mediawiki-extensions-AbuseFilter/AbuseFilter.class.php

<?php
if ( ! defined( 'MEDIAWIKI' ) )
	die();

class AbuseFilter {

	public static $statsStoragePeriod = 86400;
	public static $tokenCache = array();
	public static $modifyCache = array();
	public static $condLimitEnabled = true;
	public static $condCount = 0;
	public static $filters = array();
	public static $tagsToSet = array();
	public static $history_mappings = array( 'af_pattern' => 'afh_pattern', 'af_user' => 'afh_user', 'af_user_text' => 'afh_user_text', 'af_timestamp' => 'afh_timestamp', 'af_comments' => 'afh_comments', 'af_public_comments' => 'afh_public_comments', 'af_deleted' => 'afh_deleted', 'af_id' => 'afh_filter' );
	public static $builderValues = array(
			'op-arithmetic' => array('+' => 'addition', '-' => 'subtraction', '*' => 'multiplication', '/' => 'divide', '%' => 'modulo', '**' => 'pow'),
			'op-comparison' => array('==' => 'equal', '!=' => 'notequal', '<' => 'lt', '>' => 'gt', '<=' => 'lte', '>=' => 'gte'),
			'op-bool' => array( '!' => 'not', '&' => 'and', '|' => 'or', '^' => 'xor' ),
			'misc' => array( 'in' => 'in', 'like' => 'like', '""' => 'stringlit', ),
			'funcs' => array( 'length(string)' => 'length', 'lcase(string)' => 'lcase', 'ccnorm(string)' => 'ccnorm', 'rmdoubles(string)' => 'rmdoubles', 'specialratio(string)' => 'specialratio', 'norm(string)' => 'norm', 'count(needle,haystack)' => 'count' ),
			'vars' => array( 'ACCOUNTNAME' => 'accountname', 'ACTION' => 'action', 'ADDED_LINES' => 'addedlines', 'EDIT_DELTA' => 'delta', 'EDIT_DIFF' => 'diff', 'NEW_SIZE' => 'newsize', 'OLD_SIZE' => 'oldsize', 'REMOVED_LINES' => 'removedlines', 'SUMMARY' => 'summary', 'ARTICLE_ARTICLEID' => 'article-id', 'ARTICLE_NAMESPACE' => 'article-ns', 'ARTICLE_TEXT' => 'article-text', 'ARTICLE_PREFIXEDTEXT' => 'article-prefixedtext', 'MOVED_FROM_ARTICLEID' => 'movedfrom-id', 'MOVED_FROM_NAMESPACE' => 'movedfrom-ns', 'MOVED_FROM_TEXT' => 'movedfrom-text', 'MOVED_FROM_PREFIXEDTEXT' => 'movedfrom-prefixedtext', 'MOVED_TO_ARTICLEID' => 'movedto-id', 'MOVED_TO_NAMESPACE' => 'movedto-ns', 'MOVED_TO_TEXT' => 'movedto-text', 'MOVED_TO_PREFIXEDTEXT' => 'movedto-prefixedtext', 'USER_EDITCOUNT' =>  'user-editcount', 'USER_AGE' => 'user-age', 'USER_NAME' => 'user-name', 'USER_GROUPS' => 'user-groups', 'USER_EMAILCONFIRM' => 'user-emailconfirm', 'OLD_TEXT' => 'old-text', 'NEW_TEXT' => 'new-text'),
	);

	public static function generateUserVars( $user ) {
		$vars = array();
		
		// Load all the data we want.
		$user->load();
		
		$vars['USER_EDITCOUNT'] = $user->getEditCount();
		$vars['USER_AGE'] = time() - wfTimestampOrNull( TS_UNIX, $user->getRegistration() );
		$vars['USER_NAME'] = $user->getName();
		$vars['USER_GROUPS'] = implode(',', $user->getEffectiveGroups() );
		$vars['USER_EMAILCONFIRM'] = $user->getEmailAuthenticationTimestamp();
		
		// More to come
		
		return $vars;
	}
	
	public static function ajaxCheckSyntax( $filter ) {
		wfLoadExtensionMessages( 'AbuseFilter' );
		
