<?php
// namespace administrator\components\com_jchat\framework\facebook;
/**
 * @package JCHAT::FRAMEWORK::administrator::components::com_jchat
 * @subpackage framework
 * @subpackage facebook
 * @author Joomla! Extensions Store
 * @copyright (C) 2015 - Joomla! Extensions Store
 * @license GNU/GPLv2 http://www.gnu.org/licenses/gpl-2.0.html
 */
defined ( '_JEXEC' ) or die ();

/**
 * Provides access to the Facebook Platform.
 * This class provides
 * a majority of the functionality needed, but the class is abstract
 * because it is designed to be sub-classed. The subclass must
 * implement the four abstract methods listed at the bottom of
 * the file.
 */
abstract class JChatFacebookBase {
	/**
	 * Version.
	 */
	const VERSION = '3.1.1';

	/**
	 * Default options for curl.
	 */
	public static $CURL_OPTS = array (
			CURLOPT_CONNECTTIMEOUT => 10,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_TIMEOUT => 60,
			CURLOPT_USERAGENT => 'facebook-php-3.1'
	);

	/**
	 * List of query parameters that get automatically dropped when rebuilding
	 * the current URL.
	*/
	protected static $DROP_QUERY_PARAMS = array (
			'code',
			'state',
			'signed_request'
	);

	/**
	 * Maps aliases to Facebook domains.
	*/
	public static $DOMAIN_MAP = array (
			'api' => 'https://api.facebook.com/',
			'api_video' => 'https://api-video.facebook.com/',
			'api_read' => 'https://api-read.facebook.com/',
			'graph' => 'https://graph.facebook.com/',
			'graph_video' => 'https://graph-video.facebook.com/',
			'www' => 'https://www.facebook.com/'
	);

	/**
	 * The Application ID.
	 *
	 * @var string
	*/
	protected $appId;

	/**
	 * The Application App Secret.
	 *
	 * @var string
	 */
	protected $appSecret;

	/**
	 * The ID of the Facebook user, or 0 if the user is logged out.
	 *
	 * @var integer
	 */
	protected $user;

	/**
	 * The data from the signed_request token.
	 */
	protected $signedRequest;

	/**
	 * A CSRF state variable to assist in the defense against CSRF attacks.
	 */
	protected $state;

	/**
	 * The OAuth access token received in exchange for a valid authorization
	 * code.
	 * null means the access token has yet to be determined.
	 *
	 * @var string
	 */
	protected $accessToken = null;

	/**
	 * Indicates if the CURL based @ syntax for file uploads is enabled.
	 *
	 * @var boolean
	 */
	protected $fileUploadSupport = false;

	/**
	 * Initialize a Facebook Application.
	 *
	 * The configuration:
	 * - appId: the application ID
	 * - secret: the application secret
	 * - fileUpload: (optional) boolean indicating if file uploads are enabled
	 *
	 * @param array $config
	 *        	The application configuration
	 */
	public function __construct($config) {
		$this->setAppId ( $config ['appId'] );
		$this->setAppSecret ( $config ['secret'] );
		if (isset ( $config ['fileUpload'] )) {
			$this->setFileUploadSupport ( $config ['fileUpload'] );
		}

		$state = $this->getPersistentData ( 'state' );
		if (! empty ( $state )) {
			$this->state = $this->getPersistentData ( 'state' );
		}
	}

	/**
	 * Set the Application ID.
	 *
	 * @param string $appId
	 *        	The Application ID
	 * @return BaseFacebook
	 */
	public function setAppId($appId) {
		$this->appId = $appId;
		return $this;
	}

	/**
	 * Get the Application ID.
	 *
	 * @return string the Application ID
	 */
	public function getAppId() {
		return $this->appId;
	}

	/**
	 * Set the App Secret.
	 *
	 * @param string $apiSecret
	 *        	The App Secret
	 * @return BaseFacebook
	 * @deprecated
	 *
	 */
	public function setApiSecret($apiSecret) {
		$this->setAppSecret ( $apiSecret );
		return $this;
	}

	/**
	 * Set the App Secret.
	 *
	 * @param string $appSecret
	 *        	The App Secret
	 * @return BaseFacebook
	 */
	public function setAppSecret($appSecret) {
		$this->appSecret = $appSecret;
		return $this;
	}

	/**
	 * Get the App Secret.
	 *
	 * @return string the App Secret
	 * @deprecated
	 *
	 */
	public function getApiSecret() {
		return $this->getAppSecret ();
	}

