<?php

class EchoHooks {
	const EMAIL_NEVER = -1; // Never send email notifications
	const EMAIL_IMMEDIATELY = 0; // Send email notificaitons immediately as they come in
	const EMAIL_DAILY_DIGEST = 1; // Send daily email digests
	const EMAIL_WEEKLY_DIGEST = 7; // Send weekly email digests
	const EMAIL_FORMAT_HTML = 'html';
	const EMAIL_FORMAT_PLAIN_TEXT = 'plain-text';

	/**
	 * Initialize Echo extension with necessary data, this function is invoked
	 * from $wgExtensionFunctions
	 */
	public static function initEchoExtension() {
		global $wgEchoBackend, $wgEchoBackendName, $wgEchoNotifications,
			$wgEchoNotificationCategories, $wgEchoNotificationIcons, $wgEchoConfig;

		// allow extensions to define their own event
		wfRunHooks( 'BeforeCreateEchoEvent', array( &$wgEchoNotifications, &$wgEchoNotificationCategories, &$wgEchoNotificationIcons ) );

		$wgEchoBackend = MWEchoBackend::factory( $wgEchoBackendName );

		// turn schema off if eventLogging is not enabled
		if ( !function_exists( 'efLogServerSideEvent' ) ) {
			foreach ( $wgEchoConfig['eventlogging'] as $schema => $property ) {
				if ( $property['enabled'] ) {
					$wgEchoConfig['eventlogging'][$schema]['enabled'] = false;
				}
			}
		}
	}

	/**
	 * Handler for ResourceLoaderRegisterModules hook
	 */
	public static function onResourceLoaderRegisterModules( ResourceLoader &$resourceLoader ) {
		global $wgResourceModules, $wgEchoConfig;

		foreach ( $wgEchoConfig['eventlogging'] as $schema => $property ) {
			if ( $property['enabled'] ) {
				$wgResourceModules[ 'schema.' . $schema ] = array(
					'class'  => 'ResourceLoaderSchemaModule',
					'schema' => $schema,
					'revision' => $property['revision'],
				);
				$wgResourceModules['ext.echo.base']['dependencies'][] = 'schema.' . $schema;
			}
		}

		return true;
	}

	/**
	 * @param $updater DatabaseUpdater object
	 * @return bool true in all cases
	 */
	public static function getSchemaUpdates( $updater ) {
		$dir = __DIR__;
		$baseSQLFile = "$dir/echo.sql";
		$updater->addExtensionTable( 'echo_event', $baseSQLFile );
		$updater->addExtensionTable( 'echo_email_batch', "$dir/db_patches/echo_email_batch.sql" );

		if ( $updater->getDB()->getType() === 'sqlite' ) {
			$updater->modifyExtensionField( 'echo_event', 'event_agent', "$dir/db_patches/patch-event_agent-split.sqlite.sql" );
			$updater->modifyExtensionField( 'echo_event', 'event_variant', "$dir/db_patches/patch-event_variant_nullability.sqlite.sql" );
			// There is no need to run the patch-event_extra-size or patch-event_agent_ip-size because
			// sqlite ignores numeric arguments in parentheses that follow the type name (ex: VARCHAR(255))
			// see http://www.sqlite.org/datatype3.html Section 2.2 for more info
		} else {
			$updater->modifyExtensionField( 'echo_event', 'event_agent', "$dir/db_patches/patch-event_agent-split.sql" );
			$updater->modifyExtensionField( 'echo_event', 'event_variant', "$dir/db_patches/patch-event_variant_nullability.sql" );
			$updater->modifyExtensionField( 'echo_event', 'event_extra', "$dir/db_patches/patch-event_extra-size.sql" );
			$updater->modifyExtensionField( 'echo_event', 'event_agent_ip', "$dir/db_patches/patch-event_agent_ip-size.sql" );
		}

		$updater->addExtensionField( 'echo_notification', 'notification_bundle_base',
			"$dir/db_patches/patch-notification-bundling-field.sql" );
		// This index was renamed twice,  first from type_page to event_type and later from event_type to echo_event_type
		if ( $updater->getDB()->indexExists( 'echo_event', 'type_page', __METHOD__ ) ) {
			$updater->addExtensionIndex( 'echo_event', 'event_type', "$dir/db_patches/patch-alter-type_page-index.sql" );
		}
		$updater->dropTable( 'echo_subscription' );
		$updater->dropExtensionField( 'echo_event', 'event_timestamp', "$dir/db_patches/patch-drop-echo_event-event_timestamp.sql" );
		$updater->addExtensionField( 'echo_email_batch', 'eeb_event_hash',
			"$dir/db_patches/patch-email_batch-new-field.sql" );
		$updater->addExtensionField( 'echo_event', 'event_page_id', "$dir/db_patches/patch-add-echo_event-event_page_id.sql" );
		$updater->addExtensionIndex( 'echo_event', 'echo_event_type', "$dir/db_patches/patch-alter-event_type-index.sql" );
		$updater->addExtensionIndex( 'echo_notification', 'echo_user_timestamp', "$dir/db_patches/patch-alter-user_timestamp-index.sql" );

