// 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.Undo;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.VisualStudio.Text.Operations;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Interactive
{
    [ExportWorkspaceServiceFactory(typeof(IGlobalUndoService), [WorkspaceKind.Interactive]), Shared]
    internal sealed class InteractiveGlobalUndoServiceFactory : IWorkspaceServiceFactory
    {
        private readonly GlobalUndoService _singleton;
 
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public InteractiveGlobalUndoServiceFactory(ITextUndoHistoryRegistry undoHistoryRegistry)
            => _singleton = new GlobalUndoService(undoHistoryRegistry);
 
        public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
            => _singleton;
 
        private class GlobalUndoService : IGlobalUndoService
        {
            private readonly ITextUndoHistoryRegistry _undoHistoryRegistry;
 
            public bool IsGlobalTransactionOpen(Workspace workspace)
                => GetHistory(workspace).CurrentTransaction != null;
 
            public GlobalUndoService(ITextUndoHistoryRegistry undoHistoryRegistry)
                => _undoHistoryRegistry = undoHistoryRegistry;
 
            public bool CanUndo(Workspace workspace)
            {
                // only primary workspace supports global undo
                return workspace is InteractiveWindowWorkspace;
            }
 
            public IWorkspaceGlobalUndoTransaction OpenGlobalUndoTransaction(Workspace workspace, string description)
            {
                if (!CanUndo(workspace))
                {
                    throw new ArgumentException(EditorFeaturesResources.Given_Workspace_doesn_t_support_Undo);
                }
 
                var textUndoHistory = GetHistory(workspace);
 
                var transaction = textUndoHistory.CreateTransaction(description);
 
                return new InteractiveGlobalUndoTransaction(transaction);
            }
 
            private ITextUndoHistory GetHistory(Workspace workspace)
            {
                var interactiveWorkspace = (InteractiveWindowWorkspace)workspace;
                var textBuffer = interactiveWorkspace.Window.TextView.TextBuffer;
 
                Contract.ThrowIfFalse(_undoHistoryRegistry.TryGetHistory(textBuffer, out var textUndoHistory));
 
                return textUndoHistory;
            }
 
            private class InteractiveGlobalUndoTransaction : IWorkspaceGlobalUndoTransaction
            {
                private readonly ITextUndoTransaction _transaction;
 
                public InteractiveGlobalUndoTransaction(ITextUndoTransaction transaction)
                    => _transaction = transaction;
 
                public void AddDocument(DocumentId id)
                {
                    // Nothing to do.
                }
 
                public void Commit()
                    => _transaction.Complete();
 
                public void Dispose()
                    => _transaction.Dispose();
            }
        }
    }
}