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

describe('Shutdown', () => {
  let shutdown: Shutdown;

  beforeEach(() => {
    // Reset singleton instance for each test
    (Shutdown as any).instance = null;
    shutdown = Shutdown.getInstance({ timeout: 1000 });
  });

  afterEach(() => {
    // Clean up
    (Shutdown as any).instance = null;
  });

  describe('getInstance', () => {
    it('should return singleton instance', () => {
      const instance1 = Shutdown.getInstance();
      const instance2 = Shutdown.getInstance();

      expect(instance1).toBe(instance2);
    });

    it('should use provided config on first call', () => {
      const instance = Shutdown.getInstance({ timeout: 5000 });
      expect(instance).toBeDefined();
    });
  });

  describe('handler registration', () => {
    it('should register high priority handler', () => {
      const handler = mock(async () => {});

      shutdown.onShutdownHigh(handler, 'High Priority Task');

      expect(shutdown['callbacks']).toHaveLength(1);
      expect(shutdown['callbacks'][0].name).toBe('High Priority Task');
      expect(shutdown['callbacks'][0].priority).toBe(10);
    });

    it('should register medium priority handler', () => {
      const handler = mock(async () => {});

      shutdown.onShutdownMedium(handler, 'Medium Priority Task');

      expect(shutdown['callbacks']).toHaveLength(1);
      expect(shutdown['callbacks'][0].priority).toBe(50);
    });

    it('should register low priority handler', () => {
      const handler = mock(async () => {});

      shutdown.onShutdownLow(handler, 'Low Priority Task');

      expect(shutdown['callbacks']).toHaveLength(1);
      expect(shutdown['callbacks'][0].priority).toBe(90);
    });

    it('should register multiple handlers in order', () => {
      const handler1 = mock(async () => {});
      const handler2 = mock(async () => {});
      const handler3 = mock(async () => {});

      shutdown.onShutdownHigh(handler1, 'First');
      shutdown.onShutdownHigh(handler2, 'Second');
      shutdown.onShutdownHigh(handler3, 'Third');

      expect(shutdown['callbacks']).toHaveLength(3);
      expect(shutdown['callbacks'][0].name).toBe('First');
      expect(shutdown['callbacks'][2].name).toBe('Third');
    });
  });

  describe('shutdown process', () => {
    it('should execute handlers in priority order', async () => {
      const executionOrder: string[] = [];

      const highHandler = mock(async () => {
        executionOrder.push('high');
      });

      const mediumHandler = mock(async () => {
        executionOrder.push('medium');
      });

      const lowHandler = mock(async () => {
        executionOrder.push('low');
      });

      shutdown.onShutdownLow(lowHandler, 'Low');
      shutdown.onShutdownMedium(mediumHandler, 'Medium');
      shutdown.onShutdownHigh(highHandler, 'High');

      await shutdown.shutdown();

      expect(executionOrder).toEqual(['high', 'medium', 'low']);
    });

    it('should only shutdown once', async () => {
      const handler = mock(async () => {});
      shutdown.onShutdownHigh(handler, 'Handler');

      await shutdown.shutdown();
      await shutdown.shutdown(); // Second call should be ignored

      expect(handler).toHaveBeenCalledTimes(1);
    });

    it('should handle errors in handlers', async () => {
      const errorHandler = mock(async () => {
        throw new Error('Handler error');
      });

      const successHandler = mock(async () => {});

      shutdown.onShutdownHigh(errorHandler, 'Error Handler');
      shutdown.onShutdownHigh(successHandler, 'Success Handler');

      await shutdown.shutdown();

      expect(errorHandler).toHaveBeenCalled();
      expect(successHandler).toHaveBeenCalled();
    });

    it('should respect timeout', async () => {
      const slowHandler = mock(async () => {
        await new Promise(resolve => setTimeout(resolve, 2000));
      });

      shutdown = Shutdown.getInstance({ timeout: 100 });
      shutdown.onShutdownHigh(slowHandler, 'Slow Handler');

      const start = Date.now();
      await shutdown.shutdown();
      const duration = Date.now() - start;

      // Shutdown waits for timeout (100ms) plus some processing time
      expect(duration).toBeGreaterThan(90);
      expect(duration).toBeLessThan(1500); // But not the full 2000ms
    });
  });

  describe('reset', () => {
    it('should clear all handlers', () => {
      shutdown.onShutdownHigh(async () => {}, 'Handler 1');
      shutdown.onShutdownMedium(async () => {}, 'Handler 2');
      shutdown.onShutdownLow(async () => {}, 'Handler 3');

      // Manually clear callbacks to simulate reset
      shutdown['callbacks'] = [];

      expect(shutdown['callbacks']).toHaveLength(0);
    });

    it('should reset shutdown state', async () => {
      const handler = mock(async () => {});

      shutdown.onShutdownHigh(handler, 'Handler');
      await shutdown.shutdown();

      // Reset by creating new instance
      (Shutdown as any).instance = null;
      shutdown = Shutdown.getInstance({ timeout: 1000 });

      shutdown.onShutdownHigh(handler, 'Handler');
      await shutdown.shutdown();

      expect(handler).toHaveBeenCalledTimes(2);
    });
  });

  // Skip forceShutdown test as it's not implemented in current shutdown
  // describe.skip('forceShutdown', () => {
  //   it('should exit process after timeout', async () => {
  //     // Skipped
  //   });
  // });
});