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

namespace StitchATon2.Infra.Buffers;

internal sealed unsafe class ImmovableMemory<T> : MemoryManager<T> where T : unmanaged
{
    private readonly T* _pointer;
    private readonly int _length;
    private bool _disposed;

    public ImmovableMemory(int count)
    {
        _pointer = (T*)NativeMemory.Alloc((nuint)count, (nuint)Unsafe.SizeOf<T>());
        _length = count;
    }
    
    protected override void Dispose(bool disposing)
    {
        if (!_disposed)
        {
            NativeMemory.Free(_pointer);
            _disposed = true;
        }
    }

    public override Span<T> GetSpan()
        => new(_pointer, _length);

    public override MemoryHandle Pin(int elementIndex = 0)
        => new(_pointer + elementIndex);

    public override void Unpin()
    {
    }
}