import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
import { AnalyticsClient } from './analytics-client';

describe('AnalyticsClient', () => {
  let fetchMock: ReturnType<typeof vi.fn>;

  beforeEach(() => {
    fetchMock = vi.fn().mockResolvedValue({
      ok: true,
      json: async () => ({ success: true }),
    });
    global.fetch = fetchMock;
    localStorage.clear();
    vi.useFakeTimers();
  });

  afterEach(() => {
    vi.restoreAllMocks();
    vi.useRealTimers();
  });

  it('should create a client with default config', () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
    });

    expect(client).toBeDefined();
    client.destroy();
  });

  it('should track view events', async () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
      batchSize: 1,
    });

    client.trackView({
      contentId: 'post-123',
      contentType: 'post',
    });

    await Promise.resolve();

    expect(fetchMock).toHaveBeenCalledWith(
      'http://localhost:4000/analytics/track/view',
      expect.objectContaining({
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: expect.stringContaining('post-123'),
      }),
    );

    client.destroy();
  });

  it('should track engagement events', async () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
      batchSize: 1,
    });

    client.trackEngagement({
      userId: 'user-123',
      metricType: 'like',
      targetId: 'post-456',
      targetType: 'content',
    });

    await Promise.resolve();

    expect(fetchMock).toHaveBeenCalledWith(
      'http://localhost:4000/analytics/track/engagement',
      expect.objectContaining({
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: expect.stringContaining('user-123'),
        credentials: 'include',
      }),
    );

    client.destroy();
  });

  it('should batch multiple events', async () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
      batchSize: 1,
    });

    client.trackView({ contentId: '1', contentType: 'post' });
    client.trackView({ contentId: '2', contentType: 'post' });
    client.trackView({ contentId: '3', contentType: 'post' });

    await Promise.resolve();

    expect(fetchMock).toHaveBeenCalledTimes(3);

    client.destroy();
  });

  it('should generate and store session ID', () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
    });

    const sessionId = localStorage.getItem('analytics_session_id');
    expect(sessionId).toBeTruthy();
    expect(typeof sessionId).toBe('string');

    client.destroy();
  });

  it('should flush on destroy', async () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'http://localhost:4000',
      appName: 'test-app',
      batchSize: 10,
    });

    client.trackView({ contentId: '1', contentType: 'post' });
    client.destroy();

    await Promise.resolve();

    expect(fetchMock).toHaveBeenCalled();
  });

  describe('trackInteraction', () => {
    it('should track click interaction events', async () => {
      const client = new AnalyticsClient({
        apiBaseUrl: 'http://localhost:4000',
        appName: 'test-app',
        batchSize: 1,
      });

      client.trackInteraction({
        type: 'click',
        data: {
          elementId: 'signup-btn',
          elementText: 'Sign Up',
          elementType: 'button',
          pageUrl: 'http://localhost:3000/',
          eventName: 'signup_cta',
        },
      });

      // Wait for flush interval
      vi.advanceTimersByTime(5000);
      await Promise.resolve();

      expect(fetchMock).toHaveBeenCalledWith(
        'http://localhost:4000/analytics/track/interaction',
        expect.objectContaining({
          method: 'POST',
          body: expect.stringContaining('signup-btn'),
        }),
      );

      client.destroy();
    });

    it('should track scroll interaction events', async () => {
      const client = new AnalyticsClient({
        apiBaseUrl: 'http://localhost:4000',
        appName: 'test-app',
        batchSize: 1,
      });

      client.trackInteraction({
        type: 'scroll',
        data: {
          pageUrl: 'http://localhost:3000/',
          depth: 50,
          timeToReachMs: 2500,
          isBeyondFold: true,
        },
      });

      vi.advanceTimersByTime(5000);
      await Promise.resolve();

      expect(fetchMock).toHaveBeenCalledWith(
        'http://localhost:4000/analytics/track/interaction',
        expect.objectContaining({
          method: 'POST',
          body: expect.stringContaining('"depth":50'),
        }),
      );

      client.destroy();
    });

    it('should track funnel step events', async () => {
      const client = new AnalyticsClient({
        apiBaseUrl: 'http://localhost:4000',
        appName: 'test-app',
        batchSize: 1,
      });

      client.trackInteraction({
        type: 'funnel_step',
        data: {
          funnelId: 'signup',
          stepId: 'email',
          stepNumber: 1,
          action: 'enter',
        },
      });

      vi.advanceTimersByTime(5000);
      await Promise.resolve();

      expect(fetchMock).toHaveBeenCalledWith(
        'http://localhost:4000/analytics/track/interaction',
        expect.objectContaining({
          method: 'POST',
          body: expect.stringContaining('funnel_step'),
        }),
      );

      client.destroy();
    });

    it('should batch multiple interaction events', async () => {
      const client = new AnalyticsClient({
        apiBaseUrl: 'http://localhost:4000',
        appName: 'test-app',
        batchSize: 3,
      });

      // Queue 3 events
      client.trackInteraction({
        type: 'click',
        data: { elementType: 'button', pageUrl: '/' },
      });
      client.trackInteraction({
        type: 'scroll',
        data: { pageUrl: '/', depth: 25, timeToReachMs: 1000, isBeyondFold: false },
      });
      client.trackInteraction({
        type: 'scroll',
        data: { pageUrl: '/', depth: 50, timeToReachMs: 2000, isBeyondFold: true },
      });

      // Should auto-flush at batchSize
      await Promise.resolve();

      expect(fetchMock).toHaveBeenCalledWith(
        'http://localhost:4000/analytics/track/interaction',
        expect.objectContaining({
          method: 'POST',
        }),
      );

      client.destroy();
    });

    it('should include sessionId in interaction events', async () => {
      const client = new AnalyticsClient({
        apiBaseUrl: 'http://localhost:4000',
        appName: 'test-app',
        batchSize: 1,
      });

      client.trackInteraction({
        type: 'click',
        data: { elementType: 'button', pageUrl: '/' },
      });

      vi.advanceTimersByTime(5000);
      await Promise.resolve();

      const body = fetchMock.mock.calls.find(
        (call) => call[0].includes('/track/interaction'),
      )?.[1]?.body;

      expect(body).toContain('sessionId');

      client.destroy();
    });
  });
});