import { afterEach, beforeEach, describe, expect, it, mock } from 'bun:test';
import { Shutdown } from '../src/shutdown';

describe('Shutdown Signal Handlers', () => {
  let shutdown: Shutdown;
  let processOnSpy: any;
  let processExitSpy: any;
  const originalPlatform = Object.getOwnPropertyDescriptor(process, 'platform');
  const originalOn = process.on;
  const originalExit = process.exit;

  beforeEach(() => {
    // Reset singleton instance
    (Shutdown as any).instance = null;

    // Clean up global flag
    delete (global as any).__SHUTDOWN_SIGNAL_RECEIVED__;

    // Mock process.on
    const listeners: Record<string, Function[]> = {};
    processOnSpy = mock((event: string, handler: Function) => {
      if (!listeners[event]) {
        listeners[event] = [];
      }
      listeners[event].push(handler);
    });
    process.on = processOnSpy as any;

    // Mock process.exit
    processExitSpy = mock((code?: number) => {
      // Just record the call, don't throw
      return;
    });
    process.exit = processExitSpy as any;

    // Store listeners for manual triggering
    (global as any).__testListeners = listeners;
  });

  afterEach(() => {
    // Restore original methods
    process.on = originalOn;
    process.exit = originalExit;
    if (originalPlatform) {
      Object.defineProperty(process, 'platform', originalPlatform);
    }

    // Clean up
    (Shutdown as any).instance = null;
    delete (global as any).__testListeners;
  });

  describe('Signal Handler Registration', () => {
    it('should register Unix signal handlers on non-Windows', () => {
      Object.defineProperty(process, 'platform', {
        value: 'linux',
        configurable: true,
      });

      shutdown = new Shutdown({ autoRegister: true });

      // Check that Unix signals were registered
      expect(processOnSpy).toHaveBeenCalledWith('SIGTERM', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('SIGINT', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('SIGUSR2', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('uncaughtException', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('unhandledRejection', expect.any(Function));
    });

    it('should register Windows signal handlers on Windows', () => {
      Object.defineProperty(process, 'platform', {
        value: 'win32',
        configurable: true,
      });

      shutdown = new Shutdown({ autoRegister: true });

      // Check that Windows signals were registered
      expect(processOnSpy).toHaveBeenCalledWith('SIGTERM', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('SIGINT', expect.any(Function));
      expect(processOnSpy).not.toHaveBeenCalledWith('SIGUSR2', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('uncaughtException', expect.any(Function));
      expect(processOnSpy).toHaveBeenCalledWith('unhandledRejection', expect.any(Function));
    });

    it('should not register handlers when autoRegister is false', () => {
      shutdown = new Shutdown({ autoRegister: false });

      expect(processOnSpy).not.toHaveBeenCalled();
    });

    it('should not register handlers twice', () => {
      shutdown = new Shutdown({ autoRegister: true });
      const callCount = processOnSpy.mock.calls.length;

      // Try to setup handlers again (internally)
      shutdown['setupSignalHandlers']();

      // Should not register additional handlers
      expect(processOnSpy.mock.calls.length).toBe(callCount);
    });
  });

  describe('Signal Handler Behavior', () => {
    it('should handle SIGTERM signal', async () => {
      shutdown = new Shutdown({ autoRegister: true });
      const callback = mock(async () => {});
      shutdown.onShutdown(callback);

      const listeners = (global as any).__testListeners;
      const sigtermHandler = listeners['SIGTERM'][0];

      // Trigger SIGTERM (this starts async shutdown)
      sigtermHandler();

      // Verify flags are set immediately
      expect(shutdown.isShutdownSignalReceived()).toBe(true);
      expect((global as any).__SHUTDOWN_SIGNAL_RECEIVED__).toBe(true);

      // Wait a bit for async shutdown to complete
      await new Promise(resolve => setTimeout(resolve, 10));

      // Now process.exit should have been called
      expect(processExitSpy).toHaveBeenCalledWith(0);
    });

    it('should handle SIGINT signal', async () => {
      shutdown = new Shutdown({ autoRegister: true });
      const callback = mock(async () => {});
      shutdown.onShutdown(callback);

      const listeners = (global as any).__testListeners;
      const sigintHandler = listeners['SIGINT'][0];

