case RC_LOG:
				$type = 'log';
				break;
			case RC_EXTERNAL:
				$type = 'external';
				break;
			default:
				$type = "$rcType";
		}

		return $type;
	}

	/**
	 * Obtain the recent change with a given rc_id value
	 *
	 * @param int $rcid The rc_id value to retrieve
	 * @return RecentChange
	 */
	public static function newFromId( $rcid ) {
		return self::newFromConds( array( 'rc_id' => $rcid ), __METHOD__ );
	}

	/**
	 * Find the first recent change matching some specific conditions
	 *
	 * @param array $conds Array of conditions
	 * @param mixed $fname Override the method name in profiling/logs
	 * @param array $options Query options
	 * @return RecentChange
	 */
	public static function newFromConds( $conds, $fname = __METHOD__, $options = array() ) {
		$dbr = wfGetDB( DB_SLAVE );
		$row = $dbr->selectRow( 'recentchanges', self::selectFields(), $conds, $fname, $options );
		if ( $row !== false ) {
			return self::newFromRow( $row );
		} else {
			return null;
		}
	}

	/**
	 * Return the list of recentchanges fields that should be selected to create
	 * a new recentchanges object.
	 * @return array
	 */
	public static function selectFields() {
		return array(
			'rc_id',
			'rc_timestamp',
			'rc_user',
			'rc_user_text',
			'rc_namespace',
			'rc_title',
			'rc_comment',
			'rc_minor',
			'rc_bot',
			'rc_new',
			'rc_cur_id',
			'rc_this_oldid',
			'rc_last_oldid',
			'rc_type',
			'rc_source',
			'rc_patrolled',
			'rc_ip',
			'rc_old_len',
			'rc_new_len',
			'rc_deleted',
			'rc_logid',
			'rc_log_type',
			'rc_log_action',
			'rc_params',
		);
	}

	# Accessors

	/**
	 * @param array $attribs
	 */
	public function setAttribs( $attribs ) {
		$this->mAttribs = $attribs;
	}

	/**
	 * @param array $extra
	 */
	public function setExtra( $extra ) {
		$this->mExtra = $extra;
	}

	/**
	 * @return Title
	 */
	public function &getTitle() {
		if ( $this->mTitle === false ) {
			$this->mTitle = Title::makeTitle( $this->mAttribs['rc_namespace'], $this->mAttribs['rc_title'] );
		}

		return $this->mTitle;
	}

	/**
	 * Get the User object of the person who performed this change.
	 *
	 * @return User
	 */
	public function getPerformer() {
		if ( $this->mPerformer === false ) {
			if ( $this->mAttribs['rc_user'] ) {
				$this->mPerformer = User::newFromID( $this->mAttribs['rc_user'] );
			} else {
				$this->mPerformer = User::newFromName( $this->mAttribs['rc_user_text'], false );
			}
		}

		return $this->mPerformer;
	}

	/**
	 * Writes the data in this object to the database
	 * @param bool $noudp
	 */
	public function save( $noudp = false ) {
		global $wgPutIPinRC, $wgUseEnotif, $wgShowUpdatedMarker, $wgContLang;

		$dbw = wfGetDB( DB_MASTER );
		if ( !is_array( $this->mExtra ) ) {
			$this->mExtra = array();
		}

		if ( !$wgPutIPinRC ) {
			$this->mAttribs['rc_ip'] = '';
		}

		# If our database is strict about IP addresses, use NULL instead of an empty string
		if ( $dbw->strictIPs() and $this->mAttribs['rc_ip'] == '' ) {
			unset( $this->mAttribs['rc_ip'] );
		}

		# Trim spaces on user supplied text
		$this->mAttribs['rc_comment'] = trim( $this->mAttribs['rc_comment'] );

		# Make sure summary is truncated (whole multibyte characters)
		$this->mAttribs['rc_comment'] = $wgContLang->truncate( $this->mAttribs['rc_comment'], 255 );

		# Fixup database timestamps
		$this->mAttribs['rc_timestamp'] = $dbw->timestamp( $this->mAttribs['rc_timestamp'] );
		$this->mAttribs['rc_id'] = $dbw->nextSequenceValue( 'recentchanges_rc_id_seq' );

		## If we are using foreign keys, an entry of 0 for the page_id will fail, so use NULL
		if ( $dbw->cascadingDeletes() and $this->mAttribs['rc_cur_id'] == 0 ) {
			unset( $this->mAttribs['rc_cur_id'] );
		}

