/**
 * Test Generation Tool Tests
 *
 * Tests for the aqe/generate-tests MCP tool that provides
 * AI-powered test generation across different paradigms.
 */

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

// ============================================================================
// Mock Types
// ============================================================================

interface GenerateTestsInput {
  targetPath: string;
  testType?: 'unit' | 'integration' | 'e2e' | 'property' | 'mutation';
  framework?: 'vitest' | 'jest' | 'mocha' | 'pytest';
  coverage?: {
    target?: number;
    focusGaps?: boolean;
    excludePatterns?: string[];
  };
  style?: 'london' | 'chicago';
  options?: {
    includeEdgeCases?: boolean;
    includeMocks?: boolean;
    includeFixtures?: boolean;
    maxTestsPerFunction?: number;
  };
}

interface GenerateTestsOutput {
  success: boolean;
  tests: GeneratedTest[];
  summary: {
    totalTests: number;
    targetCoverage: number;
    estimatedCoverage: number;
    testTypes: Record<string, number>;
  };
  errors?: string[];
}

interface GeneratedTest {
  name: string;
  description: string;
  code: string;
  type: string;
  targetFunction?: string;
  assertions: number;
}

// ============================================================================
// Mock Implementation
// ============================================================================

class MockGenerateTestsTool {
  private config: {
    defaultFramework: string;
    defaultStyle: string;
    maxTestsPerFunction: number;
  };

  constructor(config: Partial<typeof MockGenerateTestsTool.prototype.config> = {}) {
    this.config = {
      defaultFramework: 'vitest',
      defaultStyle: 'london',
      maxTestsPerFunction: 5,
      ...config,
    };
  }

  async execute(input: GenerateTestsInput): Promise<GenerateTestsOutput> {
    // Validate input
    const errors = this.validateInput(input);
    if (errors.length > 0) {
      return {
        success: false,
        tests: [],
        summary: {
          totalTests: 0,
          targetCoverage: 0,
          estimatedCoverage: 0,
          testTypes: {},
        },
        errors,
      };
    }

    // Generate mock tests based on input
    const tests = this.generateTests(input);

    return {
      success: true,
      tests,
      summary: {
        totalTests: tests.length,
        targetCoverage: input.coverage?.target ?? 80,
        estimatedCoverage: Math.min(tests.length * 15, 95),
        testTypes: this.countTestTypes(tests),
      },
    };
  }

  private validateInput(input: GenerateTestsInput): string[] {
    const errors: string[] = [];

    if (!input.targetPath) {
      errors.push('targetPath is required');
    }

    if (input.targetPath && !input.targetPath.match(/\.(ts|js|tsx|jsx|py)$/)) {
      errors.push('targetPath must be a source file (.ts, .js, .tsx, .jsx, .py)');
    }

    if (input.coverage?.target && (input.coverage.target < 0 || input.coverage.target > 100)) {
      errors.push('coverage.target must be between 0 and 100');
    }

    if (input.options?.maxTestsPerFunction !== undefined && input.options.maxTestsPerFunction < 1) {
      errors.push('options.maxTestsPerFunction must be at least 1');
    }

    return errors;
  }

  private generateTests(input: GenerateTestsInput): GeneratedTest[] {
    const tests: GeneratedTest[] = [];
    const framework = input.framework ?? this.config.defaultFramework;
    const testType = input.testType ?? 'unit';
    const maxTests = input.options?.maxTestsPerFunction ?? this.config.maxTestsPerFunction;

    // Generate mock tests based on type
    const baseTestCount = Math.min(maxTests, 3);

    for (let i = 0; i < baseTestCount; i++) {
      tests.push({
        name: `should handle case ${i + 1}`,
        description: `Test case ${i + 1} for ${input.targetPath}`,
        code: this.generateTestCode(framework, testType, i),
        type: testType,
        targetFunction: `function${i + 1}`,
        assertions: i + 1,
      });
    }

    // Add edge case tests if requested
    if (input.options?.includeEdgeCases) {
      tests.push({
        name: 'should handle empty input',
        description: 'Edge case: empty input handling',
        code: this.generateTestCode(framework, testType, -1, 'empty'),
        type: 'edge-case',
        assertions: 1,
      });

      tests.push({
        name: 'should handle null/undefined',
        description: 'Edge case: null/undefined handling',
        code: this.generateTestCode(framework, testType, -1, 'null'),
        type: 'edge-case',
        assertions: 2,
      });
    }

    return tests;
  }

  private generateTestCode(
    framework: string,
    testType: string,
    index: number,
    variant?: string
  ): string {
    const testFn = framework === 'jest' || framework === 'vitest' ? 'it' : 'test';
    const describeFn = 'describe';

    if (variant === 'empty') {
      return `${testFn}('should handle empty input', () => {
  expect(() => processInput('')).not.toThrow();
  expect(processInput('')).toEqual([]);
});`;
    }

    if (variant === 'null') {
      return `${testFn}('should handle null/undefined', () => {
  expect(() => processInput(null)).toThrow('Invalid input');
  expect(() => processInput(undefined)).toThrow('Invalid input');
});`;
    }

    return `${testFn}('should handle case ${index + 1}', async () => {
  // Arrange
  const input = createTestInput(${index});
  const expected = createExpectedOutput(${index});

