const m3u8Parser = require('m3u8-parser');
const fetch = require('node-fetch');
const url = require('url');
const { test } = require('@jest/globals');

const HLS_SUBDIRECTORY = '/hls/';
const PLAYLIST_NAME = 'stream.m3u8';
const TEST_OWNCAST_INSTANCE = 'http://localhost:8080';
const HLS_FETCH_ITERATIONS = 5;

jest.setTimeout(40000);

async function getPlaylist(urlString) {
	const response = await fetch(urlString);
	expect(response.status).toBe(200);
	const body = await response.text();

	var parser = new m3u8Parser.Parser();

	parser.push(body);
	parser.end();

	return parser.manifest;
}

function normalizeUrl(urlString, baseUrl) {
	let parsedString = url.parse(urlString);
	if (!parsedString.host) {
		const testInstanceRoot = url.parse(baseUrl);
		parsedString.protocol = testInstanceRoot.protocol;
		parsedString.host = testInstanceRoot.host;

		const filename = baseUrl.substring(baseUrl.lastIndexOf('/') + 1);
		parsedString.pathname =
			testInstanceRoot.pathname.replace(filename, '') + urlString;
	}
	return url.format(parsedString).toString();
}

// Iterate over an array of video segments and make sure they return back
// valid status.
async function validateSegments(segments) {
	for (let segment of segments) {
		const res = await fetch(segment);
		expect(res.status).toBe(200);
	}
}

describe('fetch and parse HLS', () => {
	const masterPlaylistUrl = `${TEST_OWNCAST_INSTANCE}${HLS_SUBDIRECTORY}${PLAYLIST_NAME}`;
	var masterPlaylist;
	var mediaPlaylistUrl;

	test('fetch master playlist', async () => {
		try {
			masterPlaylist = await getPlaylist(masterPlaylistUrl);
		} catch (e) {
			console.error('error fetching and parsing master playlist', e);
		}
	});

	test('verify there is a media playlist', () => {
		// Master playlist should have at least one media playlist.
		expect(masterPlaylist.playlists.length).toBe(1);

		try {
			mediaPlaylistUrl = normalizeUrl(
				masterPlaylist.playlists[0].uri,
				masterPlaylistUrl
			);
		} catch (e) {
			console.error('error fetching and parsing media playlist', e);
		}
	});

	test('verify there are segments', async () => {
		let playlist;
		try {
			playlist = await getPlaylist(mediaPlaylistUrl);
		} catch (e) {
			console.error('error verifying segments in media playlist', e);
		}

		const segments = playlist.segments;
		expect(segments.length).toBeGreaterThan(0);
	});

	// Iterate over segments and make sure they change.
	// Use the reported duration of the segment to wait to
	// fetch another just like a real HLS player would do.
	var lastSegmentUrl;
	for (let i = 0; i < HLS_FETCH_ITERATIONS; i++) {
		test('fetch and monitor media playlist segments ' + i, async () => {
			await new Promise((r) => setTimeout(r, 5000));

			try {
				var playlist = await getPlaylist(mediaPlaylistUrl);
			} catch (e) {
				console.error('error updating media playlist', mediaPlaylistUrl, e);
			}

			const segments = playlist.segments;
			const segment = segments[segments.length - 1];
			expect(segment.uri).not.toBe(lastSegmentUrl);

			try {
				var segmentUrl = normalizeUrl(segment.uri, mediaPlaylistUrl);
				await validateSegments([segmentUrl]);
			} catch (e) {
				console.error('unable to validate HLS segment', segmentUrl, e);
			}

			lastSegmentUrl = segment.uri;
		});
	}
});