using System;
using System.Text;
namespace ln.templates.streams
{
    public class PeekAbleStream<T>
    {
        private T[] buffer;
        private int position;

        public int Position => position;
        public bool EndOfBuffer => (position >= buffer.Length);

        public int MarkedPosition { get; set; }

        public PeekAbleStream(T[] buffer)
        {
            this.buffer = buffer;
        }

        public T Read(){
            if (position < buffer.Length)
                return buffer[position++];

            throw new IndexOutOfRangeException("Tried to read after end of buffer");
        }

        public T Peek(int shift = 0)
        {
            if ((position + shift) < buffer.Length)
                return buffer[position + shift];
            
            throw new IndexOutOfRangeException("Tried to peek after end of buffer");
        }

        public void Mark()
        {
            MarkedPosition = position;
        }

        public T[] GetMarkedIntervall()
        {
            T[] intervall = new T[position - MarkedPosition];
            Array.Copy(buffer, MarkedPosition, intervall, 0, intervall.Length);
            return intervall;
        }

        public int Remaining => buffer.Length - position;

    }
}