// 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 Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.Text;
 
namespace Microsoft.CodeAnalysis.Editor.Shared.Tagging;
 
/// <summary>
/// An abstract implementation of a tagger event source that takes a buffer and tracks
/// the workspace that it's attached to.
/// </summary>
internal abstract class AbstractWorkspaceTrackingTaggerEventSource : AbstractTaggerEventSource
{
    private readonly WorkspaceRegistration _workspaceRegistration;
 
    protected ITextBuffer SubjectBuffer { get; }
    protected Workspace? CurrentWorkspace { get; private set; }
 
    protected AbstractWorkspaceTrackingTaggerEventSource(ITextBuffer subjectBuffer)
    {
        this.SubjectBuffer = subjectBuffer;
        _workspaceRegistration = Workspace.GetWorkspaceRegistration(subjectBuffer.AsTextContainer());
    }
 
    protected abstract void ConnectToWorkspace(Workspace workspace);
    protected abstract void DisconnectFromWorkspace(Workspace workspace);
 
    public override void Connect()
    {
        this.CurrentWorkspace = _workspaceRegistration.Workspace;
        _workspaceRegistration.WorkspaceChanged += OnWorkspaceRegistrationChanged;
 
        if (this.CurrentWorkspace != null)
        {
            ConnectToWorkspace(this.CurrentWorkspace);
        }
    }
 
    private void OnWorkspaceRegistrationChanged(object? sender, EventArgs e)
    {
        if (this.CurrentWorkspace != null)
        {
            DisconnectFromWorkspace(this.CurrentWorkspace);
        }
 
        this.CurrentWorkspace = _workspaceRegistration.Workspace;
 
        if (this.CurrentWorkspace != null)
        {
            ConnectToWorkspace(this.CurrentWorkspace);
        }
    }
 
    public override void Disconnect()
    {
        if (this.CurrentWorkspace != null)
        {
            DisconnectFromWorkspace(this.CurrentWorkspace);
            this.CurrentWorkspace = null;
        }
 
        _workspaceRegistration.WorkspaceChanged -= OnWorkspaceRegistrationChanged;
    }
}