Telemetry.h

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#ifndef Telemetry_h
#define Telemetry_h
 
// Local includes.
#include "Configuration.h"
 
// Library includes.
#include <ArduinoJson.h>
#if THINGSBOARD_ENABLE_STL
#include <type_traits>
#endif // THINGSBOARD_ENABLE_STL
 
 
class Telemetry {
  public:
    Telemetry();
 
    template <typename T,
#if THINGSBOARD_ENABLE_STL
              // Standard library is_integral, includes bool, char, signed char, unsigned char, short, unsigned short, int, unsigned int, long, unsigned long, long long, and unsigned long long
              typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
#else
              // Workaround for ArduinoJson version after 6.21.0, to still be able to access internal enable_if and is_integral declarations, previously accessible with ARDUINOJSON_NAMESPACE
              typename ArduinoJson::ARDUINOJSON_VERSION_NAMESPACE::detail::enable_if<ArduinoJson::ARDUINOJSON_VERSION_NAMESPACE::detail::is_integral<T>::value>::type* = nullptr>
#endif // THINGSBOARD_ENABLE_STL
    Telemetry(char const * key, T const & value)
      : m_type(DataType::TYPE_INT)
      , m_key(key)
      , m_value()
    {
        m_value.integer = value;
    }
 
    template <typename T,
#if THINGSBOARD_ENABLE_STL
              // Standard library is_floating_point, includes float and double
              typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
#else
              // Workaround for ArduinoJson version after 6.21.0, to still be able to access internal enable_if and is_floating_point declarations, previously accessible with ARDUINOJSON_NAMESPACE
              typename ArduinoJson::ARDUINOJSON_VERSION_NAMESPACE::detail::enable_if<ArduinoJson::ARDUINOJSON_VERSION_NAMESPACE::detail::is_floating_point<T>::value>::type* = nullptr>
#endif // THINGSBOARD_ENABLE_STL
    Telemetry(char const * key, T const & value)
      : m_type(DataType::TYPE_REAL)
      , m_key(key)
      , m_value()
    {
        m_value.real = value;
    }
 
    Telemetry(char const * key, bool value);
 
    Telemetry(char const * key, char const * value);
 
    bool IsEmpty() const;
 
    template <typename TSource>
    bool SerializeKeyValue(TSource & source) const {
        switch (m_type) {
            case DataType::TYPE_BOOL:
                if (m_key) {
                    source[m_key] = m_value.boolean;
                    return source.containsKey(m_key);
                }
                return source.set(m_value.boolean);
            case DataType::TYPE_INT:
                if (m_key) {
                    source[m_key] = m_value.integer;
                    return source.containsKey(m_key);
                }
                return source.set(m_value.integer);
            case DataType::TYPE_REAL:
                if (m_key) {
                    source[m_key] = m_value.real;
                    return source.containsKey(m_key);
                }
                return source.set(m_value.real);
            case DataType::TYPE_STR:
                if (m_key) {
                    source[m_key] = m_value.str;
                    return source.containsKey(m_key);
                }
                return source.set(m_value.str);
            default:
                // Nothing to do
                break;
        }
        return false;
    }
 
  private:
    union Data {
        const char  *str;
        bool        boolean;
        int64_t     integer;
        double      real;
    };
 
    enum class DataType: uint8_t {
        TYPE_NONE, 
        TYPE_BOOL, 
        TYPE_INT, 
        TYPE_REAL, 
        TYPE_STR 
    };
 
    DataType     m_type = {};  // Data type flag, showing which value is saved in the class instance
    const char   *m_key = {};  // Data key of the key-value pair
    Data         m_value = {}; // Data value of the key-value pair
};
 
using Attribute = Telemetry;
 
#endif // Telemetry_h