// Node.js 22+. Run: node email-mock-server.mjs
// Local protocol fixture, not a mail server. No SMTP or provider SDK is used.
import http from 'node:http';
import { randomUUID, createHash } from 'node:crypto';
const messages = new Map();
const keys = new Map();
const server = http.createServer(async (request, response) => {
  const reply = (status, value) => { response.writeHead(status, { 'content-type': 'application/json' }); response.end(JSON.stringify(value)); };
  if (request.method === 'POST' && request.url === '/api/v1/emails') {
    let body = '';
    for await (const part of request) {
      body += part;
      if (Buffer.byteLength(body) > 16384) return reply(413, { error: 'Too large' });
    }
    let payload;
    try { payload = JSON.parse(body); } catch { return reply(400, { error: 'Invalid JSON' }); }
    const key = request.headers['idempotency-key'];
    if (typeof key !== 'string' || !key || key.length > 120 || !payload || typeof payload.to !== 'string' || typeof payload.subject !== 'string' || typeof payload.text !== 'string') return reply(400, { error: 'Key, to, subject and text required' });
    const fingerprint = createHash('sha256').update(body).digest('hex');
    const old = keys.get(key);
    if (old && old.fingerprint !== fingerprint) return reply(409, { error: 'Idempotency conflict' });
    if (old) return reply(202, messages.get(old.id));
    const id = randomUUID();
    const message = { id, status: 'queued', mode: 'demo' };
    messages.set(id, message); keys.set(key, { id, fingerprint });
    return reply(202, message);
  }
  if (request.method === 'GET' && request.url?.startsWith('/api/v1/emails/')) {
    const message = messages.get(request.url.split('/').pop());
    return reply(message ? 200 : 404, message || { error: 'Not found' });
  }
  reply(404, { error: 'Not found' });
});
server.requestTimeout = 5000;
server.headersTimeout = 5000;
// Set EMAIL_FIXTURE_PORT=0 to let the operating system choose a free port.
const port = Number(process.env.EMAIL_FIXTURE_PORT ?? 3027);
server.listen(port, '127.0.0.1', () => console.log(`Email fixture: http://127.0.0.1:${server.address().port} (simulated; memory only)`));