//
// Created by 张衡 on 25-7-8.
//

#ifndef LOGGER_H
#define LOGGER_H

#include <queue>
#include <mutex>
#include <string>
#include <condition_variable>
#include <thread>
#include <fstream>
#include <atomic>
#include <sstream>
#include <vector>
#include <stdexcept>



//辅助函数，多个参数转化字符串
template <typename T>
std::string to_string_helper(T&& arg) {
    std::ostringstream oss;
    oss << std::forward<T>(arg);
    return oss.str();
}

class LogQueue {
public:
    void push(const std::string& msg) {
        std::lock_guard<std::mutex> lock(mutex_);
        //构造好自动加锁，析构自动解锁
        cond_var_.notify_one();
    }; //字符串放队列中
    bool pop(std::string& msg) {
        std::unique_lock<std::mutex> lock(mutex_);
        //条件变量唤醒之后直接加锁
        cond_var_.wait(lock, [this]() {
           return !queue_.empty() || is_shutdown_; //返回true就继续往下走
        });
        //消费逻辑
        //队列不为空or已经关闭
        if (is_shutdown_ && queue_.empty()) {
            return false;
        }
        msg = queue_.front(); //返回消息给msg指针
        queue_.pop();
        return true;
    };
    void shutdown() {
        std::lock_guard<std::mutex> lock(mutex_);
        is_shutdown_ = true;
        cond_var_.notify_all();
    };
private:
    std::queue<std::string> queue_;
    std::mutex mutex_;
    std::condition_variable cond_var_;
    bool is_shutdown_ = false;
};

class Logger {
public:
    Logger(const std::string& filename) : log_file_(filename, std::ios::out | std::ios::app)
    , exit_flag_(false) {
        if (!log_file_.is_open()) {
            throw std::runtime_error("Failed to open log file");
        }

        worker_thread_ = std::thread([this]() {
            std::string msg;
            while (log_queue_.pop(msg)) {
                log_file_ << msg << std::endl;
            }
        });
    };
    ~Logger();

    template<typename ... Args>
    void log(const std::string& format, Args&& ...args);

private:
    LogQueue log_queue_;
    std::thread worker_thread_;
    std::ofstream log_file_;
    std::atomic<bool> exit_flag_;
};




#endif //LOGGER_H