		return true;
	}

	/**
	 * Handler for EchoGetBundleRule hook, which defines the bundle rule for each notification
	 * @param $event EchoEvent
	 * @param $bundleString string Determines how the notification should be bundled, for example,
	 * talk page notification is bundled based on namespace and title, the bundle string would be
	 * 'edit-user-talk-' + namespace + title, email digest/email bundling would use this hash as
	 * a key to identify bundle-able event.  For web bundling, we bundle further based on user's
	 * visit to the overlay, we would generate a display hash based on the hash of $bundleString
	 *
	 */
	public static function onEchoGetBundleRules( $event, &$bundleString ) {
		switch ( $event->getType() ) {
			case 'edit-user-talk':
				$bundleString = 'edit-user-talk';
				if ( $event->getTitle() ) {
					$bundleString .= '-' . $event->getTitle()->getNamespace()
								. '-' . $event->getTitle()->getDBkey();
				}
			break;
			case 'page-linked':
				$bundleString = 'page-linked';
				if ( $event->getTitle() ) {
					$bundleString .= '-' . $event->getTitle()->getNamespace()
								. '-' . $event->getTitle()->getDBkey();
				}
			break;
		}
		return true;
	}

	/**
	 * Handler for EchoGetDefaultNotifiedUsers hook.
	 * @param $event EchoEvent to get implicitly subscribed users for
	 * @param &$users Array to append implicitly subscribed users to.
	 * @return bool true in all cases
	 */
	public static function getDefaultNotifiedUsers( $event, &$users ) {
		switch ( $event->getType() ) {
			// Everyone deserves to know when something happens
			// on their user talk page
			case 'edit-user-talk':
				if ( !$event->getTitle() || !$event->getTitle()->getNamespace() == NS_USER_TALK ) {
					break;
				}

				$username = $event->getTitle()->getText();
				$user = User::newFromName( $username );
				if ( $user && $user->getId() ) {
					$users[$user->getId()] = $user;
				}
				break;
			case 'add-comment':
			case 'add-talkpage-topic':
				// Handled by EchoDiscussionParser
				$extraData = $event->getExtra();

				if ( !isset( $extraData['revid'] ) || !$extraData['revid'] ) {
					break;
				}

				$revision = Revision::newFromId( $extraData['revid'] );
				if ( $revision ) {
					$users += EchoDiscussionParser::getNotifiedUsersForComment( $revision );
				}
				break;
			case 'welcome':
				$users[$event->getAgent()->getId()] = $event->getAgent();
				break;
			case 'reverted':
				$extra = $event->getExtra();

				if ( !$extra || !isset( $extra['reverted-user-id'] ) ) {
					break;
				}
				$victimID = $extra['reverted-user-id'];
				$victim = User::newFromId( $victimID );
				$users[$victim->getId()] = $victim;
				break;
			case 'page-linked':
				$agent = $event->getAgent();
				$title = $event->getTitle();

				if ( !$title || $title->getArticleID() <= 0 || !$agent ) {
					break;
				}

				$dbr = wfGetDB( DB_SLAVE );

				$res = $dbr->selectRow(
					array( 'revision' ),
					array( 'rev_user' ),
					array( 'rev_page' => $title->getArticleID() ),
					__METHOD__,
					array( 'LIMIT' => 1, 'ORDER BY' => 'rev_timestamp, rev_id' )
				);
				// No notification if agents link their own articles
				if ( $res && $res->rev_user && $agent->getID() != $res->rev_user ) {
					// Map each linked page to a corresponding author
					$user = User::newFromId( $res->rev_user );
					if ( $user ) {
						$users[$user->getID()] = $user;
					}
				}
				break;
			case 'mention':
				$extraData = $event->getExtra();
				foreach ( $extraData['mentioned-users'] as $userId ) {
					//backward compatibility
					if ( $userId instanceof User ) {
						$users[$userId->getID()] = $userId;
					} else {
						$users[$userId] = User::newFromId( $userId );
					}
				}
				break;
			case 'user-rights':
				$extraData = $event->getExtra();
				$users[$extraData['user']] = User::newFromId( $extraData['user'] );
				break;
		}

