// 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.CSharp.Syntax;

namespace Microsoft.CodeAnalysis.CSharp.Utilities;

internal sealed class NameSyntaxIterator : IEnumerable<NameSyntax>
{
    private readonly NameSyntax _name;

    public NameSyntaxIterator(NameSyntax name)
        => _name = name ?? throw new ArgumentNullException(nameof(name));

    public IEnumerator<NameSyntax> GetEnumerator()
    {
        var nodes = new LinkedList<NameSyntax>();

        var currentNode = _name;
        while (true)
        {
            if (currentNode.Kind() == SyntaxKind.QualifiedName)
            {
                var qualifiedName = currentNode as QualifiedNameSyntax;
                nodes.AddFirst(qualifiedName.Right);
                currentNode = qualifiedName.Left;
            }
            else
            {
                nodes.AddFirst(currentNode);
                break;
            }
        }

        return nodes.GetEnumerator();
    }

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        => GetEnumerator();
}