DoubleLinkedList<T>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DoubleLinkedListExample
{
    public class Node<T>
    {
        public T item;
        public Node<T> next;
        public Node<T> prev;

        public Node(T data)
        {
            this.item = data;
            this.next = null;
            this.prev = null;
        }
    }
    public class DoubleLinkedList<T>
    {
        public int Size { get; set; }

        private Node<T> head;
        private Node<T> current;

        public DoubleLinkedList()
        {
            this.Size = 0;
            this.head = null;
            this.current = null;
        }

        public void Add(Node<T> element)
        {
            if (this.head == null)
            {
                this.head = element;
                this.head.prev = null;
                this.current = this.head;
                this.head.next = this.current;
                this.Size++;
            }
            else
            {
                this.current.prev = this.current;
                this.current.next = element;
                this.current = this.current.next;
                this.Size++;
            }
        }

        public void AddToHead(Node<T> element)
        {
            if (this.head == null)
            {
                this.head = element;
                this.current = this.head;
                this.head.next = this.current;
                this.Size++;
            }
            else
            {
                this.head.prev = element;
                this.head.prev.next = this.head;
                this.head = this.head.prev;
                this.head.prev = null;
                this.Size++;
            }
        }

        public T this[int index]
        {
            get
            {
                if(index >= this.Size || index<0)
                {
                    throw new IndexOutOfRangeException(
                    String.Format("The index is out range! (index: {0}, size: {1})", index, this.Size));
                }

                Node<T> result = this.head;
                result = GetElementOfPosition(index, result);
                return result.item;
            }
        }

        public void InsertAt(Node<T> element, int position)
        {
            if (position > this.Size || position < 0)
            {
                throw new IndexOutOfRangeException(
                    String.Format("The position is out range! (pos: {0}, size: {1})", position, this.Size));
            }
            if (position == this.Size)
            {
                Add(element);
            }
            else
            {
                Node<T> currentAtPosition = this.head;
                currentAtPosition = GetElementOfPosition(position - 1, currentAtPosition);
                Node<T> nextToCurrentAtPosition = currentAtPosition.next;
                currentAtPosition.next = element;
                element.next = nextToCurrentAtPosition;
                this.Size++;
            }
        }

        private Node<T> GetElementOfPosition(int index, Node<T> result)
        {
            for (int i = 0; i < index; i++)
            {
                result = GetNext(result);
            }
            return result;
        }

        private Node<T> GetNext(Node<T> element)
        {
            Node<T> result = element.next;
            return result;
        }
    }
}