		return true;
	}

	/**
	 * Handler for EchoGetNotificationTypes hook, Adjust the notify types (e.g. web, email) which
	 * are applicable to this event and user based on various user options. In other words, allow
	 * certain non-echo user options to override the echo notification options.
	 * @param $user User
	 * @param $event EchoEvent
	 * @param $notifyTypes
	 * @return bool
	 */
	public static function getNotificationTypes( $user, $event, &$notifyTypes ) {
		$type = $event->getType();
		if ( !$user->getOption( 'enotifminoredits' ) ) {
			$extra = $event->getExtra();
			if ( !empty( $extra['revid'] ) ) {
				$rev = Revision::newFromID( $extra['revid'] );

				if ( $rev->isMinor() ) {
					$notifyTypes = array_diff( $notifyTypes, array( 'email' ) );
				}
			}
		}
		return true;
	}

	/**
	 * Handler for GetPreferences hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/GetPreferences
	 * @param $user User to get preferences for
	 * @param &$preferences Preferences array
	 * @return bool true in all cases
	 */
	public static function getPreferences( $user, &$preferences ) {
		global $wgEchoDefaultNotificationTypes, $wgAuth, $wgEchoEnableEmailBatch,
			$wgEchoNotifiers, $wgEchoNotificationCategories, $wgEchoNotifications,
			$wgEchoHelpPage, $wgEchoNewMsgAlert, $wgAllowHTMLEmail;

		// Don't show echo preference page if echo is disabled for this user
		if ( self::isEchoDisabled( $user ) ) {
			return true;
		}

		// Show email frequency options
		$never = wfMessage( 'echo-pref-email-frequency-never' )->plain();
		$immediately = wfMessage( 'echo-pref-email-frequency-immediately' )->plain();
		$freqOptions = array(
			$never => self::EMAIL_NEVER,
			$immediately => self::EMAIL_IMMEDIATELY,
		);
		// Only show digest options if email batch is enabled
		if ( $wgEchoEnableEmailBatch ) {
			$daily = wfMessage( 'echo-pref-email-frequency-daily' )->plain();
			$weekly = wfMessage( 'echo-pref-email-frequency-weekly' )->plain();
			$freqOptions += array(
				$daily => self::EMAIL_DAILY_DIGEST,
				$weekly => self::EMAIL_WEEKLY_DIGEST
			);
		}
		$preferences['echo-email-frequency'] = array(
			'type' => 'select',
			'label-message' => 'echo-pref-send-me',
			'section' => 'echo/emailsettings',
			'options' => $freqOptions
		);

		// Display information about the user's currently set email address
		$prefsTitle = SpecialPage::getTitleFor( 'Preferences', false, 'mw-prefsection-echo' );
		$link = Linker::link(
			SpecialPage::getTitleFor( 'ChangeEmail' ),
			wfMessage( $user->getEmail() ? 'prefs-changeemail' : 'prefs-setemail' )->escaped(),
			array(),
			array( 'returnto' => $prefsTitle->getFullText() )
		);
		$emailAddress = $user->getEmail() ? htmlspecialchars( $user->getEmail() ) : '';
		if ( $wgAuth->allowPropChange( 'emailaddress' ) ) {
			if ( $emailAddress === '' ) {
				$emailAddress .= $link;
			} else {
				$emailAddress .= wfMessage( 'word-separator' )->escaped()
					. wfMessage( 'parentheses' )->rawParams( $link )->escaped();
			}
		}
		$preferences['echo-emailaddress'] = array(
			'type' => 'info',
			'raw' => true,
			'default' => $emailAddress,
			'label-message' => 'echo-pref-send-to',
			'section' => 'echo/emailsettings'
		);

		// Only show this option if html email is allowed, otherwise it is always plain text format
		if ( $wgAllowHTMLEmail ) {
			// Email format
			$preferences['echo-email-format'] = array(
				'type' => 'select',
				'label-message' => 'echo-pref-email-format',
				'section' => 'echo/emailsettings',
				'options' => array (
					wfMessage( 'echo-pref-email-format-html' )->plain() => self::EMAIL_FORMAT_HTML,
					wfMessage( 'echo-pref-email-format-plain-text' )->plain() => self::EMAIL_FORMAT_PLAIN_TEXT
				)
			);
		}