		$result = self::checkSyntax( $filter );
		
		$ok = ($result === true);
		
		if ($ok) {
			return "OK";
		} else {
			return "ERR: ".json_encode( $result );
		}
	}

	public static function triggerLimiter( $val = 1 ) {
		self::$condCount += $val;

		global $wgAbuseFilterConditionLimit;

		if (self::$condCount > $wgAbuseFilterConditionLimit) {
			throw new MWException( "Condition limit reached." );
		}
	}

	public static function disableConditionLimit() {
		// For use in batch scripts and the like
		self::$condLimitEnabled = false;
	}
	
	public static function generateTitleVars( $title, $prefix ) {
		$vars = array();
		
		$vars[$prefix."_ARTICLEID"] = $title->getArticleId();
		$vars[$prefix."_NAMESPACE"] = $title->getNamespace();
		$vars[$prefix."_TEXT"] = $title->getText();
		$vars[$prefix."_PREFIXEDTEXT"] = $title->getPrefixedText();

		// Use restrictions.
		if ($title->mRestrictionsLoaded) {
			// Don't bother if they're unloaded
			foreach( $title->mRestrictions as $action => $rights ) {
				$rights = count($rights) ? $rights : array();
				$vars[$prefix."_RESTRICTIONS_".$action] = implode(',', $rights );
			}
		}
		
		// Find last 5 authors.
		$dbr = wfGetDB( DB_SLAVE );
		$res = $dbr->select( 'revision', 'distinct rev_user_text', array('rev_page' => $title->getArticleId() ), __METHOD__, array( 'order by' => 'rev_timestamp desc', 'limit' => 10 ) );
		$users = array();
		while ($user = $dbr->fetchRow($res)) {
			$users[] = $user[0];
		}
		$vars[$prefix."_RECENT_CONTRIBUTORS"] = implode(',', $users);
		
		return $vars;
	}
	
	public static function checkSyntax( $filter ) {
		global $wgAbuseFilterParserClass;
		
		$parser = new $wgAbuseFilterParserClass;
		
		return $parser->checkSyntax( $filter );
	}
	
	public static function evaluateExpression( $expr, $vars = array() ) {
		global $wgAbuseFilterParserClass;
		
		$parser = new $wgAbuseFilterParserClass;
		
		$parser->setVars( $vars );
		
		return $parser->evaluateExpression( $expr );
	}
	
	public static function ajaxReAutoconfirm( $username ) {
	
		if (!$wgUser->isAllowed('abusefilter-modify')) {
			// Don't allow it.
			return wfMsg( 'abusefilter-reautoconfirm-notallowed' );
		}
	
		$u = User::newFromName( $username );
		
		global $wgMemc;
		$k = AbuseFilter::autoPromoteBlockKey($u);
		
		if (!$wgMemc->get( $k ) ) {
			return wfMsg( 'abusefilter-reautoconfirm-none' );
		}
		
		$wgMemc->delete( $k );
	}
	
	public static function ajaxEvaluateExpression( $expr ) {
		return self::evaluateExpression( $expr );
	}

	public static function checkConditions( $conds, $vars, $ignoreError = true ) {
		global $wgAbuseFilterParserClass;
		
		wfProfileIn( __METHOD__ );
		
		try {
			$parser = new $wgAbuseFilterParserClass;
			
			$parser->setVars( $vars );
			$result = $parser->parse( $conds, self::$condCount );
		} catch (Exception $excep) {
			// Sigh.
			$result = false;

			if (!$ignoreError) {
				throw $excep;
			}
		}
		
		wfProfileOut( __METHOD__ );
		
		return $result;
	}

	/** Returns an associative array of filters which were tripped */
	public static function checkAllFilters( $vars ) {
		// Fetch from the database.
		$dbr = wfGetDB( DB_SLAVE );
		$res = $dbr->select( 'abuse_filter', '*', array( 'af_enabled' => 1, 'af_deleted' => 0 ) );

		while ( $row = $dbr->fetchObject( $res ) ) {
			// Store the row somewhere convenient
			self::$filters[$row->af_id] = $row;

