<?php

/**
 * Entity that represents a notification target user
 */
class MWEchoNotifUser {

	/**
	 * Notification target user
	 * @var User
	 */
	private $mUser;

	/**
	 * Object cache
	 * @var BagOStuff
	 */
	private $cache;

	/**
	 * Database access gateway
	 * @var EchoUserNotificationGateway
	 */
	private $userNotifGateway;

	/**
	 * Notification mapper
	 * @var EchoNotificationMapper
	 */
	private $notifMapper;

	/**
	 * Target page mapper
	 * @var EchoTargetPageMapper
	 */
	private $targetPageMapper;

	/**
	 * @var EchoForeignNotifications
	 */
	private $foreignNotifications = null;

	/**
	 * @var array
	 */
	private $cached;

	/**
	 * @var array|null
	 */
	private $mForeignData = null;

	// The max notification count shown in badge

	// The max number shown in bundled message, eg, <user> and 99+ others <action>.
	// This is really a totally separate thing, and could be its own constant.

	// WARNING: If you change this, you should also change all references in the
	// i18n messages (100 and 99) in all repositories using Echo.
	const MAX_BADGE_COUNT = 99;

	/**
	 * Usually client code doesn't need to initialize the object directly
	 * because it could be obtained from factory method newFromUser()
	 * @param User $user
	 * @param BagOStuff $cache
	 * @param EchoUserNotificationGateway $userNotifGateway
	 * @param EchoNotificationMapper $notifMapper
	 * @param EchoTargetPageMapper $targetPageMapper
	 */
	public function __construct(
		User $user,
		BagOStuff $cache,
		EchoUserNotificationGateway $userNotifGateway,
		EchoNotificationMapper $notifMapper,
		EchoTargetPageMapper $targetPageMapper
	) {
		$this->mUser = $user;
		$this->userNotifGateway = $userNotifGateway;
		$this->cache = $cache;
		$this->notifMapper = $notifMapper;
		$this->targetPageMapper = $targetPageMapper;
	}

	/**
	 * Factory method
	 * @param $user User
	 * @throws MWException
	 * @return MWEchoNotifUser
	 */
	public static function newFromUser( User $user ) {
		if ( $user->isAnon() ) {
			throw new MWException( 'User must be logged in to view notification!' );
		}

		return new MWEchoNotifUser(
			$user,
			ObjectCache::getMainStashInstance(),
			new EchoUserNotificationGateway( $user, MWEchoDbFactory::newFromDefault() ),
			new EchoNotificationMapper(),
			new EchoTargetPageMapper()
		);
	}

	/**
	 * Clear talk page notification when users visit their talk pages.  This
	 * only resets if the notification count is less than max notification
	 * count. If the user has 99+ notifications, decrementing 1 bundled talk
	 * page notification would not really affect the count
	 */
	public function clearTalkNotification() {
		// There is no new talk notification
		if ( $this->cache->get( $this->getTalkNotificationCacheKey() ) === '0' ) {
			return;
		}

		// Do nothing if the count display meets the max 99+
		if ( $this->notifCountHasReachedMax() ) {
			return;
		}

		// Mark the talk page notification as read
		$this->markRead(
			$this->userNotifGateway->getUnreadNotifications(
				'edit-user-talk'
			)
		);

		$this->flagCacheWithNoTalkNotification();
	}

	/**
	 * Flag the cache with new talk notification
	 */
	public function flagCacheWithNewTalkNotification() {
		$this->cache->set( $this->getTalkNotificationCacheKey(), '1', 86400 );
	}

	/**
	 * Flag the cache with no talk notification
	 */
	public function flagCacheWithNoTalkNotification() {
		$this->cache->set( $this->getTalkNotificationCacheKey(), '0', 86400 );
	}

	/**
	 * Memcache key for talk notification
	 */
	public function getTalkNotificationCacheKey() {
		global $wgEchoConfig;

		return wfMemcKey( 'echo-new-talk-notification', $this->mUser->getId(), $wgEchoConfig['version'] );
	}

