// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Notification;
using Microsoft.CodeAnalysis.Shared.TestHooks;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.SolutionCrawler
{
    internal abstract class GlobalOperationAwareIdleProcessor : IdleProcessor
    {
        /// <summary>
        /// We're not at a layer where we are guaranteed to have an IGlobalOperationNotificationService.  So allow for
        /// it being null.
        /// </summary>
        private readonly IGlobalOperationNotificationService? _globalOperationNotificationService;
 
        public GlobalOperationAwareIdleProcessor(
            IAsynchronousOperationListener listener,
            IGlobalOperationNotificationService? globalOperationNotificationService,
            TimeSpan backOffTimeSpan,
            CancellationToken shutdownToken)
            : base(listener, backOffTimeSpan, shutdownToken)
        {
            _globalOperationNotificationService = globalOperationNotificationService;
 
            if (_globalOperationNotificationService != null)
            {
                _globalOperationNotificationService.Started += OnGlobalOperationStarted;
                _globalOperationNotificationService.Stopped += OnGlobalOperationStopped;
            }
        }
 
        public virtual void Shutdown()
        {
            if (_globalOperationNotificationService != null)
            {
                _globalOperationNotificationService.Started -= OnGlobalOperationStarted;
                _globalOperationNotificationService.Stopped -= OnGlobalOperationStopped;
            }
        }
 
        private void OnGlobalOperationStarted(object? sender, EventArgs e)
            => this.SetIsPaused(isPaused: true);
 
        private void OnGlobalOperationStopped(object? sender, EventArgs e)
            => this.SetIsPaused(isPaused: false);
    }
}