var player;
var pos_int;

function init() {
	player = document.getElementById('player');

	player.addEventListener("ended", nextTrack);

	navigator.mediaSession.setActionHandler('play', playTrack);
	navigator.mediaSession.setActionHandler('pause', pauseTrack);
	navigator.mediaSession.setActionHandler('stop', stopTrack);
	navigator.mediaSession.setActionHandler('previoustrack', prevTrack);
	navigator.mediaSession.setActionHandler('nexttrack', nextTrack);

	pos_int = setInterval(update_position, 300);
}

async function get_rand_track() {
	let res = await fetch("./rand_track/")
	let data = await res.json();
	return data;
}

async function nextTrack() {
	track = await get_rand_track();
	player.src = track.source;
	playTrack();
}

function prevTrack() {
	// TODO: implement a history array
}

async function playTrack() {
	if (!player.src) {
		return nextTrack();
	}
	player.play(); 
	navigator.mediaSession.playbackState = "playing";
	setMediaSession(track);

	document.querySelector("#play-btn").style.display = "none";
	document.querySelector("#pause-btn").style.display = "initial";
}

function pauseTrack() {
	player.pause();
	navigator.mediaSession.playbackState = "paused";

	document.querySelector("#play-btn").style.display = "initial";
	document.querySelector("#pause-btn").style.display = "none";
}

function stopTrack() {
	player.pause();
	player.load();
	navigator.mediaSession.playbackState = "none";

	document.querySelector("#play-btn").style.display = "initial";
	document.querySelector("#pause-btn").style.display = "none";
}

function setMediaSession(track) {
	navigator.mediaSession.metadata = new MediaMetadata({
		title: track.title,
		artist: track.artist,
		album: track.album,
		artwork: track.artwork
	});
}

function update_position() {
	if (player.paused){return;}
	if (player.duration > 0 === false){return;}
	navigator.mediaSession.setPositionState({
		duration: parseInt(player.duration),
		playbackRate: player.playbackRate,
		position: parseInt(player.currentTime)
	});
}