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

        public static Queue<T> Create()
        {
            //Create a new queue without a head / tail
            return new Queue<T>();
        }

        public static Queue<T> Create(T value)
        {
            //Create a new Queue with a head + tail
            QueueNode<T> newNode = QueueNode<T>.Create(value, default);
            return new Queue<T>
            {
                Head = newNode,
                Tail = newNode,
                Count = 1
            };
        }

        public void Push(T value)
        {
            //Add an Item to the end of the Queue
            Count++;
            if (Count > 1)
            {
                Tail!.Next = QueueNode<T>.Create(value, default);
                Tail = Tail!.Next;
                return;
            }
            Head = QueueNode<T>.Create(value, default);
            Tail = Head;
            return;
        }

        public T? Pop()
        {
            //Take the item off the front of the queue
            T? value = default;
            if (Count > 0)
            {//Assign the default value if there are any items left in the Queue
                Count--;
                value = Head!.Value;
                Head = Head.Next;
                if (Count == 0)
                {
                    Head = default;
                    Tail = Head;
                }
            }
            return value;
        }

        public T? Peek()
        {
            //View item at the front of the Queue
            if (Count > 0)
            {
                return Head!.Value;
            }
            return default;
        }
    }
}