		# Insert new row
		$dbw->insert( 'recentchanges', $this->mAttribs, __METHOD__ );

		# Set the ID
		$this->mAttribs['rc_id'] = $dbw->insertId();

		# Notify extensions
		wfRunHooks( 'RecentChange_save', array( &$this ) );

		# Notify external application via UDP
		if ( !$noudp ) {
			$this->notifyRCFeeds();
		}

		# E-mail notifications
		if ( $wgUseEnotif || $wgShowUpdatedMarker ) {
			$editor = $this->getPerformer();
			$title = $this->getTitle();

			if ( wfRunHooks( 'AbortEmailNotification', array( $editor, $title, $this ) ) ) {
				# @todo FIXME: This would be better as an extension hook
				$enotif = new EmailNotification();
				$enotif->notifyOnPageChange( $editor, $title,
					$this->mAttribs['rc_timestamp'],
					$this->mAttribs['rc_comment'],
					$this->mAttribs['rc_minor'],
					$this->mAttribs['rc_last_oldid'],
					$this->mExtra['pageStatus'] );
			}
		}
	}

	/**
	 * Notify all the feeds about the change.
	 * @param array $feeds Optional feeds to send to, defaults to $wgRCFeeds
	 */
	public function notifyRCFeeds( array $feeds = null ) {
		global $wgRCFeeds;
		if ( $feeds === null ) {
			$feeds = $wgRCFeeds;
		}

		$performer = $this->getPerformer();

		foreach ( $feeds as $feed ) {
			$feed += array(
				'omit_bots' => false,
				'omit_anon' => false,
				'omit_user' => false,
				'omit_minor' => false,
				'omit_patrolled' => false,
			);

			if (
				( $feed['omit_bots'] && $this->mAttribs['rc_bot'] ) ||
				( $feed['omit_anon'] && $performer->isAnon() ) ||
				( $feed['omit_user'] && !$performer->isAnon() ) ||
				( $feed['omit_minor'] && $this->mAttribs['rc_minor'] ) ||
				( $feed['omit_patrolled'] && $this->mAttribs['rc_patrolled'] ) ||
				$this->mAttribs['rc_type'] == RC_EXTERNAL
			) {
				continue;
			}

			$engine = self::getEngine( $feed['uri'] );

			if ( isset( $this->mExtra['actionCommentIRC'] ) ) {
				$actionComment = $this->mExtra['actionCommentIRC'];
			} else {
				$actionComment = null;
			}

			/** @var $formatter RCFeedFormatter */
			$formatter = is_object( $feed['formatter'] ) ? $feed['formatter'] : new $feed['formatter']();
			$line = $formatter->getLine( $feed, $this, $actionComment );

			$engine->send( $feed, $line );
		}
	}

	/**
	 * Gets the stream engine object for a given URI from $wgRCEngines
	 *
	 * @param string $uri URI to get the engine object for
	 * @throws MWException
	 * @return RCFeedEngine The engine object
	 */
	public static function getEngine( $uri ) {
		global $wgRCEngines;

		$scheme = parse_url( $uri, PHP_URL_SCHEME );
		if ( !$scheme ) {
			throw new MWException( __FUNCTION__ . ": Invalid stream logger URI: '$uri'" );
		}

		if ( !isset( $wgRCEngines[$scheme] ) ) {
			throw new MWException( __FUNCTION__ . ": Unknown stream logger URI scheme: $scheme" );
		}

		return new $wgRCEngines[$scheme];
	}

	/**
	 * Mark a given change as patrolled
	 *
	 * @param RecentChange|int $change RecentChange or corresponding rc_id
	 * @param bool $auto For automatic patrol
	 * @return array See doMarkPatrolled(), or null if $change is not an existing rc_id
	 */
	public static function markPatrolled( $change, $auto = false ) {
		global $wgUser;

		$change = $change instanceof RecentChange
			? $change
			: RecentChange::newFromId( $change );

