// 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 Microsoft.CodeAnalysis.ConvertTypeOfToNameOf;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
 
namespace Microsoft.CodeAnalysis.CSharp.ConvertTypeOfToNameOf;
 
/// <summary>
/// Finds code like typeof(someType).Name and determines whether it can be changed to nameof(someType), if yes then it offers a diagnostic
/// </summary>
[DiagnosticAnalyzer(LanguageNames.CSharp)]
internal sealed class CSharpConvertTypeOfToNameOfDiagnosticAnalyzer : AbstractConvertTypeOfToNameOfDiagnosticAnalyzer
{
    private static readonly string s_title = CSharpAnalyzersResources.typeof_can_be_converted_to_nameof;
 
    public CSharpConvertTypeOfToNameOfDiagnosticAnalyzer() : base(s_title)
    {
    }
 
    protected override bool IsValidTypeofAction(OperationAnalysisContext context)
    {
        var node = context.Operation.Syntax;
 
        // nameof was added in CSharp 6.0, so don't offer it for any languages before that time
        if (node.GetLanguageVersion() < LanguageVersion.CSharp6)
        {
            return false;
        }
 
        // Make sure that the syntax that we're looking at is actually a typeof expression and that
        // the parent syntax is a member access expression otherwise the syntax is not the kind of
        // expression that we want to analyze
        return node is TypeOfExpressionSyntax { Parent: MemberAccessExpressionSyntax } typeofExpression &&
            // nameof(System.Void) isn't allowed in C#.
            typeofExpression is not { Type: PredefinedTypeSyntax { Keyword.RawKind: (int)SyntaxKind.VoidKeyword } };
    }
}