using C_.Datastructures.Nodes;

namespace C_.Datastructures
{
    internal class Stack<T>
    {
        internal StackNode<T>? Head { get; set; }
        private int Count { get; set; } = 0;

        public Stack<T> Create(){
            //Create a new stack without a head
            return new Stack<T>();
        }

        public Stack<T> Create(T value){
            //Create a new Stack with a head
            return new Stack<T>{
                Head = StackNode<T>.Create(value, default),
                Count = 1
            };
        }

        public void Push(T value){
            //Add an Item to the end of the list
            if (Count > 0)
            {    
                Count++;
                Head = StackNode<T>.Create(value, Head);
                return;
            }
        }

        public T? Pop(){
            T? value = default;
            if (Count > 0)
            {//Assign the default value if there are any items left in the stack
                Count--;
                value = Head!.Value;
                Head = Head.Next;
            }
            return value;
        }

        public T? Peek(){
            if (Count > 0)
            {
                return Head!.Value;
            }
            return default;
        }
    }
}