// 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.Threading;
using Microsoft.CodeAnalysis.Shared.TestHooks;
using Microsoft.VisualStudio.Text;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Editor.Shared.Tagging;
 
internal partial class TaggerEventSources
{
    private class WorkspaceChangedEventSource : AbstractWorkspaceTrackingTaggerEventSource
    {
        private readonly AsyncBatchingWorkQueue _asyncDelay;
 
        public WorkspaceChangedEventSource(
            ITextBuffer subjectBuffer,
            IAsynchronousOperationListener asyncListener)
            : base(subjectBuffer)
        {
            // That will ensure that even if we get a flurry of workspace events that we
            // only process a tag change once.
            _asyncDelay = new AsyncBatchingWorkQueue(
                DelayTimeSpan.Short,
                processBatchAsync: cancellationToken =>
                {
                    RaiseChanged();
                    return ValueTaskFactory.CompletedTask;
                },
                asyncListener,
                CancellationToken.None);
        }
 
        protected override void ConnectToWorkspace(Workspace workspace)
        {
            workspace.WorkspaceChanged += OnWorkspaceChanged;
            this.RaiseChanged();
        }
 
        protected override void DisconnectFromWorkspace(Workspace workspace)
        {
            workspace.WorkspaceChanged -= OnWorkspaceChanged;
            this.RaiseChanged();
        }
 
        private void OnWorkspaceChanged(object? sender, WorkspaceChangeEventArgs eventArgs)
            => _asyncDelay.AddWork();
    }
}