const test = require('node:test');
const assert = require('node:assert/strict');
const { sendPriceChangeEmail, formatPrice, createTransport } = require('../src/mailer');

test('formatPrice formats with comma decimal separator', () => {
  assert.equal(formatPrice(19.9), '19,90');
  assert.equal(formatPrice(24.5), '24,50');
});

test('sendPriceChangeEmail sends mail with expected fields', async () => {
  const calls = [];
  const fakeTransport = { sendMail: async (opts) => { calls.push(opts); } };
  await sendPriceChangeEmail(fakeTransport, {
    from: 'korting@sjoerd.app',
    to: 'me@example.com',
    name: 'Voorbeeld product',
    url: 'https://shop.example/product',
    oldPrice: 19.99,
    newPrice: 17.5,
  });
  assert.equal(calls.length, 1);
  assert.equal(calls[0].from, 'korting@sjoerd.app');
  assert.equal(calls[0].to, 'me@example.com');
  assert.equal(calls[0].subject, 'Prijs gewijzigd: Voorbeeld product');
  assert.match(calls[0].text, /19,99/);
  assert.match(calls[0].text, /17,50/);
  assert.match(calls[0].text, /https:\/\/shop\.example\/product/);
});

test('sendPriceChangeEmail propagates transport errors', async () => {
  const fakeTransport = { sendMail: async () => { throw new Error('smtp down'); } };
  await assert.rejects(
    () => sendPriceChangeEmail(fakeTransport, {
      from: 'a@b.com', to: 'c@d.com', name: 'X', url: 'https://x', oldPrice: 1, newPrice: 2,
    }),
    /smtp down/
  );
});

test('createTransport builds a transport from env vars', () => {
  const transport = createTransport({ SMTP_HOST: 'mail.sjoerd.app', SMTP_PORT: '587', SMTP_USER: 'u', SMTP_PASS: 'p' });
  assert.equal(typeof transport.sendMail, 'function');
});