	/**
	 * Check if the user has more notification count than max count display
	 * @return bool
	 */
	public function notifCountHasReachedMax() {
		if ( $this->getLocalNotificationCount() >= self::MAX_BADGE_COUNT ) {
			return true;
		} else {
			return false;
		}
	}

	/**
	 * Get message count for this user.
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @return int
	 */
	public function getMessageCount( $cached = true, $dbSource = DB_SLAVE ) {
		return $this->getNotificationCount( $cached, $dbSource, EchoAttributeManager::MESSAGE );
	}

	/**
	 * Get alert count for this user.
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @return int
	 */
	public function getAlertCount( $cached = true, $dbSource = DB_SLAVE ) {
		return $this->getNotificationCount( $cached, $dbSource, EchoAttributeManager::ALERT );
	}

	public function getLocalNotificationCount( $cached = true, $dbSource = DB_SLAVE, $section = EchoAttributeManager::ALL ) {
		return $this->getNotificationCount( $cached, $dbSource, $section, false );
	}

	/**
	 * Retrieves number of unread notifications that a user has, would return
	 * MWEchoNotifUser::MAX_BADGE_COUNT + 1 at most.
	 *
	 * If $wgEchoCrossWikiNotifications is disabled, the $global parameter is ignored.
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @param string $section Notification section
	 * @param bool|string $global Whether to include foreign notifications. If set to 'preference', uses the user's preference.
	 * @return int
	 */
	public function getNotificationCount( $cached = true, $dbSource = DB_SLAVE, $section = EchoAttributeManager::ALL, $global = 'preference' ) {
		if ( $this->mUser->isAnon() ) {
			return 0;
		}

		global $wgEchoCrossWikiNotifications;
		if ( !$wgEchoCrossWikiNotifications ) {
			// Ignore the $global parameter
			$global = false;
		}

		if ( $global === 'preference' ) {
			$global = $this->getForeignNotifications()->isEnabledByUser();
		}

		$memcKey = $this->getMemcKey( 'echo-notification-count' . ( $section === EchoAttributeManager::ALL ? '' : ( '-' . $section ) ), $global );
		if ( $cached ) {
			$data = $this->getFromCache( $memcKey );
			if ( $data !== false && $data !== null ) {
				return (int)$data;
			}
		}

		$attributeManager = EchoAttributeManager::newFromGlobalVars();
		if ( $section === EchoAttributeManager::ALL ) {
			$eventTypesToLoad = $attributeManager->getUserEnabledEvents( $this->mUser, 'web' );
		} else {
			$eventTypesToLoad = $attributeManager->getUserEnabledEventsbySections( $this->mUser, 'web', array( $section ) );
		}

		$count = (int) $this->userNotifGateway->getCappedNotificationCount( $dbSource, $eventTypesToLoad, MWEchoNotifUser::MAX_BADGE_COUNT + 1 );

		if ( $global ) {
			$count += $this->getForeignCount( $section );
		}

		$this->setInCache( $memcKey, $count, 86400 );
		return $count;
	}

	/**
	 * Get the unread timestamp of the latest alert
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @return bool|MWTimestamp
	 */
	public function getLastUnreadAlertTime( $cached = true, $dbSource = DB_SLAVE ) {
		return $this->getLastUnreadNotificationTime( $cached, $dbSource, EchoAttributeManager::ALERT );
	}

	/**
	 * Get the unread timestamp of the latest message
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @return bool|MWTimestamp
	 */
	public function getLastUnreadMessageTime( $cached = true, $dbSource = DB_SLAVE ) {
		return $this->getLastUnreadNotificationTime( $cached, $dbSource, EchoAttributeManager::MESSAGE );
	}

