//+-----------------------------------------+
//| TCP Server                  |
//| Description: MySQL connector.       |
//|    Speaks JSON over TCP         |
//+-----------------------------------------+
//| Author: /usr/share              |
//+-----------------------------------------+
//| Dependencies: Node.js, MySQL,       |
//|   MySQL for Node.js             |
//+-----------------------------------------+

/********************************************
 * Standard functions               *
 ********************************************/

/*
 * Deletes trailing spaces
 */
function trim(str) {
    return str.replace(/^s*/, "").replace(/s*$/, "");
}

/*
 * Writes the log with the operations executed in order
 */
function writeLog(str) {
    var fs = require('fs');
    var log = fs.createWriteStream('log.txt', {'flags': 'a'});
    log.write(str);
}

/*
 * Executes DML instructions on the MySQL DB
 * op parameters:
 * [0] Select
 * [1] Insert
 * [2] Update
 * [3] Delete
 */
function queryDB(request, socket) {
    var Client = require('mysql').Client;
    var client = new Client();
    client.user = 'root';
    client.password = '';
    client.host='127.0.0.1';
    client.port='3306';
    client.database='usrshare';

    var op = request['op'];
    var query;

    // Parse a query from its corresponding op
    if(op == 0) {
    query = 'SELECT * FROM DATA';
    } else if(op == 1) {
    query = "INSERT INTO `usrshare`.`data` (`str`) VALUES ('" + request['data'] + "');";
    } else if(op == 2) {
    query = "DELETE FROM `usrshare`.`data` WHERE `id` = " + request['id'];
    } else if(op == 3) {
    query = "UPDATE `usrshare`.`data` SET `str` = '" + request['data'] + "' where `id` = " + request['id'];
    }else {
    console.log("This shouldn't be happening");
    return null;
    }

    // Query the current database
    client.query(
    query,
    function selectData(err, results, fields) {
        if (err) {
        console.log("Error: " + err.message + "n");
        socket.write("Error: " + err.message + "n");
        writeLog("Error: " + err.message + "n");
        return null;
        }
        client.end();

        if(op == 0) {
        socket.write(JSON.stringify(results) + "n");
        writeLog("op:" + op + "n");
        } else if(op == 1) {
        socket.write("Row insertedn");
        writeLog("op:" + op + " data: " + request['data'] + "n");
        } else if(op == 2) {
        socket.write("Row deletedn");
        writeLog("op:" + op + " id: " + request['id'] + "n");
        } else if(op == 3) {
        writeLog("op:" + op + " id: " + request['id'] + " data: " + request['data'] + "n");
        socket.write("Row updatedn");
        }

        return results;
    });
}

//-------------------------------------------
//-------------------------------------------

/********************************************
 * Entry point                  *
 ********************************************/
if(process.argv.length != 3) {
    console.log('Error, use: ' + process.argv[0] + ' ' + process.argv[1] + ' <port>');
    process.exit(1);
}

var port = process.argv[2];
var net = require('net');

// Actual server
var server = net.createServer(function (socket) {
    socket.setEncoding('utf8');
    socket.on('data', function(data) {
    request = JSON.parse(data);
    queryDB(request, socket);
    });
});

// Listening on localhost
server.listen(port, '127.0.0.1');
console.log('Listening on port ' + port);