<?php
  /**
   * ownCloud
   *
   * @author Frank Karlitschek
   * @copyright 2012 Frank Karlitschek frank@owncloud.org
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
   * License as published by the Free Software Foundation; either
   * version 3 of the License, or any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
   *
   * You should have received a copy of the GNU Affero General Public
   * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  /**
   * This class provides all methods needed for managing groups.
   *
   * Hooks provided:
   *   pre_createGroup(&run, gid)
   *   post_createGroup(gid)
   *   pre_deleteGroup(&run, gid)
   *   post_deleteGroup(gid)
   *   pre_addToGroup(&run, uid, gid)
   *   post_addToGroup(uid, gid)
   *   pre_removeFromGroup(&run, uid, gid)
   *   post_removeFromGroup(uid, gid)
   */
  class OC_Group {
  	// The backend used for group management
  	/**
  	 * @var OC_Group_Interface[]
  	 */
  	private static $_usedBackends = array();
  
  	/**
  	 * @brief set the group backend
  	 * @param  string  $backend  The backend to use for user managment
  	 * @return bool
  	 */
  	public static function useBackend( $backend ) {
  		if($backend instanceof OC_Group_Interface) {
  			self::$_usedBackends[]=$backend;
  		}
  	}
  
  	/**
  	 * remove all used backends
  	 */
  	public static function clearBackends() {
  		self::$_usedBackends=array();
  	}
  
  	/**
  	 * @brief Try to create a new group
  	 * @param string $gid The name of the group to create
  	 * @return bool
  	 *
  	 * Tries to create a new group. If the group name already exists, false will
  	 * be returned. Basic checking of Group name
  	 */
  	public static function createGroup( $gid ) {
  		// No empty group names!
  		if( !$gid ) {
  			return false;
  		}
  		// No duplicate group names
  		if( in_array( $gid, self::getGroups())) {
  			return false;
  		}
  
  		$run = true;
  		OC_Hook::emit( "OC_Group", "pre_createGroup", array( "run" => &$run, "gid" => $gid ));
  
  		if($run) {
  			//create the group in the first backend that supports creating groups
  			foreach(self::$_usedBackends as $backend) {
  				if(!$backend->implementsActions(OC_GROUP_BACKEND_CREATE_GROUP))
  					continue;
  
  				$backend->createGroup($gid);
  				OC_Hook::emit( "OC_User", "post_createGroup", array( "gid" => $gid ));
  
  				return true;
  			}
  			return false;
  		}else{
  			return false;
  		}
  	}
  
  	/**
  	 * @brief delete a group
  	 * @param string $gid gid of the group to delete
  	 * @return bool
  	 *
  	 * Deletes a group and removes it from the group_user-table
  	 */
  	public static function deleteGroup( $gid ) {
  		// Prevent users from deleting group admin
  		if( $gid == "admin" ) {
  			return false;
  		}
  
  		$run = true;
  		OC_Hook::emit( "OC_Group", "pre_deleteGroup", array( "run" => &$run, "gid" => $gid ));
  
  		if($run) {
  			//delete the group from all backends
  			foreach(self::$_usedBackends as $backend) {
  				if(!$backend->implementsActions(OC_GROUP_BACKEND_DELETE_GROUP))
  					continue;
  
  				$backend->deleteGroup($gid);
  				OC_Hook::emit( "OC_User", "post_deleteGroup", array( "gid" => $gid ));
  
  				return true;
  			}
  			return false;
  		}else{
  			return false;
  		}
  	}
  
  	/**
  	 * @brief is user in group?
  	 * @param string $uid uid of the user
  	 * @param string $gid gid of the group
  	 * @return bool
  	 *
  	 * Checks whether the user is member of a group or not.
  	 */
  	public static function inGroup( $uid, $gid ) {
  		foreach(self::$_usedBackends as $backend) {
  			if($backend->inGroup($uid, $gid)) {
  				return true;
  			}
  		}
  		return false;
  	}
  
  	/**
  	 * @brief Add a user to a group
  	 * @param string $uid Name of the user to add to group
  	 * @param string $gid Name of the group in which add the user
  	 * @return bool
  	 *
  	 * Adds a user to a group.
  	 */
  	public static function addToGroup( $uid, $gid ) {
  		// Does the group exist?
  		if( !OC_Group::groupExists($gid)) {
  			return false;
  		}
  
  		// Go go go
  		$run = true;
  		OC_Hook::emit( "OC_Group", "pre_addToGroup", array( "run" => &$run, "uid" => $uid, "gid" => $gid ));
  
  		if($run) {
  			$success=false;
  
  			//add the user to the all backends that have the group
  			foreach(self::$_usedBackends as $backend) {
  				if(!$backend->implementsActions(OC_GROUP_BACKEND_ADD_TO_GROUP))
  					continue;
  
  				if($backend->groupExists($gid)) {
  					$success|=$backend->addToGroup($uid, $gid);
  				}
  			}
  			if($success) {
  				OC_Hook::emit( "OC_User", "post_addToGroup", array( "uid" => $uid, "gid" => $gid ));
  			}
  			return $success;
  		}else{
  			return false;
  		}
  	}
  
