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

namespace Foodsoft.Alpm.Marshalling
{
    internal readonly struct UTF8In : ICustomMarshaler
    {
        private static readonly UTF8In _instance = default;

        public void CleanUpManagedData(object managedObj) { }

        public void CleanUpNativeData(IntPtr pNativeData)
        {
            if (pNativeData == IntPtr.Zero)
                return;
            Marshal.FreeCoTaskMem(pNativeData);
        }

        public int GetNativeDataSize()
        {
            return -1;
        }

        public IntPtr MarshalManagedToNative(object? managedObj)
        {
            return Marshal.StringToCoTaskMemUTF8((string?) managedObj);
        }

        public object MarshalNativeToManaged(IntPtr pNativeData)
        {
            return Marshal.PtrToStringUTF8(pNativeData)!;
        }
        
        [UsedImplicitly]
        private static ICustomMarshaler GetInstance(string cookie)
        {
            return _instance;
        }
    }
}