		// Sort notification categories by priority
		$categoriesAndPriorities = array();
		foreach ( $wgEchoNotificationCategories as $category => $categoryData ) {
			// See if the category is not dismissable at all. Must do strict
			// comparison to true since no-dismiss can also be an array
			if ( isset( $categoryData['no-dismiss'] ) && in_array( 'all' , $categoryData['no-dismiss'] ) ) {
				continue;
			}
			// See if user is eligible to recieve this notification (per user group restrictions)
			if ( EchoNotificationController::getCategoryEligibility( $user, $category ) ) {
				$categoriesAndPriorities[$category] = EchoNotificationController::getCategoryPriority( $category );
			}
		}
		asort( $categoriesAndPriorities );
		$validSortedCategories = array_keys( $categoriesAndPriorities );

		// Show subscription options.  IMPORTANT: 'echo-subscriptions-email-edit-user-talk' is a
		// virtual option, its value is saved to existing talk page notification option
		// 'enotifusertalkpages', see onUserLoadOptions() and onUserSaveOptions() for more
		// information on how it is handled. Doing it in this way, we can avoid keeping running
		// massive data migration script to keep these two options synced when echo is enabled on
		// new wikis or Echo is disabled and re-enabled for some reason.  We can update the name
		// if Echo is ever merged to core

		// Build the columns (output formats)
		$columns = array();
		foreach ( $wgEchoNotifiers as $notifierType => $notifierData ) {
			$formatMessage = wfMessage( 'echo-pref-' . $notifierType )->escaped();
			$columns[$formatMessage] = $notifierType;
		}

		// Build the rows (notification categories)
		$rows = array();
		$tooltips = array();
		foreach ( $validSortedCategories as $category ) {
			$categoryMessage = wfMessage( 'echo-category-title-' . $category )->numParams( 1 )->escaped();
			$rows[$categoryMessage] = $category;
			if ( isset( $wgEchoNotificationCategories[$category]['tooltip'] ) ) {
				$tooltips[$categoryMessage] = wfMessage( $wgEchoNotificationCategories[$category]['tooltip'] )->text();
			}
		}

		// Figure out the individual exceptions in the matrix and make them disabled
		$forceOptionsOff = $forceOptionsOn = array();
		foreach ( $wgEchoNotifiers as $notifierType => $notifierData ) {
			foreach ( $validSortedCategories as $category ) {
				// See if this output format is non-dismissable
				if ( isset( $wgEchoNotificationCategories[$category]['no-dismiss'] )
					&& in_array( $notifierType, $wgEchoNotificationCategories[$category]['no-dismiss'] ) )
				{
					$forceOptionsOn[] = "$notifierType-$category";
				}

				// Make sure this output format is possible for this notification category
				if ( isset( $wgEchoDefaultNotificationTypes[$category] ) ) {
					if ( !$wgEchoDefaultNotificationTypes[$category][$notifierType] ) {
						$forceOptionsOff[] = "$notifierType-$category";
					}
				} elseif ( !$wgEchoDefaultNotificationTypes['all'][$notifierType] ) {
					$forceOptionsOff[] = "$notifierType-$category";
				}
			}
		}

		$invalid = array_intersect( $forceOptionsOff, $forceOptionsOn );
		if ( $invalid ) {
			throw new MWException( sprintf(
				'The following notifications are both forced and removed: %s',
				implode( ', ', $invalid )
			) );
		}
		$preferences['echo-subscriptions'] = array(
			'class' => 'HTMLCheckMatrix',
			'section' => 'echo/echosubscriptions',
			'rows' => $rows,
			'columns' => $columns,
			'prefix' => 'echo-subscriptions-',
			'force-options-off' => $forceOptionsOff,
			'force-options-on' => $forceOptionsOn,
			'tooltips' => $tooltips,
		);

		if ( $wgEchoNewMsgAlert ) {
			$preferences['echo-show-alert'] = array(
				'type' => 'toggle',
				'label-message' => 'echo-pref-new-message-indicator',
				'section' => 'echo/newmessageindicator',
			);
		}

		// If we're using Echo to handle user talk page post notifications,
		// hide the old (non-Echo) preference for this. If Echo is moved to core
		// we'll want to remove this old user option entirely. For now, though,
		// we need to keep it defined in case Echo is ever uninstalled.
		// Otherwise, that preference could be lost entirely. This hiding logic
		// is not abstracted since there is only a single preference in core
		// that is potentially made obsolete by Echo.
		if ( isset( $wgEchoNotifications['edit-user-talk'] ) ) {
			$preferences['enotifusertalkpages']['type'] = 'hidden';
			unset( $preferences['enotifusertalkpages']['section'] );
		}

