/* eslint-disable @typescript-eslint/no-require-imports */
const { createServer } = require('http');
const { parse } = require('url');
const next = require('next');

const port = Number(process.env.PORT || 4000);

/**
 * 自定义 server 若写 `next({ dev: false })` 不传 port，Next 内部仍默认 3000（见 next/dist/server/next.js），
 * 与 `listen(4000)` 不一致时，307 Location 会变成 `http://jinclab.com:3000/zh` 这类错误地址。
 *
 * 反代终止 TLS 后须传 `X-Forwarded-Proto: https`；若漏传，协议会判成 http。
 * 若 Host 误带内网端口，与 NEXT_PUBLIC_SITE_URL 对齐时去掉端口。
 */
function normalizeProxyHeaders(req) {
	const site = process.env.NEXT_PUBLIC_SITE_URL?.trim().replace(/\/$/, '');
	if (!site || process.env.NODE_ENV !== 'production') return;

	let canonicalHost;
	try {
		canonicalHost = new URL(site).hostname;
	} catch {
		return;
	}

	const allowed = new Set([canonicalHost, `www.${canonicalHost}`]);
	const raw = req.headers.host;
	if (typeof raw !== 'string') return;

	const colon = raw.indexOf(':');
	const hostnameOnly = colon === -1 ? raw : raw.slice(0, colon);

	if (!allowed.has(hostnameOnly)) return;

	if (colon !== -1) {
		req.headers.host = hostnameOnly;
	}

	if (site.startsWith('https:') && !req.headers['x-forwarded-proto']) {
		req.headers['x-forwarded-proto'] = 'https';
	}
}

// port 必须与 listen 一致，避免 Next 内部仍按 3000 拼绝对 URL（勿改 hostname，以免内部 initURL 变成 127.0.0.1）
const app = next({ dev: false, port });
const handle = app.getRequestHandler();

app.prepare().then(() => {
	const server = createServer((req, res) => {
		normalizeProxyHeaders(req);
		handle(req, res, parse(req.url, true));
	});

	server.on('error', (error) => {
		if (error.code === 'EADDRINUSE') {
			const fallbackPort = port + 1;
			console.warn(`Port ${port} is in use, retrying on ${fallbackPort}...`);
			server.listen(fallbackPort);
			return;
		}
		throw error;
	});

	server.listen(port);
});