import { beforeEach, describe, expect, it, vi } from 'vitest';
import { ImapFlow } from 'imapflow';
import { ImapProvider } from './imap.provider';
import type { InboxConfig } from './inbox.types';

/**
 * ImapProvider.fetchMessages spec (Plan 14-01, Task 2, TDD).
 *
 * Net-new coverage for the additive fetchMessages() method (D-02) — the seam
 * the Plan 14-03 EmailAlertAdapter consumes. fetchPdfAttachments is NOT
 * touched or retested here (regression coverage lives in the DKV suite).
 *
 * ImapFlow is mocked entirely — no real IMAP connection. Mirrors the mock
 * style used in tender-mail.service.spec.ts (module-level vi.mock +
 * mockImplementation returning a stub client).
 */

vi.mock('imapflow', () => ({
  ImapFlow: vi.fn(),
}));

function makeReadable(text: string): NodeJS.ReadableStream {
  const { Readable } = require('node:stream') as typeof import('stream');
  return Readable.from([Buffer.from(text, 'utf8')]);
}

const BASE_CONFIG: InboxConfig = {
  protocol: 'imap',
  host: 'imap.example.com',
  port: 993,
  username: 'alerts@example.com',
  password: 'secret',
  encryption: 'ssl-tls',
  folder: 'INBOX',
};

/** Body structure with a text/html part (id '1') and a text/plain part (id '2'). */
const MULTIPART_BODY_STRUCTURE = {
  type: 'multipart/alternative',
  childNodes: [
    { type: 'text/plain', part: '2' },
    { type: 'text/html', part: '1' },
  ],
};

function makeMockClient(overrides: Partial<Record<string, unknown>> = {}) {
  return {
    connect: vi.fn().mockResolvedValue(undefined),
    logout: vi.fn().mockResolvedValue(undefined),
    getMailboxLock: vi.fn().mockResolvedValue({ release: vi.fn() }),
    search: vi.fn().mockResolvedValue([42]),
    fetchAll: vi.fn().mockResolvedValue([
      {
        uid: 42,
        envelope: {
          messageId: '<msg-42@example.com>',
          subject: 'Neue Ausschreibung verfügbar',
          from: [{ address: 'noreply@vergabeportal.de' }],
          date: new Date('2026-07-20T08:00:00Z'),
        },
        bodyStructure: MULTIPART_BODY_STRUCTURE,
      },
    ]),
    download: vi.fn(async (_uid: string, partId: string) => {
      if (partId === '1') {
        return { content: makeReadable('<p>Hallo <b>Welt</b></p>') };
      }
      return { content: makeReadable('Hallo Welt (Text)') };
    }),
    messageFlagsAdd: vi.fn().mockResolvedValue(undefined),
    ...overrides,
  };
}

/**
 * Haengt ein Testdoppel als ImapFlow-Klient ein.
 *
 * Der Modul-Mock oben ersetzt den Konstruktor durch `vi.fn()`; diese Funktion
 * ist die einzige Stelle im Test, die das ausnutzt. Vorher stand dieselbe
 * Umdeutung in jedem einzelnen Fall.
 */
function useMockClient(client: ReturnType<typeof makeMockClient>): void {
  (ImapFlow as unknown as ReturnType<typeof vi.fn>).mockImplementation(() => client);
}

beforeEach(() => {
  vi.clearAllMocks();
});

describe('ImapProvider.fetchMessages', () => {
  it('returns one InboxMessage with bodyHtml from the html part and bodyText from the plain part', async () => {
    const client = makeMockClient();
    useMockClient(client);
    const provider = new ImapProvider();

    const messages = await provider.fetchMessages(BASE_CONFIG);

    expect(messages).toHaveLength(1);
    expect(messages[0]).toMatchObject({
      uid: 42,
      messageId: '<msg-42@example.com>',
      subject: 'Neue Ausschreibung verfügbar',
      from: 'noreply@vergabeportal.de',
      bodyHtml: '<p>Hallo <b>Welt</b></p>',
      bodyText: 'Hallo Welt (Text)',
    });
  });

