<?php
  
  /**
   * ownCloud - Django Authentification Backend
   *
   * @author Florian Reinhard
   * @copyright 2012 Florian Reinhard <florian.reinhard@googlemail.com>
   *
   * 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/>.
   *
   */
  
  require_once 'django_auth/3rdparty/phpsec.crypt.php';
  
  /**
  * @brief Class providing django users to ownCloud
  * @see http://www.djangoproject.com
  *
  * Authentification backend to authenticate agains a django webapplication using
  * django.contrib.auth.
  */
  class OC_USER_DJANGO extends OC_User_Backend {
  	/**
  	* @brief Create a new user
  	* @param $uid The username of the user to create
  	* @param $password The password of the new user
  	* @returns true/false
  	*
  	* Creates a new user. Basic checking of username is done in OC_User
  	* itself, not in its subclasses.
  	*/
  	public function createUser($uid, $password) {
  		OCP\Util::writeLog('OC_User_Django', 'Use the django webinterface to create users',3);
  		return OC_USER_BACKEND_NOT_IMPLEMENTED;
  	}
  
  	/**
  	* @brief delete a user
  	* @param $uid The username of the user to delete
  	* @returns true/false
  	*
  	* Deletes a user
  	*/
  	public function deleteUser( $uid ) {
  		OCP\Util::writeLog('OC_User_Django', 'Use the django webinterface to delete users',3);
  		return OC_USER_BACKEND_NOT_IMPLEMENTED;
  	}
  
  	/**
  	* @brief Set password
  	* @param $uid The username
  	* @param $password The new password
  	* @returns true/false
  	*
  	* Change the password of a user
  	*/
  	public function setPassword($uid, $password) {
  		OCP\Util::writeLog('OC_User_Django', 'Use the django webinterface to change passwords',3);
  		return OC_USER_BACKEND_NOT_IMPLEMENTED;
  	}
  
  	/**
  	* @brief Helper function for checkPassword
  	* @param $str The String to be searched
  	* @param $sub The String to be found
  	* @returns true/false
  	*/
  	private function beginsWith($str,$sub) {
  		return ( substr( $str, 0, strlen( $sub ) ) === $sub );
  	}
  
  	/**
  	* @brief Check if the password is correct
  	* @param $uid The username
  	* @param $password The password
  	* @returns true/false
  	*
  	* Check if the password is correct without logging in the user
  	*/
  	public function checkPassword($uid, $password) {
  		$query  = OCP\DB::prepare( 'SELECT username, password FROM auth_user WHERE username =  ?' );
  		$result = $query->execute( array( $uid));
  		$row    = $result->fetchRow();
  		if ($row) {
  			$storedHash=$row['password'];
  			if (self::beginsWith($storedHash, 'sha1')) {
  				$chunks = preg_split('/\$/', $storedHash,3);
  				$salt   = $chunks[1];
  				$hash   = $chunks[2];
  
  				if (sha1($salt.$password) === $hash)
  					return $uid;
  				else
  					return false;
  			}
  			elseif (self::beginsWith($storedHash, 'pbkdf2')) {
  				$chunks = preg_split('/\$/', $storedHash,4);
  				list($pbkdf, $algorithm) = preg_split('/_/', $chunks[0]);
  				$iter = $chunks[1];
  				$salt = $chunks[2];
  				$hash = $chunks[3];
  
  				if ($algorithm === 'sha1') {
  					$digest_size = 20;
  				}
  				elseif ($algorithm === 'sha256') {
  					$digest_size = 32;
  				}
  				else {
  					return false;
  				}
  
  				if (base64_encode (phpsecCrypt::pbkdf2($password, $salt, $iter, $digest_size, $algorithm)) === $hash) {
  					return $uid;
  				}
  				else {
  					return false;
  				}
  			}
  		}
  		else {
  			return false;
  		}
  	}
  
  	/**
  	* @brief Get a list of all users
  	* @returns array with all active usernames
  	*
  	* Get a list of all users.
  	*/
  	public function getUsers($search = '', $limit = 10, $offset = 0) {
  		$query  = OCP\DB::prepare( 'SELECT id, username, is_active FROM `auth_user` WHERE is_active=1 ORDER BY username' );
  		$result = $query->execute();
  		$users  = array();
  		while ( $row = $result->fetchRow()) {
  			$users[] = $row['username'];
  		}
  		return $users;
  	}
  
  	/**
  	* @brief check if a user exists
  	* @param string $uid the username
  	* @return boolean
  	*/
  	public function userExists($uid) {
  		$query  = OCP\DB::prepare( 'SELECT username FROM `auth_user` WHERE username = ? AND is_active=1' );
  		$result = $query->execute( array( $uid ));
  		return $result->numRows() > 0;
  	}
  }