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

/*
 * Test Template for Vitest Unit Tests (Utilities, Stores, API Clients)
 * 
 * Copy this file and replace:
 * - {{module}} with the module name
 * - {{capability}} with the capability name
 * 
 * Mark pending tests with test.skip() during Red Phase
 * Remove .skip and implement during Green Phase
 */

describe('{{module}}', () => {
  
  beforeEach(() => {
    // Reset state before each test
    vi.clearAllMocks();
  });
  
  /*
   * Test: Core functionality
   */
  it.skip('{{functionality_description}}', () => {
    // Arrange
    const input = {
      // Test input
    };
    
    const expected = {
      // Expected output
    };
    
    // Act
    const result = {{module}}.{{method}}(input);
    
    // Assert
    expect(result).toEqual(expected);
  });
  
  /*
   * Test: Edge cases
   */
  it.skip('handles {{edge_case}}', () => {
    // Arrange
    const edgeCaseInput = null;
    
    // Act & Assert
    expect(() => {{module}}.{{method}}(edgeCaseInput))
      .toThrow('Invalid input');
  });
  
  /*
   * Test: Async operations
   */
  it.skip('{{async_description}}', async () => {
    // Arrange
    const mockResponse = { data: 'test' };
    global.fetch = vi.fn().mockResolvedValue({
      ok: true,
      json: () => Promise.resolve(mockResponse)
    });
    
    // Act
    const result = await {{module}}.{{async_method}}();
    
    // Assert
    expect(result).toEqual(mockResponse);
    expect(fetch).toHaveBeenCalledWith('/api/{{endpoint}}');
  });
  
  /*
   * Test: Error handling
   */
  it.skip('handles API errors', async () => {
    // Arrange
    global.fetch = vi.fn().mockResolvedValue({
      ok: false,
      status: 500,
      json: () => Promise.resolve({ message: 'Server error' })
    });
    
    // Act & Assert
    await expect({{module}}.{{async_method}}())
      .rejects.toThrow('Server error');
  });
  
  /*
   * Test: Store behavior (if testing Svelte stores)
   */
  it.skip('updates store value', () => {
    // Arrange
    const store = {{module}}.{{store_name}};
    
    // Act
    store.set({ value: 'new value' });
    
    // Assert
    let value;
    store.subscribe(v => { value = v; })();
    expect(value).toEqual({ value: 'new value' });
  });
  
  /*
   * Test: Store derived values
   */
  it.skip('computes derived value correctly', () => {
    // Arrange
    const store = {{module}}.{{store_name}};
    store.set({ items: [1, 2, 3] });
    
    // Act
    let derivedValue;
    {{module}}.{{derived_store}}.subscribe(v => { derivedValue = v; })();
    
    // Assert
    expect(derivedValue).toBe(6); // sum of items
  });
  
  /*
   * Test: Validation logic
   */
  it.skip('validates {{field}} correctly', () => {
    // Valid cases
    expect({{module}}.validate{{field}}('valid')).toBe(true);
    expect({{module}}.validate{{field}}('another-valid')).toBe(true);
    
    // Invalid cases
    expect({{module}}.validate{{field}}('')).toBe(false);
    expect({{module}}.validate{{field}}(null)).toBe(false);
    expect({{module}}.validate{{field}}('invalid!')).toBe(false);
  });
  
  /*
   * Test: Calculation accuracy
   */
  it.skip('calculates {{calculation}} correctly', () => {
    expect({{module}}.calculate(10, 20)).toBe(30);
    expect({{module}}.calculate(0, 0)).toBe(0);
    expect({{module}}.calculate(-5, 5)).toBe(0);
  });
  
  /*
   * Test: Formatting functions
   */
  it.skip('formats {{data_type}} correctly', () => {
    expect({{module}}.format{{data_type}}(1000)).toBe('$1,000.00');
    expect({{module}}.format{{data_type}}(0)).toBe('$0.00');
    expect({{module}}.format{{data_type}}(-500)).toBe('-$500.00');
  });
  
  /*
   * Test: Date/time utilities
   */
  it.skip('parses date correctly', () => {
    const result = {{module}}.parseDate('2024-01-15');
    expect(result).toBeInstanceOf(Date);
    expect(result.getFullYear()).toBe(2024);
    expect(result.getMonth()).toBe(0); // January is 0
    expect(result.getDate()).toBe(15);
  });
  
  it.skip('formats date as YYYY-MM', () => {
    const date = new Date(2024, 0, 15); // January 15, 2024
    expect({{module}}.formatMonth(date)).toBe('2024-01');
  });
  
  /*
   * Test: Local storage operations
   */
  it.skip('saves to localStorage', () => {
    const data = { key: 'value' };
    {{module}}.saveToStorage('test-key', data);
    
    expect(localStorage.setItem).toHaveBeenCalledWith(
      'test-key',
      JSON.stringify(data)
    );
  });
  
  it.skip('loads from localStorage', () => {
    const data = { key: 'value' };
    localStorage.getItem.mockReturnValue(JSON.stringify(data));
    
    const result = {{module}}.loadFromStorage('test-key');
    
    expect(result).toEqual(data);
  });
  
});

/*
 * Data providers for parameterized tests
 */
const testCases = [
  { input: 'case1', expected: 'result1' },
  { input: 'case2', expected: 'result2' },
  { input: 'case3', expected: 'result3' },
];

it.skip('processes multiple cases correctly', () => {
  testCases.forEach(({ input, expected }) => {
    expect({{module}}.process(input)).toBe(expected);
  });
});