	/**
	 * Get the App Secret.
	 *
	 * @return string the App Secret
	 */
	public function getAppSecret() {
		return $this->appSecret;
	}

	/**
	 * Set the file upload support status.
	 *
	 * @param boolean $fileUploadSupport
	 *        	The file upload support status.
	 * @return BaseFacebook
	 */
	public function setFileUploadSupport($fileUploadSupport) {
		$this->fileUploadSupport = $fileUploadSupport;
		return $this;
	}

	/**
	 * Get the file upload support status.
	 *
	 * @return boolean true if and only if the server supports file upload.
	 */
	public function getFileUploadSupport() {
		return $this->fileUploadSupport;
	}

	/**
	 * DEPRECATED! Please use getFileUploadSupport instead.
	 *
	 * Get the file upload support status.
	 *
	 * @return boolean true if and only if the server supports file upload.
	 */
	public function useFileUploadSupport() {
		return $this->getFileUploadSupport ();
	}

	/**
	 * Sets the access token for api calls.
	 * Use this if you get
	 * your access token by other means and just want the SDK
	 * to use it.
	 *
	 * @param string $access_token
	 *        	an access token.
	 * @return BaseFacebook
	 */
	public function setAccessToken($access_token) {
		$this->accessToken = $access_token;
		return $this;
	}

	/**
	 * Determines the access token that should be used for API calls.
	 * The first time this is called, $this->accessToken is set equal
	 * to either a valid user access token, or it's set to the application
	 * access token if a valid user access token wasn't available. Subsequent
	 * calls return whatever the first call returned.
	 *
	 * @return string The access token
	 */
	public function getAccessToken() {
		if ($this->accessToken !== null) {
			// we've done this already and cached it. Just return.
			return $this->accessToken;
		}

		// first establish access token to be the application
		// access token, in case we navigate to the /oauth/access_token
		// endpoint, where SOME access token is required.
		$this->setAccessToken ( $this->getApplicationAccessToken () );
		$user_access_token = $this->getUserAccessToken ();
		if ($user_access_token) {
			$this->setAccessToken ( $user_access_token );
		}

		return $this->accessToken;
	}

	/**
	 * Determines and returns the user access token, first using
	 * the signed request if present, and then falling back on
	 * the authorization code if present.
	 * The intent is to
	 * return a valid user access token, or false if one is determined
	 * to not be available.
	 *
	 * @return string A valid user access token, or false if one
	 *         could not be determined.
	 */
	protected function getUserAccessToken() {
		// first, consider a signed request if it's supplied.
		// if there is a signed request, then it alone determines
		// the access token.
		$signed_request = $this->getSignedRequest ();
		if ($signed_request) {
			// apps.facebook.com hands the access_token in the signed_request
			if (array_key_exists ( 'oauth_token', $signed_request )) {
				$access_token = $signed_request ['oauth_token'];
				$this->setPersistentData ( 'access_token', $access_token );
				return $access_token;
			}
				
			// the JS SDK puts a code in with the redirect_uri of ''
			if (array_key_exists ( 'code', $signed_request )) {
				$code = $signed_request ['code'];
				$access_token = $this->getAccessTokenFromCode ( $code, '' );
				if ($access_token) {
					$this->setPersistentData ( 'code', $code );
					$this->setPersistentData ( 'access_token', $access_token );
					return $access_token;
				}
			}
				
			// signed request states there's no access token, so anything
			// stored should be cleared.
			$this->clearAllPersistentData ();
			return false; // respect the signed request's data, even
			// if there's an authorization code or something else
		}

		$code = $this->getCode ();
		if ($code && $code != $this->getPersistentData ( 'code' )) {
			$access_token = $this->getAccessTokenFromCode ( $code );
			if ($access_token) {
				$this->setPersistentData ( 'code', $code );
				$this->setPersistentData ( 'access_token', $access_token );
				return $access_token;
			}
				
			// code was bogus, so everything based on it should be invalidated.
			$this->clearAllPersistentData ();
			return false;
		}

		// as a fallback, just return whatever is in the persistent
		// store, knowing nothing explicit (signed request, authorization
		// code, etc.) was present to shadow it (or we saw a code in $_REQUEST,
		// but it's the same as what's in the persistent store)
		return $this->getPersistentData ( 'access_token' );
	}

