<?php
  /**
  * ownCloud
  *
  * @author Tom Needham
  * @author Michael Gapczynski
  * @author Bart Visscher
  * @copyright 2012 Tom Needham tom@owncloud.com
  * @copyright 2012 Michael Gapczynski mtgap@owncloud.com
  * @copyright 2012 Bart Visscher bartv@thisnet.nl
  *
  * 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/>.
  *
  */
  
  class OC_API {
  
  	/**
  	 * API authentication levels
  	 */
  	const GUEST_AUTH = 0;
  	const USER_AUTH = 1;
  	const SUBADMIN_AUTH = 2;
  	const ADMIN_AUTH = 3;
  	
  	/**
  	 * API Response Codes
  	 */
  	const RESPOND_UNAUTHORISED = 997;
  	const RESPOND_SERVER_ERROR = 996;
  	const RESPOND_NOT_FOUND = 998;
  	const RESPOND_UNKNOWN_ERROR = 999;
  	
  	/**
  	 * api actions
  	 */
  	protected static $actions = array();
  	
  	/**
  	 * registers an api call
  	 * @param string $method the http method
  	 * @param string $url the url to match
  	 * @param callable $action the function to run
  	 * @param string $app the id of the app registering the call
  	 * @param int $authLevel the level of authentication required for the call
  	 * @param array $defaults
  	 * @param array $requirements
  	 */
  	public static function register($method, $url, $action, $app, 
  				$authLevel = OC_API::USER_AUTH,
  				$defaults = array(),
  				$requirements = array()) {
  		$name = strtolower($method).$url;
  		$name = str_replace(array('/', '{', '}'), '_', $name);
  		if(!isset(self::$actions[$name])) {
  			OC::getRouter()->useCollection('ocs');
  			OC::getRouter()->create($name, $url)
  				->method($method)
  				->action('OC_API', 'call');
  			self::$actions[$name] = array();
  		}
  		self::$actions[$name][] = array('app' => $app, 'action' => $action, 'authlevel' => $authLevel);
  	}
  	
  	/**
  	 * handles an api call
  	 * @param array $parameters
  	 */
  	public static function call($parameters) {
  		// Prepare the request variables
  		if($_SERVER['REQUEST_METHOD'] == 'PUT') {
  			parse_str(file_get_contents("php://input"), $parameters['_put']);
  		} else if($_SERVER['REQUEST_METHOD'] == 'DELETE') {
  			parse_str(file_get_contents("php://input"), $parameters['_delete']);
  		}
  		$name = $parameters['_route'];
  		// Foreach registered action
  		$responses = array();
  		foreach(self::$actions[$name] as $action) {
  			// Check authentication and availability
  			if(!self::isAuthorised($action)) {
  				$responses[] = array(
  					'app' => $action['app'],
  					'response' => new OC_OCS_Result(null, OC_API::RESPOND_UNAUTHORISED, 'Unauthorised'),
  					);
  				continue;
  			}
  			if(!is_callable($action['action'])) {
  				$responses[] = array(
  					'app' => $action['app'],
  					'response' => new OC_OCS_Result(null, OC_API::RESPOND_NOT_FOUND, 'Api method not found'),
  					);
  				continue;
  			}
  			// Run the action
  			$responses[] = array(
  				'app' => $action['app'],
  				'response' => call_user_func($action['action'], $parameters),
  				);
  		}
  		$response = self::mergeResponses($responses);
  		$formats = array('json', 'xml');
  
  		$format = !empty($_GET['format']) && in_array($_GET['format'], $formats) ? $_GET['format'] : 'xml';
  		OC_User::logout();
  
  		self::respond($response, $format);
  	}
  	
  	/**
  	 * merge the returned result objects into one response
  	 * @param array $responses
  	 */
  	private static function mergeResponses($responses) {
  		$response = array();
  		// Sort into shipped and thirdparty
  		$shipped = array(
  			'succeeded' => array(),
  			'failed' => array(),
  			);
  		$thirdparty = array(
  			'succeeded' => array(),
  			'failed' => array(),
  			);
  
  		foreach($responses as $response) {
  			if(OC_App::isShipped($response['app']) || ($response['app'] === 'core')) {
  				if($response['response']->succeeded()) {
  					$shipped['succeeded'][$response['app']] = $response['response'];
  				} else {
  					$shipped['failed'][$response['app']] = $response['response'];
  				}
  			} else {
  				if($response['response']->succeeded()) {
  					$thirdparty['succeeded'][$response['app']] = $response['response'];
  				} else {
  					$thirdparty['failed'][$response['app']] = $response['response'];
  				}
  			}
  		}
  
