// 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.Utilities;
using Microsoft.CodeAnalysis.Editor.Undo;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.VisualStudio.Shell;
using Microsoft.VisualStudio.Text.Operations;
using Microsoft.VisualStudio.TextManager.Interop;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation;
 
using Workspace = Microsoft.CodeAnalysis.Workspace;
 
/// <summary>
/// A service that provide a way to undo operations applied to the workspace
/// </summary>
[ExportWorkspaceServiceFactory(typeof(IGlobalUndoService), ServiceLayer.Host), Shared]
internal partial class GlobalUndoServiceFactory : IWorkspaceServiceFactory
{
    private readonly GlobalUndoService _singleton;
 
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public GlobalUndoServiceFactory(
        IThreadingContext threadingContext,
        ITextUndoHistoryRegistry undoHistoryRegistry,
        SVsServiceProvider serviceProvider,
        Lazy<VisualStudioWorkspace> workspace)
    {
        _singleton = new GlobalUndoService(threadingContext, undoHistoryRegistry, serviceProvider, workspace);
    }
 
    public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
        => _singleton;
 
    private class GlobalUndoService : IGlobalUndoService
    {
        private readonly IThreadingContext _threadingContext;
        private readonly ITextUndoHistoryRegistry _undoHistoryRegistry;
        private readonly IVsLinkedUndoTransactionManager _undoManager;
        private readonly Lazy<VisualStudioWorkspace> _lazyVSWorkspace;
        internal int ActiveTransactions;
 
        public GlobalUndoService(IThreadingContext threadingContext, ITextUndoHistoryRegistry undoHistoryRegistry, SVsServiceProvider serviceProvider, Lazy<VisualStudioWorkspace> lazyVSWorkspace)
        {
            _threadingContext = threadingContext;
            _undoHistoryRegistry = undoHistoryRegistry;
            _undoManager = (IVsLinkedUndoTransactionManager)serviceProvider.GetService(typeof(SVsLinkedUndoTransactionManager));
            _lazyVSWorkspace = lazyVSWorkspace;
        }
 
        public bool CanUndo(Workspace workspace)
        {
            // only primary workspace supports global undo
            return _lazyVSWorkspace.Value == workspace;
        }
 
        public IWorkspaceGlobalUndoTransaction OpenGlobalUndoTransaction(Workspace workspace, string description)
        {
            if (!CanUndo(workspace))
            {
                throw new ArgumentException(ServicesVSResources.given_workspace_doesn_t_support_undo);
            }
 
            var transaction = new WorkspaceUndoTransaction(_threadingContext, _undoHistoryRegistry, _undoManager, workspace, description, this);
            ActiveTransactions++;
            return transaction;
        }
 
        public bool IsGlobalTransactionOpen(Workspace workspace)
            => ActiveTransactions > 0;
    }
}