#include "TextureCooker.h"

#include <cstdlib>
#include <memory>
#include <span>
#include <stdexcept>
#include <string>

#include <tinyexr.h>

#include <destrum/Assets/TextureFile.h>

bool TextureCooker::CookFileIfNeeded(const fs::path& source, const fs::path& output) const
{
    if (!NeedsRebuild(source, output))
        return false;

    float* rgba = nullptr;
    int width = 0;
    int height = 0;
    const char* error = nullptr;

    if (LoadEXR(&rgba, &width, &height, source.string().c_str(), &error) != TINYEXR_SUCCESS)
    {
        const std::string message = error ? error : "unknown error";
        FreeEXRErrorMessage(error);
        throw std::runtime_error("TinyEXR failed to load '" + source.string() + "': " + message);
    }

    const std::unique_ptr<float, decltype(&std::free)> pixels(rgba, &std::free);
    const std::size_t floatCount = static_cast<std::size_t>(width) * static_cast<std::size_t>(height) * 4;

    const TextureFile::Texture texture = TextureFile::FromRGBA32Float(
        static_cast<std::uint32_t>(width),
        static_cast<std::uint32_t>(height),
        std::span<const float>(pixels.get(), floatCount));

    fs::create_directories(output.parent_path());
    TextureFile::WriteToFile(texture, output);
    return true;
}

fs::path TextureCooker::MakeOutputPath(const fs::path& dstLikeSrc)
{
    fs::path out = dstLikeSrc;
    out.replace_extension(dstLikeSrc.extension().string() + std::string(TextureFile::Extension));
    return out;
}

bool TextureCooker::NeedsRebuild(const fs::path& source, const fs::path& output)
{
    if (!fs::exists(output))
        return true;
    if (fs::last_write_time(source) > fs::last_write_time(output))
        return true;
    return TextureFile::ReadVersionFromFile(output) != TextureFile::Version;
}