			// Check conditions...
			$pattern = trim($row->af_pattern);
			if ( self::checkConditions( $pattern, $vars ) ) {
				// Record match.
				$filter_matched[$row->af_id] = true;
			} else {
				// Record non-match.
				$filter_matched[$row->af_id] = false;
			}
		}

		// Update statistics, and disable filters which are over-blocking.
		self::recordStats( $filter_matched );

		return $filter_matched;
	}

	/** Returns an array [ list of actions taken by filter, error message to display, if any ] */
	public static function executeFilterActions( $filters, $title, $vars ) {
		$dbr = wfGetDB( DB_SLAVE );
		// Retrieve the consequences.
		$res = $dbr->select( 'abuse_filter_action', '*', array( 'afa_filter' => $filters ), __METHOD__ );

		$actionsByFilter = array_fill_keys( $filters, array() );
		$actionsTaken = array_fill_keys( $filters, array() );

		// Categorise consequences by filter.
		while ( $row = $dbr->fetchObject( $res ) ) {
			$actionsByFilter[$row->afa_filter][$row->afa_consequence] = array( 'action' => $row->afa_consequence, 'parameters' => explode( "\n", $row->afa_parameters ) );
		}

		wfLoadExtensionMessages( 'AbuseFilter' );

		$messages = array();

		foreach( $actionsByFilter as $filter => $actions ) {
			// Special-case handling for warnings.

			if ( !empty( $actions['throttle'] ) ) {
				$parameters = $actions['throttle']['parameters'];
				$throttleId = array_shift( $parameters );
				list( $rateCount, $ratePeriod ) = explode( ',', array_shift( $parameters ) );

				$hitThrottle = false;

				// The rest are throttle-types.
				foreach( $parameters as $throttleType ) {
					$hitThrottle = $hitThrottle || self::isThrottled( $throttleId, $throttleType, $title, $rateCount, $ratePeriod );
				}

				unset( $actions['throttle'] );
				if (!$hitThrottle) {
					$actionsTaken[$filter][] = 'throttle';
					continue;
				}
			}
			
			if ( !empty( $actions['warn'] ) ) {
				$parameters = $actions['warn']['parameters'];
				$warnKey = 'abusefilter-warned-'.$title->getPrefixedText();
				if (!isset($_SESSION[$warnKey]) || !$_SESSION[$warnKey]) {
					$_SESSION[$warnKey] = true;

					// Threaten them a little bit
					$msg = ( !empty($parameters[0]) && strlen($parameters[0]) ) ? $parameters[0] : 'abusefilter-warning';
					$messages[] = wfMsgNoTrans( $msg, self::$filters[$filter]->af_public_comments ) . "<br />\n";

					$actionsTaken[$filter][] = 'warn';

					continue; // Don't do anything else.
				} else {
					// We already warned them
					$_SESSION[$warnKey] = false;
				}
				
				unset( $actions['warn'] );
			}

			// Do the rest of the actions
			foreach( $actions as $action => $info ) {
				$newMsg = self::takeConsequenceAction( $action, $info['parameters'], $title, $vars, self::$filters[$filter]->af_public_comments );

				if ($newMsg)
					$messages[] = $newMsg;
				$actionsTaken[$filter][] = $action;
			}
		}

		return array( $actionsTaken, implode( "\n", $messages ) );
	}
	
	public static function filterAction( $vars, $title ) {
		global $wgUser,$wgMemc;

		$dbr = wfGetDB( DB_SLAVE );

		$filter_matched = self::checkAllFilters( $vars );

		// Short-cut any remaining code if no filters were hit.
		if ( count( array_filter( $filter_matched) ) == 0 ) {
			return true;
		}

		list( $actions_taken, $error_msg ) = self::executeFilterActions( array_keys( array_filter( $filter_matched ) ), $title, $vars );

