// 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.

#nullable disable

using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace Microsoft.CodeAnalysis.CSharp.Extensions
{
    internal static partial class TypeSyntaxExtensions
    {
        public static bool IsVoid(this TypeSyntax typeSyntax)
            => typeSyntax is PredefinedTypeSyntax predefinedType &&
               predefinedType.Keyword.IsKind(SyntaxKind.VoidKeyword);

        public static bool IsPartial(this TypeSyntax typeSyntax)
        {
            return typeSyntax is IdentifierNameSyntax &&
                ((IdentifierNameSyntax)typeSyntax).Identifier.IsKind(SyntaxKind.PartialKeyword);
        }

        /// <summary>
        /// Determines whether the specified TypeSyntax is actually 'var'.
        /// </summary>
        public static bool IsTypeInferred(this TypeSyntax typeSyntax, SemanticModel semanticModel)
        {
            if (!typeSyntax.IsVar)
            {
                return false;
            }

            if (semanticModel.GetAliasInfo(typeSyntax) != null)
            {
                return false;
            }

            var type = semanticModel.GetTypeInfo(typeSyntax).Type;
            if (type == null)
            {
                return false;
            }

            if (type.Name == "var")
            {
                return false;
            }

            return true;
        }

        public static TypeSyntax StripRefIfNeeded(this TypeSyntax type)
            => type is RefTypeSyntax refType ? refType.Type : type;
    }
}