  	/**
  	 * @brief Removes a user from a group
  	 * @param string $uid Name of the user to remove from group
  	 * @param string $gid Name of the group from which remove the user
  	 * @return bool
  	 *
  	 * removes the user from a group.
  	 */
  	public static function removeFromGroup( $uid, $gid ) {
  		$run = true;
  		OC_Hook::emit( "OC_Group", "pre_removeFromGroup", array( "run" => &$run, "uid" => $uid, "gid" => $gid ));
  
  		if($run) {
  			//remove the user from the all backends that have the group
  			foreach(self::$_usedBackends as $backend) {
  				if(!$backend->implementsActions(OC_GROUP_BACKEND_REMOVE_FROM_GOUP))
  					continue;
  
  				$backend->removeFromGroup($uid, $gid);
  				OC_Hook::emit( "OC_User", "post_removeFromGroup", array( "uid" => $uid, "gid" => $gid ));
  			}
  			return true;
  		}else{
  			return false;
  		}
  	}
  
  	/**
  	 * @brief Get all groups a user belongs to
  	 * @param string $uid Name of the user
  	 * @return array with group names
  	 *
  	 * This function fetches all groups a user belongs to. It does not check
  	 * if the user exists at all.
  	 */
  	public static function getUserGroups( $uid ) {
  		$groups=array();
  		foreach(self::$_usedBackends as $backend) {
  			$groups=array_merge($backend->getUserGroups($uid), $groups);
  		}
  		asort($groups);
  		return $groups;
  	}
  
  	/**
  	 * @brief get a list of all groups
  	 * @returns array with group names
  	 *
  	 * Returns a list with all groups
  	 */
  	public static function getGroups($search = '', $limit = -1, $offset = 0) {
  		$groups = array();
  		foreach (self::$_usedBackends as $backend) {
  			$groups = array_merge($backend->getGroups($search, $limit, $offset), $groups);
  		}
  		asort($groups);
  		return $groups;
  	}
  
  	/**
  	 * check if a group exists
  	 * @param string $gid
  	 * @return bool
  	 */
  	public static function groupExists($gid) {
  		foreach(self::$_usedBackends as $backend) {
  			if ($backend->groupExists($gid)) {
  				return true;
  			}
  		}
  		return false;
  	}
  
  	/**
  	 * @brief get a list of all users in a group
  	 * @returns array with user ids
  	 */
  	public static function usersInGroup($gid, $search = '', $limit = -1, $offset = 0) {
  		$users=array();
  		foreach(self::$_usedBackends as $backend) {
  			$users = array_merge($backend->usersInGroup($gid, $search, $limit, $offset), $users);
  		}
  		return $users;
  	}
  
  	/**
  	 * @brief get a list of all users in several groups
  	 * @param array $gids
  	 * @param string $search
  	 * @param int $limit
  	 * @param int $offset
  	 * @return array with user ids
  	 */
  	public static function usersInGroups($gids, $search = '', $limit = -1, $offset = 0) {
  		$users = array();
  		foreach ($gids as $gid) {
  			// TODO Need to apply limits to groups as total
  			$users = array_merge(array_diff(self::usersInGroup($gid, $search, $limit, $offset), $users), $users);
  		}
  		return $users;
  	}
  
  	/**
  	 * @brief get a list of all display names in a group
  	 * @returns array with display names (value) and user ids(key)
  	 */
  	public static function displayNamesInGroup($gid, $search = '', $limit = -1, $offset = 0) {
  		$displayNames=array();
  		foreach(self::$_usedBackends as $backend) {
  			if($backend->implementsActions(OC_GROUP_BACKEND_GET_DISPLAYNAME)) {
  				$displayNames = array_merge($backend->displayNamesInGroup($gid, $search, $limit, $offset), $displayNames);
  			} else {
  				$users = $backend->usersInGroup($gid, $search, $limit, $offset);
  				$names = array_combine($users, $users);
  				$displayNames = array_merge($names, $displayNames);
  			}
  		}
  		return $displayNames;
  	}
  
  	/**
  	 * @brief get a list of all display names in several groups
  	 * @param array $gids
  	 * @param string $search
  	 * @param int $limit
  	 * @param int $offset
  	 * @return array with display names (Key) user ids (value)
  	 */
  	public static function displayNamesInGroups($gids, $search = '', $limit = -1, $offset = 0) {
  		$displayNames = array();
  		foreach ($gids as $gid) {
  			// TODO Need to apply limits to groups as total
  			$diff = array_diff(
  				self::displayNamesInGroup($gid, $search, $limit, $offset),
  				$displayNames
  			);
  			if ($diff) {
  				$displayNames = array_merge($diff, $displayNames);
  			}
  		}
  		return $displayNames;
  	}
  }