  		// Remove any error responses if there is one shipped response that succeeded
  		if(!empty($shipped['succeeded'])) {
  			$responses = array_merge($shipped['succeeded'], $thirdparty['succeeded']);
  		} else if(!empty($shipped['failed'])) {
  			// Which shipped response do we use if they all failed?
  			// They may have failed for different reasons (different status codes)
  			// Which reponse code should we return?
  			// Maybe any that are not OC_API::RESPOND_SERVER_ERROR
  			$response = reset($shipped['failed']);
  			return $response;
  		} elseif(!empty($thirdparty['failed'])) {
  			// Return the third party failure result
  			$response = reset($thirdparty['failed']);
  			return $response;
  		} else {
  			$responses = array_merge($shipped['succeeded'], $thirdparty['succeeded']);
  		}
  		// Merge the successful responses
  		$meta = array();
  		$data = array();
  
  		foreach($responses as $app => $response) {
  			if(OC_App::isShipped($app)) {
  				$data = array_merge_recursive($response->getData(), $data);
  			} else {
  				$data = array_merge_recursive($data, $response->getData());
  			}
  		}
  		$result = new OC_OCS_Result($data, 100);
  		return $result;
  	}
  	
  	/**
  	 * authenticate the api call
  	 * @param array $action the action details as supplied to OC_API::register()
  	 * @return bool
  	 */
  	private static function isAuthorised($action) {
  		$level = $action['authlevel'];
  		switch($level) {
  			case OC_API::GUEST_AUTH:
  				// Anyone can access
  				return true;
  				break;
  			case OC_API::USER_AUTH:
  				// User required
  				return self::loginUser();
  				break;
  			case OC_API::SUBADMIN_AUTH:
  				// Check for subadmin
  				$user = self::loginUser();
  				if(!$user) {
  					return false;
  				} else {
  					$subAdmin = OC_SubAdmin::isSubAdmin($user);
  					$admin = OC_User::isAdminUser($user);
  					if($subAdmin || $admin) {
  						return true;
  					} else {
  						return false;
  					}
  				}
  				break;
  			case OC_API::ADMIN_AUTH:
  				// Check for admin
  				$user = self::loginUser();
  				if(!$user) {
  					return false;
  				} else {
  					return OC_User::isAdminUser($user);
  				}
  				break;
  			default:
  				// oops looks like invalid level supplied
  				return false;
  				break;
  		}
  	} 
  	
  	/**
  	 * http basic auth
  	 * @return string|false (username, or false on failure)
  	 */
  	private static function loginUser(){ 
  		$authUser = isset($_SERVER['PHP_AUTH_USER']) ? $_SERVER['PHP_AUTH_USER'] : '';
  		$authPw = isset($_SERVER['PHP_AUTH_PW']) ? $_SERVER['PHP_AUTH_PW'] : '';
  		return OC_User::login($authUser, $authPw) ? $authUser : false;
  	}
  	
  	/**
  	 * respond to a call
  	 * @param OC_OCS_Result $result
  	 * @param string $format the format xml|json
  	 */
  	private static function respond($result, $format='xml') {
  		// Send 401 headers if unauthorised
  		if($result->getStatusCode() === self::RESPOND_UNAUTHORISED) {
  			header('WWW-Authenticate: Basic realm="Authorisation Required"');
  			header('HTTP/1.0 401 Unauthorized');
  		}
  		$response = array(
  			'ocs' => array(
  				'meta' => $result->getMeta(),
  				'data' => $result->getData(),
  				),
  			);
  		if ($format == 'json') {
  			OC_JSON::encodedPrint($response);
  		} else if ($format == 'xml') {
  			header('Content-type: text/xml; charset=UTF-8');
  			$writer = new XMLWriter();
  			$writer->openMemory();
  			$writer->setIndent( true );
  			$writer->startDocument();
  			self::toXML($response, $writer);
  			$writer->endDocument();
  			echo $writer->outputMemory(true);
  		}
  	}
  
  	private static function toXML($array, $writer) {
  		foreach($array as $k => $v) {
  			if ($k[0] === '@') {
  				$writer->writeAttribute(substr($k, 1), $v);
  				continue;
  			} else if (is_numeric($k)) {
  				$k = 'element';
  			}
  			if(is_array($v)) {
  				$writer->startElement($k);
  				self::toXML($v, $writer);
  				$writer->endElement();
  			} else {
  				$writer->writeElement($k, $v);
  			}
  		}
  	}
  	
  }