package
{
    import com.hurlant.crypto.hash.MD5;

    import flash.net.URLVariables;
    import flash.utils.ByteArray;

    import mx.utils.Base64Decoder;
    import mx.utils.Base64Encoder;

    import org.igniterealtime.xiff.auth.SASLAuth;
    import org.igniterealtime.xiff.core.XMPPConnection;

    public class FacebookSaslAuth extends SASLAuth
    {
        public static const MECHANISM:String = "X-FACEBOOK-PLATFORM";

        public static const NS:String = "urn:ietf:params:xml:ns:xmpp-sasl";

        public static var apiKey:String;

        public static var sessionKey:String;

        // hardcode for now, can get it dynamically or something later
        public static var fbApiSecret:String;

        public function FacebookSaslAuth(connection:XMPPConnection)
        {
            req.setNamespace( FacebookSaslAuth.NS );
            req.@mechanism = FacebookSaslAuth.MECHANISM;

            stage = 0;
        }

        /**
         * <challenge xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
         * dmVyc2lvbj0xJm1ldGhvZD1hdXRoLnhtcHBfbG9naW4mbm9uY2U9NDM0NkI5QkZDNUExNjBENDZBRjI1NzMyQUNGQzdDQzM=
         * </challenge>
         */
        public override function handleChallenge(stage:int, challenge:XML):XML
        {
            var base64Challenge:String = challenge.text()[0].toString();
            var decoder:Base64Decoder = new Base64Decoder();
            decoder.decode(base64Challenge);
            var byteArray:ByteArray = decoder.flush();
            var decodedString:String = byteArray.toString();

            trace(decodedString);

            var urlVars:URLVariables = new URLVariables(decodedString);

            var responseUrlVars:URLVariables = new URLVariables();
            responseUrlVars.api_key = apiKey;
            responseUrlVars.call_id = Math.floor(new Date().valueOf() / 1000);
            responseUrlVars.method = urlVars.method;
            responseUrlVars.nonce = urlVars.nonce;
            responseUrlVars.session_key = sessionKey;
            responseUrlVars.v = "1.0";

            var sig:String =
                'api_key=' + responseUrlVars.api_key +
                'call_id=' + responseUrlVars.call_id +
                'method=' + responseUrlVars.method +
                'nonce=' + responseUrlVars.nonce +
                'session_key=' + responseUrlVars.session_key +
                'v=' + responseUrlVars.v +
                fbApiSecret;

            var sigBytes:ByteArray = new ByteArray();
            sigBytes.writeUTFBytes(sig);

            var md5:MD5 = new MD5();
            var hash:ByteArray = md5.hash(sigBytes);
            hash.position = 0;
            var hashStr:String = hash.toString();
            responseUrlVars.sig = "";

            for(var x:Number = 0; x < hashStr.length; x++) {
                responseUrlVars.sig += hashStr.charCodeAt(x).toString(16);
            }

            var responseString:String = responseUrlVars.toString();

            var encoder:Base64Encoder = new Base64Encoder();
            encoder.encode(responseString);
            var responseBase64:String = encoder.toString();

            var responseXML:XML =
            <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
                {responseBase64}
            </response>;

            return responseXML;
        }

        public override function handleResponse(stage:int, response:XML):Object
        {
            var success:Boolean = response.localName() == "success";
            return {
                authComplete: true,
                authSuccess: success,
                authStage: stage++
            };
        }
    }
}