/**
 * Unit Tests for Analytics Client
 * Tests tracking methods, batching, and error handling
 */

import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';

// Mock fetch
const mockFetch = vi.fn();
global.fetch = mockFetch;

import { AnalyticsClient } from './analytics-client';

describe('AnalyticsClient', () => {
  let client: AnalyticsClient;

  beforeEach(() => {
    mockFetch.mockClear();
    mockFetch.mockResolvedValue({ ok: true, json: () => Promise.resolve({}) });
    client = new AnalyticsClient({
      apiBaseUrl: 'https://api.test.com',
      appName: 'test-app',
      batchSize: 10,
      batchInterval: 1000,
    });
  });

  afterEach(() => {
    client.destroy();
    vi.clearAllTimers();
  });

  describe('constructor', () => {
    it('should create client with required options', () => {
      const testClient = new AnalyticsClient({
        apiBaseUrl: 'https://api.test.com',
        appName: 'test',
      });
      expect(testClient).toBeDefined();
      testClient.destroy();
    });

    it('should accept custom batch options', () => {
      const customClient = new AnalyticsClient({
        apiBaseUrl: 'https://custom.api.com',
        appName: 'custom-app',
        batchSize: 50,
        batchInterval: 5000,
      });
      expect(customClient).toBeDefined();
      customClient.destroy();
    });
  });

  describe('trackView', () => {
    it('should track view event with path', () => {
      client.trackView({ path: '/dashboard', userId: 'user-123' });
      expect(client).toBeDefined();
    });

    it('should track view with all optional fields', () => {
      client.trackView({
        path: '/analytics/revenue',
        userId: 'user-456',
        referrer: 'https://google.com',
      });
      expect(client).toBeDefined();
    });
  });

  describe('trackEngagement', () => {
    it('should track engagement event', () => {
      client.trackEngagement({
        type: 'click',
        target: 'submit-button',
      });
      expect(client).toBeDefined();
    });

    it('should track engagement with metadata', () => {
      client.trackEngagement({
        type: 'like',
        target: 'post-123',
        metadata: { source: 'feed' },
      });
      expect(client).toBeDefined();
    });
  });

  describe('flush', () => {
    it('should send batched events', async () => {
      client.trackView({ path: '/test', userId: 'test-user' });
      await client.flush();
      expect(mockFetch).toHaveBeenCalled();
    });

    it('should handle flush errors gracefully', async () => {
      mockFetch.mockRejectedValueOnce(new Error('Network error'));
      client.trackView({ path: '/test', userId: 'test-user' });
      // Should not throw
      await expect(client.flush()).resolves.not.toThrow();
    });
  });

  describe('destroy', () => {
    it('should clean up resources', () => {
      const testClient = new AnalyticsClient({
        apiBaseUrl: 'https://api.test.com',
        appName: 'test',
      });
      expect(() => testClient.destroy()).not.toThrow();
    });
  });
});

describe('AnalyticsClient Session', () => {
  it('should generate session ID', () => {
    const client = new AnalyticsClient({
      apiBaseUrl: 'https://api.test.com',
      appName: 'test',
    });
    expect(client).toBeDefined();
    client.destroy();
  });
});