<?php
  
  /**
   * Copyright (c) 2013 Robin Appelman <icewind@owncloud.com>
   * This file is licensed under the Affero General Public License version 3 or
   * later.
   * See the COPYING-README file.
   */
  
  namespace OC\User;
  
  use OC\Hooks\PublicEmitter;
  
  /**
   * Class Manager
   *
   * Hooks available in scope \OC\User:
   * - preSetPassword(\OC\User\User $user, string $password, string $recoverPassword)
   * - postSetPassword(\OC\User\User $user, string $password, string $recoverPassword)
   * - preDelete(\OC\User\User $user)
   * - postDelete(\OC\User\User $user)
   * - preCreateUser(string $uid, string $password)
   * - postCreateUser(\OC\User\User $user, string $password)
   *
   * @package OC\User
   */
  class Manager extends PublicEmitter {
  	/**
  	 * @var \OC_User_Backend[] $backends
  	 */
  	private $backends = array();
  
  	/**
  	 * @var \OC\User\User[] $cachedUsers
  	 */
  	private $cachedUsers = array();

  	/**
  	 * @var \OC\AllConfig $config
  	 */
  	private $config;
  
  	/**
  	 * @param \OC\AllConfig $config
  	 */
  	public function __construct($config = null) {
  		$this->config = $config;

  		$cachedUsers = $this->cachedUsers;
  		$this->listen('\OC\User', 'postDelete', function ($user) use (&$cachedUsers) {
  			$i = array_search($user, $cachedUsers);
  			if ($i !== false) {
  				unset($cachedUsers[$i]);
  			}
  		});
  	}
  
  	/**
  	 * register a user backend
  	 *
  	 * @param \OC_User_Backend $backend
  	 */
  	public function registerBackend($backend) {
  		$this->backends[] = $backend;
  	}
  
  	/**
  	 * remove a user backend
  	 *
  	 * @param \OC_User_Backend $backend
  	 */
  	public function removeBackend($backend) {
  		$this->cachedUsers = array();
  		if (($i = array_search($backend, $this->backends)) !== false) {
  			unset($this->backends[$i]);
  		}
  	}
  
  	/**
  	 * remove all user backends
  	 */
  	public function clearBackends() {
  		$this->cachedUsers = array();
  		$this->backends = array();
  	}
  
  	/**
  	 * get a user by user id
  	 *
  	 * @param string $uid
  	 * @return \OC\User\User
  	 */
  	public function get($uid) {
  		if (isset($this->cachedUsers[$uid])) { //check the cache first to prevent having to loop over the backends
  			return $this->cachedUsers[$uid];
  		}
  		foreach ($this->backends as $backend) {
  			if ($backend->userExists($uid)) {
  				return $this->getUserObject($uid, $backend);
  			}
  		}
  		return null;
  	}
  
  	/**
  	 * get or construct the user object
  	 *
  	 * @param string $uid
  	 * @param \OC_User_Backend $backend
  	 * @return \OC\User\User
  	 */
  	protected function getUserObject($uid, $backend) {
  		if (isset($this->cachedUsers[$uid])) {
  			return $this->cachedUsers[$uid];
  		}

  		$this->cachedUsers[$uid] = new User($uid, $backend, $this, $this->config);

  		return $this->cachedUsers[$uid];
  	}
  
  	/**
  	 * check if a user exists
  	 *
  	 * @param string $uid
  	 * @return bool
  	 */
  	public function userExists($uid) {
  		$user = $this->get($uid);
  		return ($user !== null);
  	}
  
  	/**
  	 * remove deleted user from cache
  	 *
  	 * @param string $uid
  	 * @return bool
  	 */
  	public function delete($uid) {
  		if (isset($this->cachedUsers[$uid])) {
  			unset($this->cachedUsers[$uid]);
  			return true;
  		}
  		return false;
  	}
  
  	/**
  	 * Check if the password is valid for the user
  	 *
  	 * @param $loginname
  	 * @param $password
  	 * @return mixed the User object on success, false otherwise
  	 */
  	public function checkPassword($loginname, $password) {
  		foreach ($this->backends as $backend) {

  			if ($backend->implementsActions(\OC_USER_BACKEND_CHECK_PASSWORD)) {

  				$uid = $backend->checkPassword($loginname, $password);
  				if ($uid !== false) {
  					return $this->getUserObject($uid, $backend);
  				}
  			}
  		}
  		return false;
  	}
  
