// 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.Linq;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Shared.Extensions
{
    internal static class ITypeParameterSymbolExtensions
    {
        public static INamedTypeSymbol? GetNamedTypeSymbolConstraint(this ITypeParameterSymbol typeParameter)
            => typeParameter.ConstraintTypes.Select(GetNamedTypeSymbol).WhereNotNull().FirstOrDefault();
 
        private static INamedTypeSymbol? GetNamedTypeSymbol(ITypeSymbol type)
        {
            return type is INamedTypeSymbol
                ? (INamedTypeSymbol)type
                : type is ITypeParameterSymbol
                    ? GetNamedTypeSymbolConstraint((ITypeParameterSymbol)type)
                    : null;
        }
    }
}