#include "pch.h"
#include "TextureLoader.h"
#include <DDSTextureLoader.h>
#include "DeviceResources.h"
#include "App.h"
#include "Logger.h"


winrt::com_ptr<ID3D11Texture2D> LoadImg(const wchar_t* fileName) {
	winrt::com_ptr<IWICImagingFactory2> factory = App::Get().GetWICImageFactory();
	if (!factory) {
		Logger::Get().Error("GetWICImageFactory 失败");
		return nullptr;
	}

	// 读取图像文件
	winrt::com_ptr<IWICBitmapDecoder> decoder;
	HRESULT hr = factory->CreateDecoderFromFilename(fileName, nullptr, GENERIC_READ, WICDecodeMetadataCacheOnDemand, decoder.put());
	if (FAILED(hr)) {
		Logger::Get().ComError("CreateDecoderFromFilename 失败", hr);
		return nullptr;
	}

	winrt::com_ptr<IWICBitmapFrameDecode> frame;
	hr = decoder->GetFrame(0, frame.put());
	if (FAILED(hr)) {
		Logger::Get().ComError("IWICBitmapFrameDecode::GetFrame 失败", hr);
		return nullptr;
	}

	bool useFloatFormat = false;
	{
		WICPixelFormatGUID sourceFormat;
		hr = frame->GetPixelFormat(&sourceFormat);
		if (FAILED(hr)) {
			Logger::Get().ComError("GetPixelFormat 失败", hr);
			return nullptr;
		}

		winrt::com_ptr<IWICComponentInfo> cInfo;
		hr = factory->CreateComponentInfo(sourceFormat, cInfo.put());
		if (FAILED(hr)) {
			Logger::Get().ComError("CreateComponentInfo", hr);
			return nullptr;
		}
		winrt::com_ptr<IWICPixelFormatInfo2> formatInfo = cInfo.try_as<IWICPixelFormatInfo2>();
		if (!formatInfo) {
			Logger::Get().Error("IWICComponentInfo 转换为 IWICPixelFormatInfo2 时失败");
			return nullptr;
		}

		UINT bitsPerPixel;
		WICPixelFormatNumericRepresentation type;
		hr = formatInfo->GetBitsPerPixel(&bitsPerPixel);
		if (FAILED(hr)) {
			Logger::Get().ComError("GetBitsPerPixel", hr);
			return nullptr;
		}
		hr = formatInfo->GetNumericRepresentation(&type);
		if (FAILED(hr)) {
			Logger::Get().ComError("GetNumericRepresentation", hr);
			return nullptr;
		}

		useFloatFormat = bitsPerPixel > 32 || type == WICPixelFormatNumericRepresentationFixed || type == WICPixelFormatNumericRepresentationFloat;
	}

	// 转换格式
	winrt::com_ptr<IWICFormatConverter> formatConverter;
	hr = factory->CreateFormatConverter(formatConverter.put());
	if (FAILED(hr)) {
		Logger::Get().ComError("CreateFormatConverter 失败", hr);
		return nullptr;
	}

	WICPixelFormatGUID targetFormat = useFloatFormat ? GUID_WICPixelFormat64bppRGBAHalf : GUID_WICPixelFormat32bppBGRA;
	hr = formatConverter->Initialize(frame.get(), targetFormat, WICBitmapDitherTypeNone, nullptr, 0, WICBitmapPaletteTypeCustom);
	if (FAILED(hr)) {
		Logger::Get().ComError("IWICFormatConverter::Initialize 失败", hr);
		return nullptr;
	}

	// 检查 D3D 纹理尺寸限制
	UINT width, height;
	hr = formatConverter->GetSize(&width, &height);
	if (FAILED(hr)) {
		Logger::Get().ComError("GetSize 失败", hr);
		return nullptr;
	}

	if (width > D3D11_REQ_TEXTURE2D_U_OR_V_DIMENSION || height > D3D11_REQ_TEXTURE2D_U_OR_V_DIMENSION) {
		Logger::Get().Error("图像尺寸超出限制");
		return nullptr;
	}