  it('marks each processed message \\Seen (idempotency for re-polls)', async () => {
    const client = makeMockClient();
    useMockClient(client);
    const provider = new ImapProvider();

    await provider.fetchMessages(BASE_CONFIG);

    expect(client.messageFlagsAdd).toHaveBeenCalledWith('42', ['\\Seen'], { uid: true });
  });

  it('honors the same UNSEEN + optional senderFilter search as fetchPdfAttachments', async () => {
    const client = makeMockClient();
    useMockClient(client);
    const provider = new ImapProvider();

    await provider.fetchMessages({ ...BASE_CONFIG, senderFilter: 'vergabeportal.de' });

    expect(client.search).toHaveBeenCalledWith(
      { seen: false, from: 'vergabeportal.de' },
      { uid: true },
    );
  });

  it('returns [] on connect error without throwing', async () => {
    const client = makeMockClient({
      connect: vi.fn().mockRejectedValue(new Error('ECONNREFUSED')),
    });
    useMockClient(client);
    const provider = new ImapProvider();

    await expect(provider.fetchMessages(BASE_CONFIG)).resolves.toEqual([]);
  });

  it('returns [] on search error without throwing', async () => {
    const client = makeMockClient({
      search: vi.fn().mockRejectedValue(new Error('search boom')),
    });
    useMockClient(client);
    const provider = new ImapProvider();

    await expect(provider.fetchMessages(BASE_CONFIG)).resolves.toEqual([]);
    expect(client.logout).toHaveBeenCalled();
  });

  it('returns [] when there are no unread messages', async () => {
    const client = makeMockClient({ search: vi.fn().mockResolvedValue([]) });
    useMockClient(client);
    const provider = new ImapProvider();

    const messages = await provider.fetchMessages(BASE_CONFIG);

    expect(messages).toEqual([]);
  });

  it('sets bodyHtml null and bodyText empty when the message has neither part', async () => {
    const client = makeMockClient({
      fetchAll: vi.fn().mockResolvedValue([
        {
          uid: 7,
          envelope: {
            messageId: '<msg-7@example.com>',
            subject: 'Nur Betreff',
            from: [{ address: 'a@b.de' }],
            date: new Date('2026-07-20T08:00:00Z'),
          },
          bodyStructure: { type: 'text/x-unknown' },
        },
      ]),
    });
    useMockClient(client);
    const provider = new ImapProvider();

    const messages = await provider.fetchMessages(BASE_CONFIG);

    expect(messages).toHaveLength(1);
    expect(messages[0]!.bodyHtml).toBeNull();
    expect(messages[0]!.bodyText).toBe('');
  });
});

/**
 * Befund B-06 (gemeldet in 260921-m34): buildClient() uebergab `requireTLS`,
 * eine Option, die imapflow 1.4.3 gar nicht kennt — weder in `ImapFlowOptions`
 * (lib/imap-flow.d.ts) noch im Laufzeitcode (lib/imap-flow.js). Sie wurde still
 * verworfen, ein STARTTLS-Zwang entstand durch sie nie. Die richtige Option
 * heisst `doSTARTTLS` (imap-flow.d.ts:81).
 *
 * Geprueft wird hier ausschliesslich, was an `new ImapFlow(...)` uebergeben
 * wird — keine echte Verbindung.
 */
describe('ImapProvider — Transportverschluesselung (B-06)', () => {
  /** Optionen des zuletzt erzeugten ImapFlow-Klienten. */
  function lastClientOptions() {
    const calls = vi.mocked(ImapFlow).mock.calls;
    return calls[calls.length - 1]?.[0];
  }

  it('erzwingt STARTTLS, wenn die Verschluesselung auf starttls steht', async () => {
    const client = makeMockClient();
    useMockClient(client);
    const provider = new ImapProvider();

    await provider.testConnection({ ...BASE_CONFIG, port: 143, encryption: 'starttls' });