		// Show fly-out display prefs
		// Per bug 47562, we're going to hide this pref for now until we see
		// what the community reaction to Echo is on en.wiki.
		$preferences['echo-notify-show-link'] = array(
			'type' => 'hidden',
			'label-message' => 'echo-pref-notify-show-link',
			//'section' => 'echo/displaynotifications',
		);
		return true;
	}

	/**
	 * Handler for ArticleSaveComplete hook
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/ArticleSaveComplete
	 * @param $article Article edited
	 * @param $user User who edited
	 * @param $text string New article text
	 * @param $summary string Edit summary
	 * @param $minoredit bool Minor edit or not
	 * @param $watchthis bool Watch this article?
	 * @param $sectionanchor string Section that was edited
	 * @param $flags int Edit flags
	 * @param $revision Revision that was created
	 * @param $status Status
	 * @return bool true in all cases
	 */
	public static function onArticleSaved( &$article, &$user, $text, $summary, $minoredit, $watchthis, $sectionanchor, &$flags, $revision, &$status ) {
		global $wgEchoNotifications, $wgRequest;
		if ( $revision ) {
			$title = $article->getTitle();
			// If the edit is to a talk page or a project page, send it to the
			// discussion parser.
			if ( $title->isTalkPage() || $title->inNamespace( NS_PROJECT ) ) {
				EchoDiscussionParser::generateEventsForRevision( $revision );
			}

			// Handle the case of someone undoing an edit, either through the
			// 'undo' link in the article history or via the API.
			if ( isset( $wgEchoNotifications['reverted'] ) ) {
				$undidRevId = $wgRequest->getVal( 'wpUndidRevision' );
				if ( $undidRevId ) {
					$undidRevision = Revision::newFromId( $undidRevId );
					if ( $undidRevision ) {
						$victimId = $undidRevision->getUser();
						if ( $victimId ) { // No notifications for anonymous users
							EchoEvent::create( array(
								'type' => 'reverted',
								'title' => $article->getTitle(),
								'extra' => array(
									'revid' => $revision->getId(),
									'reverted-user-id' => $victimId,
									'reverted-revision-id' => $undidRevId,
									'method' => 'undo',
								),
								'agent' => $user,
							) );
						}
					}
				}
			}

		}
		return true;
	}

	/**
	 * Handler for EchoAbortEmailNotification hook
	 * @param $user User
	 * @param $event EchoEvent
	 * @return bool true - send email, false - do not send email
	 */
	public static function onEchoAbortEmailNotification( $user, $event ) {
		if ( $event->getType() === 'edit-user-talk' ) {
			$extra = $event->getExtra();
			if ( !empty( $extra['minoredit'] ) ) {
				global $wgEnotifMinorEdits;
				if ( !$wgEnotifMinorEdits || !$user->getOption( 'enotifminoredits' ) ) {
					// Do not send talk page notification email
					return false;
				}
			}
		}

		// Proceed to send talk page notification email
		return true;
	}

	/**
	 * Handler for AddNewAccount hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/AddNewAccount
	 * @param $user User object that was created.
	 * @param $byEmail bool True when account was created "by email".
	 * @return bool
	 */
	public static function onAccountCreated( $user, $byEmail ) {

		// new users get echo preferences set that are not the default settings for existing users
		$user->setOption( 'echo-subscriptions-web-reverted', false );
		$user->setOption( 'echo-subscriptions-email-reverted', false );
		$user->setOption( 'echo-subscriptions-web-article-linked', true );
		$user->setOption( 'echo-subscriptions-email-mention', true );
		$user->setOption( 'echo-subscriptions-email-article-linked', true );
		$user->saveSettings();

		EchoEvent::create( array(
			'type' => 'welcome',
			'agent' => $user,
		) );

		return true;
	}

	/**
	 * Handler for UserRights hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UserRights
	 * @param $user User User object that was changed
	 * @param $add array Array of strings corresponding to groups added
	 * @param $remove array Array of strings corresponding to groups removed
	 */
	public static function onUserRights( &$user, $add, $remove ) {
		global $wgUser;

		if ( $user instanceof User && !$user->isAnon() && $wgUser->getId() != $user->getId() && ( $add || $remove ) ) {
			EchoEvent::create(
				array(
					'type' => 'user-rights',
					'title' => Title::newMainPage(),
					'extra' => array(
						'user' => $user->getID(),
						'add' => $add,
						'remove' => $remove
					),
					'agent' => $wgUser,
				)
			);
		}
		return true;
	}