	/**
	 * Returns the timestamp of the last unread notification.
	 *
	 * If $wgEchoCrossWikiNotifications is disabled, the $global parameter is ignored.
	 *
	 * @param boolean $cached Set to false to bypass the cache. (Optional. Defaults to true)
	 * @param int $dbSource Use master or slave database to pull count (Optional. Defaults to DB_SLAVE)
	 * @param string $section Notification section
	 * @param bool|string $global Whether to include foreign notifications. If set to 'preference', uses the user's preference.
	 * @return bool|MWTimestamp Timestamp of last notification, or false if there is none
	 */
	public function getLastUnreadNotificationTime( $cached = true, $dbSource = DB_SLAVE, $section = EchoAttributeManager::ALL, $global = 'preference' ) {
		if ( $this->mUser->isAnon() ) {
			return false;
		}

		global $wgEchoCrossWikiNotifications;
		if ( !$wgEchoCrossWikiNotifications ) {
			// Ignore the $global parameter
			$global = false;
		}

		if ( $global === 'preference' ) {
			$global = $this->getForeignNotifications()->isEnabledByUser();
		}

		$memcKey = $this->getMemcKey( 'echo-notification-timestamp' . ( $section === EchoAttributeManager::ALL ? '' : ( '-' . $section ) ), $global );

		// read from cache, if allowed
		if ( $cached ) {
			$timestamp = $this->getFromCache( $memcKey );
			if ( $timestamp === -1 ) {
				// -1 means the user has no notifications
				return false;
			} elseif ( $timestamp !== false ) {
				return new MWTimestamp( $timestamp );
			}
			// else cache miss
		}

		$timestamp = false;

		// Get timestamp of most recent local notification, if there is one
		$attributeManager = EchoAttributeManager::newFromGlobalVars();
		if ( $section === EchoAttributeManager::ALL ) {
			$eventTypesToLoad = $attributeManager->getUserEnabledEvents( $this->mUser, 'web' );
		} else {
			$eventTypesToLoad = $attributeManager->getUserEnabledEventsbySections( $this->mUser, 'web', array( $section ) );
		}
		$notifications = $this->notifMapper->fetchUnreadByUser( $this->mUser, 1, null, $eventTypesToLoad, null, $dbSource );
		if ( $notifications ) {
			$notification = reset( $notifications );
			$timestamp = new MWTimestamp( $notification->getTimestamp() );
		}

		// Use timestamp of most recent foreign notification, if it's more recent
		if ( $global ) {
			$foreignTime = $this->getForeignTimestamp( $section );

			if (
				$foreignTime !== false &&
				// $foreignTime < $timestamp = invert 0
				// $foreignTime > $timestamp = invert 1
				( $timestamp === false || $foreignTime->diff( $timestamp )->invert === 1 )
			) {
				$timestamp = $foreignTime;
			}
		}

		if ( $timestamp === false ) {
			// No notifications, so no timestamp
			$returnValue = false;
			$cacheValue = -1;
		} else {
			$returnValue = $timestamp;
			$cacheValue = $timestamp->getTimestamp( TS_MW );
		}

		$this->setInCache( $memcKey, $cacheValue, 86400 );
		return $returnValue;
	}

	/**
	 * Mark one or more notifications read for a user.
	 * @param $eventIds Array of event IDs to mark read
	 * @return boolean
	 */
	public function markRead( $eventIds ) {
		$eventIds = array_filter( (array)$eventIds, 'is_numeric' );
		if ( !$eventIds || wfReadOnly() ) {
			return false;
		}

		$res = $this->userNotifGateway->markRead( $eventIds );
		if ( $res ) {
			// Update notification count in cache
			$this->resetNotificationCount( DB_MASTER );

			// After this 'mark read', is there any unread edit-user-talk
			// remaining?  If not, we should clear the newtalk flag.
			if ( $this->mUser->getNewtalk() ) {
				$unreadEditUserTalk = $this->notifMapper->fetchUnreadByUser( $this->mUser, 1, null, array( 'edit-user-talk' ), null, DB_MASTER );
				if ( count( $unreadEditUserTalk ) === 0 ) {
					$this->mUser->setNewtalk( false );
				}
			}
		}

		return $res;
	}

	/**
	 * Mark one or more notifications unread for a user.
	 * @param $eventIds Array of event IDs to mark unread
	 * @return boolean
	 */
	public function markUnRead( $eventIds ) {
		$eventIds = array_filter( (array)$eventIds, 'is_numeric' );
		if ( !$eventIds || wfReadOnly() ) {
			return false;
		}