    const options = lastClientOptions();
    expect(options?.secure).toBe(false);
    expect(options?.doSTARTTLS).toBe(true);
    expect(options).not.toHaveProperty('requireTLS');
  });

  it('setzt doSTARTTLS nicht auf true, wenn die Verschluesselung auf ssl-tls steht', async () => {
    const client = makeMockClient();
    useMockClient(client);
    const provider = new ImapProvider();

    await provider.testConnection({ ...BASE_CONFIG, encryption: 'ssl-tls' });

    const options = lastClientOptions();
    // imapflow wirft bei secure=true zusammen mit doSTARTTLS=true
    // ("Misconfiguration", imap-flow.js:1201) — diese Kombination darf nie entstehen.
    expect(options?.secure).toBe(true);
    expect(options?.doSTARTTLS).not.toBe(true);
    expect(options).not.toHaveProperty('requireTLS');
  });
});

/**
 * Befund B-05 (gemeldet in 260921-m34): der Dateiname aus Content-Disposition
 * wurde als `disposition.parameters.filename` gelesen. imapflow deklariert
 * `disposition` aber als Zeichenkette (imap-flow.d.ts:448) und legt die
 * Parameter in ein eigenes Feld `dispositionParameters` (:450, gefuellt in
 * tools.js:887 mit kleingeschriebenen Schluesseln). Der alte Ausdruck war zur
 * Laufzeit immer undefined — Anhaenge, die als application/octet-stream
 * ankommen (typisch fuer Outlook), wurden darueber nie erkannt.
 */
describe('ImapProvider.fetchPdfAttachments — Dateiname aus Content-Disposition (B-05)', () => {
  function makeAttachmentClient(bodyStructure: unknown) {
    return makeMockClient({
      search: vi.fn().mockResolvedValue([7]),
      fetchAll: vi.fn().mockResolvedValue([
        {
          uid: 7,
          envelope: {
            messageId: '<msg-7@example.com>',
            subject: 'Rechnung',
            from: [{ address: 'rechnung@dkv.de' }],
            date: new Date('2026-07-20T08:00:00Z'),
          },
          bodyStructure,
        },
      ]),
      download: vi.fn(async () => ({ content: makeReadable('%PDF-1.4 inhalt') })),
    });
  }

  it('erkennt einen application/octet-stream-Anhang am Dateinamen aus dispositionParameters', async () => {
    const client = makeAttachmentClient({
      type: 'multipart/mixed',
      childNodes: [
        { type: 'text/plain', part: '1' },
        {
          type: 'application/octet-stream',
          part: '2',
          disposition: 'attachment',
          dispositionParameters: { filename: 'Rechnung-4711.PDF' },
        },
      ],
    });
    useMockClient(client);
    const provider = new ImapProvider();

    const emails = await provider.fetchPdfAttachments(BASE_CONFIG);

    expect(emails).toHaveLength(1);
    expect(emails[0]?.attachments ?? []).toHaveLength(1);
    expect(emails[0]?.attachments?.[0]?.contentType).toBe('application/pdf');
  });

  it('erkennt einen application/octet-stream-Anhang weiterhin am Namen aus Content-Type', async () => {
    const client = makeAttachmentClient({
      type: 'application/octet-stream',
      part: '1',
      parameters: { name: 'Rechnung-4711.pdf' },
    });
    useMockClient(client);
    const provider = new ImapProvider();

    const emails = await provider.fetchPdfAttachments(BASE_CONFIG);

    expect(emails).toHaveLength(1);
    expect(emails[0]?.attachments ?? []).toHaveLength(1);
  });

  it('sammelt einen application/octet-stream-Anhang ohne .pdf-Dateinamen nicht ein', async () => {
    const client = makeAttachmentClient({
      type: 'application/octet-stream',
      part: '1',
      disposition: 'attachment',
      dispositionParameters: { filename: 'Lieferschein.docx' },
    });
    useMockClient(client);
    const provider = new ImapProvider();

    const emails = await provider.fetchPdfAttachments(BASE_CONFIG);

    expect(emails).toEqual([]);
  });
});