// logger.cpp
#include "logger.hpp"

#include <chrono>
#include <cstdio>
#include <ctime>
#include <format>
#include <fstream>
#include <iomanip>

std::ofstream Logger::log_file;
std::string Logger::current_log_filename;

void Logger::set_log_to_file(const std::string& filename)
{
    current_log_filename = filename;
    log_file.open(filename, std::ios::app);
    if (!log_file.is_open())
    {
        std::cerr << "[Logger] Failed to open log file: " << filename << std::endl;
    }
}

std::string Logger::get_time_string()
{
    using namespace std::chrono;

    auto now = system_clock::now();
    auto zt = zoned_time{current_zone(), now};  // 自动使用系统时区（Asia/Shanghai）

    // 获取毫秒部分
    auto ms = duration_cast<milliseconds>(zt.get_local_time().time_since_epoch()) % 1000;

    // 格式化
    std::ostringstream ss;
    ss << format("{:%Y-%m-%d %H:%M:%S}", zt) << '.' << std::setw(3) << std::setfill('0') << ms.count();

    return ss.str();
}

std::string Logger::get_current_time_utc8()
{
    using namespace std::chrono;

    auto now = system_clock::now();
    zoned_time zt{current_zone(), now};

    auto ms = duration_cast<milliseconds>(zt.get_local_time().time_since_epoch()) % 1000;

    std::ostringstream ss;
    ss << format("{:%Y%m%d%H%M%S}", zt) << std::setw(3) << std::setfill('0') << ms.count();

    return ss.str();
}

void Logger::log(LogLevel level, const std::string& msg)
{
    std::string level_str;
    switch (level)
    {
        case LogLevel::INFO:
            level_str = "[INFO] ";
            break;
        case LogLevel::WARN:
            level_str = "[WARN] ";
            break;
        case LogLevel::ERROR:
            level_str = "[ERROR]";
            break;
    }

    std::string full_msg = get_time_string() + " " + level_str + " " + msg;

    std::cout << full_msg << std::endl;

    if (log_file.is_open())
    {
        log_file << full_msg << std::endl;
        log_file.flush();

        // 检查是否需要轮转
        if (get_file_size(current_log_filename) >= MAX_LOG_FILE_SIZE)
        {
            rotate_logs();
        }
    }
}

size_t Logger::get_file_size(const std::string& filename)
{
    std::ifstream in(filename, std::ifstream::ate | std::ifstream::binary);
    return in.is_open() ? static_cast<size_t>(in.tellg()) : 0;
}

void Logger::rotate_logs()
{
    log_file.close();

    // 删除最旧的日志
    std::string oldest = current_log_filename + "." + std::to_string(MAX_LOG_BACKUP_COUNT);
    std::remove(oldest.c_str());

    // 重命名 *.4 -> *.5, ..., *.1 -> *.2
    for (int i = MAX_LOG_BACKUP_COUNT - 1; i >= 1; --i)
    {
        std::string old_name = current_log_filename + "." + std::to_string(i);
        std::string new_name = current_log_filename + "." + std::to_string(i + 1);
        std::rename(old_name.c_str(), new_name.c_str());
    }

    // 当前日志 -> .1
    std::string first_backup = current_log_filename + ".1";
    std::rename(current_log_filename.c_str(), first_backup.c_str());

    // 重新打开新日志
    log_file.open(current_log_filename, std::ios::trunc);
}