<?
class Forums {
	/**
	 * Get information on a thread.
	 *
	 * @param int $ThreadID
	 *        	the thread ID.
	 * @param boolean $Return
	 *        	indicates whether thread info should be returned.
	 * @param Boolean $SelectiveCache
	 *        	cache thread info/
	 * @return array holding thread information.
	 */
	public static function get_thread_info($ThreadID, $Return = true, $SelectiveCache = false) {
		if ((!$ThreadInfo = G::$Cache->get_value('thread_' . $ThreadID . '_info')) || !isset($ThreadInfo['Ranking'])) {
			$QueryID = G::$DB->get_query_id();
			G::$DB->query(
				"SELECT
					t.Title,
					t.ForumID,
					t.IsLocked,
					t.IsSticky,
					COUNT(fp.id) AS Posts,
					t.LastPostAuthorID,
					ISNULL(p.TopicID) AS NoPoll,
					t.StickyPostID,
					t.AuthorID as OP,
					t.Ranking
					FROM forums_topics AS t
						JOIN forums_posts AS fp ON fp.TopicID = t.ID
						LEFT JOIN forums_polls AS p ON p.TopicID=t.ID
					WHERE t.ID = '$ThreadID'
					GROUP BY fp.TopicID");
			if (G::$DB->record_count() == 0) {
				error(404);
			}
			$ThreadInfo = G::$DB->next_record(MYSQLI_ASSOC, false);
			if ($ThreadInfo['StickyPostID']) {
				$ThreadInfo['Posts']--;
				G::$DB->query(
					"SELECT
						p.ID,
						p.AuthorID,
						p.AddedTime,
						p.Body,
						p.EditedUserID,
						p.EditedTime,
						ed.Username
						FROM forums_posts as p
							LEFT JOIN users_main AS ed ON ed.ID = p.EditedUserID
						WHERE p.TopicID = '$ThreadID'
							AND p.ID = '" . $ThreadInfo['StickyPostID'] . "'");
				list ($ThreadInfo['StickyPost']) = G::$DB->to_array(false, MYSQLI_ASSOC);
			}
			G::$DB->set_query_id($QueryID);
			if (!$SelectiveCache || !$ThreadInfo['IsLocked'] || $ThreadInfo['IsSticky']) {
				G::$Cache->cache_value('thread_' . $ThreadID . '_info', $ThreadInfo, 0);
			}
		}
		if ($Return) {
			return $ThreadInfo;
		}
	}

	/**
	 * Checks whether user has permissions on a forum.
	 *
	 * @param int $ForumID
	 *        	the forum ID.
	 * @param string $Perm
	 *        	the permissision to check, defaults to 'Read'
	 * @return boolean true if user has permission
	 */
	public static function check_forumperm($ForumID, $Perm = 'Read') {
		$Forums = self::get_forums();
		if (isset(G::$LoggedUser['CustomForums'][$ForumID]) && G::$LoggedUser['CustomForums'][$ForumID] == 1) {
			return true;
		}
		if ($ForumID == DONOR_FORUM && Donations::has_donor_forum(G::$LoggedUser['ID'])) {
			return true;
		}
		if ($Forums[$ForumID]['MinClass' . $Perm] > G::$LoggedUser['Class'] && (!isset(G::$LoggedUser['CustomForums'][$ForumID]) || G::$LoggedUser['CustomForums'][$ForumID] == 0)) {
			return false;
		}
		if (isset(G::$LoggedUser['CustomForums'][$ForumID]) && G::$LoggedUser['CustomForums'][$ForumID] == 0) {
			return false;
		}
		return true;
	}

	/**
	 * Gets basic info on a forum.
	 *
	 * @param int $ForumID
	 *        	the forum ID.
	 */
	public static function get_forum_info($ForumID) {
		$Forum = G::$Cache->get_value('ForumInfo_' . $ForumID);
		if (!$Forum) {
			$QueryID = G::$DB->get_query_id();
			G::$DB->query("SELECT
					Name,
					MinClassRead,
					MinClassWrite,
					MinClassCreate,
					COUNT(forums_topics.ID) AS Topics
					FROM forums
					LEFT JOIN forums_topics ON forums_topics.ForumID=forums.ID
					WHERE forums.ID='$ForumID'
					GROUP BY ForumID");
			if (G::$DB->record_count() == 0) {
				return false;
			}
			// Makes an array, with $Forum['Name'], etc.
			$Forum = G::$DB->next_record(MYSQLI_ASSOC);

			G::$DB->set_query_id($QueryID);

			G::$Cache->cache_value('ForumInfo_' . $ForumID, $Forum, 86400);
		}
		return $Forum;
	}

	/**
	 * Get the forum categories
	 * @return array ForumCategoryID => Name
	 */
	public static function get_forum_categories() {
		$ForumCats = G::$Cache->get_value('forums_categories');
		if ($ForumCats === false) {
			$QueryID = G::$DB->get_query_id();
			G::$DB->query("SELECT ID, Name FROM forums_categories");
			$ForumCats = array();
			while (list ($ID, $Name) = G::$DB->next_record()) {
				$ForumCats[$ID] = $Name;
			}
			G::$DB->set_query_id($QueryID);
			G::$Cache->cache_value('forums_categories', $ForumCats, 0);
		}
		return $ForumCats;
	}

