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

#include "RecoveryLog.h"


namespace usub::utils
{
    RecoveryLog::RecoveryLog(const std::string& dbname)
        : db_name_(dbname),
          metadata_dir_("metadata/" + dbname + "/"),
          log_file_(metadata_dir_ + "recovery.log")
    {
        ensure_metadata_dir();
        this->log_out_.open(this->log_file_, std::ios::binary | std::ios::app);
        if (!this->log_out_.is_open())
            throw std::runtime_error("Failed to open recovery log for " + this->db_name_);
    }

    RecoveryLog::~RecoveryLog()
    {
        if (log_out_.is_open()) log_out_.close();
    }

    void RecoveryLog::log_put(const std::string& key, const std::string& value)
    {
        uint8_t op = 0;
        uint32_t key_len = key.size();
        uint32_t value_len = value.size();
        this->log_out_.write(reinterpret_cast<const char*>(&op), sizeof(op));
        this->log_out_.write(reinterpret_cast<const char*>(&key_len), sizeof(key_len));
        this->log_out_.write(key.data(), key_len);
        this->log_out_.write(reinterpret_cast<const char*>(&value_len), sizeof(value_len));
        this->log_out_.write(value.data(), value_len);
        this->log_out_.flush();
    }

    void RecoveryLog::log_delete(const std::string& key)
    {
        uint8_t op = 1;
        uint32_t key_len = key.size();
        this->log_out_.write(reinterpret_cast<const char*>(&op), sizeof(op));
        this->log_out_.write(reinterpret_cast<const char*>(&key_len), sizeof(key_len));
        this->log_out_.write(key.data(), key_len);
        this->log_out_.flush();
    }

    void RecoveryLog::log_command(const core::Command& cmd)
    {
        cmd.serialize(this->log_out_);
        this->log_out_.flush();
    }

    void RecoveryLog::ensure_metadata_dir() const
    {
        try
        {
            if (!std::filesystem::exists(metadata_dir_)) std::filesystem::create_directories(metadata_dir_);
        }
        catch (const std::exception& e)
        {
            std::cerr << "Failed to create metadata directory: " << e.what() << std::endl;
        }
    }


    void RecoveryLog::replay(const std::function<void(const core::Command&)>& callback) const
    {
        std::ifstream in(this->log_file_, std::ios::binary);
        if (!in.is_open())
            return;

        while (in.peek() != EOF)
        {
            core::Command cmd = core::Command::deserialize(in);
            callback(cmd);
        }
    }
    void RecoveryLog::clear()
    {
        if (this->log_out_.is_open())
            this->log_out_.close();

        std::filesystem::remove(this->log_file_);

        this->log_out_.open(this->log_file_, std::ios::binary | std::ios::app);
        if (!this->log_out_.is_open())
            throw std::runtime_error("Failed to reopen recovery log after clear for " + this->db_name_);
    }
} // utils
// usub