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

namespace StitchATon2.Infra.Buffers;

public static class MemoryAllocator
{
    public static IBuffer<T> Allocate<T>(int count) where T : unmanaged
        => new ImmovableMemory<T>(count);
    
    public static IMemoryOwner<T> AllocateManaged<T>(int count)
        => MemoryPool<T>.Shared.Rent(count);
    
    public static ArrayOwner<T> AllocateArray<T>(int count) where T : unmanaged
        => new(ArrayPool<T>.Shared, count);

    public static unsafe IBuffer<T> Clone<T>(this IBuffer<T> buffer) where T : unmanaged
    {
        if (buffer is not ImmovableMemory<T> unmanagedMemory)
            throw new NotSupportedException();
        
        var newBuffer = new ImmovableMemory<T>(buffer.Length);
        var byteCount = (uint)(Unsafe.SizeOf<T>() * buffer.Length);
        Unsafe.CopyBlock(newBuffer.Pointer, unmanagedMemory.Pointer, byteCount);
        return newBuffer;
    }

    public static unsafe void Copy<T>(this IBuffer<T> source, IBuffer<T> destination, int count) where T : unmanaged
    {
        if (source is not ImmovableMemory<T> sourceBuffer || destination is not ImmovableMemory<T> destinationBuffer)
            throw new NotSupportedException();
        
        var byteCount = (uint)(Unsafe.SizeOf<T>() * count);
        Unsafe.CopyBlock(destinationBuffer.Pointer, sourceBuffer.Pointer, byteCount);
    }
}