import { describe, expect, it } from 'vitest';
import {
  getDeferredRestartAction,
  getReconnectSkipReason,
  isLifecycleSuperseded,
  nextLifecycleEpoch,
  shouldDeferRestart,
} from '@electron/gateway/process-policy';

describe('gateway process policy helpers', () => {
  describe('lifecycle epoch helpers', () => {
    it('increments lifecycle epoch by one', () => {
      expect(nextLifecycleEpoch(0)).toBe(1);
      expect(nextLifecycleEpoch(5)).toBe(6);
    });

    it('detects superseded lifecycle epochs', () => {
      expect(isLifecycleSuperseded(3, 4)).toBe(true);
      expect(isLifecycleSuperseded(8, 8)).toBe(false);
    });
  });

  describe('getReconnectSkipReason', () => {
    it('skips reconnect when auto-reconnect is disabled', () => {
      expect(
        getReconnectSkipReason({
          scheduledEpoch: 10,
          currentEpoch: 10,
          shouldReconnect: false,
        })
      ).toBe('auto-reconnect disabled');
    });

    it('skips stale reconnect callbacks when lifecycle epoch changed', () => {
      expect(
        getReconnectSkipReason({
          scheduledEpoch: 11,
          currentEpoch: 12,
          shouldReconnect: true,
        })
      ).toContain('stale reconnect callback');
    });

    it('allows reconnect when callback is current and reconnect enabled', () => {
      expect(
        getReconnectSkipReason({
          scheduledEpoch: 7,
          currentEpoch: 7,
          shouldReconnect: true,
        })
      ).toBeNull();
    });
  });

  describe('restart deferral policy', () => {
    it('defers restart while startup or reconnect is in progress', () => {
      expect(shouldDeferRestart({ state: 'starting', startLock: false })).toBe(true);
      expect(shouldDeferRestart({ state: 'reconnecting', startLock: false })).toBe(true);
      expect(shouldDeferRestart({ state: 'running', startLock: true })).toBe(true);
    });

    it('does not defer restart for stable states when no start lock', () => {
      expect(shouldDeferRestart({ state: 'running', startLock: false })).toBe(false);
      expect(shouldDeferRestart({ state: 'stopped', startLock: false })).toBe(false);
      expect(shouldDeferRestart({ state: 'error', startLock: false })).toBe(false);
    });

    it('drops deferred restart once lifecycle recovers to running', () => {
      expect(
        getDeferredRestartAction({
          hasPendingRestart: true,
          state: 'running',
          startLock: false,
          shouldReconnect: true,
        })
      ).toBe('drop');
    });

    it('waits deferred restart while lifecycle is still busy', () => {
      expect(
        getDeferredRestartAction({
          hasPendingRestart: true,
          state: 'starting',
          startLock: false,
          shouldReconnect: true,
        })
      ).toBe('wait');
    });

    it('executes deferred restart when manager is idle and not running', () => {
      expect(
        getDeferredRestartAction({
          hasPendingRestart: true,
          state: 'error',
          startLock: false,
          shouldReconnect: true,
        })
      ).toBe('execute');
    });

    it('drops deferred restart when reconnect is disabled', () => {
      expect(
        getDeferredRestartAction({
          hasPendingRestart: true,
          state: 'stopped',
          startLock: false,
          shouldReconnect: false,
        })
      ).toBe('drop');
    });
  });
});