/*
 * Express 5 web server — REST bridge to video-node.
 *
 * Usage:
 *   node server.mjs [--host IP] [--port PORT] [--listen PORT]
 *
 * Discovery runs at startup unconditionally — the server joins the multicast
 * group and sends an announcement immediately so nodes respond right away.
 * The /api/discover SSE endpoint subscribes to the running peer feed.
 */

import express from 'express';
import { EventEmitter } from 'node:events';
import { fileURLToPath } from 'node:url';
import path from 'node:path';
import { Node_Client } from './node_client.mjs';
import { start_discovery } from './discovery.mjs';

/* -------------------------------------------------------------------------
 * Argument parsing
 * ------------------------------------------------------------------------- */

const args = process.argv.slice(2);
const arg = name => {
	const i = args.indexOf(name);
	return i >= 0 ? args[i + 1] : null;
};

const opt_host    = arg('--host');
const opt_port    = arg('--port') ? parseInt(arg('--port')) : null;
const listen_port = arg('--listen') ? parseInt(arg('--listen')) : 3000;

/* -------------------------------------------------------------------------
 * Persistent discovery — runs from startup, feeds the SSE endpoint
 * ------------------------------------------------------------------------- */

const peer_bus   = new EventEmitter();
const known_peers = new Map();   /* key: addr:name -> peer */

start_discovery(
	peer => {
		const key = `${peer.addr}:${peer.name}`;
		known_peers.set(key, peer);
		peer_bus.emit('peer', peer);
		console.log(`discovered: ${peer.name} at ${peer.addr}:${peer.tcp_port}`);
	},
	err => {
		console.error('discovery error:', err.message);
		peer_bus.emit('discovery_error', err);
	},
);

/* -------------------------------------------------------------------------
 * Node client (singleton)
 * ------------------------------------------------------------------------- */

const client = new Node_Client();

client.on('disconnect', () => {
	console.log('video-node disconnected');
});

/* -------------------------------------------------------------------------
 * Express app
 * ------------------------------------------------------------------------- */

const app = express();
app.use(express.json());

const __dir = path.dirname(fileURLToPath(import.meta.url));
app.use(express.static(path.join(__dir, 'public')));

/* -- Status ---------------------------------------------------------------- */

app.get('/api/status', (_req, res) => {
	res.json({
		connected: client.connected,
		host:      client.host,
		port:      client.port,
	});
});

/* -- Connect --------------------------------------------------------------- */

app.post('/api/connect', async (req, res) => {
	const { host, port } = req.body ?? {};
	if (!host || !port) {
		return res.status(400).json({ error: 'host and port required' });
	}
	try {
		await client.connect(host, parseInt(port));
		res.json({ ok: true, host: client.host, port: client.port });
	} catch (err) {
		res.status(502).json({ error: err.message });
	}
});

app.post('/api/disconnect', (_req, res) => {
	client.disconnect();
	res.json({ ok: true });
});

/*
 * SSE stream — immediately replays already-known peers, then streams new ones
 * as they arrive.  Client closes when done (user picked a node or dismissed).
 */
app.get('/api/discover', (req, res) => {
	res.setHeader('Content-Type',  'text/event-stream');
	res.setHeader('Cache-Control', 'no-cache');
	res.setHeader('Connection',    'keep-alive');
	res.flushHeaders();

	const send_peer  = peer => res.write(`data: ${JSON.stringify(peer)}\n\n`);
	const send_error = err  => res.write(`event: discovery_error\ndata: ${JSON.stringify({ error: err.message })}\n\n`);

	/* replay peers already seen before this SSE was opened */
	for (const peer of known_peers.values()) { send_peer(peer); }

	peer_bus.on('peer',            send_peer);
	peer_bus.on('discovery_error', send_error);

	req.on('close', () => {
		peer_bus.off('peer',            send_peer);
		peer_bus.off('discovery_error', send_error);
	});
});

/* -- Devices --------------------------------------------------------------- */

app.get('/api/devices', async (_req, res) => {
	try {
		const result = await client.enum_devices();
		res.json(result);
	} catch (err) {
		res.status(502).json({ error: err.message });
	}
});

/* -- Controls -------------------------------------------------------------- */

app.get('/api/devices/:idx/controls', async (req, res) => {
	const idx = parseInt(req.params.idx);
	if (isNaN(idx)) { return res.status(400).json({ error: 'invalid device index' }); }
	try {
		const result = await client.enum_controls(idx);
		res.json(result);
	} catch (err) {
		res.status(502).json({ error: err.message });
	}
});

app.get('/api/devices/:idx/controls/:ctrl_id', async (req, res) => {
	const idx     = parseInt(req.params.idx);
	const ctrl_id = parseInt(req.params.ctrl_id, 16) || parseInt(req.params.ctrl_id);
	if (isNaN(idx) || isNaN(ctrl_id)) {
		return res.status(400).json({ error: 'invalid params' });
	}
	try {
		const result = await client.get_control(idx, ctrl_id);
		res.json(result);
	} catch (err) {
		res.status(502).json({ error: err.message });
	}
});

app.post('/api/devices/:idx/controls/:ctrl_id', async (req, res) => {
	const idx     = parseInt(req.params.idx);
	const ctrl_id = parseInt(req.params.ctrl_id, 16) || parseInt(req.params.ctrl_id);
	const value   = req.body?.value;
	if (isNaN(idx) || isNaN(ctrl_id) || value === undefined) {
		return res.status(400).json({ error: 'invalid params' });
	}
	try {
		const result = await client.set_control(idx, ctrl_id, parseInt(value));
		res.json(result);
	} catch (err) {
		res.status(502).json({ error: err.message });
	}
});

/* -------------------------------------------------------------------------
 * Startup
 * ------------------------------------------------------------------------- */

app.listen(listen_port, () => {
	console.log(`listening on http://localhost:${listen_port}`);
});

if (opt_host && opt_port) {
	client.connect(opt_host, opt_port)
		.then(() => console.log(`connected to ${opt_host}:${opt_port}`))
		.catch(err => console.error('connect failed:', err.message));
}