import type { NodeApp } from 'astro/app/node';
import { createAppHandler } from './serve-app.js';
import type { RequestHandler } from './types.js';

/**
 * Creates a middleware that can be used with Express, Connect, etc.
 *
 * Similar to `createAppHandler` but can additionally be placed in the express
 * chain as an error middleware.
 *
 * https://expressjs.com/en/guide/using-middleware.html#middleware.error-handling
 */
export default function createMiddleware(app: NodeApp): RequestHandler {
	const handler = createAppHandler(app);
	const logger = app.getAdapterLogger();
	// using spread args because express trips up if the function's
	// stringified body includes req, res, next, locals directly
	return async (...args) => {
		// assume normal invocation at first
		const [req, res, next, locals] = args;
		// short circuit if it is an error invocation
		if (req instanceof Error) {
			const error = req;
			if (next) {
				return next(error);
			} else {
				throw error;
			}
		}
		try {
			await handler(req, res, next, locals);
		} catch (err) {
			logger.error(`Could not render ${req.url}`);
			console.error(err);
			if (!res.headersSent) {
				res.writeHead(500, `Server error`);
				res.end();
			}
		}
	};
}