	/**
	 * Retrieve the signed request, either from a request parameter or,
	 * if not present, from a cookie.
	 *
	 * @return string the signed request, if available, or null otherwise.
	 */
	public function getSignedRequest() {
		if (! $this->signedRequest) {
			if (isset ( $_REQUEST ['signed_request'] )) {
				$this->signedRequest = $this->parseSignedRequest ( $_REQUEST ['signed_request'] );
			} else if (isset ( $GLOBALS['_' . strtoupper('cookie')] [$this->getSignedRequestCookieName ()] )) {
				$this->signedRequest = $this->parseSignedRequest ( $GLOBALS['_' . strtoupper('cookie')] [$this->getSignedRequestCookieName ()] );
			}
		}
		return $this->signedRequest;
	}

	/**
	 * Get the UID of the connected user, or 0
	 * if the Facebook user is not connected.
	 *
	 * @return string the UID if available.
	 */
	public function getUser() {
		if ($this->user !== null) {
			// we've already determined this and cached the value.
			return $this->user;
		}

		return $this->user = $this->getUserFromAvailableData ();
	}

	/**
	 * Determines the connected user by first examining any signed
	 * requests, then considering an authorization code, and then
	 * falling back to any persistent store storing the user.
	 *
	 * @return integer The id of the connected Facebook user,
	 *         or 0 if no such user exists.
	 */
	protected function getUserFromAvailableData() {
		// if a signed request is supplied, then it solely determines
		// who the user is.
		$signed_request = $this->getSignedRequest ();
		if ($signed_request) {
			if (array_key_exists ( 'user_id', $signed_request )) {
				$user = $signed_request ['user_id'];
				$this->setPersistentData ( 'user_id', $signed_request ['user_id'] );
				return $user;
			}
				
			// if the signed request didn't present a user id, then invalidate
			// all entries in any persistent store.
			$this->clearAllPersistentData ();
			return 0;
		}

		$user = $this->getPersistentData ( 'user_id', $default = 0 );
		$persisted_access_token = $this->getPersistentData ( 'access_token' );

		// use access_token to fetch user id if we have a user access_token, or if
		// the cached access token has changed.
		$access_token = $this->getAccessToken ();
		if ($access_token && $access_token != $this->getApplicationAccessToken () && ! ($user && $persisted_access_token == $access_token)) {
			$user = $this->getUserFromAccessToken ();
			if ($user) {
				$this->setPersistentData ( 'user_id', $user );
			} else {
				$this->clearAllPersistentData ();
			}
		}

		return $user;
	}

	/**
	 * Get a Login URL for use with redirects.
	 * By default, full page redirect is
	 * assumed. If you are using the generated URL with a window.open() call in
	 * JavaScript, you can pass in display=popup as part of the $params.
	 *
	 * The parameters:
	 * - redirect_uri: the url to go to after a successful login
	 * - scope: comma separated list of requested extended perms
	 *
	 * @param array $params
	 *        	Provide custom parameters
	 * @return string The URL for the login flow
	 */
	public function getLoginUrl($params = array()) {
		$this->establishCSRFTokenState ();
		$currentUrl = $this->getCurrentUrl ();

		// if 'scope' is passed as an array, convert to comma separated list
		$scopeParams = isset ( $params ['scope'] ) ? $params ['scope'] : null;
		if ($scopeParams && is_array ( $scopeParams )) {
			$params ['scope'] = implode ( ',', $scopeParams );
		}

		return $this->getUrl ( 'www', 'dialog/oauth', array_merge ( array (
				'client_id' => $this->getAppId (),
				'redirect_uri' => $currentUrl, // possibly overwritten
				'state' => $this->state
		), $params ) );
	}

	/**
	 * Get a Logout URL suitable for use with redirects.
	 *
	 * The parameters:
	 * - next: the url to go to after a successful logout
	 *
	 * @param array $params
	 *        	Provide custom parameters
	 * @return string The URL for the logout flow
	 */
	public function getLogoutUrl($params = array()) {
		return $this->getUrl ( 'www', 'logout.php', array_merge ( array (
				'next' => $this->getCurrentUrl (),
				'access_token' => $this->getAccessToken ()
		), $params ) );
	}

