#include "core/rendering/screenshot.hpp"

#include <chrono>
#include <cstdint>
#include <ctime>
#include <filesystem>
#include <string>
#include <vector>

#include "external/stb_image_write.h"

namespace Screenshot {

    namespace {

        // Crea la carpeta `screenshots/` si no existeix i torna la ruta
        // completa al fitxer. El paràmetre `filename` rep el nom nu (sense
        // directori) per poder mostrar-lo a la notificació.
        auto generateFilePath(std::string& filename) -> std::string {
            std::filesystem::create_directories("screenshots");

            const auto NOW = std::chrono::system_clock::now();
            const std::time_t TIME = std::chrono::system_clock::to_time_t(NOW);
            const std::tm* tm = std::localtime(&TIME);

            char timestamp[20];
            std::strftime(timestamp, sizeof(timestamp), "%Y%m%d_%H%M%S", tm);

            filename = std::string("scr_") + timestamp + ".png";
            return "screenshots/" + filename;
        }

        // Converteix ARGB8888 → RGBA8888 in-place i escriu el PNG. stb_image_write
        // espera RGBA en ordre byte (little-endian: R al byte baix, A al byte alt).
        auto writePng(std::uint32_t* buffer, int width, int height, const std::string& filepath) -> bool {
            const int TOTAL = width * height;
            for (int i = 0; i < TOTAL; ++i) {
                const std::uint32_t P = buffer[i];
                const std::uint32_t A = (P >> 24) & 0xFF;
                const std::uint32_t R = (P >> 16) & 0xFF;
                const std::uint32_t G = (P >> 8) & 0xFF;
                const std::uint32_t B = P & 0xFF;
                buffer[i] = R | (G << 8) | (B << 16) | (A << 24);
            }
            return stbi_write_png(filepath.c_str(), width, height, 4, buffer, width * 4) != 0;
        }

    }  // namespace

    auto save(const std::uint32_t* buffer, int width, int height) -> std::string {
        // Còpia local per no tocar el canvas original durant la conversió.
        std::vector<std::uint32_t> copy(buffer, buffer + (static_cast<size_t>(width) * height));

        std::string filename;
        const std::string FILEPATH = generateFilePath(filename);

        return writePng(copy.data(), width, height, FILEPATH) ? filename : "";
    }

}  // namespace Screenshot