define(function (require, exports, module) {
	var sessMgr = require("../account/sessionMgr.js");

	var keystr = "iFishMessagePack";
	var step = Math.pow(2, 32);

	exports.encode = function (item) {
		if (!item)
			return [];

		if (!item.fromUser)
			item.fromUser = {
				username: sessMgr.current.username,
				realname: sessMgr.current.dispname
			};

		var buffer = [];
		var keyidx = Math.floor(Math.random() * keystr.length);
		var key = keystr.charCodeAt(keyidx);

		//helper
		var putInt16 = function (value) {
			value = value || 0;
			for (var i = 0; i < 2; i++) {
				buffer.push(value - (value >> 8 << 8));
				value >>= 8;
			}
		};

		var putInt32 = function (value) {
			value = value || 0;
			for (var i = 0; i < 4; i++) {
				buffer.push(value - (value >> 8 << 8));
				value >>= 8;
			}
		};

		var putInt64 = function (value) {
			value = value || 0;
			var int1 = value % step;
			var int2 = Math.floor((value - int1) / step);
			putInt32(int1);
			putInt32(int2);
		};

		var putBool = function (value) {
			value = value || false;
			buffer.push(value ? 1 : 0);
		};

		var putString = function (str, unicode, writeLengthPrefix) {
			str = str || "";

			if (typeof writeLengthPrefix === 'undefined')
				writeLengthPrefix = true;

			if (writeLengthPrefix) {
				putInt32((unicode ? 2 : 1) * str.length);
			}
			for (var i = 0; i < str.length; i++) {
				var code = str.charCodeAt(i);
				if (unicode)
					putInt16(code);
				else buffer.push(code);
			}
		};

		//1.
		buffer.push(keyidx);
		//2. keystr
		putString(keystr, false, false);
		//3.action
		putInt64(item.id);
		putString(item.action, false);
		//4.success
		putBool(item.success);
		//5.time
		putInt64(item.time.getTime());
		//6.system message
		putBool(item.systemMessage);
		//7.8.
		putInt32(item.sysMsgType);
		putInt32(item.userMsgType);
		//9.content
		putString(item.content, true);
		//10.color
		putString(item.color, false);
		//11.images
		putInt32(item.images ? item.images.length || 0 : 0);
		if (item.images) {
			item.images.forEach(function (image) {
				putString(image, false);
			});
		}
		//12.from user
		putString(item.fromUser.username || "", false);
		putString(item.fromUser.realname || "", true);
		//13.images
		putInt32(item.toUsers ? item.toUsers.length || 0 : 0);
		if (item.toUsers) {
			item.toUsers.forEach(function (user) {
				putString(user.username, false);
				putString(user.realname, true);
			});
		}

		//encrypt
		for (var j = 1; j < buffer.length; j++) {
			key = buffer[j] ^= key;
		}

		return buffer;
	};

	exports.decode = function (data) {
		var keyIndex = data[0];
		var key = keystr.charCodeAt(keyIndex);

		//decrypt
		for (var i = 1; i < data.length; i++) {
			var bit = data[i];
			data[i] = bit ^ key;
			key = bit;
		}

		var pos = 1;

		//helper
		var readInt16 = function () {
			var b1 = data[pos++];
			var b2 = data[pos++];

			return b1 | b2 << 8;
		};
		var readInt32 = function () {
			var b1 = data[pos++];
			var b2 = data[pos++];
			var b3 = data[pos++];
			var b4 = data[pos++];

			return b1 | b2 << 8 | b3 << 16 | b4 << 24;
		};
		var readInt64 = function () {
			var int1 = readInt32();
			var int2 = readInt32();

			return int2 * step + int1;
		};
		var readString = function (unicode, length) {
			if (typeof (unicode) === 'undefined') {
				unicode = false;
			}
			if (typeof (length) === 'undefined') {
				length = readInt32();
			}

			var buffer = [];
			var textLength = length / (unicode ? 2 : 1);
			for (var j = 0; j < textLength; j++) {
				if (unicode) {
					buffer.push(String.fromCharCode(readInt16()));
				} else {
					buffer.push(String.fromCharCode(data[pos++]));
				}
			}

			return buffer.join("");
		};
		var readMessageUser = function () {
			return {
				username: readString(false),
				realname: readString(true)
			};
		};


		//check package header
		if (readString(false, keystr.length) !== keystr)
			return null;

		var item = {};
		item.id = readInt64();
		item.action = readString(false);
		item.success = data[pos++] === 1;
		item.time = new Date(readInt64());
		item.systemMessage = data[pos++] === 1;
		item.sysMsgType = readInt32();
		item.userMsgType = readInt32();
		item.content = readString(true);
		item.color = readString(false);
		var imgCount = readInt32();
		if (imgCount > 0) {
			item.images = [];
			for (var j = 0; j < imgCount; j++) {
				item.images.push(readString(false));
			}
		}
		item.fromUser = readMessageUser();
		var toUserCount = readInt32();
		if (toUserCount > 0) {
			item.toUsers = [];
			for (var j = 0; j < toUserCount; j++) {
				item.toUsers.push(readMessageUser());
			}
		}
		return item;
	};
});