// Copy to app/api/email-example/route.ts in a local Next.js App Router project.
// Run email-mock-server.mjs separately. This route is development-only.
// It always calls the local fixture. It cannot send real email.
export async function POST(request: Request) {
  if (process.env.NODE_ENV !== 'development') return new Response(null, { status: 404 });
  const url = new URL(request.url);
  if (!['localhost', '127.0.0.1'].includes(url.hostname) || request.headers.get('origin') !== url.origin) {
    return Response.json({ error: 'Local same-origin requests only' }, { status: 403 });
  }
  const key = request.headers.get('idempotency-key');
  if (!key || !/^[a-zA-Z0-9:_-]{1,120}$/.test(key)) {
    return Response.json({ error: 'Supply a stable Idempotency-Key' }, { status: 400 });
  }
  try {
    const response = await fetch('http://127.0.0.1:3027/api/v1/emails', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'Idempotency-Key': key },
      body: JSON.stringify({ from: 'hello@example.test', to: 'reader@example.test', subject: 'A local test', text: 'No email leaves this fixture.' }),
      signal: AbortSignal.timeout(5000),
      cache: 'no-store',
    });
    const result = await response.json();
    if (!response.ok) return Response.json({ error: 'Fixture rejected the request' }, { status: response.status });
    return Response.json(result, { status: 202 });
  } catch {
    return Response.json({ error: 'Result unknown. Retry with the same key.' }, { status: 503 });
  }
}