using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Dalamud.Bindings.ImGui;
using TerraFX.Interop.DirectX;

namespace Auspex.Rendering.Direct3D;

internal sealed class HighResFontAtlas : IDisposable
{
	private struct ImFontConfigHead
	{
		public IntPtr FontData;

		public int FontDataSize;

		public byte FontDataOwnedByAtlas;

		private byte _pad1;

		private byte _pad2;

		private byte _pad3;

		public int FontNo;

		public float SizePixels;
	}

	private const float HighResFontSize = 64f;

	private IntPtr _atlas;

	private unsafe ID3D11Texture2D* _texture;

	private unsafe ID3D11ShaderResourceView* _srv;

	public ImFontPtr Font { get; }

	public unsafe IntPtr TextureSRV => (nint)_srv;

	public unsafe HighResFontAtlas(FrameRenderContext ctx)
	{
		_atlas = ImFontAtlas_ImFontAtlas();
		try
		{
			IntPtr intPtr = ImFontConfig_ImFontConfig();
			try
			{
				((ImFontConfigHead*)intPtr)->SizePixels = 64f;
				IntPtr intPtr2 = ImFontAtlas_AddFontDefault(_atlas, intPtr);
				Font = Unsafe.As<IntPtr, ImFontPtr>(ref intPtr2);
			}
			finally
			{
				ImFontConfig_destroy(intPtr);
			}
			if (!ImFontAtlas_Build(_atlas))
			{
				throw new InvalidOperationException("Failed to build high-res font atlas");
			}
			byte* pSysMem = default(byte*);
			int num = default(int);
			int height = default(int);
			int num2 = default(int);
			ImFontAtlas_GetTexDataAsRGBA32(_atlas, 0, &pSysMem, &num, &height, &num2);
			D3D11_TEXTURE2D_DESC d3D11_TEXTURE2D_DESC = new D3D11_TEXTURE2D_DESC
			{
				Width = (uint)num,
				Height = (uint)height,
				MipLevels = 1u,
				ArraySize = 1u,
				Format = DXGI_FORMAT.DXGI_FORMAT_R8G8B8A8_UNORM,
				SampleDesc = new DXGI_SAMPLE_DESC
				{
					Count = 1u,
					Quality = 0u
				},
				Usage = D3D11_USAGE.D3D11_USAGE_DEFAULT,
				BindFlags = 8u
			};
			D3D11_SUBRESOURCE_DATA d3D11_SUBRESOURCE_DATA = new D3D11_SUBRESOURCE_DATA
			{
				pSysMem = pSysMem,
				SysMemPitch = (uint)(num * num2)
			};
			ID3D11Texture2D* texture = default(ID3D11Texture2D*);
			Marshal.ThrowExceptionForHR(ctx.Device->CreateTexture2D(&d3D11_TEXTURE2D_DESC, &d3D11_SUBRESOURCE_DATA, &texture));
			_texture = texture;
			ID3D11ShaderResourceView* srv = default(ID3D11ShaderResourceView*);
			Marshal.ThrowExceptionForHR(ctx.Device->CreateShaderResourceView((ID3D11Resource*)_texture, null, &srv));
			_srv = srv;
			ImFontAtlas_ClearTexData(_atlas);
		}
		catch
		{
			Dispose();
			throw;
		}
	}

	public unsafe void Dispose()
	{
		if (_srv != null)
		{
			_srv->Release();
			_srv = null;
		}
		if (_texture != null)
		{
			_texture->Release();
			_texture = null;
		}
		if (_atlas != (IntPtr)0)
		{
			ImFontAtlas_destroy(_atlas);
			_atlas = (IntPtr)0;
		}
		GC.SuppressFinalize(this);
	}

	[DllImport("cimgui")]
	private static extern IntPtr ImFontAtlas_ImFontAtlas();

	[DllImport("cimgui")]
	private static extern void ImFontAtlas_destroy(IntPtr self);

	[DllImport("cimgui")]
	private static extern IntPtr ImFontAtlas_AddFontDefault(IntPtr self, IntPtr font_cfg);

	[DllImport("cimgui")]
	[return: MarshalAs(UnmanagedType.U1)]
	private static extern bool ImFontAtlas_Build(IntPtr self);

	[DllImport("cimgui")]
	private unsafe static extern void ImFontAtlas_GetTexDataAsRGBA32(IntPtr self, int texture_index, byte** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel);

	[DllImport("cimgui")]
	private static extern void ImFontAtlas_ClearTexData(IntPtr self);

	[DllImport("cimgui")]
	private static extern IntPtr ImFontConfig_ImFontConfig();

	[DllImport("cimgui")]
	private static extern void ImFontConfig_destroy(IntPtr self);
}