// 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.
 
#nullable disable
 
using System;
using System.Composition;
using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.Text;
 
namespace Microsoft.CodeAnalysis.PasteTracking;
 
[Export(typeof(IPasteTrackingService)), Shared]
[Export(typeof(PasteTrackingService))]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal class PasteTrackingService(IThreadingContext threadingContext) : IPasteTrackingService
{
    private readonly IThreadingContext _threadingContext = threadingContext;
    private readonly object _pastedTextSpanKey = new();
 
    public bool TryGetPastedTextSpan(SourceTextContainer sourceTextContainer, out TextSpan textSpan)
    {
        var textBuffer = sourceTextContainer.TryGetTextBuffer();
        if (textBuffer is null)
        {
            textSpan = default;
            return false;
        }
 
        // `PropertiesCollection` is thread-safe
        return textBuffer.Properties.TryGetProperty(_pastedTextSpanKey, out textSpan);
    }
 
    internal void RegisterPastedTextSpan(ITextBuffer textBuffer, TextSpan textSpan)
    {
        _threadingContext.ThrowIfNotOnUIThread();
 
        // Use the TextBuffer properties to store the pasted text span. 
        // The `PropertiesCollection` is thread-safe and will be cleared
        // when all TextViews that share this buffer are closed.
        // Any change to the TextBuffer will remove the pasted text span.
        // This includes consecutive paste operations which will fire the
        // Changed event prior to the handler registering a new text span.
        textBuffer.Properties[_pastedTextSpanKey] = textSpan;
        textBuffer.Changed += RemovePastedTextSpan;
 
        return;
 
        void RemovePastedTextSpan(object sender, TextContentChangedEventArgs e)
        {
            textBuffer.Changed -= RemovePastedTextSpan;
            textBuffer.Properties.RemoveProperty(_pastedTextSpanKey);
        }
    }
}