	/**
	 * Handler for LinksUpdateAfterInsert hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/LinksUpdateAfterInsert
	 * @param $linksUpdate LinksUpdate
	 * @param $table string
	 * @param $insertions array
	 * @return bool
	 */
	public static function onLinksUpdateAfterInsert( $linksUpdate, $table, $insertions ) {
		global $wgRequest, $wgUser;

		// Rollback or undo should not trigger link notification
		// @Todo Implement a better solution so it doesn't depend on the checking of
		// a specific set of request variables
		if ( $wgRequest->getVal( 'wpUndidRevision' ) || $wgRequest->getVal( 'action' ) == 'rollback' ) {
			return true;
		}

		// Handle only
		// 1. inserts to pagelinks table &&
		// 2. content namespace pages &&
		// 3. non-transcluding pages &&
		// 4. non-redirect pages
		if ( $table !== 'pagelinks' || !MWNamespace::isContent( $linksUpdate->mTitle->getNamespace() )
			|| !$linksUpdate->mRecursive || $linksUpdate->mTitle->isRedirect() )
		{
			return true;
		}

		global $wgUser;

		// link notification is boundless as you can include infinite number of links in a page
		// db insert is expensive, limit it to a reasonable amount, we can increase this limit
		// once the storage is on Redis
		$max = 10;
		// Only create notifications for links to content namespace pages
		// @Todo - use one big insert instead of individual insert inside foreach loop
		foreach ( $insertions as $key => $page ) {
			if ( MWNamespace::isContent( $page['pl_namespace'] ) ) {
				$title = Title::makeTitle( $page['pl_namespace'], $page['pl_title'] );
				if ( $title->isRedirect() ) {
					continue;
				}

				EchoEvent::create( array(
					'type' => 'page-linked',
					'title' => $title,
					'agent' => $wgUser,
					'extra' => array(
						'link-from-page-id' => $linksUpdate->mTitle->getArticleId(),
					)
				) );
				$max--;
			}
			if ( $max < 0 ) {
				break;
			}
		}

		return true;
	}

	/**
	 * Handler for BeforePageDisplay hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/BeforePageDisplay
	 * @param $out OutputPage object
	 * @param $skin Skin being used.
	 * @return bool true in all cases
	 */
	static function beforePageDisplay( $out, $skin ) {
		global $wgEchoNewMsgAlert;
		$user = $out->getUser();

		// Don't show the alert message and badge if echo is disabled for this user
		if ( self::isEchoDisabled( $user ) ) {
			return true;
		}

		if ( $user->isLoggedIn() && $user->getOption( 'echo-notify-show-link' ) ) {
			// Load the module for the Notifications flyout
			$out->addModules( array( 'ext.echo.overlay' ) );
			// Load the styles for the Notifications badge
			$out->addModuleStyles( 'ext.echo.badge' );
		}
		if ( $wgEchoNewMsgAlert && $user->isLoggedIn() && $user->getOption( 'echo-show-alert' ) ) {
			$out->addModules( array( 'ext.echo.alert' ) );
		}
		return true;
	}

	/**
	 * Handler for PersonalUrls hook.
	 * Add a "Notifications" item to the user toolbar ('personal URLs').
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/PersonalUrls
	 * @param &$personal_urls Array of URLs to append to.
	 * @param &$title Title of page being visited.
	 * @return bool true in all cases
	 */
	static function onPersonalUrls( &$personal_urls, &$title ) {
		global $wgUser;
		// Add a "My notifications" item to personal URLs
		if ( $wgUser->isAnon() || self::isEchoDisabled( $wgUser ) || !$wgUser->getOption( 'echo-notify-show-link' ) ) {
			return true;
		}

		$notificationCount = MWEchoNotifUser::newFromUser( $wgUser )->getNotificationCount();
		$text = EchoNotificationController::formatNotificationCount( $notificationCount );
		$url = SpecialPage::getTitleFor( 'Notifications' )->getLocalURL();
		if ( $notificationCount == 0 ) {
			$linkClasses = array( 'mw-echo-notifications-badge' );
		} else {
			$linkClasses = array( 'mw-echo-unread-notifications', 'mw-echo-notifications-badge' );
		}
		$notificationsLink = array(
			'href' => $url,
			'text' => $text,
			'active' => ( $url == $title->getLocalUrl() ),
			'class' => $linkClasses,
		);

		$insertUrls = array( 'notifications' => $notificationsLink );
		$personal_urls = wfArrayInsertAfter( $personal_urls, $insertUrls, 'userpage' );
		return true;
	}