		$res = $this->userNotifGateway->markUnRead( $eventIds );
		if ( $res ) {
			// Update notification count in cache
			$this->resetNotificationCount( DB_MASTER );

			// After this 'mark unread', is there any unread edit-user-talk?
			// If so, we should add the edit-user-talk flag
			if ( !$this->mUser->getNewtalk() ) {
				$unreadEditUserTalk = $this->notifMapper->fetchUnreadByUser( $this->mUser, 1, null, array( 'edit-user-talk' ), null, DB_MASTER );
				if ( count( $unreadEditUserTalk ) > 0 ) {
					$this->mUser->setNewtalk( true );
				}
			}
		}

		return $res;
	}

	/**
	 * Attempt to mark all or sections of notifications as read, this only
	 * updates up to $wgEchoMaxUpdateCount records per request, see more
	 * detail about this in Echo.php, the other reason is that mediawiki
	 * database interface doesn't support updateJoin() that would update
	 * across multiple tables, we would visit this later
	 *
	 * @param string[] $sections
	 * @return boolean
	 */
	public function markAllRead( array $sections = array( EchoAttributeManager::ALL ) ) {
		if ( wfReadOnly() ) {
			return false;
		}

		global $wgEchoMaxUpdateCount;

		// Mark all sections as read if this is the case
		if ( in_array( EchoAttributeManager::ALL, $sections ) ) {
			$sections = EchoAttributeManager::$sections;
		}

		$attributeManager = EchoAttributeManager::newFromGlobalVars();
		$eventTypes = $attributeManager->getUserEnabledEventsbySections( $this->mUser, 'web', $sections );

		$notifs = $this->notifMapper->fetchUnreadByUser( $this->mUser, $wgEchoMaxUpdateCount, null, $eventTypes );

		$eventIds = array_filter(
			array_map( function ( EchoNotification $notif ) {
				// This should not happen at all, but use 0 in
				// such case so to keep the code running
				if ( $notif->getEvent() ) {
					return $notif->getEvent()->getId();
				} else {
					return 0;
				}
			}, $notifs )
		);

		$res = $this->markRead( $eventIds );
		if ( $res ) {
			// Delete records from echo_target_page
			/**
			 * Keep the 'echo_target_page' records so they can be used for moderation.
			 */
			// $this->targetPageMapper->deleteByUserEvents( $this->mUser, $eventIds );
			if ( count( $notifs ) < $wgEchoMaxUpdateCount ) {
				$this->flagCacheWithNoTalkNotification();
			}
		}

		return $res;
	}

	/**
	 * Recalculates the number of notifications that a user has.
	 * @param $dbSource int use master or slave database to pull count
	 */
	public function resetNotificationCount( $dbSource = DB_SLAVE ) {
		global $wgEchoCrossWikiNotifications;
		// Reset alert and message counts, and store them for later
		$alertCount = $this->getNotificationCount( false, $dbSource, EchoAttributeManager::ALERT, false );
		$msgCount = $this->getNotificationCount( false, $dbSource, EchoAttributeManager::MESSAGE, false );
		// For performance, compute the ALL count by adding alerts and messages
		$allCount = $alertCount + $msgCount;

		// When notification counts need to be updated, the last notification may have changed,
		// so we also need to recompute the cached timestamp values.
		$alertUnread = $this->getLastUnreadNotificationTime( false, $dbSource, EchoAttributeManager::ALERT, false );
		$msgUnread = $this->getLastUnreadNotificationTime( false, $dbSource, EchoAttributeManager::MESSAGE, false );
		// For performance, compute the ALL count as the highest of these two
		$allUnread = $alertUnread !== false &&
			( $msgUnread === false || $alertUnread->diff( $msgUnread )->invert === 1 ) ?
			$alertUnread : $msgUnread;

		// Write computed values to cache
		$this->setInCache( $this->getMemcKey( 'echo-notification-count' ), $allCount, 86400 );
		$this->setInCache( $this->getMemcKey( 'echo-notification-timestamp' ), $allUnread === false ? -1 : $allUnread->getTimestamp( TS_MW ), 86400 );

		if ( $wgEchoCrossWikiNotifications ) {
			// For performance, compute the global counts by adding foreign counts to the above
			$globalAlertCount = $alertCount + $this->getForeignCount( EchoAttributeManager::ALERT );
			$globalMsgCount = $msgCount + $this->getForeignCount( EchoAttributeManager::MESSAGE );
			$globalAllCount = $globalAlertCount + $globalMsgCount;

