import { afterEach, describe, expect, it, vi } from 'vitest';
import { clearTranslationMemory, isTranslationPairSupported, translateText } from './translation';

class FakeWorker {
  onmessage: ((event: MessageEvent) => void) | null = null;
  onerror: (() => void) | null = null;

  postMessage(request: { id: number; text: string }) {
    queueMicrotask(() => {
      this.onmessage?.({
        data: { type: 'result', id: request.id, text: `translated:${request.text}` },
      } as MessageEvent);
    });
  }

  terminate() {}
}

describe('translateText', () => {
  afterEach(() => {
    vi.unstubAllGlobals();
    clearTranslationMemory();
  });

  it('keeps the message local and never calls fetch', async () => {
    const fetchSpy = vi.fn();
    const received: string[] = [];

    class RecordingWorker extends FakeWorker {
      postMessage(request: { id: number; text: string }) {
        received.push(request.text);
        super.postMessage(request);
      }
    }

    vi.stubGlobal('fetch', fetchSpy);
    vi.stubGlobal('Worker', RecordingWorker);
    clearTranslationMemory();

    const result = await translateText({
      id: 'message-1',
      text: 'SENTINEL-MESSAGE-TEXT',
      source: 'en',
      target: 'es',
    });

    expect(result).toBe('translated:SENTINEL-MESSAGE-TEXT');
    expect(received).toEqual(['SENTINEL-MESSAGE-TEXT']);
    expect(fetchSpy).not.toHaveBeenCalled();
  });

  it('returns the input when source and target match', async () => {
    const result = await translateText({
      id: 'message-2',
      text: 'same language',
      source: 'en',
      target: 'en',
    });
    expect(result).toBe('same language');
  });

  it('supports all app language pairs (M2M100 + Basque Opus)', () => {
    expect(isTranslationPairSupported('ca', 'en')).toBe(true);
    expect(isTranslationPairSupported('eu', 'en')).toBe(true);
    expect(isTranslationPairSupported('hi', 'es')).toBe(true);
    expect(isTranslationPairSupported('en', 'en')).toBe(false);
  });
});