<?php
/* For licensing terms, see /license.txt */
/**
 * @package chamilo.webservices
 */
require_once(dirname(__FILE__).'/../inc/global.inc.php');

/**
 * Error returned by one of the methods of the web service.
 * Contains an error code and an error message
 */
class WSError
{
	/**
	 * Error handler. This needs to be a class that implements the interface WSErrorHandler
	 *
	 * @var WSErrorHandler
	 */
	protected static $_handler;

	/**
	 * Error code
	 *
	 * @var int
	 */
	public $code;

	/**
	 * Error message
	 *
	 * @var string
	 */
	public $message;

	/**
	 * Constructor
	 *
	 * @param int Error code
	 * @param string Error message
	 */
	public function __construct($code, $message) {
		$this->code = $code;
		$this->message = $message;
	}

	/**
	 * Sets the error handler
	 *
	 * @param WSErrorHandler Error handler
	 */
	public static function setErrorHandler($handler) {
		if($handler instanceof WSErrorHandler) {
			self::$_handler = $handler;
		}
	}

	/**
	 * Returns the error handler
	 *
	 * @return WSErrorHandler Error handler
	 */
	public static function getErrorHandler() {
		return self::$_handler;
	}

	/**
	 * Transforms the error into an array
	 *
	 * @return array Associative array with code and message
	 */
	public function toArray() {
		return array('code' => $this->code, 'message' => $this->message);
	}
}

/**
 * Interface that must be implemented by any error handler
 */
interface WSErrorHandler {
	/**
	 * Handle method
	 *
	 * @param WSError Error
	 */
	public function handle($error);
}

/**
 * Main class of the webservice. Webservice classes extend this class
 */
class WS {
	/**
	 * Chamilo configuration
	 *
	 * @var array
	 */
	protected $_configuration;

	/**
	 * Constructor
	 */
	public function __construct() {
		$this->_configuration = $GLOBALS['_configuration'];
	}

	/**
	 * Verifies the API key
	 *
	 * @param string Secret key
	 * @return mixed WSError in case of failure, null in case of success
	 */
	protected function verifyKey($secret_key) {
		$ip = trim($_SERVER['REMOTE_ADDR']);
		// if we are behind a reverse proxy, assume it will send the
		// HTTP_X_FORWARDED_FOR header and use this IP instead
		if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
			list($ip1,$ip2) = preg_split('/,/',$_SERVER['HTTP_X_FORWARDED_FOR']);
			$ip = trim($ip1);
		}
		$security_key = $ip.$this->_configuration['security_key'];

		if(!api_is_valid_secret_key($secret_key, $security_key)) {
			return new WSError(1, "API key is invalid");
		} else {
			return null;
		}
	}

	/**
	 * Gets the real user id based on the user id field name and value.
	 * Note that if the user id field name is "chamilo_user_id", it will use the user id
	 * in the system database
	 *
	 * @param string User id field name
	 * @param string User id value
	 * @return mixed System user id if the user was found, WSError otherwise
	 */
	protected function getUserId($user_id_field_name, $user_id_value) {
		if($user_id_field_name == "chamilo_user_id") {
			if(UserManager::is_user_id_valid(intval($user_id_value))) {
				return intval($user_id_value);
			} else {
				return new WSError(100, "User not found");
			}
		} else {
			$user_id = UserManager::get_user_id_from_original_id($user_id_value, $user_id_field_name);
			if($user_id == 0) {
				return new WSError(100, "User not found");
			} else {
				return $user_id;
			}
		}
	}

	/**
	 * Gets the real course id based on the course id field name and value.
	 * Note that if the course id field name is "chamilo_course_id", it will use the course id
	 * in the system database
	 *
	 * @param string Course id field name
	 * @param string Course id value
	 * @return mixed System course id if the course was found, WSError otherwise
	 */
	protected function getCourseId($course_id_field_name, $course_id_value)
	{
		if ($course_id_field_name == "chamilo_course_id") {
			if (CourseManager::get_course_code_from_course_id(
					intval($course_id_value)
				) != null
			) {
				return intval($course_id_value);
			} else {
				return new WSError(200, "Course not found");
			}
		} else {
			$courseId = CourseManager::get_course_code_from_original_id(
				$course_id_value,
				$course_id_field_name
			);
			if (!empty($courseId)) {
				return $courseId;
			} else {
				return new WSError(200, "Course not found");
			}
		}
	}

	/**
	 * Gets the real session id based on the session id field name and value.
	 * Note that if the session id field name is "chamilo_session_id", it will use the session id
	 * in the system database
	 *
	 * @param string Session id field name
	 * @param string Session id value
	 * @return mixed System session id if the session was found, WSError otherwise
	 */
	protected function getSessionId($session_id_field_name, $session_id_value)
	{
		if ($session_id_field_name == "chamilo_session_id") {
			$session = SessionManager::fetch((int)$session_id_value);
			if (!empty($session)) {
				return intval($session_id_value);
			} else {
				return new WSError(300, "Session not found");
			}
		} else {
			$session_id = SessionManager::getSessionIdFromOriginalId(
				$session_id_value,
				$session_id_field_name
			);
			if ($session_id == 0) {
				return new WSError(300, "Session not found");
			} else {
				return $session_id;
			}
		}
	}

	/**
	 * Handles an error by calling the WSError error handler
	 *
	 * @param WSError Error
	 */
	protected function handleError($error) {
		$handler = WSError::getErrorHandler();
		$handler->handle($error);
	}

	/**
	 * Gets a successful result
	 *
	 * @return array Array with a code of 0 and a message 'Operation was successful'
	 */
	protected function getSuccessfulResult() {
		return array('code' => 0, 'message' => 'Operation was successful');
	}

	/**
	 * Test function. Returns the string success
	 *
	 * @return string Success
	 */
	public function test() {
		return "success";
	}
}