			// For performance, compute the global timestamps as max( localTimestamp, foreignTimestamp )
			$foreignAlertUnread = $this->getForeignTimestamp( EchoAttributeManager::ALERT );
			$globalAlertUnread = $alertUnread !== false &&
				( $foreignAlertUnread === false || $alertUnread->diff( $foreignAlertUnread )->invert === 1 ) ?
				$alertUnread : $foreignAlertUnread;
			$foreignMsgUnread = $this->getForeignTimestamp( EchoAttributeManager::MESSAGE );
			$globalMsgUnread = $msgUnread !== false &&
				( $foreignMsgUnread === false || $msgUnread->diff( $foreignMsgUnread )->invert === 1 ) ?
				$msgUnread : $foreignMsgUnread;
			$globalAllUnread = $globalAlertUnread !== false &&
				( $globalMsgUnread === false || $globalAlertUnread->diff( $globalMsgUnread )->invert === 1 ) ?
				$globalAlertUnread : $globalMsgUnread;

			// Write computed values to cache
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-count-alert' ), $globalAlertCount, 86400 );
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-count-message' ), $globalMsgCount, 86400 );
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-count' ), $globalAllCount, 86400 );
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-timestamp-alert' ), $globalAlertUnread === false ? -1 : $globalAlertUnread->getTimestamp( TS_MW ), 86400 );
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-timestamp-message' ), $globalMsgUnread === false ? -1 : $globalMsgUnread->getTimestamp( TS_MW ), 86400 );
			$this->setInCache( $this->getGlobalMemcKey( 'echo-notification-timestamp' ), $globalAllUnread === false ? -1 : $globalAllUnread->getTimestamp( TS_MW ), 86400 );

			// Schedule an update to the echo_unread_wikis table
			$user = $this->mUser;
			DeferredUpdates::addCallableUpdate( function () use ( $user, $alertCount, $alertUnread, $msgCount, $msgUnread ) {
				$uw = EchoUnreadWikis::newFromUser( $user );
				if ( $uw ) {
					$uw->updateCount( wfWikiID(), $alertCount, $alertUnread, $msgCount, $msgUnread );
				}
			} );
		}

		$this->invalidateCache();
	}

	/**
	 * Get the timestamp of the last time the global notification counts/timestamps were updated, if available.
	 *
	 * If the timestamp of the last update is not known, this will return the current timestamp.
	 * If the user is not attached, this will return false.
	 *
	 * @return string|false MW timestamp of the last update, or false if the user is not attached
	 */
	public function getGlobalUpdateTime() {
		$key = $this->getGlobalMemcKey( 'echo-notification-updated' );
		if ( $key === false ) {
			return false;
		}
		return wfTimestamp( TS_MW, ObjectCache::getMainWANInstance()->getCheckKeyTime( $key ) );
	}

	/**
	 * Invalidate user caches related to notification counts/timestamps.
	 *
	 * This bumps the local user's touched timestamp as well as the timestamp returned by getGlobalUpdateTime().
	 */
	protected function invalidateCache() {
		// Update the user touched timestamp for the local user
		$this->mUser->invalidateCache();

		global $wgEchoCrossWikiNotifications;
		if ( $wgEchoCrossWikiNotifications ) {
			// Update the global touched timestamp
			$key = $this->getGlobalMemcKey( 'echo-notification-updated' );
			if ( $key ) {
				ObjectCache::getMainWANInstance()->touchCheckKey( $key );
			}
		}
	}

	/**
	 * Get the user's email notification format
	 * @return string
	 */
	public function getEmailFormat() {
		global $wgAllowHTMLEmail;

		if ( $wgAllowHTMLEmail ) {
			return $this->mUser->getOption( 'echo-email-format' );
		} else {
			return EchoEmailFormat::PLAIN_TEXT;
		}
	}