		// Create a template
		$log_template = array( 'afl_user' => $wgUser->getId(), 'afl_user_text' => $wgUser->getName(),
					'afl_var_dump' => serialize( $vars ), 'afl_timestamp' => $dbr->timestamp(wfTimestampNow()),
					'afl_namespace' => $title->getNamespace(), 'afl_title' => $title->getDBKey(), 'afl_ip' => wfGetIp() );

		self::addLogEntries( $actions_taken, $log_template, $vars['ACTION'] );
		
		return $error_msg;
	}

	public static function addLogEntries( $actions_taken, $log_template, $action ) {
		$dbw = wfGetDB( DB_MASTER );

		$log_rows = array();

		foreach( $actions_taken as $filter => $actions ) {
			$thisLog = $log_template;
			$thisLog['afl_filter'] = $filter;
			$thisLog['afl_action'] = $action;
			$thisLog['afl_actions'] = implode( ',', $actions );

			// Don't log if we were only throttling.
			if ($thisLog['afl_actions'] != 'throttle') {
				$log_rows[] = $thisLog;
			}
		}

		if (!count($log_rows)) {
			return;
		}

		$dbw->insert( 'abuse_filter_log', $log_rows, __METHOD__ );
	}
	
	public static function takeConsequenceAction( $action, $parameters, $title, $vars, $rule_desc ) {
		wfLoadExtensionMessages( 'AbuseFilter' );
		$display = '';
		switch ($action) {
			case 'disallow':
				if (strlen($parameters[0])) {
					$display .= wfMsgNoTrans( $parameters[0], $rule_desc ) . "\n";
				} else {
					// Generic message.
					$display .= wfMsgNoTrans( 'abusefilter-disallowed', $rule_desc ) ."<br />\n";
				}
				break;
				
			case 'block':
				global $wgUser;
				$filterUser = AbuseFilter::getFilterUser();

				// Create a block.
				$block = new Block;
				$block->mAddress = $wgUser->getName();
				$block->mUser = $wgUser->getId();
				$block->mBy = $filterUser->getId();
				$block->mByName = $filterUser->getName();
				$block->mReason = wfMsgForContent( 'abusefilter-blockreason', $rule_desc );
				$block->mTimestamp = wfTimestampNow();
				$block->mAnonOnly = 1;
				$block->mCreateAccount = 1;
				$block->mExpiry = 'infinity';

				$block->insert();
				
				// Log it
				# Prepare log parameters
				$logParams = array();
				$logParams[] = 'indefinite';
				$logParams[] = 'nocreate, angry-autoblock';
	
				$log = new LogPage( 'block' );
				$log->addEntry( 'block', Title::makeTitle( NS_USER, $wgUser->getName() ),
					wfMsgForContent( 'abusefilter-blockreason', $rule_desc ), $logParams, self::getFilterUser() );
				
				$display .= wfMsgNoTrans( 'abusefilter-blocked-display', $rule_desc ) ."<br />\n";
				break;
			case 'rangeblock':
				global $wgUser;
				$filterUser = AbuseFilter::getFilterUser();
				
				$range = IP::toHex( wfGetIP() );
				$range = substr( $range, 0, 4 ) . '0000';
				$range = long2ip( hexdec( $range ) );
				$range .= "/16";
				$range = Block::normaliseRange( $range );

				// Create a block.
				$block = new Block;
				$block->mAddress = $range;
				$block->mUser = 0;
				$block->mBy = $filterUser->getId();
				$block->mByName = $filterUser->getName();
				$block->mReason = wfMsgForContent( 'abusefilter-blockreason', $rule_desc );
				$block->mTimestamp = wfTimestampNow();
				$block->mAnonOnly = 0;
				$block->mCreateAccount = 1;
				$block->mExpiry = Block::parseExpiryInput( '1 week' );

				$block->insert();
				
				// Log it
				# Prepare log parameters
				$logParams = array();
				$logParams[] = 'indefinite';
				$logParams[] = 'nocreate, angry-autoblock';
	
				$log = new LogPage( 'block' );
				$log->addEntry( 'block', Title::makeTitle( NS_USER, $range ),
					wfMsgForContent( 'abusefilter-blockreason', $rule_desc ), $logParams, self::getFilterUser() );
				
