api.js

var express         = require('express');
var bodyParser      = require('body-parser');
var https           = require('https');
var pool            = require('./lib/utils').pool;
var utils           = require('./lib/utils');

var app             = express();

// use some express packages
app.use(bodyParser.urlencoded({extended: true}));
app.use(bodyParser.json());
app.use(express.static(`${__dirname}/views`));


const listener = app.listen(process.env.PORT, function() {
    console.log(`The server is listening on port: ${listener.address().port}`);
});

/***********************************/
/*        CLIENT ENDPOINTS         */
/***********************************/

// ROOT PAGE
app.get('/', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/index.html`);
});

app.get('/addSong', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/addSong.html`);
});

app.get('/searchSongsByTitle', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/listSongsByTitles.html`);
});

app.get('/searchSongsByArtist', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/listSongsByArtists.html`);
});

app.get('/showSong', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/showSong.html`);
});

app.get('/editSong', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/editSong.html`);
});

app.get('/register', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/register.html`);
});

app.get('/deleteAccount', function(request, response) {
    response.status(200).sendFile(`${__dirname}/views/deleteAccount.html`);
});

/********************************/
/*        API ENDPOINTS         */
/********************************/

// Register in the API.
app.post('/api/join', async function(request, response) {
    var username        = request.headers.username.split("'").join("`");
    var password        = request.headers.password.split("'").join("`");

    if (!await utils.validateUsername(username))
        response.status(422).send(`Username not available.`);
    else if (!utils.validatePassword(password))
        response.status(422).send(`Wrong password format.`);
    else {
        var queryString = `INSERT INTO public."Users" (username, password) ` +
                          `VALUES ('${username}', '${password}')`;       
        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else {
                console.log(`New account created: ` + username);
                response.status(200).send(`${username}, registration successful.`);
            }
        });
    }
});

// Delete account in the API. 
app.delete('/api/deleteAccount', function (request, response) {
    var username        = request.headers.username.split("'").join("`");
    var password        = request.headers.password.split("'").join("`");

    var queryString     = `DELETE FROM public."Users" WHERE username='${username}' AND password='${password}'`;

    pool.query(queryString, function(error, result) {
        if (error) {
            console.log(error);
            response.status(400).send(error);
        } else 
            if (result.rowCount > 0) {
                console.log(`${username} deleted.`);
                response.status(200).send(`${username} deleted.`);
            }
            else {
                console.log(`${request.ip} tried to delete the account: ${username}`);
                response.status(401).send(`Authentication Failed: invalid username and/or password.`);
            }
    });
})

// Add a new song in the API.
app.post('/api/addSong', async function(request, response) {
    var title           = request.body.title.split("'").join("`");
    var artist          = request.body.artist.split("'").join("`");
    var tuning          = request.body.tuning.split("'").join("`");
    var capo            = request.body.capo.split("'").join("`");
    var note            = request.body.note.split("'").join("`");
    var content         = request.body.content.split("'").join("`");

    var username        = request.headers.username;
    var password        = request.headers.password;

    if (!await utils.validateAuth(username, password))
        response.status(401).send(`Authentication Failed: invalid username and/or password.`);
    else if (!await utils.validateSong(title, artist))
        response.status(403).send(`The song already exists.`);
    else { 
        var queryString = `INSERT INTO public."Songs" (title, username_fk, artist, tuning, capo, note, content) ` +
                          `VALUES ('${[title, username, artist, tuning, capo, note, content].join('\',\'')}')`;

        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else {
                console.log(`${username} added: ${title} by ${artist}`);
                response.status(200).send(`Song successfully added.`);
            }
        });
    }
});

// Edit a song in the API.
app.put('/api/song/:artist/:title', async function(request, response) {
    var title           = request.params.title.split("`").join("'");
    var artist          = request.params.artist.split("`").join("'");

    var tuning          = request.body.tuning.split("'").join("`");
    var capo            = request.body.capo.split("'").join("`");
    var note            = request.body.note.split("'").join("`");
    var content         = request.body.content.split("'").join("`");

    var username        = request.headers.username.split("'").join("`");
    var password        = request.headers.password.split("'").join("`");

    if (await utils.validateSong(title, artist))
        response.status(404).send(`Song not found.`);
    else if (await utils.getUserFromTitle(title) != username)
        response.status(403).send(`The user: ${username}, does not have permission to edit the song.`);
    else if (!await utils.validateAuth(username, password))
        response.status(401).send(`Authentication Failed: invalid username and/or password.`);
    else {
        var queryString = `UPDATE public."Songs" ` +
                          `SET artist='${artist}', tuning='${tuning}', capo='${capo}', note='${note}', content='${content}' ` + 
                          `WHERE title='${title}'`;
        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else {
                console.log(`${username} edited: ${title} by ${artist}`);
                response.status(200).send(`Song successfully edited.`);
            }
        });
    }
});

