import * as cheerio from 'cheerio';
import escapeHTML from 'escape-html';
import { ACCESS_TOKEN, SERVER_URL, SOURCE_ROOM_ID, TARGET_ROOM_ID } from "./conf.js";
import {readFileSync, writeFileSync} from "fs";


async function fetchMatrix(url, options = {}) {
	options.headers ||= {};
	options.headers.Authorization ||= `Bearer ${ACCESS_TOKEN}`;
	url = SERVER_URL + url;
	while (true) {
		console.debug("fetch", url);
		try {
			var res = await fetch(url, options);
			if (res.ok) break;
			console.warn("status:", res.status);
			if (res.status == 429) {
				var {retry_after_ms} = await res.json();
			}
		} catch (error) {
			console.error(error);
		}
		await new Promise(r => setTimeout(r, retry_after_ms || 60000));
	}
	if (!res.ok) throw new Error(`HTTP ${res.status} ${await res.text()}`);
	return res;
}

async function getMatrixEvents(room_id, until_event_id) {
	var events = [];
	do {
		var url = `/_matrix/client/v3/rooms/${encodeURIComponent(room_id)}/messages?dir=b&limit=50`;//use 1000 for initial fill
		if (end) url += `&from=${end}`;
		var {chunk, end} = await fetchMatrix(url).then(res => res.json());
		console.log(`got ${chunk.length}`);
		for (let event of chunk) {
			if (until_event_id && event.event_id == until_event_id) return events;
			events.push(event);
		}
	} while (end)
	return events;
}

async function getNewMatrixEvents(room_id) {
	var fn = `last_event_id_${room_id.replace(/[^\w]/g,'')}`;
	try {
		var last_event_id = readFileSync(fn, "utf8");
	} catch (error) {
		console.log(error.message);
	}
	var events = await getMatrixEvents(room_id, last_event_id);
	for (let event of events) {
		event.hasBeenProcessed = function () {
			writeFileSync(fn, event.event_id);
		}
	}
	return events;
}

function getHrefs(html) {
	const $ = cheerio.load(html);
	const links = [];

	$('a[href]').each((_, el) => {
		links.push($(el).attr('href'));
	});

	return links;
}



var events = await getNewMatrixEvents(SOURCE_ROOM_ID);

for (let event of events.reverse()) {
	if (typeof event.content == "object") {
		let links;
		if (event.content.format == "org.matrix.custom.html" && typeof event.content.formatted_body == "string") {
			links = getHrefs(event.content.formatted_body);
		} else if (typeof event.content.body == "string") {
			links = event.content.body.match(/https?:\/\/[^\s<>()]+/g);
		}
		if (links) links = links.filter(l => !l.startsWith("https://matrix.to/#/"));
		if (links?.length) {
			let event_url = `https://matrix.to/#/${encodeURIComponent(event.room_id)}/${encodeURIComponent(event.event_id)}`;
			await fetchMatrix(`/_matrix/client/v3/rooms/${encodeURIComponent(TARGET_ROOM_ID)}/send/m.room.message/${Math.random()}`, {
				method: "PUT",
				headers: {
					"Content-Type": "application/json"
				},
				body: JSON.stringify({
					msgtype: "m.text",
					body: `${links.join(" ")} ${event_url}`,
					format: "org.matrix.custom.html",
					formatted_body: `${links.map(l => `<a href="${encodeURI(l)}">${escapeHTML(l)}</a>`).join(" ")} <a href="${encodeURI(event_url)}">🔗</a>`
				})
			});
		}
	}
	event.hasBeenProcessed();
}