				$display .= wfMsgNoTrans( 'abusefilter-blocked-display', $rule_desc ) ."<br />\n";
				break;
			case 'degroup':
				global $wgUser;
				if (!$wgUser->isAnon()) {
					// Remove all groups from the user. Ouch.
					$groups = $wgUser->getGroups();

					foreach( $groups as $group ) {
						$wgUser->removeGroup( $group );
					}

					$display .= wfMsgNoTrans( 'abusefilter-degrouped', $rule_desc ) ."<br />\n";

					// Don't log it if there aren't any groups being removed!
					if (!count($groups)) {
						break;
					}
					
					// Log it.
					$log = new LogPage( 'rights' );

					$log->addEntry( 'rights',
						$wgUser->getUserPage(),
						wfMsgForContent( 'abusefilter-degroupreason', $rule_desc ),
						array(
							implode( ', ', $groups ),
							wfMsgForContent( 'rightsnone' )
						)
					, self::getFilterUser() );
				}

				break;
			case 'blockautopromote':
				global $wgUser, $wgMemc;
				if (!$wgUser->isAnon()) {
					$blockPeriod = (int)mt_rand( 3*86400, 7*86400 ); // Block for 3-7 days.
					$wgMemc->set( self::autoPromoteBlockKey( $wgUser ), true, $blockPeriod );

					$display .= wfMsgNoTrans( 'abusefilter-autopromote-blocked', $rule_desc ) ."<br />\n";
				}
				break;

			case 'flag':
				// Do nothing. Here for completeness.
				break;

// 			case 'tag':
// 				// Mark with a tag on recentchanges.
// 				global $wgUser;
// 				
// 				$actionID = implode( '-', array(
// 						$title->getPrefixedText(), $wgUser->getName(), $vars['ACTION']
// 					) );
// 
// 				AbuseFilter::$tagsToSet[$actionID] = $parameters;
// 				break;
		}
		
		return $display;
	}
	
	public static function isThrottled( $throttleId, $types, $title, $rateCount, $ratePeriod ) {
		global $wgMemc;
		
		$key = self::throttleKey( $throttleId, $types, $title );
		$count = $wgMemc->get( $key );
		
		if ($count > 0) {
			$wgMemc->incr( $key );
			if ($count > $rateCount) {
				return true; // THROTTLED
			}
		} else {
			$wgMemc->add( $key, 1, $ratePeriod );
		}
		
		return false; // NOT THROTTLED
	}
	
	public static function throttleIdentifier( $type, $title ) {
		global $wgUser;
		
		switch ($type) {
			case 'ip':
				$identifier = wfGetIp();
				break;
			case 'user':
				$identifier = $wgUser->getId();
				break;
			case 'range':
				$identifier = substr(IP::toHex(wfGetIp()),0,4);
				break;
			case 'creationdate':
				$reg = $wgUser->getRegistration();
				$identifier = $reg - ($reg % 86400);
				break;
			case 'editcount':
				// Hack for detecting different single-purpose accounts.
				$identifier = $wgUser->getEditCount();
				break;
			case 'site':
				return 1;
				break;
			case 'page':
				return $title->getPrefixedText();
				break;
		}
		
		return $identifier;
	}
	
	public static function throttleKey( $throttleId, $type, $title ) {
		$identifier = '';

		$types = explode(',', $type);
		
		$identifiers = array();
		
		foreach( $types as $subtype ) {
			$identifiers[] = self::throttleIdentifier( $subtype, $title );
		}
		
		$identifier = implode( ':', $identifiers );
	
		return wfMemcKey( 'abusefilter', 'throttle', $throttleId, $type, $identifier );
	}
	
	public static function autoPromoteBlockKey( $user ) {
		return wfMemcKey( 'abusefilter', 'block-autopromote', $user->getId() );
	}
	
	public static function recordStats( $filters ) {
		global $wgAbuseFilterConditionLimit,$wgMemc;
		
		$blocking_filters = array_keys( array_filter( $filters ) );

		// Figure out if we've triggered overflows and blocks.
		$overflow_triggered = (self::$condCount > $wgAbuseFilterConditionLimit);
		$filter_triggered = count( $blocking_filters ) > 0;

