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

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Xml;
using System.Xml.XPath;

namespace MS.Internal.Xml.XPath
{
    [DebuggerDisplay("Position = {CurrentPosition}, Current = {debuggerDisplayProxy, nq}")]
    internal class XPathArrayIterator : ResettableIterator
    {
        protected IList list;
        protected int index;

        public XPathArrayIterator(IList list)
        {
            this.list = list;
        }

        public XPathArrayIterator(XPathArrayIterator it)
        {
            this.list = it.list;
            this.index = it.index;
        }

        public XPathArrayIterator(XPathNodeIterator nodeIterator)
        {
            this.list = new ArrayList();
            while (nodeIterator.MoveNext())
            {
                Debug.Assert(nodeIterator.Current != null);
                this.list.Add(nodeIterator.Current.Clone());
            }
        }

        public IList AsList
        {
            get { return this.list; }
        }

        public override XPathNodeIterator Clone()
        {
            return new XPathArrayIterator(this);
        }

        public override XPathNavigator? Current
        {
            get
            {
                Debug.Assert(index <= list.Count);

                if (index < 1)
                {
                    throw new InvalidOperationException(SR.Format(SR.Sch_EnumNotStarted, string.Empty));
                }
                return (XPathNavigator?)list[index - 1];
            }
        }

        public override int CurrentPosition { get { return index; } }
        public override int Count { get { return list.Count; } }

        public override bool MoveNext()
        {
            Debug.Assert(index <= list.Count);
            if (index == list.Count)
            {
                return false;
            }
            index++;
            return true;
        }

        public override void Reset()
        {
            index = 0;
        }

        public override IEnumerator GetEnumerator()
        {
            return list.GetEnumerator();
        }

        private object? debuggerDisplayProxy { get { return index < 1 ? null : (object)new XPathNavigator.DebuggerDisplayProxy(Current!); } }
    }
}