// 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.ComponentModel.Composition;
using Microsoft.CodeAnalysis.Editor;
using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
using Microsoft.VisualStudio.Utilities;
 
namespace Microsoft.CodeAnalysis.PasteTracking;
 
[Export]
[Export(typeof(ICommandHandler))]
[ContentType(ContentTypeNames.RoslynContentType)]
[Name(PredefinedCommandHandlerNames.PasteTrackingPaste)]
// By registering to run prior to FormatDocument and deferring until it has completed we
// will be able to register the pasted text span after any formatting changes have been
// applied. This is important because the PasteTrackingService will dismiss the registered
// textspan when the textbuffer is changed.
[Order(Before = PredefinedCommandHandlerNames.FormatDocument)]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal class PasteTrackingPasteCommandHandler(PasteTrackingService pasteTrackingService) : IChainedCommandHandler<PasteCommandArgs>
{
    public string DisplayName => EditorFeaturesResources.Paste_Tracking;
 
    private readonly PasteTrackingService _pasteTrackingService = pasteTrackingService;
 
    public CommandState GetCommandState(PasteCommandArgs args, Func<CommandState> nextCommandHandler)
        => nextCommandHandler();
 
    public void ExecuteCommand(PasteCommandArgs args, Action nextCommandHandler, CommandExecutionContext executionContext)
    {
        // Capture the pre-paste caret position
        var caretPosition = args.TextView.GetCaretPoint(args.SubjectBuffer);
        if (!caretPosition.HasValue)
        {
            return;
        }
 
        // Allow the pasted text to be inserted and formatted.
        nextCommandHandler();
 
        if (!args.SubjectBuffer.CanApplyChangeDocumentToWorkspace())
        {
            return;
        }
 
        // Create a tracking span from the pre-paste caret position that will grow as text is inserted.
        var trackingSpan = caretPosition.Value.Snapshot.CreateTrackingSpan(caretPosition.Value.Position, 0, SpanTrackingMode.EdgeInclusive);
 
        // Applying the post-paste snapshot to the tracking span gives us the span of pasted text.
        var snapshotSpan = trackingSpan.GetSpan(args.SubjectBuffer.CurrentSnapshot);
        var textSpan = TextSpan.FromBounds(snapshotSpan.Start, snapshotSpan.End);
 
        _pasteTrackingService.RegisterPastedTextSpan(args.SubjectBuffer, textSpan);
    }
}