API de correo temporal en Node.js: leer un buzón con fetch

// grabmail.ts — a disposable inbox from Node 18+, Deno or Bun. No dependency, no key.
const API = 'https://grabmail.io/api/v1';
const DOMAIN = 'grabmail.io';

export type Summary = {
  id: string; from: string; subject: string; date: string;
  seen: boolean; attachments: number; expires_at: string;
};
export type Attachment = { filename: string; mime: string; size: number; url: string };
export type Message = {
  id: string; from: string; to: string; subject: string; date: string;
  text: string | null; html: string | null; attachments: Attachment[];
};
type Listing = { address: string; alias: string | null; count: number; next: string | null; messages: Summary[] };
type WaitOpts = { timeoutMs?: number; subjectContains?: string; fromContains?: string };

const sleep = (ms: number) => new Promise<void>(r => setTimeout(r, ms));

/** A mailbox nothing else is using. Nothing has to be created first. */
export function freshAddress(prefix = 'node'): string {
  return `${prefix}-${crypto.randomUUID().slice(0, 8)}@${DOMAIN}`;
}

/** One GET, with the only retry that is ever right: waiting out a 429. */
async function get(url: string): Promise<Response> {
  for (;;) {
    const res = await fetch(url);
    if (res.status === 429) {
      await sleep(Number(res.headers.get('retry-after') ?? 1) * 1000);
      continue;
    }
    if (!res.ok) throw new Error(`${url} answered ${res.status}`);
    return res;
  }
}

export class Inbox {
  constructor(readonly address: string = freshAddress()) {}

  async list(limit = 50, before?: string): Promise<Listing> {
    const q = new URLSearchParams({ address: this.address, limit: String(limit) });
    if (before) q.set('before', before);
    return (await get(`${API}/mailbox?${q}`)).json();
  }

  /** Block until a matching message arrives, then return it in full. */
  async waitFor(opts: WaitOpts = {}): Promise<Message> {
    const deadline = Date.now() + (opts.timeoutMs ?? 60_000);
    while (Date.now() < deadline) {
      const { messages } = await this.list();
      const hit = messages.find(m =>
        (!opts.subjectContains || m.subject.toLowerCase().includes(opts.subjectContains.toLowerCase())) &&
        (!opts.fromContains    || m.from.toLowerCase().includes(opts.fromContains.toLowerCase())));
      if (hit) return this.read(hit.id);
      await sleep(1000);                              // one read a second, never throttled
    }
    throw new Error(`no message for ${this.address} within the deadline`);
  }

  async read(id: string): Promise<Message> {
    return (await get(`${API}/message/${id}?mailbox=${encodeURIComponent(this.address)}`)).json();
  }

  /** Optional and idempotent: everything expires on its own. */
  async delete(id: string): Promise<void> {
    await fetch(`${API}/message/${id}?mailbox=${encodeURIComponent(this.address)}`, { method: 'DELETE' });
  }

  /** The bytes of one attachment. Its URL already carries ?mailbox=. */
  async download(a: Attachment): Promise<Response> {
    return get(`https://grabmail.io${a.url}`);
  }
}

import { Inbox } from './grabmail';

const inbox = new Inbox();
console.log('sign up with:', inbox.address);

const message = await inbox.waitFor({ subjectContains: 'code' });
console.log(message.subject);
console.log(message.text);      // the plain-text part; message.html is the HTML part or null

// grabmail.mjs — plain JavaScript, Node 18+: the same class without the types.
const API = 'https://grabmail.io/api/v1';
const sleep = ms => new Promise(r => setTimeout(r, ms));

export const freshAddress = (prefix = 'node') => `${prefix}-${crypto.randomUUID().slice(0, 8)}@grabmail.io`;

export async function waitFor(address, { timeoutMs = 60_000, subjectContains } = {}) {
  const deadline = Date.now() + timeoutMs;
  while (Date.now() < deadline) {
    const res = await fetch(`${API}/mailbox?address=${encodeURIComponent(address)}`);
    if (res.status === 429) { await sleep(Number(res.headers.get('retry-after') ?? 1) * 1000); continue; }
    if (!res.ok) throw new Error(`GET /mailbox answered ${res.status}`);
    const { messages } = await res.json();
    const hit = messages.find(m => !subjectContains || m.subject.toLowerCase().includes(subjectContains.toLowerCase()));
    if (hit) return (await fetch(`${API}/message/${hit.id}?mailbox=${encodeURIComponent(address)}`)).json();
    await sleep(1000);
  }
  throw new Error(`no message for ${address} within ${timeoutMs} ms`);
}

/** Every summary in the mailbox, newest first, however many pages it takes. */
export async function* allMessages(inbox: Inbox): AsyncGenerator<Summary> {
  let before: string | undefined;
  for (;;) {
    const page = await inbox.list(200, before);
    yield* page.messages;
    if (!page.next) return;
    before = page.next;
  }
}

for await (const m of allMessages(inbox)) {
  console.log(m.date, m.from, m.subject, 'expires', m.expires_at);
}

import { createWriteStream } from 'node:fs';
import { mkdir } from 'node:fs/promises';
import { Readable } from 'node:stream';
import { pipeline } from 'node:stream/promises';

const message = await inbox.waitFor({ subjectContains: 'invoice' });
await mkdir(`downloads/${message.id}`, { recursive: true });

for (const a of message.attachments) {
  console.log(a.filename, a.mime, a.size, 'bytes');
  const res = await inbox.download(a);
  await pipeline(Readable.fromWeb(res.body as any), createWriteStream(`downloads/${message.id}/${a.filename}`));
}

import { describe, it, expect } from 'vitest';
import { Inbox } from '../src/grabmail';
import { app } from '../src/app';               // whatever starts your server in-process

const CODE = /code is\D{0,12}(\d{6})/i;            // anchored on YOUR template's wording

describe('sign-up', () => {
  it('emails a code that confirms the account', async () => {
    const inbox = new Inbox();                     // a brand-new mailbox for this test only

    await app.request('/signup', { method: 'POST', body: JSON.stringify({ email: inbox.address, password: 'hunter2hunter2' }) });

    const message = await inbox.waitFor({ subjectContains: 'confirm' });
    const code = `${message.text ?? ''} ${message.html ?? ''}`.match(CODE)?.[1];
    expect(code).toBeDefined();

    const res = await app.request('/confirm', { method: 'POST', body: JSON.stringify({ email: inbox.address, code }) });
    expect(res.status).toBe(200);
  }, 120_000);                                     // above the 60 s mail deadline
});