		// Store some keys...
		$overflow_key = self::filterLimitReachedKey();
		$total_key = self::filterUsedKey();
		
		$total = $wgMemc->get( $total_key );

		$storage_period = self::$statsStoragePeriod;
		
		if (!$total || $total > 1000) {
			// This is for if the total doesn't exist, or has gone past 1000.
			//  Recreate all the keys at the same time, so they expire together.
			$wgMemc->set( $total_key, 0, $storage_period );
			$wgMemc->set( $overflow_key, 0, $storage_period );

			foreach( $filters as $filter => $matched ) {
				$wgMemc->set( self::filterMatchesKey( $filter ), 0, $storage_period );
			}
			$wgMemc->set( self::filterMatchesKey(), 0, $storage_period );
		}

		// Increment total
		$wgMemc->incr( $total_key );

		// Increment overflow counter, if our condition limit overflowed
		if ($overflow_triggered) {
			$wgMemc->incr( $overflow_key );
		}

		if (!$filter_triggered) {
			return; // The rest will only apply if a filter was triggered.
		}

		self::checkEmergencyDisable( $filters );

		// Increment trigger counter
		if ($filter_triggered) {
			$wgMemc->incr( self::filterMatchesKey() );
		}

		$dbw = wfGetDB( DB_MASTER );

		// Update hit-counter.
		$dbw->update( 'abuse_filter', array( 'af_hit_count=af_hit_count+1' ), array( 'af_id' => array_keys( array_filter( $filters ) ) ), __METHOD__ );
	}

	public static function checkEmergencyDisable( $filters ) {
		global $wgAbuseFilterEmergencyDisableThreshold, $wgAbuseFilterEmergencyDisableCount, $wgAbuseFilterEmergencyDisableAge, $wgMemc;

		foreach( $filters as $filter => $matched ) {
			if ($matched) {
				// Increment counter
				$matchCount = $wgMemc->get( self::filterMatchesKey( $filter ) );

				// Handle missing keys...
				if (!$matchCount) {
					$wgMemc->set( self::filterMatchesKey( $filter ), 1, self::$statsStoragePeriod );
				} else {
					$wgMemc->incr( self::filterMatchesKey( $filter ) );
				}
				$matchCount++;
			
				// Figure out if the filter is subject to being deleted.
				$filter_age = wfTimestamp( TS_UNIX, self::$filters[$filter]->af_timestamp );
				$throttle_exempt_time = $filter_age + $wgAbuseFilterEmergencyDisableAge;

				if ($throttle_exempt_time > time() && $matchCount > $wgAbuseFilterEmergencyDisableCount && ($matchCount / $total) > $wgAbuseFilterEmergencyDisableThreshold) {
					// More than $wgAbuseFilterEmergencyDisableCount matches, constituting more than $wgAbuseFilterEmergencyDisableThreshold (a fraction) of last few edits. Disable it.
					$dbw = wfGetDB( DB_MASTER );
					$dbw->update( 'abuse_filter', array( 'af_enabled' => 0, 'af_throttled' => 1 ), array( 'af_id' => $filter ), __METHOD__ );
				}
			}
		}
	}
	
	public static function filterLimitReachedKey() {
		return wfMemcKey( 'abusefilter', 'stats', 'overflow' );
	}
	
	public static function filterUsedKey() {
		return wfMemcKey( 'abusefilter', 'stats', 'total' );
	}
	
	public static function filterMatchesKey( $filter = null ) {
		return wfMemcKey( 'abusefilter', 'stats', 'matches', $filter );
	}
	
	public static function getFilterUser() {
		wfLoadExtensionMessages( 'AbuseFilter' );
		
		$user = User::newFromName( wfMsgForContent( 'abusefilter-blocker' ) );
		$user->load();
		if ($user->getId() && $user->mPassword == '') {
			// Already set up.
			return $user;
		}
		
		// Not set up. Create it.
		
		if (!$user->getId()) {
			$user->addToDatabase();
			$user->saveSettings();
		} else {
			// Take over the account
			$user->setPassword( null );
			$user->setEmail( null );
			$user->saveSettings();
		}
		
