var mysql = require('mysql');

var serverDB = (function(connectionData, callback) {
    var queries = {
        markRead    : "UPDATE messages SET readable = TRUE WHERE message_id = ?",
        getHistory  : "SELECT * FROM messages WHERE (date_time >= ?) AND ((from_login = ? AND to_login = ?) OR (from_login = ? AND to_login = ?) ) ORDER BY date_time",
        getUG       : "SELECT * FROM users; SELECT * FROM groups",
        login       : "SELECT 1 FROM users WHERE login = ? AND password = ?",
        userExists  : "SELECT 1 FROM users WHERE login = ?",
        insertMess  : "INSERT INTO messages SET ?",
        newSession  : "INSERT INTO sessions SET ?",
        delSession  : "DELETE FROM sessions WHERE session_id = ?",
        ldSessions  : "SELECT login, session_id, expires FROM sessions"
    };

    var connData = connectionData;
    connData.multipleStatements = true;

    var mysqlConnection = mysql.createConnection (connectionData);
    mysqlConnection.connect ( function (error) {
        if (error)
            throw error;
        console.log ('Successfully connected to MySQL server.');

        if (callback)
            callback(this);
    });


    function _messageSetRead(id, callback) {
        var query = util.format (queries.markRead, id);
        mysqlConnection.query (query, function (err) {
            if (err)
                throw err;
            if (callback)
                callback();
        });
    }

    function _getHistory (loginFrom, loginTo, dateAfter, callback) {
        mysqlConnection.query (
                queries.getHistory,
                [dateAfter, loginFrom, loginTo, loginTo, loginFrom],
                function (err, rows) {
                    if (err)
                        throw err;
                    if (callback)
                        callback (rows);
                }
        );
    }

    function _getUG(callback) {
        mysqlConnection.query (queries.getUG, function (err, result) {
            if (err)
                throw err;
            if (callback)
                callback (result[0], result[1]);
        });
    }

    function _checkUser(login, password, callback){
        mysqlConnection.query (queries.login, [login, password], function (err, result) {
            if (err)
                throw err;
            if (callback)
                callback (result.length !== 0);
        });
    }

    function _insertMessage (from, to, message, time, callback){
        var insertSet = {
            'from_login' : from,
            'to_login' : to,
            'message' : message,
            'date_time' : time
        };

        mysqlConnection.query (queries.insertMess, insertSet, function (err, result) {
            if (err)
                throw err;
            if (callback)
                callback (result.id);
        });
    }

    function _userExists (login, callback){
        mysqlConnection.query (queries.userExists, login, function (err, result) {
            if(err)
                throw err;
            if (callback)
                callback (result.length !== 0);
        });
    }

    function _insertNewSession (login, expires, session_id, callback){
        var sessionDesc = {
            'login' : login,
            'session_id' : session_id,
            'expires' : expires
        };

        mysqlConnection.query (queries.newSession, sessionDesc, function (err, result) {
            if(err)
                throw err;
            if (callback)
                callback ();
        });
    }

    function _removeSession (session_id, callback){
        mysqlConnection.query (queries.delSession, session_id, function (err, result) {
            if(err)
                throw err;
            if (callback)
                callback ();
        });
    }

    function _loadSessions () {
        mysqlConnection.query (queries.ldSessions, function (err, result) {
            if(err)
                throw err;
            if (callback)
                callback (result);
        });
    }

    return {
        messageSetRead : _messageSetRead,
        getHistory : _getHistory,
        getUG : _getUG,
        checkUser : _checkUser,
        insertMessage : _insertMessage,
        userExists : _userExists,
        insertNewSession : _insertNewSession,
        removeSession : _removeSession
        loadSessions : _loadSessions,
    };

    // ADMIN FUNCTIONS
})({
     host     : '178.62.178.14',
     user     : 'root',
     password : 'databasepassword',
     database : 'corporative_messenger'
});

var sessionManager;

function ChatClient (login, clientSocket, server) {
    this.login = login;
    this.server = server;
    this.websocket = clientSocket;
    this.session = null;
}

ChatClient.prototype.checkSession = function (message, callback){
    var userSessionId =
    if (!session || session.session_id != message.session_id)
        this.sessionExpired (callback);
    else if (callback)
        callback();
}

ChatClient.prototype.sendData = function (data, callback){
    if (this.websocket)
        this.websocket.send (JSON.stringify (data), function (error) {
            if (error)
                throw error;
            if (callback)
                callback();
        });
}

ChatClient.prototype.obtainSession = function (login, password, callback) {
    sessionManager.obtainSession (login, password, function (session) {
        this.session = session;
        this.sendData ({
            type : 'SessionObtained',
            session: session,
        }, callback);
    });
}

ChatClient.prototype.sessionExpired = function (callback) {
    this.sendData ({
        type: 'SessionExpired'
    }, callback);
}

ChatClient.prototype.sendMessage = function (to, message, callback) {
    var currentTime = new Date();
    serverDB.insertMessage (this.login, to, message, currentTime, function (id) {
        var messageData = {
            type: 'RenderMessageRequest',
            id:         id,
            from:       this.login,
            to:         to,
            message:    message,
            date_time:  currentTime,
            readable:   false
        };

        this.sendData(messageData, function (){
            server.sendTo (msg.to, messageData, callback);
        });
    });
}

ChatClient.prototype.historyRequest = function (loginTo, dateAfter, callback) {
    serverDB.getHistory (this.login, loginTo, dateAfter, function (history){
        this.sendData ({
            type: 'HistoryRequestAnswer',
            answer: history
        }, callback);
    });
}

ChatClient.prototype.messageRead = function (id, callback) {
    serverDB.messageSetRead (id, callback);
}