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

namespace Aitex.Core.Util
{
    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;
        }

    }
}