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

describe('index.ts - Shutdown Logic Patterns', () => {
  beforeEach(() => {
    vi.clearAllMocks();
  });

  describe('Shutdown Flag Pattern', () => {
    it('should prevent multiple simultaneous shutdowns', async () => {
      let shutdownInProgress = false;
      let shutdownCount = 0;

      const mockGracefulShutdown = async () => {
        if (shutdownInProgress) {
          return;
        }

        shutdownInProgress = true;
        shutdownCount++;

        await Promise.resolve();
      };

      await Promise.all([mockGracefulShutdown(), mockGracefulShutdown()]);

      expect(shutdownCount).toBe(1);
      expect(shutdownInProgress).toBe(true);
    });

    it('should allow subsequent calls after shutdown flag is checked', async () => {
      let shutdownInProgress = false;
      let callCount = 0;

      const mockShutdownCheck = () => {
        if (shutdownInProgress) {
          return false;
        }
        callCount++;
        return true;
      };

      expect(mockShutdownCheck()).toBe(true);
      expect(callCount).toBe(1);

      expect(mockShutdownCheck()).toBe(true);
      expect(callCount).toBe(2);

      shutdownInProgress = true;

      expect(mockShutdownCheck()).toBe(false);
      expect(callCount).toBe(2);
    });
  });

  describe('Timeout Management Pattern', () => {
    it('should set and clear timeout', () => {
      let shutdownTimeout: ReturnType<typeof setTimeout> | null = null;
      let forcedExitCalled = false;

      shutdownTimeout = setTimeout(() => {
        forcedExitCalled = true;
      }, 5000);

      expect(shutdownTimeout).not.toBeNull();

      if (shutdownTimeout) {
        clearTimeout(shutdownTimeout);
        shutdownTimeout = null;
      }

      expect(shutdownTimeout).toBeNull();

      expect(forcedExitCalled).toBe(false);
    });

    it('should handle timeout in both try and catch blocks', () => {
      let shutdownTimeout: ReturnType<typeof setTimeout> | null = null;

      try {
        shutdownTimeout = setTimeout(() => {}, 5000);

        if (shutdownTimeout) {
          clearTimeout(shutdownTimeout);
          shutdownTimeout = null;
        }

        expect(shutdownTimeout).toBeNull();
      } catch {
        if (shutdownTimeout) {
          clearTimeout(shutdownTimeout);
          shutdownTimeout = null;
        }
      }

      expect(shutdownTimeout).toBeNull();
    });

    it('should handle multiple timeout checks', () => {
      let shutdownTimeout: ReturnType<typeof setTimeout> | null = null;

      if (shutdownTimeout) {
        clearTimeout(shutdownTimeout);
      }
      shutdownTimeout = setTimeout(() => {}, 5000);

      expect(shutdownTimeout).not.toBeNull();

      if (shutdownTimeout) {
        clearTimeout(shutdownTimeout);
        shutdownTimeout = null;
      }
      shutdownTimeout = setTimeout(() => {}, 5000);

      expect(shutdownTimeout).not.toBeNull();

      if (shutdownTimeout) {
        clearTimeout(shutdownTimeout);
        shutdownTimeout = null;
      }

      expect(shutdownTimeout).toBeNull();
    });
  });

  describe('Error Handling Pattern', () => {
    it('should ignore errors in nested try-catch', async () => {
      const mockClose = vi.fn().mockRejectedValue(new Error('Close failed'));
      let errorCaught = false;

      try {
        try {
          await mockClose();
        } catch {
          errorCaught = true;
        }

        expect(errorCaught).toBe(true);
        expect(mockClose).toHaveBeenCalled();
      } catch {
        throw new Error('Should not reach outer catch');
      }
    });

    it('should handle cleanup errors in outer catch', () => {
      const mockCleanup = vi.fn().mockImplementation(() => {
        throw new Error('Cleanup failed');
      });

      let outerCatchReached = false;

      try {
        mockCleanup();
      } catch {
        outerCatchReached = true;
      }

      expect(outerCatchReached).toBe(true);
      expect(mockCleanup).toHaveBeenCalled();
    });
  });

  describe('Logger Conditional Pattern', () => {
    it('should call logger methods only when logger exists', async () => {
      const mockLogger = {
        info: vi.fn().mockResolvedValue(undefined),
        error: vi.fn().mockResolvedValue(undefined),
      };

      type LoggerType = typeof mockLogger;
      let logger: LoggerType | null = mockLogger;

      if (logger) {
        await logger.info('test');
      }

      expect(mockLogger.info).toHaveBeenCalledWith('test');

      logger = null;
      mockLogger.info.mockClear();

      expect(mockLogger.info).not.toHaveBeenCalled();
    });

    it('should handle logger calls with context', async () => {
      const mockLogger = {
        info: vi.fn().mockResolvedValue(undefined),
      };

      const logger = mockLogger;

      if (logger) {
        await logger.info('Shutting down', { signal: 'SIGINT' });
      }

