// 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 System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.SolutionCrawler;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Remote;
 
/// <summary>
/// Provide document difference service specific to remote workspace's behavior.
/// 
/// Default <see cref="AbstractDocumentDifferenceService"/> is optimized for typing case in editor where we have events
/// for each typing. But in remote workspace, we aggregate changes and update solution in bulk and we don't have concept
/// of active file making default implementation unsuitable. Functionally, default one is still correct, but it often
/// time makes us to do more than we need. Basically, it always says this project has semantic change which can cause
/// a lot of re-analysis.
/// </summary>
internal class RemoteDocumentDifferenceService : IDocumentDifferenceService
{
    [ExportLanguageService(typeof(IDocumentDifferenceService), LanguageNames.CSharp, layer: ServiceLayer.Host), Shared]
    internal sealed class CSharpDocumentDifferenceService : RemoteDocumentDifferenceService
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public CSharpDocumentDifferenceService()
        {
        }
    }
 
    [ExportLanguageService(typeof(IDocumentDifferenceService), LanguageNames.VisualBasic, layer: ServiceLayer.Host), Shared]
    internal sealed class VisualBasicDocumentDifferenceService : AbstractDocumentDifferenceService
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public VisualBasicDocumentDifferenceService()
        {
        }
    }
 
    public Task<SyntaxNode?> GetChangedMemberAsync(Document oldDocument, Document newDocument, CancellationToken cancellationToken)
    {
        return SpecializedTasks.Null<SyntaxNode>();
    }
}