'use strict';
/**
 * Мок Unisender Go (goapi.unisender.ru/ru/transactional/api/v1/email/send.json).
 * Реальных отправок НЕТ — каждое письмо пишется в MAIL_DIR как JSON-файл.
 * Валидирует контракт как настоящий API (те же коды ошибок) — чтобы ловить
 * регрессии формы (body.text vs plaintext и т.п.) без платных писем.
 *
 * Эндпоинты:
 *   POST /ru/transactional/api/v1/email/send.json — приём письма (X-API-KEY или api_key)
 *   GET  /health — живость
 */
const http = require('node:http');
const fs = require('node:fs');
const path = require('node:path');

const PORT = Number(process.env.PORT || 8080);
const MAIL_DIR = process.env.MAIL_DIR || '/mail';

fs.mkdirSync(MAIL_DIR, { recursive: true });

function json(res, code, body) {
  const payload = JSON.stringify(body);
  res.writeHead(code, { 'content-type': 'application/json' });
  res.end(payload);
}

function apiError(res, code, message) {
  json(res, 400, { status: 'error', code, message });
}

function saveMail(payload, apiKey) {
  const ts = new Date().toISOString().replace(/[:.]/g, '-');
  const jobId = `mock-${ts}`;
  const file = path.join(MAIL_DIR, `${ts}.json`);
  const msg = payload.message || {};
  const recipients = (msg.recipients || []).map((r) => r.email);
  const record = {
    job_id: jobId,
    receivedAt: new Date().toISOString(),
    api_key: apiKey,
    from_email: msg.from_email || null,
    from_name: msg.from_name || null,
    subject: msg.subject || null,
    recipients,
    body: msg.body || null,
    raw: payload,
  };
  fs.writeFileSync(file, JSON.stringify(record, null, 2) + '\n');
  return { jobId, recipients };
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://${req.headers.host || 'localhost'}`);

  if (req.method === 'GET' && url.pathname === '/health') return json(res, 200, { ok: true });

  if (req.method === 'POST' && url.pathname === '/ru/transactional/api/v1/email/send.json') {
    const chunks = [];
    for await (const c of req) chunks.push(c);
    let payload;
    try {
      payload = JSON.parse(Buffer.concat(chunks).toString('utf8'));
    } catch {
      return apiError(res, 111, 'JSON parsing error');
    }

    const apiKey = req.headers['x-api-key'] || payload.api_key;
    if (!apiKey) return apiError(res, 101, 'API key is missing');

    const msg = payload.message;
    if (!msg || typeof msg !== 'object') return apiError(res, 2000, "Error in 'message' field. Message object required.");
    if (!Array.isArray(msg.recipients) || msg.recipients.length === 0 || !msg.recipients[0].email) {
      return apiError(res, 2001, "Error in 'recipients' field. Recipients required.");
    }
    const body = msg.body || {};
    if (!body.plaintext && !body.html) {
      // зеркалит реальный ответ: 400 code 1577 No message body passed
      return apiError(res, 1577, "Error in 'body' field. No message body passed.");
    }
    if (!msg.from_email) return apiError(res, 2002, "Error in 'from_email' field. Sender required.");

    const { jobId, recipients } = saveMail(payload, apiKey);
    console.log(`✉️  mock email: ${msg.subject || '(no subject)'} -> ${recipients.join(', ')} (${jobId})`);
    return json(res, 200, { status: 'success', job_id: jobId, emails: recipients, tags: [] });
  }

  return json(res, 404, { status: 'error', code: 404, message: 'not found' });
});

server.listen(PORT, '0.0.0.0', () => {
  console.log(`unisender-mock on :${PORT}, mail dir: ${MAIL_DIR}`);
});