using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace UnityStudio
{
    public enum EndianType
    {
        BigEndian,
        LittleEndian
    }

    public class EndianBinaryReader : BinaryReader
    {
        public EndianType endian;
        private byte[] a16 = new byte[2];
        private byte[] a32 = new byte[4];
        private byte[] a64 = new byte[8];

        public EndianBinaryReader(Stream stream, EndianType endian = EndianType.BigEndian)
            : base(stream)
        { this.endian = endian; }

        public long Position
        {
            get => BaseStream.Position;
            set => BaseStream.Position = value;
        }

        public override short ReadInt16()
        {
            if (endian == EndianType.BigEndian)
            {
                a16 = ReadBytes(2);
                Array.Reverse(a16);
                return BitConverter.ToInt16(a16, 0);
            }
            return base.ReadInt16();
        }

        public override int ReadInt32()
        {
            if (endian == EndianType.BigEndian)
            {
                a32 = ReadBytes(4);
                Array.Reverse(a32);
                return BitConverter.ToInt32(a32, 0);
            }
            return base.ReadInt32();
        }

        public override long ReadInt64()
        {
            if (endian == EndianType.BigEndian)
            {
                a64 = ReadBytes(8);
                Array.Reverse(a64);
                return BitConverter.ToInt64(a64, 0);
            }
            return base.ReadInt64();
        }

        public override ushort ReadUInt16()
        {
            if (endian == EndianType.BigEndian)
            {
                a16 = ReadBytes(2);
                Array.Reverse(a16);
                return BitConverter.ToUInt16(a16, 0);
            }
            return base.ReadUInt16();
        }

        public override uint ReadUInt32()
        {
            if (endian == EndianType.BigEndian)
            {
                a32 = ReadBytes(4);
                Array.Reverse(a32);
                return BitConverter.ToUInt32(a32, 0);
            }
            return base.ReadUInt32();
        }

        public override ulong ReadUInt64()
        {
            if (endian == EndianType.BigEndian)
            {
                a64 = ReadBytes(8);
                Array.Reverse(a64);
                return BitConverter.ToUInt64(a64, 0);
            }
            return base.ReadUInt64();
        }

        public override float ReadSingle()
        {
            if (endian == EndianType.BigEndian)
            {
                a32 = ReadBytes(4);
                Array.Reverse(a32);
                return BitConverter.ToSingle(a32, 0);
            }
            return base.ReadSingle();
        }

        public override double ReadDouble()
        {
            if (endian == EndianType.BigEndian)
            {
                a64 = ReadBytes(8);
                Array.Reverse(a64);
                return BitConverter.ToUInt64(a64, 0);
            }
            return base.ReadDouble();
        }

        public string ReadASCII(int length)
        {
            return Encoding.ASCII.GetString(ReadBytes(length));
        }

        public void AlignStream(int alignment)
        {
            var pos = BaseStream.Position;
            var mod = pos % alignment;
            if (mod != 0) { BaseStream.Position += alignment - mod; }
        }

        public string ReadAlignedString(int length)
        {
            if (length > 0 && length < (BaseStream.Length - BaseStream.Position))
            {
                var stringData = ReadBytes(length);
                var result = Encoding.UTF8.GetString(stringData);
                AlignStream(4);
                return result;
            }
            return "";
        }

        public string ReadStringToNull()
        {
            var bytes = new List<byte>();
            byte b;
            while (BaseStream.Position != BaseStream.Length && (b = ReadByte()) != 0)
                bytes.Add(b);
            return Encoding.UTF8.GetString(bytes.ToArray());
        }
    }
}