// 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.Threading.Tasks;
using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
using Microsoft.CodeAnalysis.SignatureHelp;
using Microsoft.VisualStudio.Threading;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.SignatureHelp
{
    internal partial class Controller
    {
        internal partial class Session
        {
            private void SetModelExplicitlySelectedItem(Func<Model, SignatureHelpItem> selector)
            {
                this.Computation.ThreadingContext.ThrowIfNotOnUIThread();
 
                Computation.ChainTaskAndNotifyControllerWhenFinished(
                    (model, cancellationToken) => Task.FromResult(SetModelExplicitlySelectedItemInBackground(model, selector)),
                    updateController: false);
            }
 
            private Model? SetModelExplicitlySelectedItemInBackground(
                Model? model,
                Func<Model, SignatureHelpItem> selector)
            {
                this.Computation.ThreadingContext.ThrowIfNotOnBackgroundThread();
                if (model == null)
                    return null;
 
                var selectedItem = selector(model);
                Contract.ThrowIfFalse(model.Items.Contains(selectedItem));
 
                return model.WithSelectedItem(selectedItem, userSelected: true);
            }
        }
    }
}