/*!
 * socket.io-node
 * Copyright(c) 2011 LearnBoost <dev@learnboost.com>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

/**
 * Packet types.
 */

var packets = exports.packets = {
		'disconnect' : 0, 'connect' : 1, 'heartbeat' : 2, 'message' : 3, 'json' : 4, 'event' : 5, 'ack' : 6, 'error' : 7, 'noop' : 8
	}
	, packetslist = Object.keys( packets );

/**
 * Errors reasons.
 */

var reasons = exports.reasons = {
		'transport not supported' : 0, 'client not handshaken' : 1, 'unauthorized' : 2
	}
	, reasonslist = Object.keys( reasons );

/**
 * Errors advice.
 */

var advice = exports.advice = {
		'reconnect' : 0
	}
	, advicelist = Object.keys( advice );

/**
 * Encodes a packet.
 *
 * @api private
 */

exports.encodePacket = function ( packet ) {
	var type = packets[packet.type]
		, id = packet.id || ''
		, endpoint = packet.endpoint || ''
		, ack = packet.ack
		, data = null;

	switch ( packet.type ) {
		case 'message':
			if ( packet.data !== '' ) {
				data = packet.data;
			}
			break;

		case 'event':
			var ev = { name : packet.name };

			if ( packet.args && packet.args.length ) {
				ev.args = packet.args;
			}

			data = JSON.stringify( ev );
			break;

		case 'json':
			data = JSON.stringify( packet.data );
			break;

		case 'ack':
			data = packet.ackId
				+ (packet.args && packet.args.length
				? '+' + JSON.stringify( packet.args ) : '');
			break;

		case 'connect':
			if ( packet.qs ) {
				data = packet.qs;
			}
			break;

		case 'error':
			var reason = packet.reason ? reasons[packet.reason] : ''
				, adv = packet.advice ? advice[packet.advice] : ''

			if ( reason !== '' || adv !== '' ) {
				data = reason + (adv !== '' ? ('+' + adv) : '')
			}

			break;
	}

	// construct packet with required fragments
	var encoded = type + ':' + id + (ack == 'data' ? '+' : '') + ':' + endpoint;

	// data fragment is optional
	if ( data !== null && data !== undefined ) {
		encoded += ':' + data;
	}

	return encoded;
};

/**
 * Encodes multiple messages (payload).
 *
 * @param {Array} messages
 * @api private
 */

exports.encodePayload = function ( packets ) {
	var decoded = '';

	if ( packets.length == 1 ) {
		return packets[0];
	}

	for ( var i = 0, l = packets.length; i < l; i++ ) {
		var packet = packets[i];
		decoded += '\ufffd' + packet.length + '\ufffd' + packets[i]
	}

	return decoded;
};

/**
 * Decodes a packet
 *
 * @api private
 */

var regexp = /([^:]+):([0-9]+)?(\+)?:([^:]+)?:?([\s\S]*)?/;

/**
 * Wrap the JSON.parse in a seperate function the crankshaft optimizer will
 * only punish this function for the usage for try catch
 *
 * @api private
 */

function parse( data ) {
	try {
		return JSON.parse( data )
	}
	catch ( e ) {
		return false
	}
}

exports.decodePacket = function ( data ) {
	var pieces = data.match( regexp );

	if ( !pieces ) {
		return {};
	}

	var id = pieces[2] || ''
		, data = pieces[5] || ''
		, packet = {
			type : packetslist[pieces[1]], endpoint : pieces[4] || ''
		};

	// whether we need to acknowledge the packet
	if ( id ) {
		packet.id = id;
		if ( pieces[3] ) {
			packet.ack = 'data';
		}
		else {
			packet.ack = true;
		}
	}

	// handle different packet types
	switch ( packet.type ) {
		case 'message':
			packet.data = data || '';
			break;

		case 'event':
			pieces = parse( data );
			if ( pieces ) {
				packet.name = pieces.name;
				packet.args = pieces.args;
			}

			packet.args = packet.args || [];
			break;

		case 'json':
			packet.data = parse( data );
			break;

		case 'connect':
			packet.qs = data || '';
			break;

		case 'ack':
			pieces = data.match( /^([0-9]+)(\+)?(.*)/ );
			if ( pieces ) {
				packet.ackId = pieces[1];
				packet.args = [];

				if ( pieces[3] ) {
					packet.args = parse( pieces[3] ) || [];
				}
			}
			break;

		case 'error':
			pieces = data.split( '+' );
			packet.reason = reasonslist[pieces[0]] || '';
			packet.advice = advicelist[pieces[1]] || '';
	}

	return packet;
};

/**
 * Decodes data payload. Detects multiple messages
 *
 * @return {Array} messages
 * @api public
 */

exports.decodePayload = function ( data ) {
	if ( undefined == data || null == data ) {
		return [];
	}

	if ( data[0] == '\ufffd' ) {
		var ret = [];

		for ( var i = 1, length = ''; i < data.length; i++ ) {
			if ( data[i] == '\ufffd' ) {
				ret.push( exports.decodePacket( data.substr( i + 1, length ) ) );
				i += Number( length ) + 1;
				length = '';
			} else {
				length += data[i];
			}
		}

		return ret;
	} else {
		return [exports.decodePacket( data )];
	}
};