import { createServer } from 'node:http';
import { Readable } from 'node:stream';
import { WebSocketServer } from 'ws';
import { config } from './env.mjs';
import { currentSession } from './domain.mjs';
import { applyCors, corsPreflight, handleError, parseCookies, writeResponse } from './http.mjs';
import { attach as attachSocket } from './realtime.mjs';
import { route } from './routes.mjs';

const server = createServer(async (nodeRequest, nodeResponse) => {
	try {
		const request = toWebRequest(nodeRequest);
		if (request.method === 'OPTIONS') {
			writeResponse(nodeResponse, applyCors(request, corsPreflight(request)));
			return;
		}
		const response = await route(request);
		logResponse(request, response);
		writeResponse(nodeResponse, applyCors(request, response));
	} catch (error) {
		const request = toWebRequest(nodeRequest, false);
		const response = handleError(error);
		logResponse(request, response);
		writeResponse(nodeResponse, applyCors(request, response));
	}
});

// ── Realtime ─────────────────────────────────────────────────────────────
//
// The WebSocket endpoint at `/api/realtime` authenticates via the same
// `dating_session` cookie the HTTP API uses, then registers the socket
// with the in-memory hub. Endpoint handlers (currently `messagesPost`)
// call `broadcast([recipientId], event)` to push events out without
// the consumer needing to track connections themselves.
//
// `noServer: true` lets us reuse the existing HTTP server for upgrades
// and run the cookie-based auth check before accepting the WebSocket.
const wss = new WebSocketServer({ noServer: true });

server.on('upgrade', async (nodeRequest, socket, head) => {
	const url = nodeRequest.url || '/';
	if (!url.startsWith('/api/realtime')) {
		socket.destroy();
		return;
	}

	// Reject upgrades from origins not in the CORS allowlist; Browsers
	// are happy to upgrade cross-origin and the server has to gate it
	// explicitly.
	const origin = nodeRequest.headers.origin;
	if (origin && !config.allowedOrigins.includes(origin)) {
		socket.write('HTTP/1.1 403 Forbidden\r\n\r\n');
		socket.destroy();
		return;
	}

	const session = await authenticateUpgrade(nodeRequest);
	if (session === null) {
		socket.write('HTTP/1.1 401 Unauthorized\r\n\r\n');
		socket.destroy();
		return;
	}

	wss.handleUpgrade(nodeRequest, socket, head, (ws) => {
		attachSocket(session.user.id, ws);
		try {
			ws.send(JSON.stringify({ type: 'hello', userId: session.user.id }));
		} catch {
			// initial frame is best-effort; the socket will recover on the next event
		}
	});
});

async function authenticateUpgrade(nodeRequest) {
	const cookies = parseCookies(nodeRequest.headers.cookie);
	const token = cookies.get(config.cookieName);
	if (!token) return null;
	// Reuse the HTTP path's session helper. It expects a `Headers`
	// object so we forge one carrying the bearer the helper looks for.
	const fakeRequest = new Request('http://internal/realtime', {
		headers: { authorization: `Bearer ${token}` }
	});
	try {
		return await currentSession(fakeRequest);
	} catch {
		return null;
	}
}

server.listen(config.port, config.host, () => {
	console.log(`Dating server listening on http://${config.host}:${config.port}`);
	console.log(`PocketBase: ${config.pocketBaseUrl}`);
});

function toWebRequest(nodeRequest, includeBody = true) {
	const protocol = nodeRequest.headers['x-forwarded-proto'] || 'http';
	const host = nodeRequest.headers.host || `${config.host}:${config.port}`;
	const url = `${protocol}://${host}${nodeRequest.url || '/'}`;
	const method = nodeRequest.method || 'GET';
	const headers = new Headers();
	for (const [name, value] of Object.entries(nodeRequest.headers)) {
		if (Array.isArray(value)) {
			for (const item of value) headers.append(name, item);
		} else if (value != null) {
			headers.set(name, String(value));
		}
	}
	const hasBody = includeBody && !['GET', 'HEAD'].includes(method);
	return new Request(url, {
		method,
		headers,
		body: hasBody ? Readable.toWeb(nodeRequest) : undefined,
		duplex: hasBody ? 'half' : undefined
	});
}

function logResponse(request, response) {
	if (response.status < 400) return;
	const url = new URL(request.url);
	const code = response.body?.error?.code || 'http_error';
	console.warn(`${request.method} ${url.pathname} -> ${response.status} ${code}`);
}