	/**
	 * Get a login status URL to fetch the status from Facebook.
	 *
	 * The parameters:
	 * - ok_session: the URL to go to if a session is found
	 * - no_session: the URL to go to if the user is not connected
	 * - no_user: the URL to go to if the user is not signed into facebook
	 *
	 * @param array $params
	 *        	Provide custom parameters
	 * @return string The URL for the logout flow
	 */
	public function getLoginStatusUrl($params = array()) {
		return $this->getUrl ( 'www', 'extern/login_status.php', array_merge ( array (
				'api_key' => $this->getAppId (),
				'no_session' => $this->getCurrentUrl (),
				'no_user' => $this->getCurrentUrl (),
				'ok_session' => $this->getCurrentUrl (),
				'session_version' => 3
		), $params ) );
	}

	/**
	 * Make an API call.
	 *
	 * @return mixed The decoded response
	 */
	public function api(/* polymorphic */) {
		$args = func_get_args ();
		if (is_array ( $args [0] )) {
			return $this->_restserver ( $args [0] );
		} else {
			return call_user_func_array ( array (
					$this,
					'_graph'
			), $args );
		}
	}

	/**
	 * Constructs and returns the name of the cookie that
	 * potentially houses the signed request for the app user.
	 * The cookie is not set by the BaseFacebook class, but
	 * it may be set by the JavaScript SDK.
	 *
	 * @return string the name of the cookie that would house
	 *         the signed request value.
	 */
	protected function getSignedRequestCookieName() {
		return 'fbsr_' . $this->getAppId ();
	}

	/**
	 * Constructs and returns the name of the coookie that potentially contain
	 * metadata.
	 * The cookie is not set by the BaseFacebook class, but it may be
	 * set by the JavaScript SDK.
	 *
	 * @return string the name of the cookie that would house metadata.
	 */
	protected function getMetadataCookieName() {
		return 'fbm_' . $this->getAppId ();
	}

	/**
	 * Get the authorization code from the query parameters, if it exists,
	 * and otherwise return false to signal no authorization code was
	 * discoverable.
	 *
	 * @return mixed The authorization code, or false if the authorization
	 *         code could not be determined.
	 */
	protected function getCode() {
		if (isset ( $_REQUEST ['code'] )) {
			if ($this->state !== null && isset ( $_REQUEST ['state'] ) && $this->state === $_REQUEST ['state']) {

				// CSRF state has done its job, so clear it
				$this->state = null;
				$this->clearPersistentData ( 'state' );
				return $_REQUEST ['code'];
			} else {
				self::errorLog ( 'CSRF state token does not match one provided.' );
				return false;
			}
		}

		return false;
	}

	/**
	 * Retrieves the UID with the understanding that
	 * $this->accessToken has already been set and is
	 * seemingly legitimate.
	 * It relies on Facebook's Graph API
	 * to retrieve user information and then extract
	 * the user ID.
	 *
	 * @return integer Returns the UID of the Facebook user, or 0
	 *         if the Facebook user could not be determined.
	 */
	protected function getUserFromAccessToken() {
		try {
			$user_info = $this->api ( '/me' );
			return $user_info ['id'];
		} catch ( JChatFacebookException $e ) {
			return 0;
		}
	}

	/**
	 * Returns the access token that should be used for logged out
	 * users when no authorization code is available.
	 *
	 * @return string The application access token, useful for gathering
	 *         public information about users and applications.
	 */
	protected function getApplicationAccessToken() {
		return $this->appId . '|' . $this->appSecret;
	}

	/**
	 * Lays down a CSRF state token for this process.
	 *
	 * @return void
	 */
	protected function establishCSRFTokenState() {
		if ($this->state === null) {
			$this->state = md5 ( uniqid ( mt_rand (), true ) );
			$this->setPersistentData ( 'state', $this->state );
		}
	}

	/**
	 * Retrieves an access token for the given authorization code
	 * (previously generated from www.facebook.com on behalf of
	 * a specific user).
	 * The authorization code is sent to graph.facebook.com
	 * and a legitimate access token is generated provided the access token
	 * and the user for which it was generated all match, and the user is
	 * either logged in to Facebook or has granted an offline access permission.
	 *
	 * @param string $code
	 *        	An authorization code.
	 * @return mixed An access token exchanged for the authorization code, or
	 *         false if an access token could not be generated.
	 */
	protected function getAccessTokenFromCode($code, $redirect_uri = null) {
		if (empty ( $code )) {
			return false;
		}

