/*
   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   Her Majesty the Queen in Right of Canada (Communications Research
   Center Canada)

   Copyright (C), 2014, Matthias P. Braendli, matthias.braendli@mpb.li
 */
/*
   This file is part of CRC-DADMOD.

   CRC-DADMOD is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as
   published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   CRC-DADMOD is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with CRC-DADMOD.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _LOG_H
#define _LOG_H

#ifdef HAVE_CONFIG_H
#   include "config.h"
#endif

#include <stdarg.h>
#include <stdio.h>
#include <syslog.h>
#include <fstream>
#include <sstream>
#include <iostream>
#include <list>
#include <stdexcept>
#include <string>

#define SYSLOG_IDENT "CRC-DABMUX"
#define SYSLOG_FACILITY LOG_LOCAL0

enum log_level_t {debug = 0, info, warn, error, alert, emerg};

/** Abstract class all backends must inherit from */
class LogBackend {
    public:
        virtual void log(log_level_t level, std::string message) = 0;
        virtual std::string get_name() = 0;
};

/** A Logging backend for Syslog */
class LogToSyslog : public LogBackend {
    public:
        LogToSyslog() {
            name = "SYSLOG";
            openlog(SYSLOG_IDENT, LOG_PID, SYSLOG_FACILITY);
        }

        ~LogToSyslog() {
            closelog();
        }

        void log(log_level_t level, std::string message) {

            int syslog_level = LOG_EMERG;
            switch (level) {
                case debug: syslog_level = LOG_DEBUG; break;
                case alert: syslog_level = LOG_ALERT; break;
                case info:  syslog_level = LOG_INFO; break;
                case warn:  syslog_level = LOG_WARNING; break;
                case error: syslog_level = LOG_ERR; break;
                case emerg: syslog_level = LOG_EMERG; break;
            }

            syslog(syslog_level, SYSLOG_IDENT " %s", message.c_str());
        }

        std::string get_name() { return name; };

    private:
        std::string name;
};

class LogToFile : public LogBackend {
    public:
        LogToFile(std::string filename) {
            name = "FILE";

            log_file = fopen(filename.c_str(), "a");
            if (log_file == NULL) {
                fprintf(stderr, "Cannot open log file !");
                throw std::runtime_error("Cannot open log file !");
            }
        }

        ~LogToFile() {
            if (log_file != NULL) {
                fclose(log_file);
            }
        }

        void log(log_level_t level, std::string message) {

            const char* log_level_text[] =
                {"DEBUG", "INFO", "WARN", "ERROR", "ALERT", "EMERG"};

            // fprintf is thread-safe
            fprintf(log_file, "CRC-DABMOD: %s: %s\n",
                    log_level_text[(size_t)level], message.c_str());
            fflush(log_file);
        }

        std::string get_name() { return name; };

    private:
        std::string name;
        FILE* log_file;
};

class LogLine;

class Logger {
    public:
        Logger() {};

        void register_backend(LogBackend* backend);

        /* Log the message to all backends */
        void log(log_level_t level, const char* fmt, ...);

        void logstr(log_level_t level, const std::string message);

        /* Return a LogLine for the given level
         * so that you can write etiLog.level(info) << "stuff = " << 21 */
        LogLine level(log_level_t level);

    private:
        std::list<LogBackend*> backends;
};

extern Logger etiLog;

// Accumulate a line of logs, using same syntax as stringstream
// The line is logged when the LogLine gets destroyed
class LogLine {
    public:
        LogLine(const LogLine& logline);
        LogLine(Logger* logger, log_level_t level) :
            logger_(logger)
        {
            level_ = level;
        }

        // Push the new element into the stringstream
        template <typename T>
        LogLine& operator<<(T s) {
            os << s;
            return *this;
        }

        ~LogLine()
        {
            logger_->logstr(level_, os.str());
        }

    private:
        std::ostringstream os;
        log_level_t level_;
        Logger* logger_;
};


#endif