	/**
	 * Get the forums
	 * @return array ForumID => (various information about the forum)
	 */
	public static function get_forums() {
		if (!$Forums = G::$Cache->get_value('forums_list')) {
			$QueryID = G::$DB->get_query_id();
			G::$DB->query("
				SELECT
					f.ID,
					f.CategoryID,
					f.Name,
					f.Description,
					f.MinClassRead AS MinClassRead,
					f.MinClassWrite AS MinClassWrite,
					f.MinClassCreate AS MinClassCreate,
					f.NumTopics,
					f.NumPosts,
					f.LastPostID,
					f.LastPostAuthorID,
					f.LastPostTopicID,
					f.LastPostTime,
					0 AS SpecificRules,
					t.Title,
					t.IsLocked AS Locked,
					t.IsSticky AS Sticky
				FROM forums AS f
					JOIN forums_categories AS fc ON fc.ID = f.CategoryID
					LEFT JOIN forums_topics as t ON t.ID = f.LastPostTopicID
				GROUP BY f.ID
				ORDER BY fc.Sort, fc.Name, f.CategoryID, f.Sort");
			$Forums = G::$DB->to_array('ID', MYSQLI_ASSOC, false);

			G::$DB->query("SELECT ForumID, ThreadID FROM forums_specific_rules");
			$SpecificRules = array();
			while (list($ForumID, $ThreadID) = G::$DB->next_record(MYSQLI_NUM, false)) {
				$SpecificRules[$ForumID][] = $ThreadID;
			}
			G::$DB->set_query_id($QueryID);
			foreach ($Forums as $ForumID => &$Forum) {
				if (isset($SpecificRules[$ForumID])) {
					$Forum['SpecificRules'] = $SpecificRules[$ForumID];
				} else {
					$Forum['SpecificRules'] = array();
				}
			}
			G::$Cache->cache_value('forums_list', $Forums, 0);
		}
		return $Forums;
	}

	/**
	 * Get all forums that the current user has special access to ("Extra forums" in the profile)
	 * @return array Array of ForumIDs
	 */
	public static function get_permitted_forums() {
		return (array)array_keys(G::$LoggedUser['CustomForums'], 1);
	}

	/**
	 * Get all forums that the current user does not have access to ("Restricted forums" in the profile)
	 * @return array Array of ForumIDs
	 */
	public static function get_restricted_forums() {
		return (array)array_keys(G::$LoggedUser['CustomForums'], 0);
	}

	/**
	 * Get the last read posts for the current user
	 * @param array $Forums Array of forums as returned by self::get_forums()
	 * @return array TopicID => array(TopicID, PostID, Page) where PostID is the ID of the last read post and Page is the page on which that post is
	 */
	public static function get_last_read($Forums) {
		if (isset(G::$LoggedUser['PostsPerPage'])) {
			$PerPage = G::$LoggedUser['PostsPerPage'];
		} else {
			$PerPage = POSTS_PER_PAGE;
		}
		$TopicIDs = array();
		foreach ($Forums as $Forum) {
			if (!empty($Forum['LastPostTopicID'])) {
				$TopicIDs[] = $Forum['LastPostTopicID'];
			}
		}
		if (!empty($TopicIDs)) {
			$QueryID = G::$DB->get_query_id();
			G::$DB->query("
				SELECT
					l.TopicID,
					l.PostID,
					CEIL(
						(
							SELECT
								COUNT(ID)
							FROM forums_posts
							WHERE forums_posts.TopicID = l.TopicID
								AND forums_posts.ID<=l.PostID
						)/$PerPage
					) AS Page
				FROM forums_last_read_topics AS l
				WHERE TopicID IN(" . implode(',', $TopicIDs) . ") AND
					UserID='" . G::$LoggedUser['ID'] . "'");
			$LastRead = G::$DB->to_array('TopicID', MYSQLI_ASSOC);
			G::$DB->set_query_id($QueryID);
		} else {
			$LastRead = array();
		}
		return $LastRead;
	}

	/**
	 * Determine if a thread is unread
	 * @param bool $Locked
	 * @param bool $Sticky
	 * @param int $LastPostID
	 * @param array $LastRead An array as returned by self::get_last_read
	 * @param int $LastTopicID TopicID of the thread where the most recent post was made
	 * @param string $LastTime Datetime of the last post
	 * @return bool
	 */
	public static function is_unread($Locked, $Sticky, $LastPostID, $LastRead, $LastTopicID, $LastTime) {
		return (!$Locked || $Sticky) && $LastPostID != 0 && ((empty($LastRead[$LastTopicID]) || $LastRead[$LastTopicID]['PostID'] < $LastPostID) && strtotime($LastTime) > G::$LoggedUser['CatchupTime']);
	}

	/**
	 * Create the part of WHERE in the sql queries used to filter forums for a
	 * specific user (MinClassRead, restricted and permitted forums).
	 * @return string
	 */
	public static function user_forums_sql() {
		// I couldn't come up with a good name, please rename this if you can. -- Y
		$RestrictedForums = self::get_restricted_forums();
		$PermittedForums = self::get_permitted_forums();
		if (Donations::has_donor_forum(G::$LoggedUser['ID']) && !in_array(DONOR_FORUM, $PermittedForums)) {
			$PermittedForums[] = DONOR_FORUM;
		}
		$SQL = "((f.MinClassRead <= '" . G::$LoggedUser['Class'] . "'";
		if (count($RestrictedForums)) {
			$SQL .= " AND f.ID NOT IN ('" . implode("', '", $RestrictedForums) . "')";
		}
		$SQL .= ')';
		if (count($PermittedForums)) {
			$SQL .= " OR f.ID IN ('" . implode("', '", $PermittedForums) . "')";
		}
		$SQL .= ')';
		return $SQL;
	}
}