// 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 Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.Text;
 
namespace Microsoft.CodeAnalysis.Editor.Shared.Tagging;
 
internal partial class TaggerEventSources
{
    private sealed class DocumentActiveContextChangedEventSource(ITextBuffer subjectBuffer) : AbstractWorkspaceTrackingTaggerEventSource(subjectBuffer)
    {
        private WorkspaceEventRegistration? _documentActiveContextChangedDisposer;
 
        // Require main thread on the callback as RaiseChanged implementors may have main thread dependencies.
        protected override void ConnectToWorkspace(Workspace workspace)
            => _documentActiveContextChangedDisposer = workspace.RegisterDocumentActiveContextChangedHandler(OnDocumentActiveContextChanged, WorkspaceEventOptions.RequiresMainThreadOptions);
 
        protected override void DisconnectFromWorkspace(Workspace workspace)
            => _documentActiveContextChangedDisposer?.Dispose();
 
        private void OnDocumentActiveContextChanged(DocumentActiveContextChangedEventArgs e)
        {
            var document = SubjectBuffer.AsTextContainer().GetOpenDocumentInCurrentContext();
 
            if (document != null && document.Id == e.NewActiveContextDocumentId)
                this.RaiseChanged();
        }
    }
}