// ==UserScript==
// @name netflix-speed
// @version 0.7
// @include https://www.netflix.com/*
// ==/UserScript==

function find_controls() {
	return new Promise(function(resolve, reject) {
		var observer = new MutationObserver(function(mutationsList) {
			mutationsList.forEach(function(mutation) {
				var nodes = Array.from(mutation.addedNodes);
				for (var node of nodes) {
					/* classic ui - black bar at the bottom */
					if (node.matches && node.matches('.classic-ui') && node.querySelector('.video-title')) {
						resolve(node.querySelector('.video-title').previousElementSibling);
						return;
					}
					/* modern ui - play/pause in the middle of the screen */
					if (node.matches && node.matches('.AkiraPlayer') && (node.querySelector('.button-nfplayerNextEpisode') || node.querySelector('.button-nfplayerSubtitles'))) {
						var elem = node.querySelector('.button-nfplayerNextEpisode') || node.querySelector('.button-nfplayerSubtitles');
						resolve(elem.parentNode);
						return;
					}
				}
			});
		});

		observer.observe(document.documentElement, { childList: true, subtree: true });
	});
}

function inject_controls() {
	find_controls().then(function(controls) {
		/* don't inject multiple times */
		if (document.querySelector('#speed-control'))
			return;

		/* create speed_control element */
		var speed_control = document.createElement('select');
		speed_control.id = 'speed-control';
		speed_control.style.cssText = `
		border-left: 1px solid #323232;
		border-right: 1px solid #151515;
		border-top: none;
		border-bottom: none;
		background: none;
		-moz-appearance: none;
		-webkit-appearance: none;
		appearance: none;
		min-width: 5em;
		width: auto;
		height: 100%;
		font-size: 2.2em;
		text-align: center;
		cursor: pointer;
		`;
		speed_control.id = 'speed-control';
		speed_control.onchange = function() {
			document.querySelector('.VideoContainer video').playbackRate = this.value;
		};
		speed_control.innerHTML = `<option value=0.5>0.5</option>
		<option value=0.75>0.75</option>
		<option value=1.0 selected="selected">Normal</option>
		<option value=1.25>1.25</option>
		<option value=1.5>1.5</option>
		<option value=1.75>1.75</option>
		<option value=2.0>2.0</option>`;

		/* inject speed_control element */
		controls.after(speed_control);

		/* redo injection, in case of video change, ... */
		inject_controls();
	});
};

inject_controls();