using StgSharp.Graphics;
using StgSharp.Logic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

namespace StgSharp
{
    public class LinkedList<T>:INode<LinkedList<T>>,IEnumerable where T: INode<T>
    {
        internal readonly ContainerNode<T> _heading;
        private ContainerNode<T> _cache;
        private bool isEmpty;

        public LinkedList()
        {
            _heading = new ContainerNode<T>(null);
            isEmpty = true;

#if DEBUG
            Console.WriteLine("Linked list init ok");
#endif
        }

        public T First
        {
            get { return _heading._next._value; }
            private set { _heading._next = value.ID; }
        }

        public T Tail
        {
            get { return _heading._previous._value; }
            private set { _heading._previous = value.ID; }
        }

        /// <summary>
        /// Add an item to the tail of linked list.
        /// </summary>
        /// <param name="t">The item ready to add to the list</param>
        public void Add(T t)
        {
            //checkout if the linkedlist is null
            if (isEmpty)
            {
                _heading._next = t.ID;
                _heading._previous = t.ID;
                t.Next = _heading;
                t.Previous = _heading;
                isEmpty = false;
                Console.WriteLine("1st item ok");
                Console.WriteLine(_heading._next);
                Console.WriteLine(_heading._previous);
            }
            else
            {
                Console.WriteLine("next begin");
                t.Next = _heading;
                Console.WriteLine("step 01 ok");
                t.Previous = _heading.Previous;
                Console.WriteLine("step 02 ok");
                _heading._previous._next = t.ID;
                Console.WriteLine("step 03 ok");
                _heading._previous = t.ID;
                
            }
        }

        public void Remove(T node)
        {
            foreach (INode<T> item in this)
            {
                if (item == node)
                {
                    node.SelfDestrcut();
                    break;
                }
            }
        }

        public void RemoveTail()
        {
            //check out if the list has only one member
            if (Tail == First)
            {
                First = default;


                isEmpty = true;
            }
            else
            {
                Tail.Previous.Next = _heading;
                Tail.Next = null;
            }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return new LinkedListEnumrator<T>(this);
        }
    }
}