// ==UserScript==
// @name         MediaSession API support for YMusic
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Add basic MediaSession support
// @match        https://music.yandex.ru/home
// @match        https://music.yandex.ru/non-music
// @match        https://music.yandex.ru/kids
// @match        https://music.yandex.ru/radio
// @icon         https://www.google.com/s2/favicons?domain=yandex.ru
// @grant        none
// ==/UserScript==

(function() {
    const UI_SELECTORS = {
        play: '.player-controls__btn_play',
        next: '.player-controls__btn_next',
        prev: '.player-controls__btn_prev',
        controls_container: '.player-controls__track-container',
        cover_image: '.track .entity-cover__image',
        track_title: '.track .track__title',
        track_artist: '.track .track__artists'
    }

    let curTrackName = null;

    setTimeout(setup, 3000);

    function setup() {
        navigator.mediaSession.setActionHandler('play', () => {
            console.log('[mediasession] handling play');
            if (!isPlaying()) {
                clickOnUI(UI_SELECTORS.play)();
            }
        });
        navigator.mediaSession.setActionHandler('pause', () => {
            console.log('[mediasession] handling pause');
            if (isPlaying()) {
                clickOnUI(UI_SELECTORS.play)();
            }
        });
        navigator.mediaSession.setActionHandler('nexttrack', clickOnUI(UI_SELECTORS.next));
        navigator.mediaSession.setActionHandler('previoustrack', clickOnUI(UI_SELECTORS.prev));

        const ctrlsContainer = document.querySelector(UI_SELECTORS.controls_container);
        if (ctrlsContainer) {
            const observer = new MutationObserver(onTrackChange);
            observer.observe(ctrlsContainer, { subtree: true, childList: true });

            updateTrackMeta();
        }
    }

    function isPlaying() {
        const PLAY_CLASS = 'player-controls__btn_pause';
        const playBtn = document.querySelector(UI_SELECTORS.play);

        if (!playBtn) {
            console.error('cannot find play button while checking plyaing status');
            return;
        }

        return playBtn.classList.contains(PLAY_CLASS);
    }

    function clickOnUI(sel) {
        return () => {
            const elm = document.querySelector(sel);
            if (!elm) {
                console.error('cannot click on element. it doesnt exist in DOM. CSS selector:', sel)
                return;
            }
            elm.click();
        }
    }

    function updateTrackMeta() {
        try {
            const trName = document.querySelector(UI_SELECTORS.track_title).textContent.trim();
            const trArtists = document.querySelector(UI_SELECTORS.track_artist).textContent.trim();
            const trCover = document.querySelector(UI_SELECTORS.cover_image).src;

            navigator.mediaSession.metadata = new MediaMetadata({
                title: trName,
                artist: trArtists,
                artwork: [
                  { src: trCover },
                ]
              });
        } catch (_err) {}
    }

    function onTrackChange(mutations) {
        setTimeout(updateTrackMeta, 1000);
    }
})();