		if ( !$change instanceof RecentChange ) {
			return null;
		}

		return $change->doMarkPatrolled( $wgUser, $auto );
	}

	/**
	 * Mark this RecentChange as patrolled
	 *
	 * NOTE: Can also return 'rcpatroldisabled', 'hookaborted' and
	 * 'markedaspatrollederror-noautopatrol' as errors
	 * @param User $user User object doing the action
	 * @param bool $auto For automatic patrol
	 * @return array Array of permissions errors, see Title::getUserPermissionsErrors()
	 */
	public function doMarkPatrolled( User $user, $auto = false ) {
		global $wgUseRCPatrol, $wgUseNPPatrol;
		$errors = array();
		// If recentchanges patrol is disabled, only new pages
		// can be patrolled
		if ( !$wgUseRCPatrol && ( !$wgUseNPPatrol || $this->getAttribute( 'rc_type' ) != RC_NEW ) ) {
			$errors[] = array( 'rcpatroldisabled' );
		}
		// Automatic patrol needs "autopatrol", ordinary patrol needs "patrol"
		$right = $auto ? 'autopatrol' : 'patrol';
		$errors = array_merge( $errors, $this->getTitle()->getUserPermissionsErrors( $right, $user ) );
		if ( !wfRunHooks( 'MarkPatrolled', array( $this->getAttribute( 'rc_id' ), &$user, false ) ) ) {
			$errors[] = array( 'hookaborted' );
		}
		// Users without the 'autopatrol' right can't patrol their
		// own revisions
		if ( $user->getName() == $this->getAttribute( 'rc_user_text' )
			&& !$user->isAllowed( 'autopatrol' )
		) {
			$errors[] = array( 'markedaspatrollederror-noautopatrol' );
		}
		if ( $errors ) {
			return $errors;
		}
		// If the change was patrolled already, do nothing
		if ( $this->getAttribute( 'rc_patrolled' ) ) {
			return array();
		}
		// Actually set the 'patrolled' flag in RC
		$this->reallyMarkPatrolled();
		// Log this patrol event
		PatrolLog::record( $this, $auto, $user );
		wfRunHooks( 'MarkPatrolledComplete', array( $this->getAttribute( 'rc_id' ), &$user, false ) );

		return array();
	}

	/**
	 * Mark this RecentChange patrolled, without error checking
	 * @return int Number of affected rows
	 */
	public function reallyMarkPatrolled() {
		$dbw = wfGetDB( DB_MASTER );
		$dbw->update(
			'recentchanges',
			array(
				'rc_patrolled' => 1
			),
			array(
				'rc_id' => $this->getAttribute( 'rc_id' )
			),
			__METHOD__
		);
		// Invalidate the page cache after the page has been patrolled
		// to make sure that the Patrol link isn't visible any longer!
		$this->getTitle()->invalidateCache();

		return $dbw->affectedRows();
	}

	/**
	 * Makes an entry in the database corresponding to an edit
	 *
	 * @param string $timestamp
	 * @param Title $title
	 * @param bool $minor
	 * @param User $user
	 * @param string $comment
	 * @param int $oldId
	 * @param string $lastTimestamp
	 * @param bool $bot
	 * @param string $ip
	 * @param int $oldSize
	 * @param int $newSize
	 * @param int $newId
	 * @param int $patrol
	 * @return RecentChange
	 */
	public static function notifyEdit( $timestamp, &$title, $minor, &$user, $comment, $oldId,
		$lastTimestamp, $bot, $ip = '', $oldSize = 0, $newSize = 0, $newId = 0, $patrol = 0 ) {
		$rc = new RecentChange;
		$rc->mTitle = $title;
		$rc->mPerformer = $user;
		$rc->mAttribs = array(
			'rc_timestamp' => $timestamp,
			'rc_namespace' => $title->getNamespace(),
			'rc_title' => $title->getDBkey(),
			'rc_type' => RC_EDIT,
			'rc_source' => self::SRC_EDIT,
			'rc_minor' => $minor ? 1 : 0,
			'rc_cur_id' => $title->getArticleID(),
			'rc_user' => $user->getId(),
			'rc_user_text' => $user->getName(),
			'rc_comment' => $comment,
			'rc_this_oldid' => $newId,
			'rc_last_oldid' => $oldId,
			'rc_bot' => $bot ? 1 : 0,
			'rc_ip' => self::checkIPAddress( $ip ),
			'rc_patrolled' => intval( $patrol ),
			'rc_new' => 0, # obsolete
			'rc_old_len' => $oldSize,
			'rc_new_len' => $newSize,
			'rc_deleted' => 0,
			'rc_logid' => 0,
			'rc_log_type' => null,
			'rc_log_action' => '',
			'rc_params' => ''
		);

