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

describe('index.ts - Startup Flow', () => {
  let originalProcessExit: typeof process.exit;
  let exitCalled: boolean;
  let exitCode: number | undefined;

  beforeEach(() => {
    vi.clearAllMocks();
    exitCalled = false;
    exitCode = undefined;

    originalProcessExit = process.exit;
    process.exit = vi.fn((code?: string | number | null | undefined) => {
      exitCalled = true;
      exitCode =
        typeof code === 'number'
          ? code
          : code
            ? parseInt(String(code))
            : undefined;
      return undefined as never;
    }) as never;
  });

  afterEach(() => {
    process.exit = originalProcessExit;
  });

  describe('Error Handler Integration', () => {
    it('should handle top-level startup errors with catch block', async () => {
      const startServer = async () => {
        throw new Error('Startup failed');
      };

      await startServer().catch(() => {
        process.exit(1);
      });

      expect(exitCalled).toBe(true);
      expect(exitCode).toBe(1);
    });

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

      for (const error of errors) {
        exitCalled = false;
        exitCode = undefined;

        const startServer = async () => {
          throw error;
        };

        await startServer().catch(() => {
          process.exit(1);
        });

        expect(exitCalled).toBe(true);
        expect(exitCode).toBe(1);
      }
    });

    it('should execute catch block even with undefined error', async () => {
      const startServer = async () => {
        throw undefined;
      };

      await startServer().catch(() => {
        process.exit(1);
      });

      expect(exitCalled).toBe(true);
      expect(exitCode).toBe(1);
    });

    it('should not call exit on successful startup', async () => {
      const startServer = async () => {};

      await startServer().catch(() => {
        process.exit(1);
      });

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

  describe('Unhandled Rejection Simulation', () => {
    it('should handle unhandled rejection with error object', async () => {
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);
      const mockGracefulShutdown = vi.fn().mockResolvedValue(undefined);

      const reason = new Error('Unhandled rejection');

      if (mockLogger) {
        await mockLogger.error('Unhandled rejection', {
          reason: String(reason),
        });
      }
      await mockLogSessionError('startup', 'UNHANDLED_REJECTION').catch(
        () => {}
      );
      await mockGracefulShutdown('UNHANDLED_REJECTION');

      expect(mockLogger.error).toHaveBeenCalledWith('Unhandled rejection', {
        reason: expect.stringContaining('Unhandled rejection'),
      });
      expect(mockLogSessionError).toHaveBeenCalledWith(
        'startup',
        'UNHANDLED_REJECTION'
      );
      expect(mockGracefulShutdown).toHaveBeenCalledWith('UNHANDLED_REJECTION');
    });

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

      const reason = 'String rejection reason';

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

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

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

      const reason = { message: 'Object rejection' };

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

      expect(mockLogger.error).toHaveBeenCalledWith('Unhandled rejection', {
        reason: '[object Object]',
      });
    });

    it('should handle unhandled rejection when logger is null', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

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

      expect(mockLogSessionError).toHaveBeenCalledWith(
        'startup',
        'UNHANDLED_REJECTION'
      );
    });
  });

  describe('Uncaught Exception Simulation', () => {
    it('should handle uncaught exception with error object', async () => {
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);
      const mockGracefulShutdown = vi.fn().mockResolvedValue(undefined);

      const error = new Error('Uncaught exception');

      if (mockLogger) {
        await mockLogger.error('Uncaught exception', {
          error: error.message,
        });
      }
      await mockLogSessionError('startup', 'UNCAUGHT_EXCEPTION').catch(
        () => {}
      );
      await mockGracefulShutdown('UNCAUGHT_EXCEPTION');

      expect(mockLogger.error).toHaveBeenCalledWith('Uncaught exception', {
        error: 'Uncaught exception',
      });
      expect(mockLogSessionError).toHaveBeenCalledWith(
        'startup',
        'UNCAUGHT_EXCEPTION'
      );
      expect(mockGracefulShutdown).toHaveBeenCalledWith('UNCAUGHT_EXCEPTION');
    });

    it('should handle uncaught exception when logger is null', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

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

      expect(mockLogSessionError).toHaveBeenCalledWith(
        'startup',
        'UNCAUGHT_EXCEPTION'
      );
    });
  });

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

      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

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

      if (mockLogger) {
        await mockLogger.error('Startup failed', {
          error: String(startupError),
        });
      }
      await mockLogSessionError('startup', 'STARTUP_FAILED');

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

    it('should handle startup error when logger is null', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

      await mockLogSessionError('startup', 'STARTUP_FAILED');

      expect(mockLogSessionError).toHaveBeenCalledWith(
        'startup',
        'STARTUP_FAILED'
      );
    });

    it('should exit with code 1 after startup error', async () => {
      const mockLogger = {
        error: vi.fn().mockResolvedValue(undefined),
      };

      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

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

      try {
        throw startupError;
      } catch (error) {
        if (mockLogger) {
          await mockLogger.error('Startup failed', { error: String(error) });
        }
        await mockLogSessionError('startup', 'STARTUP_FAILED');
        process.exit(1);
      }

      expect(exitCalled).toBe(true);
      expect(exitCode).toBe(1);
    });
  });

  describe('Session Error Logging', () => {
    it('should suppress logSessionError failures', async () => {
      const mockLogSessionError = vi
        .fn()
        .mockRejectedValue(new Error('Logging failed'));