      expect(mockLogger.info).toHaveBeenCalledWith('Shutting down', {
        signal: 'SIGINT',
      });
    });
  });

  describe('Signal Handler Pattern', () => {
    it('should call handler function with signal name', async () => {
      const handlerCalls: string[] = [];

      const mockGracefulShutdown = async (signal?: string) => {
        if (signal) {
          handlerCalls.push(signal);
        }
      };

      await mockGracefulShutdown('SIGINT');
      await mockGracefulShutdown('SIGTERM');
      await mockGracefulShutdown('STDIN_CLOSE');

      expect(handlerCalls).toEqual(['SIGINT', 'SIGTERM', 'STDIN_CLOSE']);
    });

    it('should handle error handlers with reason', async () => {
      const errorLogs: Array<{ type: string; message: string }> = [];

      const mockErrorHandler = (type: string, error: Error | string): void => {
        const message =
          typeof error === 'string' ? error : error.message || String(error);
        errorLogs.push({ type, message });
      };

      const testError = new Error('Test exception');
      mockErrorHandler('uncaughtException', testError);

      mockErrorHandler('unhandledRejection', 'Test rejection');

      expect(errorLogs).toHaveLength(2);
      expect(errorLogs[0]).toEqual({
        type: 'uncaughtException',
        message: 'Test exception',
      });
      expect(errorLogs[1]).toEqual({
        type: 'unhandledRejection',
        message: 'Test rejection',
      });
    });

    it('should convert rejection reason to string', () => {
      const reasons = [
        'string reason',
        new Error('error reason'),
        { message: 'object reason' },
        42,
        null,
        undefined,
      ];

      const converted = reasons.map(reason => String(reason));

      expect(converted).toEqual([
        'string reason',
        'Error: error reason',
        '[object Object]',
        '42',
        'null',
        'undefined',
      ]);
    });
  });

  describe('Startup Error Handling', () => {
    it('should handle startup errors', async () => {
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const logger: typeof mockLogger | null = mockLogger;

      const startupError = new Error('Startup failed');

      try {
        throw startupError;
      } catch (error) {
        if (logger) {
          await logger.error('Startup failed', { error: String(error) });
        }
      }

      expect(mockLogger.error).toHaveBeenCalledWith('Startup failed', {
        error: 'Error: Startup failed',
      });
    });

    it('should handle logger being null during startup error', async () => {
      const mockErrorFn = vi.fn().mockResolvedValue(undefined);
      type LoggerType = {
        error: (msg: string, ctx: Record<string, unknown>) => Promise<void>;
      };
      let logger: LoggerType | null = {
        error: mockErrorFn,
      };

      const startupError = new Error('Startup failed');

      try {
        throw startupError;
      } catch {
        if (logger) {
          await logger.error('Startup failed', {});
        }
      }

      expect(mockErrorFn).toHaveBeenCalledWith('Startup failed', {});

      logger = null;
      let errorHandled = false;

      try {
        throw startupError;
      } catch {
        if (!logger) {
          errorHandled = true;
        }
      }

      expect(errorHandled).toBe(true);
    });
  });

  describe('Session Error Logging Pattern', () => {
    it('should call logSessionError with correct parameters', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

      await mockLogSessionError('startup', 'UNCAUGHT_EXCEPTION').catch(
        () => {}
      );

      await mockLogSessionError('startup', 'UNHANDLED_REJECTION').catch(
        () => {}
      );

      expect(mockLogSessionError).toHaveBeenNthCalledWith(
        1,
        'startup',
        'UNCAUGHT_EXCEPTION'
      );
      expect(mockLogSessionError).toHaveBeenNthCalledWith(
        2,
        'startup',
        'UNHANDLED_REJECTION'
      );
    });

    it('should catch and ignore logSessionError failures', async () => {
      const mockLogSessionError = vi
        .fn()
        .mockRejectedValue(new Error('Logging failed'));

      await mockLogSessionError('startup', 'ERROR_CODE').catch(() => {});

      expect(mockLogSessionError).toHaveBeenCalled();
    });
  });

  describe('Process Stream Control', () => {
    it('should not call uncork on stdout (stdio MCP safety)', () => {
      const mockStdout = {
        uncork: vi.fn(),
      };
      expect(mockStdout.uncork).not.toHaveBeenCalled();
    });
  });

  describe('Unhandled Rejection Handler Pattern', () => {
    it('should convert rejection reason to string', () => {
      const reason = { message: 'Test rejection' };
      const converted = String(reason);

      expect(typeof converted).toBe('string');
    });

    it('should handle rejection with Error object', () => {
      const error = new Error('Rejection error');
      const converted = String(error);

      expect(converted).toContain('Rejection error');
    });

    it('should handle rejection with string reason', () => {
      const reason = 'String rejection';
      const converted = String(reason);

      expect(converted).toBe('String rejection');
    });

    it('should handle rejection with number reason', () => {
      const reason = 42;
      const converted = String(reason);

      expect(converted).toBe('42');
    });

