namespace ln.collections
{
	/**
	 * A backend Implementation of Double-Linked-List
	 **/ 
	public class LinkedList<T>
	{
		public LinkedListItem<T> FirstItem => (head.Next != head) ? head.Next : null;
		public LinkedListItem<T> LastItem => (head.Previous != head) ? head.Previous : null;

		public LinkedListItem<T> Head => head;

		LinkedListItem<T> head = new LinkedListItem<T>();

		public LinkedList()
		{
		}

		public void Clear()
		{
			head = new LinkedListItem<T>();
		}

		public void Add(LinkedListItem<T> item)
		{
			if (item.Previous != item)
				Remove(item);

			item.Next = head;
			item.Previous = head.Previous;
			item.Previous.Next = item;
			item.Next.Previous = item;
		}

		public void Remove(LinkedListItem<T> item)
		{
			item.Previous.Next = item.Next;
			item.Next.Previous = item.Previous;
			item.Next = item;
			item.Previous = item;
		}

	}
}