	/**
	 * Handler for AbortTalkPageEmailNotification hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/AbortTalkPageEmailNotification
	 * @param $targetUser User
	 * @param $title Title
	 * @return bool
	 */
	static function onAbortTalkPageEmailNotification( $targetUser, $title ) {
		global $wgEchoNotifications;

		// Send legacy talk page email notification if
		// 1. echo is disabled for them or
		// 2. echo talk page notification is disabled
		if ( self::isEchoDisabled( $targetUser ) || !isset( $wgEchoNotifications['edit-user-talk'] ) ) {
			// Legacy talk page email notification
			return true;
		}

		// Echo talk page email notification
		return false;
	}

	/**
	 * Handler for MakeGlobalVariablesScript hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/MakeGlobalVariablesScript
	 * @param &$vars array Variables to be added into the output
	 * @param $outputPage OutputPage instance calling the hook
	 * @return bool true in all cases
	 */
	public static function makeGlobalVariablesScript( &$vars, OutputPage $outputPage ) {
		global $wgEchoHelpPage, $wgEchoMaxNotificationCount, $wgEchoConfig;
		$user = $outputPage->getUser();

		// Provide info for the Overlay

		$timestamp = new MWTimestamp( wfTimestampNow() );
		if ( ! $user->isAnon() ) {
			$vars['wgEchoOverlayConfiguration'] = array(
				'notification-count' => MWEchoNotifUser::newFromUser( $user )->getFormattedNotificationCount(),
				'max-notification-count' => $wgEchoMaxNotificationCount,
			);
			$vars['wgEchoHelpPage'] = $wgEchoHelpPage;
			$vars['wgEchoConfig'] = $wgEchoConfig;
		}

		return true;
	}

	/**
	 * Handler for UnitTestsList hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UnitTestsList
	 * @param &$files Array of unit test files
	 * @return bool true in all cases
	 */
	static function getUnitTests( &$files ) {
		$dir = dirname( __FILE__ ) . '/tests';
		$files[] = "$dir/DiscussionParserTest.php";
		return true;
	}

	/**
	 * Handler for GetNewMessagesAlert hook.
	 * We're using the GetNewMessagesAlert hook instead of the
	 * ArticleEditUpdateNewTalk hook since we still want the user_newtalk data
	 * to be updated and availble to client-side tools and the API.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/GetNewMessagesAlert
	 * @param &$newMessagesAlert String An alert that the user has new messages
	 *     or an empty string if the user does not (empty by default)
	 * @param $newtalks Array This will be empty if the user has no new messages
	 *     or an Array containing links and revisions if there are new messages
	 * @param $user User The user who is loading the page
	 * @param $out Output object
	 * @return bool Should return false to prevent the new messages alert (OBOD)
	 *     or true to allow the new messages alert
	 */
	static function abortNewMessagesAlert( &$newMessagesAlert, $newtalks, $user, $out ) {
		global $wgEchoNotifications;

		// If the user has the notifications flyout turned on and is receiving
		// notifications for talk page messages, disable the new messages alert.
		if ( $user->isLoggedIn()
			&& $user->getOption( 'echo-notify-show-link' )
			&& isset( $wgEchoNotifications['edit-user-talk'] )
		) {
			// Show the new messages alert for users with echo disabled
			if ( self::isEchoDisabled( $user ) ) {
				return true;
			}
			// hide new messages alert
			return false;
		} else {
			// show new messages alert
			return true;
		}
	}

	/**
	 * Handler for ArticleRollbackComplete hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/ArticleRollbackComplete
	 * @param $page WikiPage The article that was edited
	 * @param $agent User The user who did the rollback
	 * @param $newRevision Revision The revision the page was reverted back to
	 * @param $oldRevision Revision The revision of the top edit that was reverted
	 * @return bool true in all cases
	 */
	static function onRollbackComplete( $page, $agent, $newRevision, $oldRevision ) {
		$victimId = $oldRevision->getUser();

		if ( $victimId ) { // No notifications for anonymous users
			EchoEvent::create( array(
				'type' => 'reverted',
				'title' => $page->getTitle(),
				'extra' => array(
					'revid' => $page->getRevision()->getId(),
					'reverted-user-id' => $victimId,
					'reverted-revision-id' => $oldRevision->getId(),
					'method' => 'rollback',
				),
				'agent' => $agent,
			) );
		}

		return true;
	}

	/**
	 * Handler for UserSaveSettings hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UserSaveSettings
	 * @param $user User whose settings were saved
	 * @return bool true in all cases
	 */
	static function onUserSaveSettings( $user ) {
		// Reset the notification count since it may have changed due to user
		// option changes. This covers both explicit changes in the preferences
		// and changes made through the options API (since both call this hook).
		MWEchoNotifUser::newFromUser( $user )->resetNotificationCount();
		return true;
	}

