// 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;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem;
using Microsoft.VisualStudio.LanguageServices.Implementation.Venus;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Operations;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation;
 
using Workspace = Microsoft.CodeAnalysis.Workspace;
 
[ExportWorkspaceServiceFactory(typeof(ITextUndoHistoryWorkspaceService), ServiceLayer.Host), Shared]
internal class VisualStudioTextUndoHistoryWorkspaceServiceFactory : IWorkspaceServiceFactory
{
    private readonly ITextUndoHistoryWorkspaceService _serviceSingleton;
 
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public VisualStudioTextUndoHistoryWorkspaceServiceFactory(ITextUndoHistoryRegistry undoHistoryRegistry)
        => _serviceSingleton = new TextUndoHistoryWorkspaceService(undoHistoryRegistry);
 
    public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
        => _serviceSingleton;
 
    private class TextUndoHistoryWorkspaceService : ITextUndoHistoryWorkspaceService
    {
        private readonly ITextUndoHistoryRegistry _undoHistoryRegistry;
 
        public TextUndoHistoryWorkspaceService(ITextUndoHistoryRegistry undoHistoryRegistry)
            => _undoHistoryRegistry = undoHistoryRegistry;
 
        public bool TryGetTextUndoHistory(Workspace editorWorkspace, ITextBuffer textBuffer, out ITextUndoHistory undoHistory)
        {
            switch (editorWorkspace)
            {
                case VisualStudioWorkspaceImpl:
 
                    // TODO: Handle undo if context changes
                    var documentId = editorWorkspace.GetDocumentIdInCurrentContext(textBuffer.AsTextContainer());
                    if (documentId == null)
                    {
                        undoHistory = null;
                        return false;
                    }
 
                    // In the Visual Studio case, there might be projection buffers involved for Venus,
                    // where we associate undo history with the surface buffer and not the subject buffer.
                    var containedDocument = ContainedDocument.TryGetContainedDocument(documentId);
 
                    if (containedDocument != null)
                    {
                        textBuffer = containedDocument.DataBuffer;
                    }
 
                    break;
 
                case MiscellaneousFilesWorkspace:
                    // Nothing to do in this case: textBuffer is correct!
                    break;
 
                default:
 
                    undoHistory = null;
                    return false;
 
            }
 
            return _undoHistoryRegistry.TryGetHistory(textBuffer, out undoHistory);
        }
    }
}