/**
 * @file debugMqtt.h
 * @author Alexander Klein (alex@kleiax.de)
 * @brief Inherits a class to send debug messages over MQTT
 * @version 0.1
 * @date 2021-12-13
 * 
 * @copyright Copyright (c) 2021
 * 
 */
#ifndef DEBUG_MQTT_H
#define DEBUG_MQTT_H

#include <iostream>
#include <PubSubClient.h>


/**
 * @brief 
 * 
 * If you want to change the default topic
 * to an other value, than you have to define this define
 * in your code befor you include this File.
 */
#ifndef MQTT_DEBUG_TOPIC
#define MQTT_DEBUG_TOPIC "Rover"
#endif // MQTT_DEBUG_TOPIC

/**
 * @brief Defualt for max message size
 * 
 * If you want to change the default size of 128 Byte
 * to an other value, than you have to define this define
 * in your code befor you include this File.
 */
#ifndef MQTT_BUFFER_SIZE
#define MQTT_BUFFER_SIZE 128
#endif //MQTT_BUFFER_SIZE

/**
 * @brief An enum to set the log level
 * 
 * The log level is the last part of the MQTT topic.
 * Unless you give sendMsg() or sendData() a additional
 * topic as String.
 * 
 * @see sendMsg()
 * @see sendData()
 * 
 */
enum Loglevel { none,
                error,
                warn,
                info,
                debug,
                influx};

/**
 * @brief A class to send debug messages over MQTT
 * 
 * This class send debug messages over MQTT with different topics
 * by the enum Loglevel. Besides that this class supports to send
 * data via Telegraf into Grafana.
 * 
 * @see Loglevel
 */
class DebugMqtt {
    public:
        /**
         * @brief Construct a new Debug Mqtt object.
         * 
         * @param name A String with send with every Message.
         * @param bufSize for the addCharacter function.
         */
        DebugMqtt(const char* name, uint8_t bufSize = 0);

        ~DebugMqtt();

        /**
         * @brief Send a Message via MQTT
         * 
         * This function uses sendData to send the given string and
         * add the name to the message given by the constructer.
         * 
         * @see sendData()
         * @see Loglevel
         * 
         * @param loglevel Loglevel given by the enum Loglevel
         * @param topic Additional topic behind loglevel
         * @param msg The message to send as String
         */
        void sendMsg(Loglevel loglevel, String topic, String msg);
        void sendMsg(Loglevel loglevel, String msg);

        /**
         * @brief Send a Message via MQTT
         * 
         * This function sends the Data via MQTT with the given topic
         * from Loglevel or followed by given String topic.
         * Normally this function is called by sendMsg() or by
         * writeToInflux()
         * 
         * @see sendData()
         * @see writeToInflux()
         * @see Loglevel
         * 
         * @param loglevel Loglevel given by the enum Loglevel
         * @param topic Additional topic behind loglevel
         * @param data The message to send as String
         */
        void sendData(Loglevel loglevel, String topic, String data);
        void sendData(Loglevel loglevel, String data);

        /**
         * @brief Send a Message via MQTT for InfluxDB
         * 
         * This function sends a MQTT message which is intended for
         * Telegraf. Telegraf can listen on MQTT messages and put 
         * them in an Influx Database.
         * 
         * @param measurement_name like a category
         * @param field_set the name of the value e.g temperature
         * @param measurement the real value
         * @param nanos Current time in nanoseconds
         */
        void writeToInflux(String measurement_name, String field_set, float measurement, uint64_t nanos);

        /**
         * @brief Adds a single character to the buf
         * 
         * The buf will be flushed out:
         *  1. when the buffer is full
         *  2. when the character is '\n'
         * 
         * @param c 
         */
        void addCharacter(char c);

        /**
         * @brief Initialize debugMQTT for all instances
         * 
         * You only have to call this function once for your project.
         * If you call this function again you overwrite the client and
         * the loglevel. If you only want du overwrite the max_loglevel
         * use changeLoglevel()
         * 
         * @see changeLoglevel()
         * 
         * @param client PubSubClient
         * @param max_loglevel Max loglevel to send.
         */
        static void init(PubSubClient* client, Loglevel max_loglevel);

        /**
         * @brief Change loglevel
         * 
         * This function changes the maximum loglevel which be send.
         * 
         * @param loglevel 
         */
        static void changeLoglevel(Loglevel loglevel);

    private:
        const char* name;
        char* buf;
        uint8_t bufPos = 0;
        uint8_t bufSize = 100;

        static String enum_to_string(Loglevel loglevel);

        static PubSubClient* client;
        static Loglevel loglevel;
        static bool isInit;
        static char msg[MQTT_BUFFER_SIZE];
        static char topic[MQTT_BUFFER_SIZE];
};

#endif // DEBUG_MQTT_H