using System;
using System.Buffers.Binary;

namespace DotRecast.Core
{
    public class ByteBuffer
    {
        private ByteOrder _order;
        private byte[] _bytes;
        private int _position;

        public ByteBuffer(byte[] bytes)
        {
            _order = BitConverter.IsLittleEndian
                ? ByteOrder.LITTLE_ENDIAN
                : ByteOrder.BIG_ENDIAN;

            _bytes = bytes;
            _position = 0;
        }

        public ByteOrder order()
        {
            return _order;
        }

        public void order(ByteOrder order)
        {
            _order = order;
        }

        public int limit()
        {
            return _bytes.Length - _position;
        }

        public int remaining()
        {
            int rem = limit();
            return rem > 0 ? rem : 0;
        }


        public void position(int pos)
        {
            _position = pos;
        }

        public int position()
        {
            return _position;
        }

        public Span<byte> ReadBytes(int length)
        {
            var nextPos = _position + length;
            (nextPos, _position) = (_position, nextPos);

            return _bytes.AsSpan(nextPos, length);
        }

        public byte get()
        {
            var span = ReadBytes(1);
            return span[0];
        }

        public short getShort()
        {
            var span = ReadBytes(2);
            if (_order == ByteOrder.BIG_ENDIAN)
            {
                return BinaryPrimitives.ReadInt16BigEndian(span);
            }
            else
            {
                return BinaryPrimitives.ReadInt16LittleEndian(span);
            }
        }


        public int getInt()
        {
            var span = ReadBytes(4);
            if (_order == ByteOrder.BIG_ENDIAN)
            {
                return BinaryPrimitives.ReadInt32BigEndian(span);
            }
            else
            {
                return BinaryPrimitives.ReadInt32LittleEndian(span);
            }
        }

        public float getFloat()
        {
            var span = ReadBytes(4);
            if (_order == ByteOrder.BIG_ENDIAN && BitConverter.IsLittleEndian)
            {
                span.Reverse();
            }
            else if (_order == ByteOrder.LITTLE_ENDIAN && !BitConverter.IsLittleEndian)
            {
                span.Reverse();
            }

            return BitConverter.ToSingle(span);
        }

        public long getLong()
        {
            var span = ReadBytes(8);
            if (_order == ByteOrder.BIG_ENDIAN)
            {
                return BinaryPrimitives.ReadInt64BigEndian(span);
            }
            else
            {
                return BinaryPrimitives.ReadInt64LittleEndian(span);
            }
        }

        public void putFloat(float v)
        {
            // ?
        }

        public void putInt(int v)
        {
            // ?
        }
    }
}