logger.hpp

//
// Created by anson on 19-2-25.
//

#ifndef FS_NDN_LOGGER_HPP
#define FS_NDN_LOGGER_HPP


#include <iostream>
#include <ctime>

enum LogLevel
{
    LOG_NONE   = 0, // Log nothing
    LOG_ERROR  = 1, // Log errors only
    LOG_DEBUG  = 2, // Log all (debug + error)
    LOG_DEBUG2 = 3
};

inline const char* toString(LogLevel l)
{
    switch (l)
    {
        case LOG_ERROR:	return "ERROR";
        default:		return "DEBUG";
    }
}

class Output2FILE // implementation of OutputPolicy
{
public:
    static FILE*& stream();
    static void output(const std::string& msg);
};
inline FILE*& Output2FILE::stream()
{
    static FILE* pStream = stderr;
    return pStream;
}
inline void Output2FILE::output(const std::string& msg)
{
    FILE* pStream = stream();
    if (!pStream)
        return;

    fprintf(pStream, "%s", msg.c_str());
    fflush(pStream);
}

template <typename OutputPolicy>
class Log
{
public:
    Log()
    {
    }

    virtual ~Log()
    {
        OutputPolicy::output(os.str());
    }

    std::ostringstream& get(LogLevel level = LOG_DEBUG)
    {
        std::time_t time = std::time(nullptr);
        os << "- " << time;
        os << " " << toString(level) << ": ";

        os << std::string(level > LOG_DEBUG ? level - LOG_DEBUG : 0, '\t');
        logLevel_ = level;
        return os;
    }
public:
    static LogLevel& reportingLevel()
    {
        static LogLevel level = LOG_DEBUG;
        return level;
    }
protected:
    std::ostringstream os;
private:
    Log(const Log&);
    Log& operator =(const Log&);
private:
    LogLevel logLevel_;
};

#define FILE_LOG(level) \
if (level > Log<Output2FILE>::reportingLevel() || !Output2FILE::stream()) ; \
else Log<Output2FILE>().get(level)


#endif //FS_NDN_LOGGER_HPP