// 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.Completion;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
using Microsoft.CodeAnalysis.Host.Mef;

namespace Microsoft.CodeAnalysis.CSharp.Completion.Providers;

[ExportArgumentProvider(nameof(ContextVariableArgumentProvider), LanguageNames.CSharp)]
[ExtensionOrder(After = nameof(FirstBuiltInArgumentProvider))]
[Shared]
internal sealed class ContextVariableArgumentProvider : AbstractContextVariableArgumentProvider
{
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public ContextVariableArgumentProvider()
    {
    }

    protected override string ThisOrMeKeyword => SyntaxFacts.GetText(SyntaxKind.ThisKeyword);

    protected override bool IsInstanceContext(SyntaxTree syntaxTree, SyntaxToken targetToken, SemanticModel semanticModel, CancellationToken cancellationToken)
        => syntaxTree.IsInstanceContext(targetToken, semanticModel, cancellationToken);

    public override async Task ProvideArgumentAsync(ArgumentContext context)
    {
        await base.ProvideArgumentAsync(context).ConfigureAwait(false);
        if (context.DefaultValue is not null)
        {
            switch (context.Parameter.RefKind)
            {
                case RefKind.Ref:
                    context.DefaultValue = "ref " + context.DefaultValue;
                    break;

                case RefKind.Out:
                    context.DefaultValue = "out " + context.DefaultValue;
                    break;

                case RefKind.In:
                case RefKind.None:
                default:
                    break;
            }
        }
    }
}