Domotique/WifiControlSensor/MQTT.ino

// Create an ESP8266 WiFiClient class to connect to the MQTT server.
WiFiClient client;
Adafruit_MQTT_Client *mqtt;
Adafruit_MQTT_Publish *mqtt_temp;
Adafruit_MQTT_Publish *mqtt_pressure;

#define NB_ELEMENTS(x) (sizeof(x)/ sizeof(x[0]))
#define FEED_MAX_SIZE 64

#define TEMPERATURE_FEED_FORMAT  "/feeds/%s/temperature"
#define PRESSURE_FEED_FORMAT     "/feeds/%s/pressure"
char temperatureFeed[FEED_MAX_SIZE] = {};
char pressureFeed[FEED_MAX_SIZE] = {};

// Should have less that MAXSUBSCRIPTIONS elements
// MAXSUBSCRIPTIONS is defined is Adafruit_mqtt.h
const int gpioWatched[] = CONFIG_MQTT_CONTROLLED_GPIO;

#define GPIO_FEED_FORMAT "/feeds/%s/gpio/%d"
#define GPIO_SET_FEED_FORMAT "/feeds/%s/gpio/%d/set"

char *mqttId;
char GPIO_FEED[MAXSUBSCRIPTIONS][FEED_MAX_SIZE] = {};
char GPIO_SET_FEED[MAXSUBSCRIPTIONS][FEED_MAX_SIZE] = {};

Adafruit_MQTT_Publish * mqttGpio[MAXSUBSCRIPTIONS] = {};

bool isMqttConfigured = false;

int MqttSetup(char *server, char *user, char *passwd, int port, char * hostname) {
  mqttId = hostname;
  snprintf(temperatureFeed, FEED_MAX_SIZE, TEMPERATURE_FEED_FORMAT, mqttId);
  snprintf(pressureFeed, FEED_MAX_SIZE, PRESSURE_FEED_FORMAT, mqttId);

  mqtt = new Adafruit_MQTT_Client(&client, server, port, user, passwd);
  mqtt_temp =  new Adafruit_MQTT_Publish(mqtt, temperatureFeed);
  mqtt_pressure =  new Adafruit_MQTT_Publish(mqtt, pressureFeed);

  isMqttConfigured = server[0] != '\0';

  for (int i = 0 ; i < NB_ELEMENTS(gpioWatched) && i < MAXSUBSCRIPTIONS; i++) {
    snprintf(GPIO_FEED[i], FEED_MAX_SIZE, GPIO_FEED_FORMAT, mqttId, gpioWatched[i]);
    snprintf(GPIO_SET_FEED[i], FEED_MAX_SIZE, GPIO_SET_FEED_FORMAT, mqttId, gpioWatched[i]);

    Adafruit_MQTT_Subscribe *gpioSet = new Adafruit_MQTT_Subscribe(mqtt, GPIO_SET_FEED[i]);
    mqtt->subscribe(gpioSet);

    Adafruit_MQTT_Publish *gpio =  new Adafruit_MQTT_Publish(mqtt, GPIO_FEED[i]);
    mqttGpio[i] = gpio;
  }
  return 0;
}

bool MqttIsConfigured(){
  return isMqttConfigured;
}
int MqttIsConnected() {
  return mqtt->connected();
}

// Function to connect and reconnect as necessary to the MQTT server.
// Should be called in the loop function and it will take care if connecting.
int MqttConnect() {
  int8_t ret;

  // Stop if already connected.
  if (mqtt->connected()) {
    return 0;
  }

  uint8_t retries = 3;
  while ((ret = mqtt->connect()) != 0) { // connect will return 0 for connected
    SKETCH_DEBUG_PRINTLN(mqtt->connectErrorString(ret));
    SKETCH_DEBUG_PRINTLN("Retrying MQTT connection ...");
    mqtt->disconnect();
    delay(100);  // wait
    retries--;
    if (retries == 0) {
      return -1;
    }
  }
  return 0;
}

int MqttPublish(double temp, double pressure) {
  if (MqttConnect() == 0) {
    SKETCH_DEBUG_PRINTLN("publishing !");
    mqtt_temp->publish(temp);
    mqtt_pressure->publish(pressure);
  }
  return 0;
}

int getGpioFromSubscription(Adafruit_MQTT_Subscribe *subscription) {
  char *temp = strstr(subscription->topic, "/gpio/");
  if (!temp)
    return -1;
  String gpioStr(temp + strlen("/gpio/"));
  int idx = gpioStr.indexOf("/");
  int gpio = gpioStr.substring(0, idx).toInt();

  if (gpio >= 0 && gpio < 32 )
    return gpio;
  else
    return -1;
}

int getGpioWatchedIndex(int gpio) {
  for ( int i = 0; i < NB_ELEMENTS(gpioWatched); i++) {
    if (gpio == gpioWatched[i])
      return i;
  }
  return -1;
}

void MqttChangeGpioValue(int gpio, int value) {
  pinMode(gpio, OUTPUT);
  digitalWrite(gpio, value);
  int watchIdx = getGpioWatchedIndex(gpio);
  if (watchIdx >= 0 ) {
    mqttGpio[watchIdx]->publish(value);
  }
}

void MqttCheckSubscription() {
  if (MqttConnect() == 0) {
    Adafruit_MQTT_Subscribe *subscription;
    while (subscription = mqtt->readSubscription(0)) {
      int gpio = getGpioFromSubscription(subscription);
      SKETCH_DEBUG_PRINT("Got Subscription for gpio ");
      SKETCH_DEBUG_PRINTLN(gpio);
      if (gpio > 0 && getGpioWatchedIndex(gpio) >= 0) {
        char *value = (char *) subscription->lastread;
        SKETCH_DEBUG_PRINT("Receive data: ");
        SKETCH_DEBUG_PRINTLN(value);
        MqttChangeGpioValue(gpio, atoi(value));
      }
    }
  }
}