	/**
	 * Get a cache entry from the cache, using a preloaded instance cache.
	 * @param  string|false $memcKey Cache key returned by getMemcKey()
	 * @return mixed Cache value
	 */
	protected function getFromCache( $memcKey ) {
		// getMemcKey() can return false
		if ( $memcKey === false ) {
			return false;
		}

		// Populate the instance cache
		if ( $this->cached === null ) {
			$keys = $this->getPreloadKeys();
			$this->cached = $this->cache->getMulti( $keys );
			// also keep track of cache values that couldn't be found (getMulti
			// omits them...)
			$this->cached += array_fill_keys( $keys, false );
		}

		if ( isset( $this->cached[$memcKey] ) ) {
			return $this->cached[$memcKey];
		}

		return $this->cache->get( $memcKey );
	}

	/**
	 * Set a cache entry both in the cache and in the instance cache.
	 * Use this to write to keys that were loaded with getFromCache().
	 * @param string|false $memcKey Cache key returned by getMemcKey()
	 * @param mixed $value Cache value to set
	 * @param int $expiry Expiry, see BagOStuff::set()
	 */
	protected function setInCache( $memcKey, $value, $expiry ) {
		// getMemcKey() can return false
		if ( $memcKey === false ) {
			return;
		}

		// Update the instance cache if it's already been populated
		if ( $this->cached !== null ) {
			$this->cached[$memcKey] = $value;
		}

		$this->cache->set( $memcKey, $value, $expiry );
	}

	/**
	 * Array of memcached keys to load at once.
	 *
	 * @return array
	 */
	protected function getPreloadKeys() {
		$keys = array(
			'echo-notification-timestamp',
			'echo-notification-timestamp-' . EchoAttributeManager::MESSAGE,
			'echo-notification-timestamp-' . EchoAttributeManager::ALERT,
			'echo-notification-count',
			'echo-notification-count-' . EchoAttributeManager::MESSAGE,
			'echo-notification-count-' . EchoAttributeManager::ALERT,
		);

		return array_filter( array_merge(
			array_map( array( $this, 'getMemcKey' ), $keys ),
			array_map( array( $this, 'getGlobalMemcKey' ), $keys )
		) );
	}

	/**
	 * Build a memcached key.
	 * @param string $key Key, typically prefixed with echo-notification-
	 * @param bool $global If true, return a global memc key; if false, return one local to this wiki
	 * @return string|false Memcached key, or false if one could not be generated
	 */
	protected function getMemcKey( $key, $global = false ) {
		global $wgEchoConfig;
		if ( !$global ) {
			return wfMemcKey( $key, $this->mUser->getId(), $wgEchoConfig['version'] );
		}

		$lookup = CentralIdLookup::factory();
		$globalId = $lookup->centralIdFromLocalUser( $this->mUser, CentralIdLookup::AUDIENCE_RAW );
		if ( !$globalId ) {
			return false;
		}
		return wfGlobalCacheKey( $key, $globalId, $wgEchoConfig['version'] );

	}

	protected function getGlobalMemcKey( $key ) {
		return $this->getMemcKey( $key, true );
	}

	/**
	 * Lazy-construct an EchoForeignNotifications instance. This instance is force-enabled, so it
	 * returns information about cross-wiki notifications even if the user has them disabled.
	 * @return EchoForeignNotifications
	 */
	protected function getForeignNotifications() {
		if ( !$this->foreignNotifications ) {
			$this->foreignNotifications = new EchoForeignNotifications( $this->mUser, true );
		}
		return $this->foreignNotifications;
	}

	/**
	 * Get data about foreign notifications from the foreign wikis' APIs.
	 *
	 * This is used when $wgEchoSectionTransition or $wgEchoBundleTransition is enabled,
	 * to deal with untrustworthy echo_unread_wikis entries. This method fetches the list of
	 * wikis that have any unread notifications at all from the echo_unread_wikis table, then
	 * queries their APIs to find the per-section counts and timestamps for those wikis.
	 *
	 * The results of this function are cached in the NotifUser object.
	 * @return array [ (str) wiki => [ (str) section => [ 'count' => (int) count, 'timestamp' => (str) ts ] ] ]
	 */
	protected function getForeignData() {
		if ( $this->mForeignData ) {
			return $this->mForeignData;
		}

