// 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.Composition;
using System.Threading;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.VisualStudio.Shell;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem;
 
// TODO: Remove this type. This factory is needed just to instantiate a singleton of VisualStudioMetadataReferenceProvider.
// We should be able to MEF-instantiate a singleton of VisualStudioMetadataReferenceProvider without creating this factory.
[ExportWorkspaceServiceFactory(typeof(VisualStudioMetadataReferenceManager), ServiceLayer.Host), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal class VisualStudioMetadataReferenceManagerFactory(SVsServiceProvider serviceProvider) : IWorkspaceServiceFactory
{
    private VisualStudioMetadataReferenceManager? _singleton;
 
    public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
    {
        if (_singleton == null)
        {
            // If we're in VS we know we must be able to get a TemporaryStorageService
            var temporaryStorage = (TemporaryStorageService)workspaceServices.GetRequiredService<ITemporaryStorageServiceInternal>();
            Interlocked.CompareExchange(ref _singleton, new VisualStudioMetadataReferenceManager(serviceProvider, temporaryStorage), null);
        }
 
        return _singleton;
    }
}