		$rc->mExtra = array(
			'prefixedDBkey' => $title->getPrefixedDBkey(),
			'lastTimestamp' => $lastTimestamp,
			'oldSize' => $oldSize,
			'newSize' => $newSize,
			'pageStatus' => 'changed'
		);
		$rc->save();

		return $rc;
	}

	/**
	 * Makes an entry in the database corresponding to page creation
	 * Note: the title object must be loaded with the new id using resetArticleID()
	 *
	 * @param string $timestamp
	 * @param Title $title
	 * @param bool $minor
	 * @param User $user
	 * @param string $comment
	 * @param bool $bot
	 * @param string $ip
	 * @param int $size
	 * @param int $newId
	 * @param int $patrol
	 * @return RecentChange
	 */
	public static function notifyNew( $timestamp, &$title, $minor, &$user, $comment, $bot,
		$ip = '', $size = 0, $newId = 0, $patrol = 0 ) {
		$rc = new RecentChange;
		$rc->mTitle = $title;
		$rc->mPerformer = $user;
		$rc->mAttribs = array(
			'rc_timestamp' => $timestamp,
			'rc_namespace' => $title->getNamespace(),
			'rc_title' => $title->getDBkey(),
			'rc_type' => RC_NEW,
			'rc_source' => self::SRC_NEW,
			'rc_minor' => $minor ? 1 : 0,
			'rc_cur_id' => $title->getArticleID(),
			'rc_user' => $user->getId(),
			'rc_user_text' => $user->getName(),
			'rc_comment' => $comment,
			'rc_this_oldid' => $newId,
			'rc_last_oldid' => 0,
			'rc_bot' => $bot ? 1 : 0,
			'rc_ip' => self::checkIPAddress( $ip ),
			'rc_patrolled' => intval( $patrol ),
			'rc_new' => 1, # obsolete
			'rc_old_len' => 0,
			'rc_new_len' => $size,
			'rc_deleted' => 0,
			'rc_logid' => 0,
			'rc_log_type' => null,
			'rc_log_action' => '',
			'rc_params' => ''
		);

		$rc->mExtra = array(
			'prefixedDBkey' => $title->getPrefixedDBkey(),
			'lastTimestamp' => 0,
			'oldSize' => 0,
			'newSize' => $size,
			'pageStatus' => 'created'
		);
		$rc->save();

		return $rc;
	}

	/**
	 * @param string $timestamp
	 * @param Title $title
	 * @param User $user
	 * @param string $actionComment
	 * @param string $ip
	 * @param string $type
	 * @param string $action
	 * @param Title $target
	 * @param string $logComment
	 * @param string $params
	 * @param int $newId
	 * @param string $actionCommentIRC
	 * @return bool
	 */
	public static function notifyLog( $timestamp, &$title, &$user, $actionComment, $ip, $type,
		$action, $target, $logComment, $params, $newId = 0, $actionCommentIRC = ''
	) {
		global $wgLogRestrictions;

		# Don't add private logs to RC!
		if ( isset( $wgLogRestrictions[$type] ) && $wgLogRestrictions[$type] != '*' ) {
			return false;
		}
		$rc = self::newLogEntry( $timestamp, $title, $user, $actionComment, $ip, $type, $action,
			$target, $logComment, $params, $newId, $actionCommentIRC );
		$rc->save();

		return true;
	}

	/**
	 * @param string $timestamp
	 * @param Title $title
	 * @param User $user
	 * @param string $actionComment
	 * @param string $ip
	 * @param string $type
	 * @param string $action
	 * @param Title $target
	 * @param string $logComment
	 * @param string $params
	 * @param int $newId
	 * @param string $actionCommentIRC
	 * @return RecentChange
	 */
	public static function newLogEntry( $timestamp, &$title, &$user, $actionComment, $ip,
		$type, $action, $target, $logComment, $params, $newId = 0, $actionCommentIRC = '' ) {
		global $wgRequest;

		## Get pageStatus for email notification
		switch ( $type . '-' . $action ) {
			case 'delete-delete':
				$pageStatus = 'deleted';
				break;
			case 'move-move':
			case 'move-move_redir':
				$pageStatus = 'moved';
				break;
			case 'delete-restore':
				$pageStatus = 'restored';
				break;
			case 'upload-upload':
				$pageStatus = 'created';
				break;
			case 'upload-overwrite':
			default:
				$pageStatus = 'changed';
				break;
		}

		$rc = new RecentChange;
		$rc->mTitle = $target;
		$rc->mPerformer = $user;
		$rc->mAttribs = array(
			'rc_timestamp' => $timestamp,
			'rc_namespace' => $target->getNamespace(),
			'rc_title' => $target->getDBkey(),
			'rc_type' => RC_LOG,
			'rc_source' => self::SRC_LOG,
			'rc_minor' => 0,
			'rc_cur_id' => $target->getArticleID(),
			'rc_user' => $user->getId(),
			'rc_user_text' => $user->getName(),
			'rc_comment' => $logComment,
			'rc_this_oldid' => 0,
			'rc_last_oldid' => 0,
			'rc_bot' => $user->isAllowed( 'bot' ) ? $wgRequest->getBool( 'bot', true ) : 0,
			'rc_ip' => self::checkIPAddress( $ip ),
			'rc_patrolled' => 1,
			'rc_new' => 0, # obsolete
			'rc_old_len' => null,
			'rc_new_len' => null,
			'rc_deleted' => 0,
			'rc_logid' => $newId,
			'rc_log_type' => $type,
			'rc_log_action' => $action,
			'rc_params' => $params
		);