	/**
	 * Handler for UserLoadOptions hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UserLoadOptions
	 * @param $user User whose options were loaded
	 * @param $options Options can be modified
	 * @return bool true in all cases
	 */
	public static function onUserLoadOptions( $user, &$options ) {
		// Use existing enotifusertalkpages option for echo-subscriptions-email-edit-user-talk
		if ( isset( $options['enotifusertalkpages'] ) ) {
			$options['echo-subscriptions-email-edit-user-talk'] =  $options['enotifusertalkpages'];
		}
		return true;
	}

	/**
	 * Handler for UserSaveOptions hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UserSaveOptions
	 * @param $user User whose options are being saved
	 * @param $options Options can be modified
	 * @return bool true in all cases
	 */
	public static function onUserSaveOptions( $user, &$options ) {
		global $wgOut;

		$context = $wgOut->getContext();

		// Capture user options saved via Special:Preferences or ApiOptions
		if ( ( $context->getTitle() && $context->getTitle()->isSpecial( 'Preferences' ) )
			|| ( defined( 'MW_API' ) && $context->getRequest()->getVal( 'action' ) === 'options' )
		) {
			// $clone is the current user object with the new option value not set
			$clone = User::newFromId( $user->getId() );
			$updated = array();

			// loop through each options that starts with 'echo-'
			foreach ( $options as $optName => $optValue ) {
				// Only capture echo related preference
				if ( substr( $optName, 0, 5 ) !== 'echo-' ) {
					continue;
				}
				// loose comparision is required since some of the values
				// are not consistent in the two variables, eg, '' vs false
				if ( $clone->getOption( $optName ) != $optValue ) {
					$updated[$optName] = $optValue;
				}
			}

			if ( $updated ) {
				MWEchoEventLogging::logSchemaEchoPrefUpdate( $user, $updated );
			}
		}

		// echo-subscriptions-email-edit-user-talk is just a virtual option,
		// save the value in the real option enotifusertalkpages
		if ( isset( $options['echo-subscriptions-email-edit-user-talk'] ) ) {
			$options['enotifusertalkpages'] = $options['echo-subscriptions-email-edit-user-talk'];
			unset( $options['echo-subscriptions-email-edit-user-talk'] );
		}

		return true;
	}

	/**
	 * Handler for UserClearNewTalkNotification hook.
	 * @see http://www.mediawiki.org/wiki/Manual:Hooks/UserClearNewTalkNotification
	 * @param $user User whose talk page notification should be marked as read
	 * @return bool true in all cases
	 */
	public static function onUserClearNewTalkNotification( User $user ) {
		if ( !$user->isAnon() ) {
			MWEchoNotifUser::newFromUser( $user )->clearTalkNotification();
		}
		return true;
	}

	/**
	 * Handler for EchoCreateNotificationComplete hook, this will allow some
	 * extra stuff to be done upon creating a new notification
	 * @param $notif EchoNotification
	 * @return bool true in all cases
	 */
	public static function onEchoCreateNotificationComplete( EchoNotification $notif ) {
		if ( $notif->getEvent() && $notif->getUser() ) {
			// Extra stuff for talk page notification
			if ( $notif->getEvent()->getType() === 'edit-user-talk' ) {
				$notifUser = MWEchoNotifUser::newFromUser( $notif->getUser() );
				$notifUser->flagCacheWithNewTalkNotification();
			}
		}

		return true;
	}

	/**
	 * Echo should be disabled for users who are under cohort study
	 * @param $user User
	 * @return bool
	 */
	public static function isEchoDisabled( User $user ) {
		global $wgEchoCohortInterval;

		// Make sure the user has an id and cohort study timestamp is specified
		if ( !$wgEchoCohortInterval || !$user->getId() ) {
			return false;
		}

		list( $start, $bucketEnd, $cohortEnd ) = $wgEchoCohortInterval;

		$regTimestamp = $user->getRegistration();

		// Cohort study is for user with a registration timestamp
		if ( !$regTimestamp ) {
			return false;
		}

		// Cohort study is for even user_id
		if ( $user->getId() % 2 === 1 ) {
			return false;
		}

		$now = wfTimestampNow();

		// Make sure the user is registered during the bucketing period
		// and the cohort study doesn't end yet
		if ( $start <= $regTimestamp && $regTimestamp <= $bucketEnd
			&& $start <= $now && $now <= $cohortEnd
		) {
			return true;
		}

		return false;
	}

}