    it('should handle rejection with null reason', () => {
      const reason = null;
      const converted = String(reason);

      expect(converted).toBe('null');
    });

    it('should handle rejection with undefined reason', () => {
      const reason = undefined;
      const converted = String(reason);

      expect(converted).toBe('undefined');
    });

    it('should call error logger with rejection reason', async () => {
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const logger: typeof mockLogger | null = mockLogger;
      const reason = 'Test unhandled rejection';

      if (logger) {
        await logger.error('Unhandled rejection', { reason: String(reason) });
      }

      expect(mockLogger.error).toHaveBeenCalledWith('Unhandled rejection', {
        reason: 'Test unhandled rejection',
      });
    });

    it('should handle logger being null during unhandled rejection', async () => {
      type LoggerType = {
        error: (msg: string, ctx: Record<string, unknown>) => Promise<void>;
      };
      const logger: LoggerType | null = null;

      const handledWithoutLogger = !logger;

      expect(handledWithoutLogger).toBe(true);
    });
  });

  describe('Top-Level Error Handler Pattern', () => {
    it('should handle top-level startup errors', async () => {
      const mockStartServer = vi
        .fn()
        .mockRejectedValue(new Error('Startup failed'));

      let catchBlockExecuted = false;

      try {
        await mockStartServer();
      } catch {
        catchBlockExecuted = true;
      }

      expect(catchBlockExecuted).toBe(true);
    });

    it('should catch and suppress errors in top-level catch', async () => {
      const mockStartServer = vi
        .fn()
        .mockRejectedValue(new Error('Startup failed'));

      await mockStartServer().catch(() => {});

      expect(mockStartServer).toHaveBeenCalled();
    });

    it('should handle various error types in top-level catch', async () => {
      const errors = [
        new Error('Standard error'),
        'String error',
        { message: 'Object error' },
        42,
        null,
        undefined,
      ];

      for (const error of errors) {
        const mockFn = vi.fn().mockRejectedValue(error);

        await mockFn().catch(() => {});

        expect(mockFn).toHaveBeenCalled();
        mockFn.mockClear();
      }
    });
  });

  describe('Async Error Handler Chains', () => {
    it('should chain multiple catch handlers', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const logger: typeof mockLogger | null = mockLogger;

      const reason = 'Test error';

      if (logger) {
        await logger.error('Unhandled rejection', { reason: String(reason) });
      }

      await mockLogSessionError('startup', 'ERROR_CODE').catch(() => {});

      expect(mockLogger.error).toHaveBeenCalled();
      expect(mockLogSessionError).toHaveBeenCalled();
    });

    it('should handle errors in async catch handlers', async () => {
      const mockLogSessionError = vi
        .fn()
        .mockRejectedValue(new Error('Logging failed'));

      await mockLogSessionError('startup', 'ERROR_CODE').catch(() => {});

      expect(mockLogSessionError).toHaveBeenCalled();
    });
  });

  describe('Initialize and Cleanup Pattern', () => {
    it('should call initialize before starting server', async () => {
      const mockInitialize = vi.fn().mockResolvedValue(undefined);
      const mockStartServer = vi.fn().mockResolvedValue(undefined);

      await mockInitialize();
      await mockStartServer();

      expect(mockInitialize).toHaveBeenCalledBefore(mockStartServer);
    });

    it('should handle initialize errors', async () => {
      const mockInitialize = vi
        .fn()
        .mockRejectedValue(new Error('Init failed'));

      let errorCaught = false;

      try {
        await mockInitialize();
      } catch {
        errorCaught = true;
      }

      expect(errorCaught).toBe(true);
    });

    it('should call cleanup during shutdown', () => {
      const mockCleanup = vi.fn();
      const mockClearAllCache = vi.fn();

      mockClearAllCache();
      mockCleanup();

      expect(mockClearAllCache).toHaveBeenCalled();
      expect(mockCleanup).toHaveBeenCalled();
    });
  });

  describe('Session Logging Patterns', () => {
    it('should call logSessionInit and suppress errors', async () => {
      const mockLogSessionInit = vi.fn().mockResolvedValue(undefined);

      await mockLogSessionInit().catch(() => {});

      expect(mockLogSessionInit).toHaveBeenCalled();
    });

    it('should handle logSessionInit errors silently', async () => {
      const mockLogSessionInit = vi
        .fn()
        .mockRejectedValue(new Error('Logging failed'));

      await mockLogSessionInit().catch(() => {});

      expect(mockLogSessionInit).toHaveBeenCalled();
    });

    it('should log multiple error codes', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

      await mockLogSessionError('startup', 'UNCAUGHT_EXCEPTION').catch(
        () => {}
      );
      await mockLogSessionError('startup', 'UNHANDLED_REJECTION').catch(
        () => {}
      );
      await mockLogSessionError('startup', 'STARTUP_FAILED').catch(() => {});

      expect(mockLogSessionError).toHaveBeenCalledTimes(3);
    });
  });
});
