// See https://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript
function uuidv4() {
    return ([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g, c =>
        (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)
    );
}

function onNewSong(song) {
    browser.runtime.sendMessage(JSON.stringify({ type: 'new-song', song: song }));
}

function onUpdateSong(song) {
    browser.runtime.sendMessage(JSON.stringify({ type: 'update-song', song: song }));
}

function onAdvertisement() {
    browser.runtime.sendMessage(JSON.stringify({ type: 'advertisement' }));
}

function onHeartbeat() {
    browser.runtime.sendMessage(JSON.stringify({ type: 'heartbeat' }));
}

let song = { name: '', artists: [] };

// Initial Song Data
function getNameElement()     { return document.querySelector('.Root__now-playing-bar .now-playing-bar-container div.track-info__name span a'); }
function getArtistElements()  { return document.querySelectorAll('.Root__now-playing-bar .now-playing-bar-container div.track-info__artists span a'); }
function getAlbumArtElement() { return document.querySelector('.Root__now-playing-bar .now-playing-bar-container .cover-art .cover-art-image'); }

// After album is loaded
function getDurationElement()     { return document.querySelector('.Root__now-playing-bar .now-playing-bar .playback-bar .playback-bar__progress-time:last-child'); }
function getAlbumNameElement()    { return document.querySelector('.TrackListHeader .mo-info-name'); }
function getAlbumArtFullElement() { return document.querySelector('.TrackListHeader .cover-art .cover-art-image'); }

function checkSong() {
    let nameElement = getNameElement();
    let artistsElement = getArtistElements();
    let albumArtElement = getAlbumArtElement();

    let name = null;
    let artists = [];
    let albumArtLink = null;

    name = nameElement ? nameElement.innerText : 'Unknown Name';

    if (
        name == 'Advertisement' ||
        document.title.toLowerCase().indexOf('advertisement') != -1 ||
        document.title.toLowerCase().indexOf('spotify') != -1
    ) {
        console.log('advertisement');
        onAdvertisement();
        return;
    }

    for (let i = 0; i < artistsElement.length; ++i) {
        let artistElement = artistsElement[i];
        artists.push(artistElement.innerText);
    }

    let albumArtLinkStyle = albumArtElement.getAttribute('style');
    albumArtLink = albumArtLinkStyle.substring('background-image: url("'.length, albumArtLinkStyle.length - '");'.length);

    if (name != song.name || artists.join(', ') != song.artists.join(', ')) {
        // new song
        song = {
            guid: uuidv4(),
            name: name,
            artists: artists,
            album: {
                name: 'Unknown Album',
                art: albumArtLink
            }
        };
        console.log('new song', song);
        onNewSong(song);
        // Click the album link
        nameElement.click();
        setTimeout(() => {
            let durationElement = getDurationElement();
            let albumNameElement = getAlbumNameElement();
            let albumArtFullElement = getAlbumArtFullElement();

            let duration = durationElement ? durationElement.innerText : null;

            if (duration) {
                let s = duration.split(':');
                duration = parseInt(s[0]) * 60 + parseInt(s[1]);
            }

            let albumName = albumNameElement ? albumNameElement.getAttribute('title') : 'Unknown Album';

            let albumArtFullLinkStyle = albumArtFullElement.getAttribute('style');
            let albumArtFullLink = albumArtLinkStyle.substring('background-image: url("'.length, albumArtFullLinkStyle.length - 3);

            song.duration = duration;
            song.album.name = albumName;
            song.album.artFull = albumArtFullLink;

            onUpdateSong(song);
        }, 5000); // give 5 seconds to load
    }
}

console.log('Spotify Song Data Sender Extension Running');

// Send heartbeats every 3 seconds as soon as the content script is loaded
setInterval(() => { onHeartbeat(); }, 3000);
onHeartbeat();

// Check for new songs every 300 ms
setInterval(() => { checkSong(); }, 300);