using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace MECF.Framework.RT.EquipmentLibrary.HardwareUnits.EndPoints.CytEndPoints
{
    public class ByteStructConverter
    {
        public static T ToStruct<T>(byte[] by) where T : struct
        {
            int objectSize = Marshal.SizeOf(typeof(T));
            if (objectSize > by.Length) return default(T);

            // Allocate some unmanaged memory.
            IntPtr buffer = Marshal.AllocHGlobal(objectSize);

            // Copy the read byte array (byte[]) into the unmanaged memory block.
            Marshal.Copy(by, 0, buffer, objectSize);

            // Push the memory into a new struct of type (T).
            T returnStruct = (T)Marshal.PtrToStructure(buffer, typeof(T));

            // Free the unmanaged memory block.
            Marshal.FreeHGlobal(buffer);

            return returnStruct;
        }

        public static object ToStruct(byte[] buffer, Type t)
        {
            int objectSize = Marshal.SizeOf(t);
            if (objectSize > buffer.Length) return null;

            // Allocate some unmanaged memory.
            IntPtr buf = Marshal.AllocHGlobal(objectSize);

            // Copy the read byte array (byte[]) into the unmanaged memory block.
            Marshal.Copy(buffer, 0, buf, objectSize);

            // Push the memory into a new struct of type (T).
            object result = Marshal.PtrToStructure(buf, t);

            // Free the unmanaged memory block.
            Marshal.FreeHGlobal(buf);

            return result;
        }

        public static byte[] Struct2Bytes(object o)
        {
            // create a new byte buffer the size of your struct
            byte[] buffer = new byte[Marshal.SizeOf(o)];
            // pin the buffer so we can copy data into it w/o GC collecting it
            GCHandle bufferHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
            // copy the struct data into the buffer
            Marshal.StructureToPtr(o, bufferHandle.AddrOfPinnedObject(), false);
            // free the GC handle
            bufferHandle.Free();

            return buffer;
        }

    }
    public class ByteReader
    {
        private byte[] buffer;
        private int idx;
        private int length;
        public int Length => length;

        public ByteReader(byte[] data, int len)
        {
            buffer = new byte[len];
            System.Buffer.BlockCopy(data, 0, buffer, 0, len);
            length = len;
            idx = 0;
        }

        public void Append(byte[] data, int len)
        {
            var buf = new byte[Length + len];
            System.Buffer.BlockCopy(buffer, 0, buf, 0, Length);
            System.Buffer.BlockCopy(data, 0, buf, Length, len);
            buffer = buf;
            length += len;
        }

        public bool Reset(int curIdx = 0)
        {
            if (curIdx < length)
                idx = curIdx;
            return idx == curIdx;
        }

        public bool ReadBytes(byte[] buf, int len)
        {
            if (idx + len <= length)
            {
                System.Buffer.BlockCopy(buffer, (int)idx, buf, 0, (int)len);
                idx += len;
                return true;
            }
            return false;
        }

        public bool ReadInt(out int data)
        {
            data = 0;
            if (idx + 4 <= length)
            {
                data = BitConverter.ToInt32(buffer, (int)idx);
                idx += 4;
                return true;
            }
            return false;
        }

        public bool ReadUInt16(out UInt16 data)
        {
            data = 0;
            if (idx + 2 <= length)
            {
                data = BitConverter.ToUInt16(buffer, (int)idx);
                idx += 2;
                return true;
            }
            return false;
        }

        public bool ReadInt64(out Int64 data)
        {
            data = 0;
            if (idx + 8 <= length)
            {
                data = BitConverter.ToInt64(buffer, (int)idx);
                idx += 8;
                return true;
            }
            return false;
        }
    }
}