using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace StitchATon2.Infra.Buffers;

/// <summary>
/// Provide non-thread safe anti GC contiguous memory. 
/// </summary>
/// <typeparam name="T"></typeparam>
internal sealed unsafe class UnmanagedMemory<T> : IBuffer<T> where T : unmanaged
{
    private readonly T* _pointer;
    private readonly int _count;
    private bool _disposed;

    public ref T this[int index] => ref Unsafe.AsRef<T>(_pointer + index);

    public Span<T> Span => new(_pointer, _count);

    public UnmanagedMemory(int count)
    {
        _pointer = (T*)NativeMemory.Alloc((nuint)count, (nuint)Unsafe.SizeOf<T>());
        _count = count;
    }
    
    ~UnmanagedMemory() => Dispose();

    public void Dispose()
    {
        if (!_disposed)
        {
            NativeMemory.Free(_pointer);
            GC.SuppressFinalize(this);
            _disposed = true;
        }
    }
}