import { afterEach, beforeEach, describe, expect, it, mock } from 'bun:test';
import {
  getShutdownCallbackCount,
  initiateShutdown,
  isShutdownSignalReceived,
  isShuttingDown,
  onShutdown,
  onShutdownHigh,
  onShutdownLow,
  onShutdownMedium,
  resetShutdown,
  setShutdownTimeout,
  Shutdown,
} from '../src';
import type { ShutdownOptions, ShutdownResult } from '../src/types';

describe('Shutdown Comprehensive Tests', () => {
  beforeEach(() => {
    // Reset before each test
    resetShutdown();
  });

  afterEach(() => {
    // Clean up after each test
    resetShutdown();
  });

  describe('Global Functions', () => {
    describe('onShutdown', () => {
      it('should register callback with custom priority', () => {
        const callback = mock(async () => {});

        onShutdown(callback, 'custom-handler', 25);

        expect(getShutdownCallbackCount()).toBe(1);
      });

      it('should handle callback without name', () => {
        const callback = mock(async () => {});

        onShutdown(callback);

        expect(getShutdownCallbackCount()).toBe(1);
      });
    });

    describe('Priority convenience functions', () => {
      it('should register high priority callback', () => {
        const callback = mock(async () => {});

        onShutdownHigh(callback, 'high-priority');

        expect(getShutdownCallbackCount()).toBe(1);
      });

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

        onShutdownMedium(callback, 'medium-priority');

        expect(getShutdownCallbackCount()).toBe(1);
      });

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

        onShutdownLow(callback, 'low-priority');

        expect(getShutdownCallbackCount()).toBe(1);
      });

      it('should execute callbacks in priority order', async () => {
        const order: string[] = [];

        const highCallback = mock(async () => {
          order.push('high');
        });
        const mediumCallback = mock(async () => {
          order.push('medium');
        });
        const lowCallback = mock(async () => {
          order.push('low');
        });

        onShutdownLow(lowCallback, 'low');
        onShutdownHigh(highCallback, 'high');
        onShutdownMedium(mediumCallback, 'medium');

        await initiateShutdown();

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

    describe('setShutdownTimeout', () => {
      it('should set custom timeout', () => {
        setShutdownTimeout(10000);

        // Timeout is set internally, we can't directly verify it
        // but we can test it works by using a long-running callback
        expect(() => setShutdownTimeout(10000)).not.toThrow();
      });

      it('should handle negative timeout values', () => {
        // Should throw for negative values
        expect(() => setShutdownTimeout(-1000)).toThrow('Shutdown timeout must be positive');
      });

      it('should handle zero timeout', () => {
        // Should throw for zero timeout
        expect(() => setShutdownTimeout(0)).toThrow('Shutdown timeout must be positive');
      });
    });

    describe('Status functions', () => {
      it('should report shutting down status correctly', async () => {
        expect(isShuttingDown()).toBe(false);

        const promise = initiateShutdown();
        expect(isShuttingDown()).toBe(true);

        await promise;
        // Still true after completion
        expect(isShuttingDown()).toBe(true);

        resetShutdown();
        expect(isShuttingDown()).toBe(false);
      });

      it('should track shutdown signal', () => {
        expect(isShutdownSignalReceived()).toBe(false);

        // Simulate signal by setting global
        (global as any).__SHUTDOWN_SIGNAL_RECEIVED__ = true;
        expect(isShutdownSignalReceived()).toBe(true);

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

      it('should count callbacks correctly', () => {
        expect(getShutdownCallbackCount()).toBe(0);

        onShutdown(async () => {});
        expect(getShutdownCallbackCount()).toBe(1);

        onShutdownHigh(async () => {});
        onShutdownMedium(async () => {});
        onShutdownLow(async () => {});
        expect(getShutdownCallbackCount()).toBe(4);
      });
    });

    describe('initiateShutdown', () => {
      it('should execute all callbacks', async () => {
        const callback1 = mock(async () => {});
        const callback2 = mock(async () => {});
        const callback3 = mock(async () => {});

        onShutdown(callback1);
        onShutdown(callback2);
        onShutdown(callback3);

        const result = await initiateShutdown();

        expect(callback1).toHaveBeenCalledTimes(1);
        expect(callback2).toHaveBeenCalledTimes(1);
        expect(callback3).toHaveBeenCalledTimes(1);
        expect(result.callbacksExecuted).toBe(3);
        expect(result.callbacksFailed).toBe(0);
        expect(result.success).toBe(true);
      });

      it('should handle errors in callbacks', async () => {
        const successCallback = mock(async () => {});
        const errorCallback = mock(async () => {
          throw new Error('Callback error');
        });

        onShutdown(successCallback, 'success-handler');
        onShutdown(errorCallback, 'error-handler');

        const result = await initiateShutdown();

        expect(result.callbacksExecuted).toBe(2);
        expect(result.callbacksFailed).toBe(1);
        expect(result.success).toBe(false);
        expect(result.error).toContain('1 callbacks failed');
      });

      it('should only execute once', async () => {
        const callback = mock(async () => {});
        onShutdown(callback);

        await initiateShutdown();
        await initiateShutdown();
        await initiateShutdown();

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

  describe('Shutdown Class Direct Usage', () => {
    it('should create instance with options', () => {
      const options: ShutdownOptions = {
        timeout: 5000,
        autoRegister: false,
      };

      const shutdown = new Shutdown(options);
      expect(shutdown).toBeInstanceOf(Shutdown);
    });

    it('should handle concurrent callback registration', () => {
      const shutdown = new Shutdown();
      const callbacks = Array.from({ length: 10 }, (_, i) => mock(async () => {}));