		# Promote user so it doesn't look too crazy.
		$user->addGroup( 'sysop' );
		
		# Increment site_stats.ss_users
		$ssu = new SiteStatsUpdate( 0, 0, 0, 0, 1 );
		$ssu->doUpdate();
		
		return $user;
	}

	static function buildEditBox( $rules, $textName = 'wpFilterRules' ) {
		global $wgOut;

		$rules = Xml::textarea( $textName, ( isset( $rules ) ? $rules."\n" : "\n" ) );

		$dropDown = self::$builderValues;

		// Generate builder drop-down
		$builder = '';

		$builder .= Xml::option( wfMsg( "abusefilter-edit-builder-select") );

		foreach( $dropDown as $group => $values ) {
			$builder .= Xml::openElement( 'optgroup', array( 'label' => wfMsg( "abusefilter-edit-builder-group-$group" ) ) ) . "\n";

			foreach( $values as $content => $name ) {
				$builder .= Xml::option( wfMsg( "abusefilter-edit-builder-$group-$name" ), $content ) . "\n";
			}

			$builder .= Xml::closeElement( 'optgroup' ) . "\n";
		}

		$rules .= Xml::tags( 'select', array( 'id' => 'wpFilterBuilder', 'onchange' => 'addText();' ), $builder ) . ' ';

		// Add syntax checking
		$rules .= Xml::element( 'input', array( 'type' => 'button', 'onclick' => 'doSyntaxCheck()', 'value' => wfMsg( 'abusefilter-edit-check' ), 'id' => 'mw-abusefilter-syntaxcheck' ) );
		$rules .= Xml::element( 'div', array( 'id' => 'mw-abusefilter-syntaxresult', 'style' => 'display: none;' ), '&nbsp;' );

		// Add script
		$editScript = file_get_contents(dirname(__FILE__)."/edit.js");
		$editScript = "var wgFilterBoxName = ".Xml::encodeJSVar( $textName ).";\n$editScript";
		$wgOut->addInlineScript( $editScript );

		return $rules;
	}

	/** Each version is expected to be an array( $row, $actions )
	    Returns an array of fields that are different.*/
	static function compareVersions( $version_1, $version_2 ) {
		$compareFields = array( 'af_public_comments', 'af_pattern', 'af_comments', 'af_deleted', 'af_enabled', 'af_hidden' );
		$differences = array();

		list($row1, $actions1) = $version_1;
		list($row2, $actions2) = $version_2;

		foreach( $compareFields as $field ) {
			if ($row1->$field != $row2->$field) {
				$differences[] = $field;
			}
		}

		global $wgAbuseFilterAvailableActions;
		foreach( $wgAbuseFilterAvailableActions as $action ) {
			if ( !isset($actions1[$action]) && !isset( $actions2[$action] ) ) {
				// They're both unset
			} elseif ( isset($actions1[$action]) && isset( $actions2[$action] ) ) {
				// They're both set.
				if ( array_diff( $actions1[$action]['parameters'], $actions2[$action]['parameters'] ) ) {
					// Different parameters
					$differences[] = 'actions';
				}
			} else {
				// One's unset, one's set.
				$differences[] = 'actions';
			}
		}

		return array_unique( $differences );
	}

	static function translateFromHistory( $row ) {
		## Translate into an abuse_filter row with some black magic. This is ever so slightly evil!
		$af_row = new StdClass;

		foreach (self::$history_mappings as $af_col => $afh_col ) {
			$af_row->$af_col = $row->$afh_col;
		}

		## Process flags

		$af_row->af_deleted = 0;
		$af_row->af_hidden = 0;
		$af_row->af_enabled = 0;

		$flags = explode(',', $row->afh_flags );
		foreach( $flags as $flag ) {
			$col_name = "af_$flag";
			$af_row->$col_name = 1;
		}

		## Process actions
		$actions_raw = unserialize($row->afh_actions);
		$actions_output = array();

		foreach( $actions_raw as $action => $parameters ) {
			$actions_output[$action] = array( 'action' => $action, 'parameters' => $parameters );
		}

		return array( $af_row, $actions_output );
	}
}