CacheHandler

using System;
using System.Collections;
using System.Collections.Generic;

namespace Cache
{
    public class CacheHandler<T> : IEnumerator, IEnumerable
    {
        private int _index = -1;
        private Func<List<T>> _refresh { get; set; }

        public List<T> Items { get; set; }

        public CacheHandler(Func<List<T>> refresh)
        {
            _refresh = refresh;
        }

        public void Refresh()
        {
            Items = _refresh();
        }

        public bool MoveNext()
        {
            _index += 1;
            return _index < Items.Count;
        }

        public void Reset()
        {
            _index = 0;
        }

        public IEnumerator GetEnumerator()
        {
            return this;
        }

        public T this[int index]
        {
            get
            {
                if (Items == null)
                    Refresh();

                if (Items == null || index < 0 || Items.Count == index)
                    return default(T);

                return Items[index];
            }
        }

        public int Count => (Items ?? new List<T>()).Count;

        public int Length => Count;

        public object Current
        {
            get
            {
                return Items[_index];
            }
        }
    }
}