import { describe, it, expect, beforeEach, vi } from 'vitest';
import { renderHook, act, waitFor } from '@testing-library/react';
import { useQuantityAdjustment } from '@/hooks/useQuantityAdjustment';
import axios from 'axios';

// Mock axios
vi.mock('axios');
const mockedAxios = axios as any;

describe('Quick Quantity Adjustment - useQuantityAdjustment Hook', () => {
  beforeEach(() => {
    vi.clearAllMocks();
    mockedAxios.patch.mockClear();
  });

  it('initializes with correct quantity', () => {
    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    expect(result.current.quantity).toBe(10);
    expect(result.current.isLoading).toBe(false);
    expect(result.current.error).toBeNull();
  });

  it('updates quantity optimistically and confirms with API', async () => {
    mockedAxios.patch.mockResolvedValueOnce({
      data: { quantity: 15 },
    });

    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      await result.current.adjustQuantity(15);
    });

    expect(result.current.quantity).toBe(15);
    expect(result.current.error).toBeNull();
    expect(mockedAxios.patch).toHaveBeenCalledWith(
      expect.stringContaining('/items/1'),
      { quantity: 15 }
    );
  });

  it('reverts quantity on API failure', async () => {
    const error = new Error('Network error');
    mockedAxios.patch.mockRejectedValueOnce(error);

    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      try {
        await result.current.adjustQuantity(15);
      } catch {
        // Expected to throw
      }
    });

    await waitFor(() => {
      expect(result.current.quantity).toBe(10);
      expect(result.current.error).toBeTruthy();
    });
  });

  it('validates quantity >= 0', async () => {
    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      await result.current.adjustQuantity(-5);
    });

    expect(result.current.error).toContain('non-negative');
    expect(mockedAxios.patch).not.toHaveBeenCalled();
  });

  it('validates integer quantities', async () => {
    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      await result.current.adjustQuantity(10.5);
    });

    expect(result.current.error).toContain('integer');
    expect(mockedAxios.patch).not.toHaveBeenCalled();
  });

  it('resets error on resetError call', async () => {
    const error = new Error('Network error');
    mockedAxios.patch.mockRejectedValueOnce(error);

    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      try {
        await result.current.adjustQuantity(15);
      } catch {
        // Expected to throw
      }
    });

    expect(result.current.error).toBeTruthy();

    act(() => {
      result.current.resetError();
    });

    expect(result.current.error).toBeNull();
  });

  it('debounces rapid successive calls', async () => {
    mockedAxios.patch.mockResolvedValue({
      data: { quantity: 15 },
    });

    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      // Queue multiple rapid adjustments
      const promises = [
        result.current.adjustQuantity(12),
        result.current.adjustQuantity(14),
        result.current.adjustQuantity(15),
      ];

      await Promise.all(promises);
    });

    // With debouncing, only the last call should fully process
    // (The implementation uses 100ms debounce)
    await waitFor(() => {
      expect(mockedAxios.patch).toHaveBeenCalled();
    });
  });

  it('handles API error responses gracefully', async () => {
    mockedAxios.patch.mockRejectedValueOnce({
      response: {
        data: {
          detail: 'Quantity exceeds available stock',
        },
      },
    });

    const { result } = renderHook(() =>
      useQuantityAdjustment('1', 10)
    );

    await act(async () => {
      try {
        await result.current.adjustQuantity(999);
      } catch {
        // Expected
      }
    });

    await waitFor(() => {
      expect(result.current.error).toBeTruthy();
      expect(result.current.quantity).toBe(10); // Reverted
    });
  });
});

describe('Quick Quantity Adjustment - Component Integration', () => {
  it('should support UI workflow: tap → +/- → commit', async () => {
    // This is a placeholder for E2E/integration test that would:
    // 1. Render QuantityDisplay
    // 2. Click on quantity to enter edit mode
    // 3. Click +/- buttons to adjust
    // 4. Press Enter to commit
    // 5. Verify API call with correct delta
    // Implementation requires React Testing Library setup with actual component rendering

    expect(true).toBe(true); // Placeholder assertion
  });

  it('should show loading state during API call', async () => {
    // Placeholder for component loading state test
    expect(true).toBe(true);
  });

  it('should show error toast on API failure', async () => {
    // Placeholder for error handling test
    expect(true).toBe(true);
  });

  it('should cancel edit on Escape key without API call', async () => {
    // Placeholder for cancel behavior test
    expect(true).toBe(true);
  });
});