carbon/build/static/sync/sync.js

import {store} from "../store/store.js"
import * as lsm from "../lsm.js"

let lastBatch = null

function sync() {
	const url = new URL(`${lsm.get("domain")}/_matrix/client/r0/sync`)
	url.searchParams.append("access_token", lsm.get("access_token"))
	const filter = {
		room: {
			// pulling more from the timeline massively increases download size
			timeline: {
				limit: 5
			},
			// members are not currently needed
			state: {
				lazy_load_members: true
			}
		},
		presence: {
			// presence is not implemented, ignore it
			types: []
		}
	}
	url.searchParams.append("filter", JSON.stringify(filter))
	url.searchParams.append("timeout", 20000)
	if (lastBatch) {
		url.searchParams.append("since", lastBatch)
	}
	return fetch(url.toString()).then(res => res.json()).then(root => {
		lastBatch = root.next_batch
		return root
	})
}

function manageSync(root) {
	try {
		// set up directs
		const directs = root.account_data.events.find(e => e.type === "m.direct")
		if (directs) {
			Object.values(directs.content).forEach(ids => {
				ids.forEach(id => store.directs.add(id))
			})
		}

		// set up rooms
		Object.entries(root.rooms.join).forEach(([id, room]) => {
			if (!store.rooms.has(id)) {
				store.rooms.askAdd(id, room)
			}
		})
	} catch (e) {
		console.error(root)
		throw e
	}
}

function syncLoop() {
	return sync().then(manageSync).then(syncLoop)
}

syncLoop()