/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include "ImageLoaderKtx.hpp"

#include <ktx.h>

#include <memory>
#include <vector>
#include <iostream>
#include <stdexcept>

namespace
{
	void KtxDestroy(ktxTexture* tex)
	{
		ktxTexture_Destroy(tex);
	}
}

namespace OpenVulkano::Image
{
	std::unique_ptr<Image> ImageLoaderKtx::loadFromFile(const std::string& filePath)
	{
		ktxTexture* tmp = nullptr;
		KTX_error_code error_code =
		ktxTexture_CreateFromNamedFile(filePath.c_str(), KTX_TEXTURE_CREATE_LOAD_IMAGE_DATA_BIT, &tmp);
		std::unique_ptr<ktxTexture, decltype(&KtxDestroy)> texture(tmp, &KtxDestroy);

		if (error_code != KTX_SUCCESS)
		{
			throw std::runtime_error("Failed to load KTX texture: " + std::string(ktxErrorString(error_code)));
		}

		auto result = ExtractImage(texture.get());
		return result;
	}

	std::unique_ptr<Image> ImageLoaderKtx::loadFromMemory(const std::vector<uint8_t>& buffer)
	{
		ktxTexture* tmp = nullptr;
		KTX_error_code error_code =
		ktxTexture_CreateFromMemory(buffer.data(), buffer.size(), KTX_TEXTURE_CREATE_LOAD_IMAGE_DATA_BIT, &tmp);
		std::unique_ptr<ktxTexture, decltype(&KtxDestroy)> texture(tmp, &KtxDestroy);

		if (error_code != KTX_SUCCESS)
		{
			throw std::runtime_error("Failed to load KTX texture from memory: " + std::string(ktxErrorString(error_code)));
		}

		auto result = ExtractImage(texture.get());
		return result;
	}

	Math::Vector2i ImageLoaderKtx::GetImageDimensions(const std::string& filename)
	{
		ktxTexture* tmp = nullptr;
		KTX_error_code result =
		ktxTexture_CreateFromNamedFile(filename.c_str(), KTX_TEXTURE_CREATE_LOAD_IMAGE_DATA_BIT, &tmp);
		std::unique_ptr<ktxTexture, decltype(&KtxDestroy)> texture(tmp, &KtxDestroy);

		if (result != KTX_SUCCESS)
		{
			throw std::runtime_error("Failed to load KTX texture for dimensions: "
			                         + std::string(ktxErrorString(result)));
		}

		Math::Vector2i dimensions(texture->baseWidth, texture->baseHeight);
		return dimensions;
	}

	std::unique_ptr<Image> ImageLoaderKtx::ExtractImage(ktxTexture* texture)
	{
		if (!texture->pData)
		{
			throw std::runtime_error("No image data found in KTX texture.");
		}

		auto width = static_cast<int>(texture->baseWidth);
		auto height = static_cast<int>(texture->baseHeight);

		auto image = std::make_unique<Image>();
		image->resolution.x = width;
		image->resolution.y = height;
		image->resolution.z = 1;

		if (texture->classId == ktxTexture1_c)
		{
			ktxTexture1* tx = reinterpret_cast<ktxTexture1*>(texture);
			DataFormat format = DataFormat::Format::UNDEFINED;
			switch (tx->glInternalformat)
			{
				case 0x8051: /* GL_RGB8_EXT */     format = DataFormat::Format::R8G8B8_UNORM; break;
				case 0x8054: /* GL_RGB16_EXT */    format = DataFormat::Format::R16G16B16_UNORM; break;
				case 0x8057: /* GL_RGB5_A1_EXT */  format = DataFormat::Format::R5G5B5A1_UNORM_PACK16; break;
				case 0x8058: /* GL_RGBA8_EXT */    format = DataFormat::Format::R8G8B8A8_UNORM; break;
				case 0x8059: /* GL_RGB10_A2_EXT */ format = DataFormat::Format::A2R10G10B10_UNORM_PACK32; break;
				case 0x805B: /* GL_RGBA16_EXT */   format = DataFormat::Format::R16G16B16A16_UNORM; break;
				default: throw std::runtime_error("Unhandled texture1 format: " + tx->glInternalformat);
			}
			image->dataFormat = format;
		}
		else if (texture->classId == ktxTexture2_c)
		{
			ktxTexture2* tx = reinterpret_cast<ktxTexture2*>(texture);
			image->dataFormat = reinterpret_cast<DataFormat::Format&>(tx->vkFormat);
		}
		else [[unlikely]]
		{
			throw std::runtime_error("ktxTexture has unhandled classId!");
		}

		image->data = Array<uint8_t>(texture->dataSize);
		memcpy(image->data.Data(), texture->pData, image->data.Size());

		return image;
	}
}