describe('Basic Test Suite', () => {
  describe('Environment Setup', () => {
    it('should have test environment configured', () => {
      expect(process.env.NODE_ENV).toBe('test');
      expect(process.env.RESEND_API_KEY).toBe('test-api-key');
      expect(process.env.FROM_DOMAIN).toBe('test.com');
    });
  });

  describe('JavaScript Fundamentals', () => {
    it('should handle basic operations', () => {
      expect(1 + 1).toBe(2);
      expect('hello'.toUpperCase()).toBe('HELLO');
      expect([1, 2, 3]).toHaveLength(3);
    });

    it('should handle async operations', async () => {
      const promise = Promise.resolve('test');
      await expect(promise).resolves.toBe('test');
    });
  });

  describe('Email Validation Logic', () => {
    it('should validate email format', () => {
      const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
      
      expect(emailRegex.test('user@example.com')).toBe(true);
      expect(emailRegex.test('test.email@domain.co.uk')).toBe(true);
      expect(emailRegex.test('invalid-email')).toBe(false);
      expect(emailRegex.test('@example.com')).toBe(false);
    });
  });

  describe('URL Validation Logic', () => {
    it('should validate URL format', () => {
      const isValidUrl = (url: string): boolean => {
        try {
          new URL(url);
          return true;
        } catch {
          return false;
        }
      };

      expect(isValidUrl('https://example.com')).toBe(true);
      expect(isValidUrl('http://localhost:3000')).toBe(true);
      expect(isValidUrl('not-a-url')).toBe(false);
      expect(isValidUrl('')).toBe(false);
    });
  });

  describe('String Sanitization', () => {
    it('should sanitize strings', () => {
      const sanitize = (input: string, maxLength = 1000): string => {
        return input
          .trim()
          .slice(0, maxLength)
          .replace(/[<>]/g, '');
      };

      expect(sanitize('  test  ')).toBe('test');
      expect(sanitize('test<script>alert(1)</script>test')).toBe('testscriptalert(1)/scripttest');
      expect(sanitize('a'.repeat(2000), 100)).toHaveLength(100);
    });
  });

  describe('Privacy Protection', () => {
    it('should mask email addresses', () => {
      const maskEmail = (email: string): string => {
        const [local, domain] = email.split('@');
        if (!local || !domain) return '***@***.***';
        
        const maskedLocal = local.length > 2 
          ? local[0] + '*'.repeat(local.length - 2) + local[local.length - 1]
          : '***';
        
        return `${maskedLocal}@${domain}`;
      };

      expect(maskEmail('user@example.com')).toBe('u**r@example.com');
      expect(maskEmail('test@domain.org')).toBe('t**t@domain.org');
      expect(maskEmail('a@b.com')).toBe('***@b.com');
    });

    it('should mask IP addresses', () => {
      const maskIp = (ip: string): string => {
        const parts = ip.split('.');
        if (parts.length === 4) {
          return `${parts[0]}.${parts[1]}.***.***.***`;
        }
        return '***.***.***';
      };

      expect(maskIp('192.168.1.100')).toBe('192.168.***.***.***');
      expect(maskIp('10.0.0.1')).toBe('10.0.***.***.***');
      expect(maskIp('invalid')).toBe('***.***.***');
    });
  });

  describe('Configuration Validation', () => {
    it('should validate domain format', () => {
      const isValidDomain = (domain: string): boolean => {
        return domain.includes('.') && domain.length > 3;
      };

      expect(isValidDomain('example.com')).toBe(true);
      expect(isValidDomain('sub.domain.org')).toBe(true);
      expect(isValidDomain('invalid-domain')).toBe(false);
      expect(isValidDomain('test')).toBe(false);
    });

    it('should validate port numbers', () => {
      const isValidPort = (port: number): boolean => {
        return port >= 1 && port <= 65535;
      };

      expect(isValidPort(3001)).toBe(true);
      expect(isValidPort(80)).toBe(true);
      expect(isValidPort(443)).toBe(true);
      expect(isValidPort(0)).toBe(false);
      expect(isValidPort(70000)).toBe(false);
    });

    it('should validate rate limit values', () => {
      const isValidRateLimit = (max: number, windowMs: number): boolean => {
        return max >= 1 && max <= 1000 && windowMs >= 60000;
      };

      expect(isValidRateLimit(10, 900000)).toBe(true);
      expect(isValidRateLimit(100, 300000)).toBe(true);
      expect(isValidRateLimit(0, 900000)).toBe(false);
      expect(isValidRateLimit(10, 30000)).toBe(false);
    });
  });
});