Crow/include/crow/logging.h

#pragma once

#include <string>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>

#include "crow/settings.h"

namespace crow
{
    enum class LogLevel
    {
#ifndef ERROR
#ifndef DEBUG
        DEBUG = 0,
        INFO,
        WARNING,
        ERROR,
        CRITICAL,
#endif
#endif

        Debug = 0,
        Info,
        Warning,
        Error,
        Critical,
    };

    class ILogHandler
    {
    public:
        virtual void log(std::string message, LogLevel level) = 0;
    };

    class CerrLogHandler : public ILogHandler
    {
    public:
        void log(std::string message, LogLevel /*level*/) override
        {
            std::cerr << message;
        }
    };

    class logger
    {

    private:
        //
        static std::string timestamp()
        {
            char date[32];
            time_t t = time(0);

            tm my_tm;

#if defined(_MSC_VER) || defined(__MINGW32__)
            gmtime_s(&my_tm, &t);
#else
            gmtime_r(&t, &my_tm);
#endif

            size_t sz = strftime(date, sizeof(date), "%Y-%m-%d %H:%M:%S", &my_tm);
            return std::string(date, date + sz);
        }

    public:
        logger(std::string prefix, LogLevel level):
          level_(level)
        {
#ifdef CROW_ENABLE_LOGGING
            stringstream_ << "(" << timestamp() << ") [" << prefix << "] ";
#endif
        }
        ~logger()
        {
#ifdef CROW_ENABLE_LOGGING
            if (level_ >= get_current_log_level())
            {
                stringstream_ << std::endl;
                get_handler_ref()->log(stringstream_.str(), level_);
            }
#endif
        }

        //
        template<typename T>
        logger& operator<<(T const& value)
        {

#ifdef CROW_ENABLE_LOGGING
            if (level_ >= get_current_log_level())
            {
                stringstream_ << value;
            }
#endif
            return *this;
        }

        //
        static void setLogLevel(LogLevel level)
        {
            get_log_level_ref() = level;
        }

        static void setHandler(ILogHandler* handler)
        {
            get_handler_ref() = handler;
        }

        static LogLevel get_current_log_level()
        {
            return get_log_level_ref();
        }

    private:
        //
        static LogLevel& get_log_level_ref()
        {
            static LogLevel current_level = static_cast<LogLevel>(CROW_LOG_LEVEL);
            return current_level;
        }
        static ILogHandler*& get_handler_ref()
        {
            static CerrLogHandler default_handler;
            static ILogHandler* current_handler = &default_handler;
            return current_handler;
        }

        //
        std::ostringstream stringstream_;
        LogLevel level_;
    };
} // namespace crow

#define CROW_LOG_CRITICAL                                                  \
    if (crow::logger::get_current_log_level() <= crow::LogLevel::Critical) \
    crow::logger("CRITICAL", crow::LogLevel::Critical)
#define CROW_LOG_ERROR                                                  \
    if (crow::logger::get_current_log_level() <= crow::LogLevel::Error) \
    crow::logger("ERROR   ", crow::LogLevel::Error)
#define CROW_LOG_WARNING                                                  \
    if (crow::logger::get_current_log_level() <= crow::LogLevel::Warning) \
    crow::logger("WARNING ", crow::LogLevel::Warning)
#define CROW_LOG_INFO                                                  \
    if (crow::logger::get_current_log_level() <= crow::LogLevel::Info) \
    crow::logger("INFO    ", crow::LogLevel::Info)
#define CROW_LOG_DEBUG                                                  \
    if (crow::logger::get_current_log_level() <= crow::LogLevel::Debug) \
    crow::logger("DEBUG   ", crow::LogLevel::Debug)