	UINT stride = width * (useFloatFormat ? 8 : 4);
	UINT size = stride * height;
	std::unique_ptr<BYTE[]> buf(new BYTE[size]);

	hr = formatConverter->CopyPixels(nullptr, stride, size, buf.get());
	if (FAILED(hr)) {
		Logger::Get().ComError("CopyPixels 失败", hr);
		return nullptr;
	}

	D3D11_TEXTURE2D_DESC desc{};
	desc.Width = width;
	desc.Height = height;
	desc.MipLevels = 1;
	desc.ArraySize = 1;
	desc.Format = useFloatFormat ? DXGI_FORMAT_R16G16B16A16_FLOAT : DXGI_FORMAT_B8G8R8A8_UNORM;
	desc.SampleDesc.Count = 1;
	desc.SampleDesc.Quality = 0;
	desc.Usage = D3D11_USAGE_DEFAULT;
	desc.BindFlags = D3D11_BIND_SHADER_RESOURCE | D3D11_BIND_RENDER_TARGET;

	D3D11_SUBRESOURCE_DATA initData{};
	initData.pSysMem = buf.get();
	initData.SysMemPitch = stride;

	winrt::com_ptr<ID3D11Texture2D> result;
	hr = App::Get().GetDeviceResources().GetD3DDevice()->CreateTexture2D(&desc, &initData, result.put());
	if (FAILED(hr)) {
		Logger::Get().ComError("CreateTexture2D 失败", hr);
		return nullptr;
	}

	return result;
}

winrt::com_ptr<ID3D11Texture2D> LoadDDS(const wchar_t* fileName) {
	winrt::com_ptr<ID3D11Resource> result;

	DirectX::DDS_ALPHA_MODE alphaMode = DirectX::DDS_ALPHA_MODE_STRAIGHT;
	HRESULT hr = DirectX::CreateDDSTextureFromFileEx(
		App::Get().GetDeviceResources().GetD3DDevice(),
		fileName,
		0,
		D3D11_USAGE_DEFAULT,
		D3D11_BIND_SHADER_RESOURCE | D3D11_BIND_RENDER_TARGET,
		0,
		0,
		false,
		result.put(),
		nullptr,
		&alphaMode
	);
	if (FAILED(hr)) {
		Logger::Get().ComInfo("CreateDDSTextureFromFile 失败，将尝试不作为渲染目标", hr);

		// 第二次尝试，不作为渲染目标
		hr = DirectX::CreateDDSTextureFromFileEx(
			App::Get().GetDeviceResources().GetD3DDevice(),
			fileName,
			0,
			D3D11_USAGE_DEFAULT,
			D3D11_BIND_SHADER_RESOURCE,
			0,
			0,
			false,
			result.put(),
			nullptr,
			&alphaMode
		);

		if (FAILED(hr)) {
			Logger::Get().ComError("CreateDDSTextureFromFile 失败", hr);
			return nullptr;
		}
	}

	winrt::com_ptr<ID3D11Texture2D> tex = result.try_as<ID3D11Texture2D>();
	if (!tex) {
		Logger::Get().Error("从 ID3D11Resource 获取 ID3D11Texture2D 失败");
		return nullptr;
	}

	return tex;
}

winrt::com_ptr<ID3D11Texture2D> TextureLoader::Load(const wchar_t* fileName) {
	std::wstring_view sv(fileName);
	size_t npos = sv.find_last_of(L'.');
	if (npos == std::wstring_view::npos) {
		Logger::Get().Error("文件名无后缀名");
		return nullptr;
	}

	std::wstring_view suffix = sv.substr(npos + 1);
	
	static std::unordered_map<std::wstring_view, winrt::com_ptr<ID3D11Texture2D>(*)(const wchar_t*)> funcs = {
		{L"bmp", LoadImg},
		{L"jpg", LoadImg},
		{L"jpeg", LoadImg},
		{L"png", LoadImg},
		{L"tif", LoadImg},
		{L"tiff", LoadImg},
		{L"dds", LoadDDS}
	};

	auto it = funcs.find(suffix);
	if (it == funcs.end()) {
		Logger::Get().Error("不支持读取该格式");
		return nullptr;
	}

	return it->second(fileName);
}