namespace LyraApi;

using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;

public static class MarshalUtils
{
    internal struct AlignmentHelper<T> where T : unmanaged
    {
#pragma warning disable CS0649 // Field is never assigned to, and will always have its default value 0
        public byte Padding;
        public T Target;
#pragma warning restore CS0649 // Field is never assigned to, and will always have its default value 0
    }

    public static int AlignmentOf<T>() where T : unmanaged
    {
        return (int)Marshal.OffsetOf<AlignmentHelper<T>>(nameof(AlignmentHelper<T>.Target));
    }

    public static byte[] GetBytes<T>([DisallowNull] T data)
    {
        int size = Marshal.SizeOf(data);
        byte[] arr = new byte[size];

        IntPtr ptr = IntPtr.Zero;
        try
        {
            ptr = Marshal.AllocHGlobal(size);
            Marshal.StructureToPtr(data, ptr, true);
            Marshal.Copy(ptr, arr, 0, size);
        }
        finally
        {
            Marshal.FreeHGlobal(ptr);
        }
        return arr;
    }

    public static T? FromBytes<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)] T>(byte[] data)
    {
        var ptr = GCHandle.Alloc(data, GCHandleType.Pinned);
        try
        {
            //var res = (T?)Marshal.PtrToStructure(ptr.AddrOfPinnedObject(), typeof(T));
            var res = Marshal.PtrToStructure<T>(ptr.AddrOfPinnedObject());
            return res;
        }
        finally
        {
            ptr.Free();

        }
    }
}