		$potentialWikis = $this->getForeignNotifications()->getWikis( EchoAttributeManager::ALL );
		$foreignReq = new EchoForeignWikiRequest(
			$this->mUser,
			array(
				'action' => 'query',
				'meta' => 'notifications',
				'notprop' => 'count|list',
				'notgroupbysection' => '1',
				'notunreadfirst' => '1',
			),
			$potentialWikis,
			'notwikis'
		);
		$foreignResults = $foreignReq->execute();

		$this->mForeignData = array();
		foreach ( $foreignResults as $wiki => $result ) {
			if ( !isset( $result['query']['notifications'] ) ) {
				continue;
			}
			$data = $result['query']['notifications'];
			foreach ( EchoAttributeManager::$sections as $section ) {
				if ( isset( $data[$section]['rawcount'] ) ) {
					$this->mForeignData[$wiki][$section]['count'] = $data[$section]['rawcount'];
				}
				if ( isset( $data[$section]['list'][0] ) ) {
					$this->mForeignData[$wiki][$section]['timestamp'] = $data[$section]['list'][0]['timestamp']['mw'];
				}
			}
		}
		return $this->mForeignData;
	}

	protected function getForeignCount( $section = EchoAttributeManager::ALL ) {
		global $wgEchoSectionTransition, $wgEchoBundleTransition;
		$count = 0;
		if (
			// In section transition mode, we don't trust the individual echo_unread_wikis rows
			// but we do trust that alert+message=all. In bundle transition mode, we don't trust
			// that either, but we do trust that wikis with rows in the table have unread notifications
			// and wikis without rows in the table don't.
			( $wgEchoSectionTransition && $section !== EchoAttributeManager::ALL ) ||
			$wgEchoBundleTransition
		) {
			$foreignData = $this->getForeignData();
			foreach ( $foreignData as $data ) {
				if ( $section === EchoAttributeManager::ALL ) {
					foreach ( $data as $subData ) {
						if ( isset( $subData['count'] ) ) {
							$count += $subData['count'];
						}
					}
				} elseif ( isset( $data[$section]['count'] ) ) {
					$count += $data[$section]['count'];
				}
			}
		} else {
			$count += $this->getForeignNotifications()->getCount( $section );
		}
		return $count;
	}

	protected function getForeignTimestamp( $section = EchoAttributeManager::ALL ) {
		global $wgEchoSectionTransition, $wgEchoBundleTransition;

		if (
			// In section transition mode, we don't trust the individual echo_unread_wikis rows
			// but we do trust that alert+message=all. In bundle transition mode, we don't trust
			// that either, but we do trust that wikis with rows in the table have unread notifications
			// and wikis without rows in the table don't.
			( $wgEchoSectionTransition && $section !== EchoAttributeManager::ALL ) ||
			$wgEchoBundleTransition
		) {
			$foreignTime = false;
			$foreignData = $this->getForeignData();
			foreach ( $foreignData as $data ) {
				if ( $section === EchoAttributeManager::ALL ) {
					foreach ( $data as $subData ) {
						if ( isset( $subData['timestamp'] ) ) {
							$wikiTime = new MWTimestamp( $data[$section]['timestamp'] );
							// $wikiTime > $foreignTime = invert 1
							if ( $foreignTime === false || $wikiTime->diff( $foreignTime )->invert === 1 ) {
								$foreignTime = $wikiTime;
							}
						}
					}
				} elseif ( isset( $data[$section]['timestamp'] ) ) {
					$wikiTime = new MWTimestamp( $data[$section]['timestamp'] );
					// $wikiTime > $foreignTime = invert 1
					if ( $foreignTime === false || $wikiTime->diff( $foreignTime )->invert === 1 ) {
						$foreignTime = $wikiTime;
					}
				}
			}
		} else {
			$foreignTime = $this->getForeignNotifications()->getTimestamp( $section );
		}
		return $foreignTime;
	}
}