  // Act
  const result = await processFunction(input);

  // Assert
  expect(result).toEqual(expected);
});`;
  }

  private countTestTypes(tests: GeneratedTest[]): Record<string, number> {
    const counts: Record<string, number> = {};

    for (const test of tests) {
      counts[test.type] = (counts[test.type] ?? 0) + 1;
    }

    return counts;
  }
}

// ============================================================================
// Tests
// ============================================================================

describe('GenerateTestsTool', () => {
  let tool: MockGenerateTestsTool;

  beforeEach(() => {
    tool = new MockGenerateTestsTool();
  });

  describe('input validation', () => {
    it('should require targetPath', async () => {
      const result = await tool.execute({ targetPath: '' });

      expect(result.success).toBe(false);
      expect(result.errors).toContain('targetPath is required');
    });

    it('should validate file extension', async () => {
      const result = await tool.execute({ targetPath: '/path/to/file.txt' });

      expect(result.success).toBe(false);
      expect(result.errors.some(e => e.includes('source file'))).toBe(true);
    });

    it('should accept valid TypeScript files', async () => {
      const result = await tool.execute({ targetPath: '/src/auth.ts' });

      expect(result.success).toBe(true);
    });

    it('should accept valid JavaScript files', async () => {
      const result = await tool.execute({ targetPath: '/src/utils.js' });

      expect(result.success).toBe(true);
    });

    it('should accept valid React files', async () => {
      const tsxResult = await tool.execute({ targetPath: '/src/Component.tsx' });
      const jsxResult = await tool.execute({ targetPath: '/src/Component.jsx' });

      expect(tsxResult.success).toBe(true);
      expect(jsxResult.success).toBe(true);
    });

    it('should accept valid Python files', async () => {
      const result = await tool.execute({ targetPath: '/src/module.py' });

      expect(result.success).toBe(true);
    });

    it('should validate coverage target range', async () => {
      const negativeResult = await tool.execute({
        targetPath: '/src/test.ts',
        coverage: { target: -10 },
      });

      const overResult = await tool.execute({
        targetPath: '/src/test.ts',
        coverage: { target: 150 },
      });

      expect(negativeResult.success).toBe(false);
      expect(overResult.success).toBe(false);
    });

    it('should validate maxTestsPerFunction', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        options: { maxTestsPerFunction: 0 },
      });

      expect(result.success).toBe(false);
      expect(result.errors.some(e => e.includes('maxTestsPerFunction'))).toBe(true);
    });
  });

  describe('test generation', () => {
    it('should generate tests for valid input', async () => {
      const result = await tool.execute({ targetPath: '/src/auth.ts' });

      expect(result.success).toBe(true);
      expect(result.tests.length).toBeGreaterThan(0);
    });

    it('should use default framework (vitest)', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      expect(result.success).toBe(true);
      // Check test code contains vitest syntax
      expect(result.tests[0].code).toContain('expect(');
    });

    it('should respect specified framework', async () => {
      const vitestResult = await tool.execute({
        targetPath: '/src/test.ts',
        framework: 'vitest',
      });

      const jestResult = await tool.execute({
        targetPath: '/src/test.ts',
        framework: 'jest',
      });

      expect(vitestResult.success).toBe(true);
      expect(jestResult.success).toBe(true);
    });

    it('should generate unit tests by default', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      expect(result.summary.testTypes.unit).toBeGreaterThan(0);
    });

    it('should generate specified test type', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        testType: 'integration',
      });

      expect(result.tests.every((t) => t.type === 'integration')).toBe(true);
    });

    it('should include edge case tests when requested', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        options: { includeEdgeCases: true },
      });

      const edgeCases = result.tests.filter((t) => t.type === 'edge-case');
      expect(edgeCases.length).toBeGreaterThan(0);
    });

    it('should respect maxTestsPerFunction', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        options: { maxTestsPerFunction: 2 },
      });

