// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections.Generic;

namespace Microsoft.AspNetCore.Razor.Language.Intermediate
{
    public abstract class IntermediateNodeWalker : IntermediateNodeVisitor
    {
        private readonly List<IntermediateNode> _ancestors = new List<IntermediateNode>();

        protected IReadOnlyList<IntermediateNode> Ancestors => _ancestors;

        protected IntermediateNode Parent => _ancestors.Count > 0 ? _ancestors[0] : null;

        public override void VisitDefault(IntermediateNode node)
        {
            var children = node.Children;
            if (node.Children.Count == 0)
            {
                return;
            }

            _ancestors.Insert(0, node);

            try
            {
                for (var i = 0; i < node.Children.Count; i++)
                {
                    var child = children[i];
                    Visit(child);
                }
            }
            finally
            {
                _ancestors.RemoveAt(0);
            }
        }
    }
}