		$rc->mExtra = array(
			'prefixedDBkey' => $title->getPrefixedDBkey(),
			'lastTimestamp' => 0,
			'actionComment' => $actionComment, // the comment appended to the action, passed from LogPage
			'pageStatus' => $pageStatus,
			'actionCommentIRC' => $actionCommentIRC
		);

		return $rc;
	}

	/**
	 * Initialises the members of this object from a mysql row object
	 *
	 * @param mixed $row
	 */
	public function loadFromRow( $row ) {
		$this->mAttribs = get_object_vars( $row );
		$this->mAttribs['rc_timestamp'] = wfTimestamp( TS_MW, $this->mAttribs['rc_timestamp'] );
		$this->mAttribs['rc_deleted'] = $row->rc_deleted; // MUST be set
	}

	/**
	 * Get an attribute value
	 *
	 * @param string $name Attribute name
	 * @return mixed
	 */
	public function getAttribute( $name ) {
		return isset( $this->mAttribs[$name] ) ? $this->mAttribs[$name] : null;
	}

	/**
	 * @return array
	 */
	public function getAttributes() {
		return $this->mAttribs;
	}

	/**
	 * Gets the end part of the diff URL associated with this object
	 * Blank if no diff link should be displayed
	 * @param bool $forceCur
	 * @return string
	 */
	public function diffLinkTrail( $forceCur ) {
		if ( $this->mAttribs['rc_type'] == RC_EDIT ) {
			$trail = "curid=" . (int)( $this->mAttribs['rc_cur_id'] ) .
				"&oldid=" . (int)( $this->mAttribs['rc_last_oldid'] );
			if ( $forceCur ) {
				$trail .= '&diff=0';
			} else {
				$trail .= '&diff=' . (int)( $this->mAttribs['rc_this_oldid'] );
			}
		} else {
			$trail = '';
		}

		return $trail;
	}

	/**
	 * Returns the change size (HTML).
	 * The lengths can be given optionally.
	 * @param int $old
	 * @param int $new
	 * @return string
	 */
	public function getCharacterDifference( $old = 0, $new = 0 ) {
		if ( $old === 0 ) {
			$old = $this->mAttribs['rc_old_len'];
		}
		if ( $new === 0 ) {
			$new = $this->mAttribs['rc_new_len'];
		}
		if ( $old === null || $new === null ) {
			return '';
		}

		return ChangesList::showCharacterDifference( $old, $new );
	}

	/**
	 * Purge expired changes from the recentchanges table
	 * @since 1.22
	 */
	public static function purgeExpiredChanges() {
		if ( wfReadOnly() ) {
			return;
		}

		$method = __METHOD__;
		$dbw = wfGetDB( DB_MASTER );
		$dbw->onTransactionIdle( function () use ( $dbw, $method ) {
			global $wgRCMaxAge;

			$cutoff = $dbw->timestamp( time() - $wgRCMaxAge );
			$dbw->delete(
				'recentchanges',
				array( 'rc_timestamp < ' . $dbw->addQuotes( $cutoff ) ),
				$method
			);
		} );
	}

	private static function checkIPAddress( $ip ) {
		global $wgRequest;
		if ( $ip ) {
			if ( !IP::isIPAddress( $ip ) ) {
				throw new MWException( "Attempt to write \"" . $ip .
					"\" as an IP address into recent changes" );
			}
		} else {
			$ip = $wgRequest->getIP();
			if ( !$ip ) {
				$ip = '';
			}
		}

		return $ip;
	}

	/**
	 * Check whether the given timestamp is new enough to have a RC row with a given tolerance
	 * as the recentchanges table might not be cleared out regularly (so older entries might exist)
	 * or rows which will be deleted soon shouldn't be included.
	 *
	 * @param mixed $timestamp MWTimestamp compatible timestamp
	 * @param int $tolerance Tolerance in seconds
	 * @return bool
	 */
	public static function isInRCLifespan( $timestamp, $tolerance = 0 ) {
		global $wgRCMaxAge;

		return wfTimestamp( TS_UNIX, $timestamp ) > time() - $tolerance - $wgRCMaxAge;
	}
}