  	/**
  	 * search by user id
  	 *
  	 * @param string $pattern
  	 * @param int $limit
  	 * @param int $offset
  	 * @return \OC\User\User[]
  	 */
  	public function search($pattern, $limit = null, $offset = null) {
  		$users = array();
  		foreach ($this->backends as $backend) {
  			$backendUsers = $backend->getUsers($pattern, $limit, $offset);
  			if (is_array($backendUsers)) {
  				foreach ($backendUsers as $uid) {

  					$users[$uid] = $this->getUserObject($uid, $backend);

  				}
  			}
  		}

  		uasort($users, function ($a, $b) {

  			/**
  			 * @var \OC\User\User $a
  			 * @var \OC\User\User $b
  			 */
  			return strcmp($a->getUID(), $b->getUID());
  		});
  		return $users;
  	}
  
  	/**
  	 * search by displayName
  	 *
  	 * @param string $pattern
  	 * @param int $limit
  	 * @param int $offset
  	 * @return \OC\User\User[]
  	 */
  	public function searchDisplayName($pattern, $limit = null, $offset = null) {
  		$users = array();
  		foreach ($this->backends as $backend) {
  			$backendUsers = $backend->getDisplayNames($pattern, $limit, $offset);
  			if (is_array($backendUsers)) {
  				foreach ($backendUsers as $uid => $displayName) {
  					$users[] = $this->getUserObject($uid, $backend);

  				}
  			}
  		}
  
  		usort($users, function ($a, $b) {
  			/**
  			 * @var \OC\User\User $a
  			 * @var \OC\User\User $b
  			 */
  			return strcmp($a->getDisplayName(), $b->getDisplayName());
  		});
  		return $users;
  	}
  
  	/**
  	 * @param string $uid
  	 * @param string $password
  	 * @throws \Exception
  	 * @return bool | \OC\User\User the created user of false
  	 */
  	public function createUser($uid, $password) {
  		// Check the name for bad characters
  		// Allowed are: "a-z", "A-Z", "0-9" and "_.@-"
  		if (preg_match('/[^a-zA-Z0-9 _\.@\-]/', $uid)) {
  			throw new \Exception('Only the following characters are allowed in a username:'

  				. ' "a-z", "A-Z", "0-9", and "_.@-"');

  		}
  		// No empty username
  		if (trim($uid) == '') {
  			throw new \Exception('A valid username must be provided');
  		}
  		// No empty password
  		if (trim($password) == '') {
  			throw new \Exception('A valid password must be provided');
  		}
  
  		// Check if user already exists
  		if ($this->userExists($uid)) {
  			throw new \Exception('The username is already being used');
  		}
  
  		$this->emit('\OC\User', 'preCreateUser', array($uid, $password));
  		foreach ($this->backends as $backend) {
  			if ($backend->implementsActions(\OC_USER_BACKEND_CREATE_USER)) {
  				$backend->createUser($uid, $password);
  				$user = $this->getUserObject($uid, $backend);
  				$this->emit('\OC\User', 'postCreateUser', array($user, $password));
  				return $user;
  			}
  		}
  		return false;
  	}

  
  	/**
  	 * returns how many users per backend exist (if supported by backend)
  	 *
  	 * @return array with backend class as key and count number as value
  	 */
  	public function countUsers() {
  		$userCountStatistics = array();
  		foreach ($this->backends as $backend) {
  			if ($backend->implementsActions(\OC_USER_BACKEND_COUNT_USERS)) {
  				$backendusers = $backend->countUsers();
  				if($backendusers !== false) {
  					if(isset($userCountStatistics[get_class($backend)])) {
  						$userCountStatistics[get_class($backend)] += $backendusers;
  					} else {
  						$userCountStatistics[get_class($backend)] = $backendusers;
  					}
  				}
  			}
  		}
  		return $userCountStatistics;
  	}

  }