		if ($redirect_uri === null) {
			$redirect_uri = $this->getCurrentUrl ();
		}

		try {
			// need to circumvent json_decode by calling _oauthRequest
			// directly, since response isn't JSON format.
			$access_token_response = $this->_oauthRequest ( $this->getUrl ( 'graph', '/oauth/access_token' ), $params = array (
					'client_id' => $this->getAppId (),
					'client_secret' => $this->getAppSecret (),
					'redirect_uri' => $redirect_uri,
					'code' => $code
			) );
		} catch ( JChatFacebookException $e ) {
			// most likely that user very recently revoked authorization.
			// In any event, we don't have an access token, so say so.
			return false;
		}

		if (empty ( $access_token_response )) {
			return false;
		}

		$response_params = array ();
		$response_params = (array)json_decode($access_token_response);
		if (! isset ( $response_params ['access_token'] )) {
			return false;
		}

		return $response_params ['access_token'];
	}

	/**
	 * Invoke the old restserver.php endpoint.
	 *
	 * @param array $params
	 *        	Method call object
	 *
	 * @return mixed The decoded response object
	 * @throws JChatFacebookException
	 */
	protected function _restserver($params) {
		// generic application level parameters
		$params ['api_key'] = $this->getAppId ();
		$params ['format'] = 'json-strings';

		$result = json_decode ( $this->_oauthRequest ( $this->getApiUrl ( $params ['method'] ), $params ), true );

		// results are returned, errors are thrown
		if (is_array ( $result ) && isset ( $result ['error_code'] )) {
			$this->throwAPIException ( $result );
		}

		if ($params ['method'] === 'auth.expireSession' || $params ['method'] === 'auth.revokeAuthorization') {
			$this->destroySession ();
		}

		return $result;
	}

	/**
	 * Return true if this is video post.
	 *
	 * @param string $path
	 *        	The path
	 * @param string $method
	 *        	The http method (default 'GET')
	 *
	 * @return boolean true if this is video post
	 */
	protected function isVideoPost($path, $method = 'GET') {
		if ($method == 'POST' && preg_match ( "/^(\/)(.+)(\/)(videos)$/", $path )) {
			return true;
		}
		return false;
	}

	/**
	 * Invoke the Graph API.
	 *
	 * @param string $path
	 *        	The path (required)
	 * @param string $method
	 *        	The http method (default 'GET')
	 * @param array $params
	 *        	The query/post data
	 *
	 * @return mixed The decoded response object
	 * @throws JChatFacebookException
	 */
	protected function _graph($path, $method = 'GET', $params = array()) {
		if (is_array ( $method ) && empty ( $params )) {
			$params = $method;
			$method = 'GET';
		}
		$params ['method'] = $method; // method override as we always do a POST

		if ($this->isVideoPost ( $path, $method )) {
			$domainKey = 'graph_video';
		} else {
			$domainKey = 'graph';
		}

		$result = json_decode ( $this->_oauthRequest ( $this->getUrl ( $domainKey, $path ), $params ), true );

		// results are returned, errors are thrown
		if (is_array ( $result ) && isset ( $result ['error'] )) {
			$this->throwAPIException ( $result );
		}

		return $result;
	}

	/**
	 * Make a OAuth Request.
	 *
	 * @param string $url
	 *        	The path (required)
	 * @param array $params
	 *        	The query/post data
	 *
	 * @return string The decoded response object
	 * @throws JChatFacebookException
	 */
	protected function _oauthRequest($url, $params) {
		if (! isset ( $params ['access_token'] )) {
			$params ['access_token'] = $this->getAccessToken ();
		}

		// json_encode all params values that are not strings
		foreach ( $params as $key => $value ) {
			if (! is_string ( $value )) {
				$params [$key] = json_encode ( $value );
			}
		}

		return $this->makeRequest ( $url, $params );
	}

	/**
	 * Makes an HTTP request.
	 * This method can be overridden by subclasses if
	 * developers want to do fancier things or use something other than curl to
	 * make the request.
	 *
	 * @param string $url
	 *        	The URL to make the request to
	 * @param array $params
	 *        	The parameters to use for the POST body
	 * @param CurlHandler $ch
	 *        	Initialized curl handle
	 *
	 * @return string The response text
	 */
	protected function makeRequest($url, $params, $ch = null) {
		if (! $ch) {
			$ch = curl_init ();
		}

		$opts = self::$CURL_OPTS;
		if ($this->getFileUploadSupport ()) {
			$opts [CURLOPT_POSTFIELDS] = $params;
		} else {
			$opts [CURLOPT_POSTFIELDS] = http_build_query ( $params, null, '&' );
		}
		$opts [CURLOPT_URL] = $url;