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

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

    it('should handle multiple sequential error logging calls', async () => {
      const mockLogSessionError = vi.fn().mockResolvedValue(undefined);

      await mockLogSessionError('startup', 'ERROR_1').catch(() => {});
      await mockLogSessionError('startup', 'ERROR_2').catch(() => {});
      await mockLogSessionError('startup', 'ERROR_3').catch(() => {});

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

  describe('Logger Initialization', () => {
    it('should handle logger creation', () => {
      const mockServer = {};
      const mockCreateLogger = vi.fn((server, prefix) => ({
        info: vi.fn().mockResolvedValue(undefined),
        error: vi.fn().mockResolvedValue(undefined),
        warning: vi.fn().mockResolvedValue(undefined),
        debug: vi.fn().mockResolvedValue(undefined),
        prefix,
        server,
      }));

      const logger = mockCreateLogger(mockServer, 'server');

      expect(logger).toBeDefined();
      expect(logger.prefix).toBe('server');
      expect(logger.server).toBe(mockServer);
    });

    it('should handle logger methods', async () => {
      const mockLogger = {
        info: vi.fn().mockResolvedValue(undefined),
        error: vi.fn().mockResolvedValue(undefined),
        warning: vi.fn().mockResolvedValue(undefined),
        debug: vi.fn().mockResolvedValue(undefined),
      };

      await mockLogger.info('Server starting', { sessionId: 'test-123' });
      await mockLogger.error('Error occurred', { error: 'test error' });

      expect(mockLogger.info).toHaveBeenCalledWith('Server starting', {
        sessionId: 'test-123',
      });
      expect(mockLogger.error).toHaveBeenCalledWith('Error occurred', {
        error: 'test error',
      });
    });
  });

  describe('Process Signal Handlers', () => {
    it('should call gracefulShutdown with SIGINT', async () => {
      const mockGracefulShutdown = vi.fn().mockResolvedValue(undefined);

      await mockGracefulShutdown('SIGINT');

      expect(mockGracefulShutdown).toHaveBeenCalledWith('SIGINT');
    });

    it('should call gracefulShutdown with SIGTERM', async () => {
      const mockGracefulShutdown = vi.fn().mockResolvedValue(undefined);

      await mockGracefulShutdown('SIGTERM');

      expect(mockGracefulShutdown).toHaveBeenCalledWith('SIGTERM');
    });

    it('should call gracefulShutdown with STDIN_CLOSE', async () => {
      const mockGracefulShutdown = vi.fn().mockResolvedValue(undefined);

      await mockGracefulShutdown('STDIN_CLOSE');

      expect(mockGracefulShutdown).toHaveBeenCalledWith('STDIN_CLOSE');
    });
  });

  describe('Complete Startup Flow', () => {
    it('should execute startup sequence in correct order', async () => {
      const callOrder: string[] = [];

      const mockInitialize = vi.fn(async () => {
        callOrder.push('initialize');
      });

      const mockLoadToolContent = vi.fn(async () => {
        callOrder.push('loadToolContent');
        return { instructions: 'test' };
      });

      const mockInitializeSession = vi.fn(() => {
        callOrder.push('initializeSession');
        return { getSessionId: () => 'test-123' };
      });

      const mockRegisterTools = vi.fn(async () => {
        callOrder.push('registerTools');
      });

      await mockInitialize();
      await mockLoadToolContent();
      mockInitializeSession();
      await mockRegisterTools();

      expect(callOrder).toEqual([
        'initialize',
        'loadToolContent',
        'initializeSession',
        'registerTools',
      ]);
    });

    it('should handle errors at any startup stage', async () => {
      const stages = [
        { name: 'initialize', error: 'Init failed' },
        { name: 'loadContent', error: 'Load failed' },
        { name: 'registerTools', error: 'Register failed' },
      ];

      for (const stage of stages) {
        let errorCaught = false;

        try {
          throw new Error(stage.error);
        } catch {
          errorCaught = true;
        }

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

  describe('Process Event Handlers', () => {
    it('should handle uncaughtException events', async () => {
      const mockLogger = {
        error: vi.fn(),
      };

      const error = new Error('Uncaught exception');

      if (mockLogger) {
        await mockLogger.error('Uncaught exception', {
          error: error.message,
        });
      }

      expect(mockLogger.error).toHaveBeenCalledWith('Uncaught exception', {
        error: 'Uncaught exception',
      });
    });

    it('should handle unhandledRejection events', async () => {
      const mockLogger = {
        error: vi.fn(),
      };

      const reason = 'Unhandled rejection';

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

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

    it('should handle gracefulShutdown error path', async () => {
      let shutdownTimeout: ReturnType<typeof setTimeout> | null = null;
      let processExitCalled = false;

      try {
        throw new Error('Shutdown error');
      } catch {
        if (shutdownTimeout) {
          clearTimeout(shutdownTimeout);
          shutdownTimeout = null;
        }
        processExitCalled = true;
      }

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

    it('should handle top-level startServer catch', () => {
      const mockExit = vi.fn();

      try {
        throw new Error('Startup failed');
      } catch {
        mockExit(1);
      }

      expect(mockExit).toHaveBeenCalledWith(1);
    });
  });
});
