//
// Created by Kirill Zhukov on 20.04.2025.
//

#include "VersionManager.h"

namespace usub::utils
{
    VersionManager::VersionManager(const std::string& dbname)
    : db_name(dbname),
      metadata_dir("metadata/" + this->db_name + "/"),
      version_file(this->metadata_dir + "version.meta")
    {
        ensure_metadata_dir();
        load_version();
    }

    uint64_t VersionManager::next_version()
    {
        return this->version.fetch_add(1, std::memory_order_relaxed);
    }

    void VersionManager::ensure_metadata_dir()
    {
        try
        {
            if (!std::filesystem::exists(this->metadata_dir))
            {
                std::filesystem::create_directories(this->metadata_dir);
            }
        }
        catch (const std::exception& e)
        {
            std::cerr << "Failed to create metadata dir: " << e.what() << std::endl;
        }
    }

    void VersionManager::load_version()
    {
        std::ifstream f(this->version_file, std::ios::binary);
        if (f.is_open())
        {
            uint64_t v = 0;
            f.read(reinterpret_cast<char*>(&v), sizeof(v));
            if (f.good() && v > 0)
            {
                this->version.store(v, std::memory_order_relaxed);
            }
            else
            {
                std::cerr << "Warning: empty or corrupted version file for " << this->db_name << "\n";
            }
        }
        else
        {
            std::cerr << "Warning: no version file for " << this->db_name << ", starting fresh\n";
        }
    }

    void VersionManager::save_version()
    {
        std::ofstream f(this->version_file, std::ios::binary | std::ios::trunc);
        if (!f.is_open())
        {
            std::cerr << "Error: cannot save version for " << this->db_name << "\n";
            return;
        }
        uint64_t v = this->version.load(std::memory_order_relaxed);
        f.write(reinterpret_cast<const char*>(&v), sizeof(v));
        if (!f.good())
        {
            std::cerr << "Error: cannot write version for " << this->db_name << "\n";
        }
    }
}