		// disable the 'Expect: 100-continue' behaviour. This causes CURL to wait
		// for 2 seconds if the server does not support this header.
		if (isset ( $opts [CURLOPT_HTTPHEADER] )) {
			$existing_headers = $opts [CURLOPT_HTTPHEADER];
			$existing_headers [] = 'Expect:';
			$opts [CURLOPT_HTTPHEADER] = $existing_headers;
		} else {
			$opts [CURLOPT_HTTPHEADER] = array (
					'Expect:'
			);
		}

		curl_setopt_array ( $ch, $opts );
		$result = curl_exec ( $ch );

		if (curl_errno ( $ch ) == 60) { // CURLE_SSL_CACERT
			self::errorLog ( 'Invalid or no certificate authority found, ' . 'using bundled information' );
			curl_setopt ( $ch, CURLOPT_CAINFO, dirname ( __FILE__ ) . '/fb_ca_chain_bundle.crt' );
			$result = curl_exec ( $ch );
		}

		if ($result === false) {
			$e = new JChatFacebookException ( array (
					'error_code' => curl_errno ( $ch ),
					'error' => array (
							'message' => curl_error ( $ch ),
							'type' => 'CurlException'
					)
			) );
			curl_close ( $ch );
			throw $e;
		}
		curl_close ( $ch );
		return $result;
	}

	/**
	 * Parses a signed_request and validates the signature.
	 *
	 * @param string $signed_request
	 *        	A signed token
	 * @return array The payload inside it or null if the sig is wrong
	 */
	protected function parseSignedRequest($signed_request) {
		list ( $encoded_sig, $payload ) = explode ( '.', $signed_request, 2 );

		// decode the data
		$sig = self::bas64UrlDecode ( $encoded_sig );
		$data = json_decode ( self::bas64UrlDecode ( $payload ), true );

		if (strtoupper ( $data ['algorithm'] ) !== 'HMAC-SHA256') {
			self::errorLog ( 'Unknown algorithm. Expected HMAC-SHA256' );
			return null;
		}

		// check sig
		$expected_sig = hash_hmac ( 'sha256', $payload, $this->getAppSecret (), $raw = true );
		if ($sig !== $expected_sig) {
			self::errorLog ( 'Bad Signed JSON signature!' );
			return null;
		}

		return $data;
	}

	/**
	 * Build the URL for api given parameters.
	 *
	 * @param $method String
	 *        	the method name.
	 * @return string The URL for the given parameters
	 */
	protected function getApiUrl($method) {
		static $READ_ONLY_CALLS = array (
				'admin.getallocation' => 1,
				'admin.getappproperties' => 1,
				'admin.getbannedusers' => 1,
				'admin.getlivestreamvialink' => 1,
				'admin.getmetrics' => 1,
				'admin.getrestrictioninfo' => 1,
				'application.getpublicinfo' => 1,
				'auth.getapppublickey' => 1,
				'auth.getsession' => 1,
				'auth.getsignedpublicsessiondata' => 1,
				'comments.get' => 1,
				'connect.getunconnectedfriendscount' => 1,
				'dashboard.getactivity' => 1,
				'dashboard.getcount' => 1,
				'dashboard.getglobalnews' => 1,
				'dashboard.getnews' => 1,
				'dashboard.multigetcount' => 1,
				'dashboard.multigetnews' => 1,
				'data.getcookies' => 1,
				'events.get' => 1,
				'events.getmembers' => 1,
				'fbml.getcustomtags' => 1,
				'feed.getappfriendstories' => 1,
				'feed.getregisteredtemplatebundlebyid' => 1,
				'feed.getregisteredtemplatebundles' => 1,
				'fql.multiquery' => 1,
				'fql.query' => 1,
				'friends.arefriends' => 1,
				'friends.get' => 1,
				'friends.getappusers' => 1,
				'friends.getlists' => 1,
				'friends.getmutualfriends' => 1,
				'gifts.get' => 1,
				'groups.get' => 1,
				'groups.getmembers' => 1,
				'intl.gettranslations' => 1,
				'links.get' => 1,
				'notes.get' => 1,
				'notifications.get' => 1,
				'pages.getinfo' => 1,
				'pages.isadmin' => 1,
				'pages.isappadded' => 1,
				'pages.isfan' => 1,
				'permissions.checkavailableapiaccess' => 1,
				'permissions.checkgrantedapiaccess' => 1,
				'photos.get' => 1,
				'photos.getalbums' => 1,
				'photos.gettags' => 1,
				'profile.getinfo' => 1,
				'profile.getinfooptions' => 1,
				'stream.get' => 1,
				'stream.getcomments' => 1,
				'stream.getfilters' => 1,
				'users.getinfo' => 1,
				'users.getloggedinuser' => 1,
				'users.getstandardinfo' => 1,
				'users.hasapppermission' => 1,
				'users.isappuser' => 1,
				'users.isverified' => 1,
				'video.getuploadlimits' => 1
		);
		$name = 'api';
		if (isset ( $READ_ONLY_CALLS [strtolower ( $method )] )) {
			$name = 'api_read';
		} else if (strtolower ( $method ) == 'video.upload') {
			$name = 'api_video';
		}
		return self::getUrl ( $name, 'restserver.php' );
	}

