import type { SSRManifest } from 'astro';
import type { IncomingMessage, ServerResponse } from 'http';
import type { Readable } from 'stream';
import { NodeApp } from 'astro/app/node';
import { polyfill } from '@astrojs/webapi';

polyfill(globalThis, {
	exclude: 'window document',
});

export function createExports(manifest: SSRManifest) {
	const app = new NodeApp(manifest);
	return {
		async handler(req: IncomingMessage, res: ServerResponse, next?: (err?: unknown) => void) {
			const route = app.match(req);

			if (route) {
				try {
					const response = await app.render(req);
					await writeWebResponse(res, response);
				} catch (err: unknown) {
					if (next) {
						next(err);
					} else {
						throw err;
					}
				}
			} else if (next) {
				return next();
			}
		},
	};
}

async function writeWebResponse(res: ServerResponse, webResponse: Response) {
	const { status, headers, body } = webResponse;
	res.writeHead(status, Object.fromEntries(headers.entries()));
	if (body) {
		for await(const chunk of (body as unknown as Readable)) {
			res.write(chunk);
		}
	}
	res.end();
}