using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Dalamud.Plugin.Services;
using TerraFX.Interop.DirectX;

namespace Auspex.Rendering.Direct3D;

internal sealed class GpuBuffer<T> : IDisposable where T : unmanaged
{
	public sealed class Builder : IDisposable
	{
		private FrameRenderContext _ctx;

		private GpuBuffer<T> _buffer;

		private unsafe byte* _dataPtr;

		private int _offset;

		private unsafe ID3D11Buffer* _staging;

		public int CurElements => _buffer.CurElements;

		internal unsafe Builder(FrameRenderContext ctx, GpuBuffer<T> buffer)
		{
			_ctx = ctx;
			_buffer = buffer;
			buffer.CurElements = 0;
			buffer._hasWarnedOverflow = false;
			_offset = 0;
			D3D11_MAPPED_SUBRESOURCE d3D11_MAPPED_SUBRESOURCE = default(D3D11_MAPPED_SUBRESOURCE);
			if (buffer.Dynamic)
			{
				Marshal.ThrowExceptionForHR(ctx.Context->Map((ID3D11Resource*)buffer.Buffer, 0u, D3D11_MAP.D3D11_MAP_WRITE_DISCARD, 0u, &d3D11_MAPPED_SUBRESOURCE));
				_dataPtr = (byte*)d3D11_MAPPED_SUBRESOURCE.pData;
				return;
			}
			D3D11_BUFFER_DESC d3D11_BUFFER_DESC = new D3D11_BUFFER_DESC
			{
				ByteWidth = (uint)(buffer.ElementSize * buffer.MaxElements),
				Usage = D3D11_USAGE.D3D11_USAGE_STAGING,
				CPUAccessFlags = 65536u
			};
			ID3D11Buffer* staging = default(ID3D11Buffer*);
			Marshal.ThrowExceptionForHR(ctx.Device->CreateBuffer(&d3D11_BUFFER_DESC, null, &staging));
			_staging = staging;
			Marshal.ThrowExceptionForHR(ctx.Context->Map((ID3D11Resource*)_staging, 0u, D3D11_MAP.D3D11_MAP_WRITE_DISCARD, 0u, &d3D11_MAPPED_SUBRESOURCE));
			_dataPtr = (byte*)d3D11_MAPPED_SUBRESOURCE.pData;
		}

		public unsafe void Dispose()
		{
			if (_buffer.Dynamic)
			{
				_ctx.Context->Unmap((ID3D11Resource*)_buffer.Buffer, 0u);
			}
			else
			{
				_ctx.Context->Unmap((ID3D11Resource*)_staging, 0u);
				_ctx.Context->CopyResource((ID3D11Resource*)_buffer.Buffer, (ID3D11Resource*)_staging);
				_staging->Release();
				_staging = null;
			}
			GC.SuppressFinalize(this);
		}

		public unsafe void Add(ref T item)
		{
			if (_buffer.CurElements >= _buffer.MaxElements)
			{
				if (!_buffer._hasWarnedOverflow)
				{
					_buffer._hasWarnedOverflow = true;
					IPluginLog log = AuspexService.Log;
					DefaultInterpolatedStringHandler val = default(DefaultInterpolatedStringHandler);
					((DefaultInterpolatedStringHandler)(ref val))._002Ector(60, 2);
					((DefaultInterpolatedStringHandler)(ref val)).AppendLiteral("[Auspex] ");
					((DefaultInterpolatedStringHandler)(ref val)).AppendFormatted(_buffer.FriendlyName);
					((DefaultInterpolatedStringHandler)(ref val)).AppendLiteral(" buffer full (");
					((DefaultInterpolatedStringHandler)(ref val)).AppendFormatted<int>(_buffer.MaxElements);
					((DefaultInterpolatedStringHandler)(ref val)).AppendLiteral(" elements); further elements dropped.");
					log.Warning(((DefaultInterpolatedStringHandler)(ref val)).ToStringAndClear());
				}
			}
			else
			{
				GpuBuffer<T> buffer = _buffer;
				int curElements = buffer.CurElements + 1;
				buffer.CurElements = curElements;
				Unsafe.CopyBlockUnaligned((void*)(_dataPtr + _offset), Unsafe.AsPointer<T>(ref item), (uint)sizeof(T));
				_offset += sizeof(T);
			}
		}

		public void Add(T item)
		{
			Add(ref item);
		}
	}

	private bool _hasWarnedOverflow;

	public string FriendlyName { get; private set; }

	public bool Dynamic { get; init; }

	public int ElementSize { get; init; }

	public int MaxElements { get; init; }

	public int CurElements { get; private set; }

	public unsafe ID3D11Buffer* Buffer { get; init; }

	public unsafe GpuBuffer(string friendlyName, FrameRenderContext ctx, int maxElements, uint bindFlags, bool dynamic)
	{
		FriendlyName = friendlyName;
		Dynamic = dynamic;
		ElementSize = sizeof(T);
		MaxElements = maxElements;
		D3D11_BUFFER_DESC d3D11_BUFFER_DESC = new D3D11_BUFFER_DESC
		{
			ByteWidth = (uint)(ElementSize * maxElements),
			Usage = (dynamic ? D3D11_USAGE.D3D11_USAGE_DYNAMIC : D3D11_USAGE.D3D11_USAGE_DEFAULT),
			BindFlags = bindFlags,
			CPUAccessFlags = (dynamic ? 65536u : 0u)
		};
		ID3D11Buffer* buffer = default(ID3D11Buffer*);
		Marshal.ThrowExceptionForHR(ctx.Device->CreateBuffer(&d3D11_BUFFER_DESC, null, &buffer));
		Buffer = buffer;
	}

	public unsafe void Dispose()
	{
		if (Buffer != null)
		{
			Buffer->Release();
		}
		GC.SuppressFinalize(this);
	}

	public Builder Map(FrameRenderContext ctx)
	{
		return new Builder(ctx, this);
	}
}