      // Register callbacks concurrently
      callbacks.forEach((cb, i) => {
        shutdown.onShutdown(cb, `handler-${i}`, i * 10);
      });

      expect(shutdown.getCallbackCount()).toBe(10);
    });

    it('should handle empty callback list', async () => {
      const shutdown = new Shutdown();

      const result = await shutdown.shutdown();

      expect(result.callbacksExecuted).toBe(0);
      expect(result.callbacksFailed).toBe(0);
      expect(result.success).toBe(true);
    });

    it('should respect timeout', async () => {
      const shutdown = new Shutdown({ timeout: 100 });

      const slowCallback = mock(async () => {
        await new Promise(resolve => setTimeout(resolve, 200));
      });

      shutdown.onShutdown(slowCallback, 'slow-handler');

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

      expect(duration).toBeLessThan(150); // Should timeout before 200ms
      expect(result.success).toBe(false);
      expect(result.error).toContain('Shutdown timeout');
    });

    it('should handle synchronous callbacks', async () => {
      const shutdown = new Shutdown();

      const syncCallback = mock(() => {
        // Synchronous callback
        return undefined;
      });

      shutdown.onShutdown(syncCallback as any, 'sync-handler');

      const result = await shutdown.shutdown();

      expect(result.callbacksExecuted).toBe(1);
      expect(result.callbacksFailed).toBe(0);
      expect(syncCallback).toHaveBeenCalled();
    });
  });

  describe('Edge Cases', () => {
    it('should handle callback that adds more callbacks', async () => {
      const addingCallback = mock(async () => {
        // Try to add callback during shutdown
        onShutdown(async () => {
          // This should not execute
        });
      });

      onShutdown(addingCallback);

      const countBefore = getShutdownCallbackCount();
      await initiateShutdown();

      // The new callback should not be executed in this shutdown
      expect(addingCallback).toHaveBeenCalledTimes(1);
    });

    it('should handle very large number of callbacks', async () => {
      const callbacks = Array.from({ length: 100 }, (_, i) => mock(async () => {}));

      callbacks.forEach((cb, i) => {
        onShutdown(cb, `handler-${i}`, i);
      });

      expect(getShutdownCallbackCount()).toBe(100);

      const result = await initiateShutdown();

      expect(result.callbacksExecuted).toBe(100);
      expect(result.callbacksFailed).toBe(0);

      callbacks.forEach(cb => {
        expect(cb).toHaveBeenCalledTimes(1);
      });
    });

    it('should handle callbacks with same priority', async () => {
      const order: string[] = [];

      const callback1 = mock(async () => {
        order.push('1');
      });
      const callback2 = mock(async () => {
        order.push('2');
      });
      const callback3 = mock(async () => {
        order.push('3');
      });

      // All with same priority
      onShutdown(callback1, 'handler-1', 50);
      onShutdown(callback2, 'handler-2', 50);
      onShutdown(callback3, 'handler-3', 50);

      await initiateShutdown();

      // Should execute all, order between same priority is not guaranteed
      expect(order).toHaveLength(3);
      expect(order).toContain('1');
      expect(order).toContain('2');
      expect(order).toContain('3');
    });

    it('should handle callback that throws non-Error', async () => {
      const throwingCallback = mock(async () => {
        throw 'string error'; // Non-Error thrown
      });

      onShutdown(throwingCallback, 'throwing-handler');

      const result = await initiateShutdown();

      expect(result.callbacksFailed).toBe(1);
      expect(result.error).toContain('1 callbacks failed');
    });

    it('should handle undefined callback name', () => {
      const callback = mock(async () => {});

      onShutdown(callback, undefined as any);

      expect(getShutdownCallbackCount()).toBe(1);
    });
  });

  describe('ShutdownResult Accuracy', () => {
    it('should provide accurate timing information', async () => {
      const delays = [10, 20, 30];
      const callbacks = delays.map((delay, i) =>
        mock(async () => {
          await new Promise(resolve => setTimeout(resolve, delay));
        })
      );

      callbacks.forEach((cb, i) => {
        onShutdown(cb, `timer-${i}`);
      });

      const startTime = Date.now();
      const result = await initiateShutdown();
      const totalTime = Date.now() - startTime;

      expect(result.duration).toBeGreaterThan(0);
      expect(result.duration).toBeLessThanOrEqual(totalTime);
      expect(result.success).toBe(true);
    });

    it('should track individual callback execution', async () => {
      const successCount = 3;
      const errorCount = 2;

      for (let i = 0; i < successCount; i++) {
        onShutdown(async () => {}, `success-${i}`);
      }

      for (let i = 0; i < errorCount; i++) {
        onShutdown(async () => {
          throw new Error(`Error ${i}`);
        }, `error-${i}`);
      }

      const result = await initiateShutdown();

      expect(result.callbacksExecuted).toBe(successCount + errorCount);
      expect(result.callbacksFailed).toBe(errorCount);
      expect(result.success).toBe(false);
      expect(result.error).toContain(`${errorCount} callbacks failed`);
    });
  });

  describe('Global State Management', () => {
    it('should properly reset global state', () => {
      // Add some callbacks
      onShutdown(async () => {});
      onShutdownHigh(async () => {});
      onShutdownLow(async () => {});

      expect(getShutdownCallbackCount()).toBe(3);

      resetShutdown();

      expect(getShutdownCallbackCount()).toBe(0);
      expect(isShuttingDown()).toBe(false);
    });

    it('should maintain singleton across imports', () => {
      const instance1 = Shutdown.getInstance();
      const instance2 = Shutdown.getInstance();

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