<?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;
	}
}