// 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.CodeGeneration;
using Microsoft.CodeAnalysis.Editing;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.CSharp.CodeGeneration
{
    internal class CSharpFlagsEnumGenerator : AbstractFlagsEnumGenerator
    {
        public static readonly CSharpFlagsEnumGenerator Instance = new();
 
        private CSharpFlagsEnumGenerator()
        {
        }
 
        protected override SyntaxNode CreateExplicitlyCastedLiteralValue(
            SyntaxGenerator generator,
            INamedTypeSymbol enumType,
            SpecialType underlyingSpecialType,
            object constantValue)
        {
            var expression = ExpressionGenerator.GenerateNonEnumValueExpression(
                generator, enumType.EnumUnderlyingType, constantValue, canUseFieldReference: true);
 
            var constantValueULong = EnumUtilities.ConvertEnumUnderlyingTypeToUInt64(constantValue, underlyingSpecialType);
            if (constantValueULong == 0)
            {
                // 0 is always convertible to an enum type without needing a cast.
                return expression;
            }
 
            return generator.CastExpression(enumType, expression);
        }
 
        protected override bool IsValidName(INamedTypeSymbol enumType, string name)
            => SyntaxFacts.IsValidIdentifier(name);
    }
}