	/**
	 * Build the URL for given domain alias, path and parameters.
	 *
	 * @param $name string
	 *        	The name of the domain
	 * @param $path string
	 *        	Optional path (without a leading slash)
	 * @param $params array
	 *        	Optional query parameters
	 *
	 * @return string The URL for the given parameters
	 */
	protected function getUrl($name, $path = '', $params = array()) {
		$url = self::$DOMAIN_MAP [$name];
		if ($path) {
			if ($path [0] === '/') {
				$path = substr ( $path, 1 );
			}
			$url .= $path;
		}
		if ($params) {
			$url .= '?' . http_build_query ( $params, null, '&' );
		}

		return $url;
	}

	/**
	 * Returns the Current URL, stripping it of known FB parameters that should
	 * not persist.
	 *
	 * @return string The current URL
	 */
	protected function getCurrentUrl() {
		if (isset ( $_SERVER ['HTTPS'] ) && ($_SERVER ['HTTPS'] == 'on' || $_SERVER ['HTTPS'] == 1) || isset ( $_SERVER ['HTTP_X_FORWARDED_PROTO'] ) && $_SERVER ['HTTP_X_FORWARDED_PROTO'] == 'https') {
			$protocol = 'https://';
		} else {
			$protocol = 'http://';
		}
		$currentUrl = $protocol . $_SERVER ['HTTP_HOST'] . $_SERVER ['REQUEST_URI'];
		$parts = parse_url ( $currentUrl );

		$query = '';
		if (! empty ( $parts ['query'] )) {
			// drop known fb params
			$params = explode ( '&', $parts ['query'] );
			$retained_params = array ();
			foreach ( $params as $param ) {
				if ($this->shouldRetainParam ( $param )) {
					$retained_params [] = $param;
				}
			}
				
			if (! empty ( $retained_params )) {
				$query = '?' . implode ( $retained_params, '&' );
			}
		}

		// use port if non default
		$port = isset ( $parts ['port'] ) && (($protocol === 'http://' && $parts ['port'] !== 80) || ($protocol === 'https://' && $parts ['port'] !== 443)) ? ':' . $parts ['port'] : '';

		// rebuild
		return $protocol . $parts ['host'] . $port . $parts ['path'] . $query;
	}

	/**
	 * Returns true if and only if the key or key/value pair should
	 * be retained as part of the query string.
	 * This amounts to
	 * a brute-force search of the very small list of Facebook-specific
	 * params that should be stripped out.
	 *
	 * @param string $param
	 *        	A key or key/value pair within a URL's query (e.g.
	 *        	'foo=a', 'foo=', or 'foo'.
	 *
	 * @return boolean
	 */
	protected function shouldRetainParam($param) {
		foreach ( self::$DROP_QUERY_PARAMS as $drop_query_param ) {
			if (strpos ( $param, $drop_query_param . '=' ) === 0) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Analyzes the supplied result to see if it was thrown
	 * because the access token is no longer valid.
	 * If that is
	 * the case, then we destroy the session.
	 *
	 * @param $result array
	 *        	A record storing the error message returned
	 *        	by a failed API call.
	 */
	protected function throwAPIException($result) {
		$e = new JChatFacebookException ( $result );
		switch ($e->getType ()) {
			// OAuth 2.0 Draft 00 style
			case 'OAuthException' :
				// OAuth 2.0 Draft 10 style
			case 'invalid_token' :
				// REST server errors are just Exceptions
			case 'Exception' :
				$message = $e->getMessage ();
				if ((strpos ( $message, 'Error validating access token' ) !== false) || (strpos ( $message, 'Invalid OAuth access token' ) !== false) || (strpos ( $message, 'An active access token must be used' ) !== false)) {
					$this->destroySession ();
				}
				break;
		}

		throw $e;
	}

	/**
	 * Prints to the error log if you aren't in command line mode.
	 *
	 * @param string $msg
	 *        	Log message
	 */
	protected static function errorLog($msg) {
	}

