import { EmailService, emailService } from '../email';

// Mock console methods
const mockConsoleWarn = jest.fn();
const mockConsoleLog = jest.fn();

describe('EmailService', () => {
  let service: EmailService;

  beforeEach(() => {
    jest.clearAllMocks();
    console.warn = mockConsoleWarn;
    console.log = mockConsoleLog;
    service = new EmailService();
  });

  afterEach(() => {
    jest.restoreAllMocks();
  });

  describe('constructor', () => {
    test('should create a new EmailService instance', () => {
      expect(service).toBeInstanceOf(EmailService);
    });
  });

  describe('sendVerificationEmail', () => {
    test('should log verification email details', async () => {
      const email = 'test@example.com';
      const token = 'test-token-123';

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `📧 Sending verification email to ${email} with token: ${token}`
      );
      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `🔗 Verification link: /verify-email?token=${token}`
      );
      expect(mockConsoleWarn).toHaveBeenCalledTimes(2);
    });

    test('should handle empty email gracefully', async () => {
      const email = '';
      const token = 'test-token-123';

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `📧 Sending verification email to ${email} with token: ${token}`
      );
      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `🔗 Verification link: /verify-email?token=${token}`
      );
    });

    test('should handle empty token gracefully', async () => {
      const email = 'test@example.com';
      const token = '';

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `📧 Sending verification email to ${email} with token: ${token}`
      );
      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `🔗 Verification link: /verify-email?token=${token}`
      );
    });

    test('should handle special characters in email and token', async () => {
      const email = 'test+user@example-domain.com';
      const token = 'abc123!@#$%^&*()_+-={}[]|\\:";\'<>?,./';

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `📧 Sending verification email to ${email} with token: ${token}`
      );
      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `🔗 Verification link: /verify-email?token=${token}`
      );
    });

    test('should simulate network delay', async () => {
      const email = 'test@example.com';
      const token = 'test-token-123';

      const startTime = Date.now();
      await service.sendVerificationEmail(email, token);
      const endTime = Date.now();

      // Should take at least 500ms due to the simulated delay
      expect(endTime - startTime).toBeGreaterThanOrEqual(450); // Allow some margin for test execution
    });

    test('should complete successfully without throwing errors', async () => {
      const email = 'test@example.com';
      const token = 'test-token-123';

      await expect(
        service.sendVerificationEmail(email, token)
      ).resolves.toBeUndefined();
    });

    test('should handle very long email addresses', async () => {
      const email = 'a'.repeat(100) + '@' + 'b'.repeat(100) + '.com';
      const token = 'test-token-123';

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `📧 Sending verification email to ${email} with token: ${token}`
      );
    });

    test('should handle very long tokens', async () => {
      const email = 'test@example.com';
      const token = 'a'.repeat(1000);

      await service.sendVerificationEmail(email, token);

      expect(mockConsoleWarn).toHaveBeenCalledWith(
        `🔗 Verification link: /verify-email?token=${token}`
      );
    });

    test('should handle null and undefined inputs gracefully', async () => {
      // Test with null values
      await service.sendVerificationEmail(null as any, null as any);
      expect(mockConsoleWarn).toHaveBeenCalled();

      jest.clearAllMocks();

      // Test with undefined values
      await service.sendVerificationEmail(undefined as any, undefined as any);
      expect(mockConsoleWarn).toHaveBeenCalled();
    });
  });

  describe('emailService singleton', () => {
    test('should export a singleton instance', () => {
      expect(emailService).toBeInstanceOf(EmailService);
    });

    test('should be the same instance when imported multiple times', () => {
      // This test verifies that the exported emailService is a singleton
      const { emailService: secondImport } = require('../email');
      expect(emailService).toBe(secondImport);
    });

    test('should have the sendVerificationEmail method', () => {
      expect(typeof emailService.sendVerificationEmail).toBe('function');
    });
  });

  describe('method return values', () => {
    test('sendVerificationEmail should return a Promise that resolves to void', async () => {
      const result = await service.sendVerificationEmail(
        'test@example.com',
        'token'
      );
      expect(result).toBeUndefined();
    });
  });

  describe('console output format', () => {
    test('should use emoji prefixes for visual identification', async () => {
      const email = 'test@example.com';
      const token = 'test-token-123';

      await service.sendVerificationEmail(email, token);

      const [firstCall, secondCall] = mockConsoleWarn.mock.calls;
      expect(firstCall[0]).toMatch(/^📧/);
      expect(secondCall[0]).toMatch(/^🔗/);
    });

    test('should format verification link consistently', async () => {
      const email = 'test@example.com';
      const token = 'test-token-123';

      await service.sendVerificationEmail(email, token);

      const secondCall = mockConsoleWarn.mock.calls[1];
      expect(secondCall[0]).toBe(
        `🔗 Verification link: /verify-email?token=${token}`
      );
    });
  });

  describe('error handling', () => {
    test('should not throw errors even with malformed inputs', async () => {
      const testCases = [
        ['', ''],
        [null, null],
        [undefined, undefined],
        ['invalid-email', 'token'],
        ['test@example.com', null],
        [null, 'token'],
      ];

      for (const [email, token] of testCases) {
        await expect(
          service.sendVerificationEmail(email as any, token as any)
        ).resolves.not.toThrow();
      }
    });
  });
});