import {Aedes} from 'aedes';
import {createServer} from 'net';
import {cfg} from './config.mjs';

const HISTORY_LIMIT = 500;
const TTL_MS = 60_000;

const satellites = new Map();

function pruneStale() {
	const now = Date.now();
	for (const [key, bucket] of satellites) {
		if (now - bucket.lastSeen > TTL_MS) satellites.delete(key);
	}
}

function safeJson(buf) {
	try { return JSON.parse(buf.toString()); } catch { return null; }
}

/**
 * Best-effort field mapping — adjust once real TinyGS payload shape is confirmed
 * from the console logs. Unknown fields are kept under `raw` for inspection.
 */
function extractReading(topic, payload) {
	const data = safeJson(payload) ?? {raw: payload.toString()};
	return {
		timestamp: Date.now(),
		topic,
		satellite: data.satellite ?? data.name ?? data.sat ?? 'unknown',
		norad: data.norad ?? data.noradId ?? data.NORAD ?? null,
		freqMHz: data.freq ?? data.frequency ?? null,
		packetRssi: data.rssi ?? null,
		packetSnr: data.snr ?? null,
		freqError: data.frequency_error ?? data.freqError ?? null,
		crcOk: data.crc_error !== undefined ? !data.crc_error : null,
		raw: data,
	};
}

function handlePacket(topic, payload) {
	const reading = extractReading(topic, payload);
	const key = reading.norad ? `${reading.satellite}-${reading.norad}` : reading.satellite;

	let bucket = satellites.get(key);
	if (!bucket) {
		bucket = {history: [], lastSeen: 0};
		satellites.set(key, bucket);
	}
	bucket.lastSeen = reading.timestamp;
	bucket.history.push(reading);
	if (bucket.history.length > HISTORY_LIMIT) bucket.history.shift();

	pruneStale();
}

export async function startTinyGSServer() {
	const {TINYGS_MQTT_PORT = 1883, TINYGS_MQTT_USER, TINYGS_MQTT_PASS} = cfg();
	const broker = await Aedes.createBroker();
	const server = createServer(broker.handle);

	if (TINYGS_MQTT_USER) {
		broker.authenticate = (client, username, password, cb) => {
			const ok = username === TINYGS_MQTT_USER && password?.toString() === TINYGS_MQTT_PASS;
			if (!ok) console.warn(`[tinygs] rejected auth from ${client.id}`);
			cb(null, ok);
		};
	}

	broker.on('publish', (packet, client) => {
		if (!client || packet.topic.startsWith('$SYS')) return;
		console.info(`[tinygs] ${packet.topic}`, packet.payload.toString().slice(0, 200));
		handlePacket(packet.topic, packet.payload);
	});
	broker.on('client', client => console.info(`[tinygs] connected: ${client.id}`));
	broker.on('clientDisconnect', client => console.info(`[tinygs] disconnected: ${client.id}`));

	server.listen(TINYGS_MQTT_PORT, () => console.info(`🛜  MQTT broker - http://localhost:${TINYGS_MQTT_PORT}`));
}

export const getTinyGSData = () => {
	pruneStale();
	return Array.from(satellites.values()).map(bucket => ({
		...bucket.history.at(-1),
		history: bucket.history.slice(0, -1),
	}));
}