app.js

const 	sdk = require('matrix-js-sdk'),
	urlParser = require('js-video-url-parser'),
	express = require('express'),
	shuffle = require('lodash.shuffle')

let config
try {
	config = require('./config')
} catch (e) {
	config = {
		HOMESERVER: process.env.HOMESERVER || 'https://matrix.org',
		USER: process.env.USER,
		PASS: process.env.PASS,
		ROOM_ID: process.env.ROOM_ID,
		LOCAL_PORT: parseInt(process.env.LOCAL_PORT || 8080),
		INIT_SYNC_LIMIT: parseInt(process.env.INIT_SYNC_LIMIT || 1000),
		ASC_ORDER: (process.env.ASC_ORDER || 'true').toLowerCase() === 'true'
	}
}

const	client = sdk.createClient(config.HOMESERVER),
	app = express()

console.log('Logging in and starting the client...')

client.login(
	'm.login.password', {
		'user': config.USER,
		'password': config.PASS
	}
).then(res => {
	
	const	isMessageEvent = e =>
		e.event.type == 'm.room.message' &&
		e.event.content.body && e.event.content.body.length,
	isRedactionEvent = e =>
		e.event.type == 'm.room.redaction',
	getId = e => {
		const obj = urlParser.parse(e.event.content.body)
		return obj && obj.provider == 'youtube' && obj.id
			? obj.id
			: null
	},
	getYouTubeUrl = ids => `https://www.youtube.com/watch_videos?video_ids=${ids.map(id => id.id).join(',')}`,
	ids = []

	client.once('sync', (state, prevState, res) => {
		console.log(`Sync: ${state}`)
		switch (state) {
			case 'PREPARED':
				console.log('Initializing Express...')
				app.get('/', (req, res) => {
					res.redirect(getYouTubeUrl(ids))
				})
				app.get('/shuffle', (req, res) => {
					res.redirect(getYouTubeUrl(shuffle(ids)))
				})
				app.listen(config.LOCAL_PORT, () => {
					console.log(`Express is listening on port ${config.LOCAL_PORT}`)
				})
		}
	})

	client.on('Room.timeline', (event, room, toStartOfTimeline) => {
		if ( room.roomId === config.ROOM_ID ) {
			if ( isMessageEvent(event) && ( id = getId(event) ) ) {
				const eventId = event.event.event_id
				if ( config.ASC_ORDER ) ids.push({id, eventId})
				else ids.unshift({id, eventId})
				console.log(`${new Date().toString()} INSERT ${id}`)
			} else if ( isRedactionEvent(event) ) {
				const redactsEventId = event.event.redacts
				if ( ( i = ids.findIndex(id => id.eventId === redactsEventId ) ) >= 0 ) {
					console.log(`${new Date().toString()} REDACT ${ids[i].id}`)
					ids.splice(i, 1)
				}
			}
		}
	})

	client.startClient({
		initialSyncLimit: config.INIT_SYNC_LIMIT
	})

})