// Delete a song in the API.
app.delete('/api/song/:artist/:title', async function(request, response) {
    var title           = request.params.title.split("`").join("'");
    var artist          = request.params.artist.split("`").join("'");

    var username        = request.headers.username.split("'").join("`");
    var password        = request.headers.password.split("'").join("`");

    if (await utils.validateSong(title, artist))
        response.status(404).send('Song not found.');
    else if (await utils.getUserFromTitle(title) != username)
        response.status(403).send(`The user: ${username}, does not have permission to delete the song.`);
    else if (!await utils.validateAuth(username, password))
        response.status(401).send(`Authentication Failed: invalid username and/or password.`);
    else {
        var queryString = `DELETE FROM public."Songs" WHERE title='${title}' AND username_fk='${username}'`;
        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else {
                console.log(`${username} deleted: ${title} by ${artist}`);
                response.status(200).send(`Song successfully deleted.`);
            }
        });
    }
});

// Get a song from the API
app.get('/api/song/:artist/:title', async function(request, response) {
    var title           = request.params.title.split("`").join("'");
    var artist          = request.params.artist.split("`").join("'");

    var queryString     = `SELECT * FROM public."Songs" WHERE title='${title.split("'").join("`")}' AND  artist='${artist.split("'").join("`")}'`;
    var path            = `/api/v1/json/${process.env.APIKEY}/searchtrack.php?s=${artist.split("`").join("`")}&t=${title.split("`").join("'")}`;
    var options         = {
        host:   'theaudiodb.com',
        path:   path.split(" ").join("%20")
    }

    try {
        var result_query = await pool.query(queryString);
        if (result_query.rowCount > 0) {
            // Request for extra data from the API theaudiodb.com
            var request = https.get(options, function (result) {

                result.on('data', function(data) {
                    // processing data from external API.
                    data = JSON.parse(data);

                    var song_obj = {
                        title:      result_query.rows[0].title,
                        artist:     result_query.rows[0].artist,
                        tuning:     result_query.rows[0].tuning,
                        capo:       result_query.rows[0].capo,
                        note:       result_query.rows[0].note,
                        content:    result_query.rows[0].content,
                        owner:      result_query.rows[0].username_fk,
                        album:      null,
                        trackNo:    null,
                        genre:      null,
                        musicVid:   null
                    }

                    if (data.track) {
                        song_obj.album      = data.track[0].strAlbum;
                        song_obj.trackNo    = data.track[0].intTrackNumber;
                        song_obj.genre      = data.track[0].strGenre;
                        song_obj.musicVid   = data.track[0].strMusicVid;
                    }

                    response.status(200).send(song_obj);
                });
            });

            request.on('error', function(error) {
                console.error(e);
            });

            request.end();
            
        } else response.status(404).send('Song not found.');

    } catch (error) {
        console.log(error);
        response.status(400).send(error);
    }
});

// Get a list of songs available in the API.
app.get('/api/songs', function(request, response) {
    var queryString = `SELECT title, artist FROM public."Songs" ` + 
                      `ORDER BY title ASC, artist ASC`;
    pool.query(queryString, function(error, result) {
        if (error) {
            console.log(error);
            response.status(400).send(error);
        } else if (result.rowCount > 0) {
            response.status(200).send(result.rows);
        } else response.status(404).send('Songs not found.');
    });
});

// Get a filtered list of songs by artist or title.
app.post('/api/songs/search', function(request, response) {
    var artist          = request.query.artist;
    var title           = request.query.title;

    if (artist != undefined & title == undefined) {
        var queryString = `SELECT title, artist FROM public."Songs" ` +
                          `WHERE artist ILIKE '${artist.split("'").join("`")}'` +
                          `ORDER BY title ASC, artist ASC`;
        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else if (result.rowCount > 0) {
                response.status(200).send(result.rows);
            } else response.status(404).send('Songs not found.');
        });
    } else if (artist == undefined & title != undefined){
        var queryString = `SELECT title, artist FROM public."Songs" ` +
                          `WHERE title ILIKE '${title.split("'").join("`")}' ` +
                          `ORDER BY title ASC, artist ASC`;
        pool.query(queryString, function(error, result) {
            if (error) {
                console.log(error);
                response.status(400).send(error);
            } else if (result.rowCount > 0) {
                response.status(200).send(result.rows);
            } else response.status(404).send('Songs not found.');
        });
    } else if (artist == undefined & title == undefined) {
        response.status(400).send('Too few arguments.');
    } else {
        response.status(400).send('Too many arguments.');
    }
});