sessionController.js

let SqlString = require('sqlstring');
var db = require('./dbHandler');

module.exports = {
    getLastSession : function(req, res) {
        let sql = SqlString.format("SELECT SessionCode FROM Session ORDER BY ID DESC LIMIT 1");
        db.get(sql, (err, item) => {
            res.send(item.SessionCode.toString());
        });
    },

        getSessionSongId : function(req, res) {
        let sql = SqlString.format("SELECT SongID FROM Session WHERE SessionCode = ? LIMIT 1", [req.query.sessionCode]);
        db.get(sql, (err, item) => {
            if (item == undefined) {
                res.status(400) // session code does not exist
                res.send("Session code does not exist.");
                return;
            }
            console.log("Returning session song id ?", [item.SongID.toString()]);
            res.send(item.SongID.toString());
        });
    },

    updateSession : function(req, res) {
        let sql = SqlString.format("UPDATE Session SET SongID = ? WHERE SessionCode = ?;", [req.body.songID, req.body.sessionCode]);
        db.run(sql);
        console.log("Update Session " + req.body.sessionCode + " with Id " + req.body.songID);
        res.end("Updated session");
    },

    checkSessionExists : function (req, res) {
        let sql = SqlString.format("SELECT ID FROM Session WHERE SessionCode = ?;", [req.query.sessionCode]);
        db.get(sql, (err, item) => {
            res.send(item != undefined)
        });
    },

    createSession : async function (req, res) {
        try {
            let newId = await CreateSessionId();
            res.send(newId);
        } catch (err) {
            console.log(err)
        }
        

        
    }
}

/**
 * Generates a random session code and adds it to the database.
 */
    function CreateSessionId() {
    let ids = [];
    let sql = SqlString.format("SELECT SessionCode FROM Session");
    db.all(sql, (err, items) => {
        ids.push(items.SessionID)
    });

    let newId = 0; // Random integer between 1000-9999 which is not already in the database
    while (newId == 0 || newId in ids) {
        newId = Math.floor(1000 + Math.random() * 9000);
    }
    sql = SqlString.format("INSERT INTO Session (SessionCode, SongID) VALUES (?, -1);", [newId]);
    return new Promise((res, rej) => {
        db.run(sql, (err) => {
            if (err) rej(err)
            res(newId.toString());
        });
    }) 
}