	/**
	 * Bas64 encoding that doesn't need to be urlencode()ed.
	 * Exactly the same as bas64 encode except it uses
	 * - instead of +
	 * _ instead of /
	 *
	 * @param string $input
	 *        	bas64UrlEncoded string
	 * @return string
	 */
	protected static function bas64UrlDecode($input) {
		$bas64FunctionNameEncode = 'base'. 64 . '_encode';
		$bas64FunctionNameDecode = 'base'. 64 . '_decode';
		return $bas64FunctionNameDecode ( strtr ( $input, '-_', '+/' ) );
	}

	/**
	 * Destroy the current session
	 */
	public function destroySession() {
		$this->accessToken = null;
		$this->signedRequest = null;
		$this->user = null;
		$this->clearAllPersistentData ();

		// Javascript sets a cookie that will be used in getSignedRequest that we
		// need to clear if we can
		$cookie_name = $this->getSignedRequestCookieName ();
		if (array_key_exists ( $cookie_name, $GLOBALS['_' . strtoupper('cookie')] )) {
			unset ( $GLOBALS['_' . strtoupper('cookie')] [$cookie_name] );
			if (! headers_sent ()) {
				// The base domain is stored in the metadata cookie if not we fallback
				// to the current hostname
				$base_domain = '.' . $_SERVER ['HTTP_HOST'];

				$metadata = $this->getMetadataCookie ();
				if (array_key_exists ( 'base_domain', $metadata ) && ! empty ( $metadata ['base_domain'] )) {
					$base_domain = $metadata ['base_domain'];
				}

				setcookie ( $cookie_name, '', 0, '/', $base_domain );
			} else {
				self::errorLog ( 'There exists a cookie that we wanted to clear that we couldn\'t ' . 'clear because headers was already sent. Make sure to do the first ' . 'API call before outputing anything' );
			}
		}
	}

	/**
	 * Parses the metadata cookie that our Javascript API set
	 *
	 * @return an array mapping key to value
	 */
	protected function getMetadataCookie() {
		$cookie_name = $this->getMetadataCookieName ();
		if (! array_key_exists ( $cookie_name, $GLOBALS['_' . strtoupper('cookie')] )) {
			return array ();
		}

		// The cookie value can be wrapped in "-characters so remove them
		$cookie_value = trim ( $GLOBALS['_' . strtoupper('cookie')] [$cookie_name], '"' );

		if (empty ( $cookie_value )) {
			return array ();
		}

		$parts = explode ( '&', $cookie_value );
		$metadata = array ();
		foreach ( $parts as $part ) {
			$pair = explode ( '=', $part, 2 );
			if (! empty ( $pair [0] )) {
				$metadata [urldecode ( $pair [0] )] = (count ( $pair ) > 1) ? urldecode ( $pair [1] ) : '';
			}
		}

		return $metadata;
	}

	/**
	 * Each of the following four methods should be overridden in
	 * a concrete subclass, as they are in the provided Facebook class.
	 * The Facebook class uses PHP sessions to provide a primitive
	 * persistent store, but another subclass--one that you implement--
	 * might use a database, memcache, or an in-memory cache.
	 *
	 * @see Facebook
	 */

	/**
	 * Stores the given ($key, $value) pair, so that future calls to
	 * getPersistentData($key) return $value.
	 * This call may be in another request.
	 *
	 * @param string $key
	 * @param array $value
	 *
	 * @return void
	 */
	abstract protected function setPersistentData($key, $value);

	/**
	 * Get the data for $key, persisted by BaseFacebook::setPersistentData()
	 *
	 * @param string $key
	 *        	The key of the data to retrieve
	 * @param boolean $default
	 *        	The default value to return if $key is not found
	 *
	 * @return mixed
	*/
	abstract protected function getPersistentData($key, $default = false);

	/**
	 * Clear the data with $key from the persistent storage
	 *
	 * @param string $key
	 * @return void
	*/
	abstract protected function clearPersistentData($key);

	/**
	 * Clear all data from the persistent storage
	 *
	 * @return void
	*/
	abstract protected function clearAllPersistentData();
}