      // Should generate at most 2 tests (not counting edge cases)
      const nonEdgeCases = result.tests.filter((t) => t.type !== 'edge-case');
      expect(nonEdgeCases.length).toBeLessThanOrEqual(2);
    });
  });

  describe('summary generation', () => {
    it('should include test count in summary', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      expect(result.summary.totalTests).toBe(result.tests.length);
    });

    it('should include target coverage', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        coverage: { target: 90 },
      });

      expect(result.summary.targetCoverage).toBe(90);
    });

    it('should use default coverage target of 80', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      expect(result.summary.targetCoverage).toBe(80);
    });

    it('should estimate coverage based on test count', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        options: { includeEdgeCases: true },
      });

      expect(result.summary.estimatedCoverage).toBeGreaterThan(0);
      expect(result.summary.estimatedCoverage).toBeLessThanOrEqual(95);
    });

    it('should categorize tests by type', async () => {
      const result = await tool.execute({
        targetPath: '/src/test.ts',
        options: { includeEdgeCases: true },
      });

      expect(result.summary.testTypes).toHaveProperty('unit');
      expect(result.summary.testTypes).toHaveProperty('edge-case');
    });
  });

  describe('generated test quality', () => {
    it('should generate tests with descriptive names', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      for (const test of result.tests) {
        expect(test.name).toBeTruthy();
        expect(test.name.length).toBeGreaterThan(5);
      }
    });

    it('should generate tests with descriptions', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      for (const test of result.tests) {
        expect(test.description).toBeTruthy();
      }
    });

    it('should generate tests with code', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      for (const test of result.tests) {
        expect(test.code).toBeTruthy();
        expect(test.code).toContain('expect');
      }
    });

    it('should include assertion count', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      for (const test of result.tests) {
        expect(test.assertions).toBeGreaterThan(0);
      }
    });

    it('should follow Arrange-Act-Assert pattern', async () => {
      const result = await tool.execute({ targetPath: '/src/test.ts' });

      const normalTests = result.tests.filter((t) => t.type !== 'edge-case');
      for (const test of normalTests) {
        expect(test.code).toContain('// Arrange');
        expect(test.code).toContain('// Act');
        expect(test.code).toContain('// Assert');
      }
    });
  });
});

describe('GenerateTestsTool Configuration', () => {
  it('should use custom default framework', async () => {
    const tool = new MockGenerateTestsTool({ defaultFramework: 'jest' });
    const result = await tool.execute({ targetPath: '/src/test.ts' });

    expect(result.success).toBe(true);
  });

  it('should use custom default style', async () => {
    const tool = new MockGenerateTestsTool({ defaultStyle: 'chicago' });
    const result = await tool.execute({ targetPath: '/src/test.ts' });

    expect(result.success).toBe(true);
  });

  it('should use custom maxTestsPerFunction', async () => {
    const tool = new MockGenerateTestsTool({ maxTestsPerFunction: 10 });
    const result = await tool.execute({ targetPath: '/src/test.ts' });

    // Should generate more tests with higher limit
    expect(result.success).toBe(true);
  });
});

describe('GenerateTestsTool Edge Cases', () => {
  let tool: MockGenerateTestsTool;

  beforeEach(() => {
    tool = new MockGenerateTestsTool();
  });

  it('should handle paths with special characters', async () => {
    const result = await tool.execute({
      targetPath: '/src/my-component.test.ts',
    });

    expect(result.success).toBe(true);
  });

  it('should handle deeply nested paths', async () => {
    const result = await tool.execute({
      targetPath: '/src/features/auth/components/LoginForm.tsx',
    });

    expect(result.success).toBe(true);
  });

  it('should handle coverage with focus gaps', async () => {
    const result = await tool.execute({
      targetPath: '/src/test.ts',
      coverage: {
        target: 85,
        focusGaps: true,
      },
    });

    expect(result.success).toBe(true);
    expect(result.summary.targetCoverage).toBe(85);
  });

  it('should handle coverage with exclude patterns', async () => {
    const result = await tool.execute({
      targetPath: '/src/test.ts',
      coverage: {
        excludePatterns: ['*.test.ts', '__mocks__/*'],
      },
    });

    expect(result.success).toBe(true);
  });

  it('should handle all options combined', async () => {
    const result = await tool.execute({
      targetPath: '/src/auth.ts',
      testType: 'unit',
      framework: 'vitest',
      coverage: {
        target: 90,
        focusGaps: true,
        excludePatterns: ['*.d.ts'],
      },
      style: 'london',
      options: {
        includeEdgeCases: true,
        includeMocks: true,
        includeFixtures: true,
        maxTestsPerFunction: 5,
      },
    });

    expect(result.success).toBe(true);
    expect(result.tests.length).toBeGreaterThan(0);
  });
});
