// 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 System;
using System.Collections.Generic;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis.ExtractMethod;
 
internal abstract partial class MethodExtractor<TSelectionResult, TStatementSyntax, TExpressionSyntax>
{
    protected class TypeParameterCollector : SymbolVisitor
    {
        private readonly List<ITypeParameterSymbol> _typeParameters = [];
 
        public static IEnumerable<ITypeParameterSymbol> Collect(ITypeSymbol typeSymbol)
        {
            var collector = new TypeParameterCollector();
            typeSymbol.Accept(collector);
 
            return collector._typeParameters;
        }
 
        public override void DefaultVisit(ISymbol node)
            => throw new NotImplementedException();
 
        public override void VisitDynamicType(IDynamicTypeSymbol dynamicTypeSymbol)
        {
        }
 
        public override void VisitFunctionPointerType(IFunctionPointerTypeSymbol symbol)
        {
            symbol.Signature.ReturnType.Accept(this);
            foreach (var param in symbol.Signature.Parameters)
            {
                param.Type.Accept(this);
            }
        }
 
        public override void VisitArrayType(IArrayTypeSymbol arrayTypeSymbol)
            => arrayTypeSymbol.ElementType.Accept(this);
 
        public override void VisitPointerType(IPointerTypeSymbol pointerTypeSymbol)
            => pointerTypeSymbol.PointedAtType.Accept(this);
 
        public override void VisitNamedType(INamedTypeSymbol namedTypeSymbol)
        {
            foreach (var argument in namedTypeSymbol.GetAllTypeArguments())
            {
                argument.Accept(this);
            }
        }
 
        public override void VisitTypeParameter(ITypeParameterSymbol typeParameterTypeSymbol)
            => _typeParameters.Add(typeParameterTypeSymbol);
    }
}