import fs from 'node:fs/promises';
import express from 'express';

// Constants
const isProduction = process.env.NODE_ENV === 'production';
const port = process.env.PORT || 5001;
const base = process.env.BASE || '/';

// Cached production assets
const templateHtml = isProduction ? await fs.readFile('./dist/client/index.html', 'utf-8') : '';
const ssrManifest = isProduction ? await fs.readFile('./dist/client/.vite/ssr-manifest.json', 'utf-8') : undefined;

// Create http server
const app = express();

// Add Vite or respective production middlewares
let vite;
if (!isProduction) {
	const {createServer} = await import('vite');
	vite = await createServer({
		server: {middlewareMode: true},
		appType: 'custom',
		base,
	});
	app.use(vite.middlewares);
} else {
	const sirv = (await import('sirv')).default;
	app.use(base, sirv('./dist/client', {extensions: []}));
}

// Serve HTML
app.use('*', async (req, res) => {
	try {
		const url = req.originalUrl.replace(base, '');

		let template;
		let render;
		if (!isProduction) {
			// Always read fresh template in development
			template = await fs.readFile('./index.html', 'utf-8');
			template = await vite.transformIndexHtml(url, template);
			render = (await vite.ssrLoadModule('/src/entry-server.tsx')).render;
		} else {
			template = templateHtml;
			render = (await import('./dist/server/entry-server.js')).render;
		}

		const rendered = await render(url, ssrManifest);

		const html = template.replace(`<!--app-head-->`, rendered.head ?? '').replace(`<!--app-html-->`, rendered.html ?? '');

		res.status(200).set({'Content-Type': 'text/html'}).send(html);
	} catch (e) {
		vite?.ssrFixStacktrace(e);
		console.log(e.stack);
		res.status(500).end(e.stack);
	}
});

// Start http server
app.listen(port, () => {
	console.log(`Server started at http://localhost:${port}`);
});