      // Trigger SIGINT (this starts async shutdown)
      sigintHandler();

      // Verify flags are set immediately
      expect(shutdown.isShutdownSignalReceived()).toBe(true);

      // Wait a bit for async shutdown to complete
      await new Promise(resolve => setTimeout(resolve, 10));

      // Now process.exit should have been called
      expect(processExitSpy).toHaveBeenCalledWith(0);
    });

    it('should handle uncaughtException', async () => {
      shutdown = new Shutdown({ autoRegister: true });

      const listeners = (global as any).__testListeners;
      const exceptionHandler = listeners['uncaughtException'][0];

      // Trigger uncaughtException (this starts async shutdown with exit code 1)
      exceptionHandler(new Error('Uncaught error'));

      // Wait a bit for async shutdown to complete
      await new Promise(resolve => setTimeout(resolve, 10));

      // Should exit with code 1 for uncaught exceptions
      expect(processExitSpy).toHaveBeenCalledWith(1);
    });

    it('should handle unhandledRejection', async () => {
      shutdown = new Shutdown({ autoRegister: true });

      const listeners = (global as any).__testListeners;
      const rejectionHandler = listeners['unhandledRejection'][0];

      // Trigger unhandledRejection (this starts async shutdown with exit code 1)
      rejectionHandler(new Error('Unhandled rejection'));

      // Wait a bit for async shutdown to complete
      await new Promise(resolve => setTimeout(resolve, 10));

      // Should exit with code 1 for unhandled rejections
      expect(processExitSpy).toHaveBeenCalledWith(1);
    });

    it('should not process signal if already shutting down', async () => {
      shutdown = new Shutdown({ autoRegister: true });

      // Start shutdown
      shutdown['isShuttingDown'] = true;

      const listeners = (global as any).__testListeners;
      const sigtermHandler = listeners['SIGTERM'][0];

      // Mock shutdownAndExit to track calls
      const shutdownAndExitSpy = mock(() => Promise.resolve());
      shutdown.shutdownAndExit = shutdownAndExitSpy as any;

      // Trigger SIGTERM
      sigtermHandler();

      // Should not call shutdownAndExit since already shutting down
      expect(shutdownAndExitSpy).not.toHaveBeenCalled();
    });

    it('should handle shutdown failure in signal handler', async () => {
      shutdown = new Shutdown({ autoRegister: true });

      // Mock shutdownAndExit to reject
      shutdown.shutdownAndExit = mock(async () => {
        throw new Error('Shutdown failed');
      }) as any;

      const listeners = (global as any).__testListeners;
      const sigtermHandler = listeners['SIGTERM'][0];

      // Trigger SIGTERM - should fall back to process.exit(1)
      sigtermHandler();

      // Wait a bit for async shutdown to fail and fallback to occur
      await new Promise(resolve => setTimeout(resolve, 10));

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

  describe('Global Flag Behavior', () => {
    it('should set global shutdown flag on signal', async () => {
      delete (global as any).__SHUTDOWN_SIGNAL_RECEIVED__;

      shutdown = new Shutdown({ autoRegister: true });

      const listeners = (global as any).__testListeners;
      const sigtermHandler = listeners['SIGTERM'][0];

      // Trigger signal (this sets the flag immediately)
      sigtermHandler();

      expect((global as any).__SHUTDOWN_SIGNAL_RECEIVED__).toBe(true);

      // Wait for async shutdown to complete to avoid hanging promises
      await new Promise(resolve => setTimeout(resolve, 10));
    });

    it('should check global flag in isShutdownSignalReceived', () => {
      shutdown = new Shutdown({ autoRegister: false });

      expect(shutdown.isShutdownSignalReceived()).toBe(false);

      // Set global flag
      (global as any).__SHUTDOWN_SIGNAL_RECEIVED__ = true;

      // Even without instance flag, should return true
      expect(shutdown.isShutdownSignalReceived()).toBe(true);

      // Clean up
      delete (global as any).__SHUTDOWN_SIGNAL_RECEIVED__;
    });
  });
});