static void app_config_callback(gcp_app_handle_t client, gcp_app_config_handle_t config, void *user_context)
{
    char *pretty_config = cJSON_Print(config);
    ESP_LOGI(TAG, "[app_config_callback] app_config:%s \n", pretty_config);
    free(pretty_config);
    gcp_app_logf(client, "love is %s", command);
}

static void app_command_callback(gcp_app_handle_t client, char *topic, char *command, void *user_context)
{
    ESP_LOGI(TAG, "[app_command_callback] topic:%s, cmd:%s", topic, command);
    gcp_app_send_telemetry(client, "topic_love", "1");
}

/* add your applications state and forget about it. This callback will be called periodically with an empty state object. If there is a change from the previos call your new state will be sent to GCP IoT state topic */
static void app_get_state_callback(gcp_app_handle_t client, gcp_app_state_handle_t state, void *user_context)
{
    ESP_LOGI(TAG, "[app_get_state_callback]");
    cJSON_AddStringToObject(state, "desire", "objet petit");
    cJSON_AddNumberToObject(state, "GPIO_18", gpio_get_level(18));
}

/* return your heap allocated jwt token it will be freed by the framework */
static char *jwt_callback(const char *project_id)
{
    ESP_LOGI(TAG, "[jwt_callback]");
    return create_GCP_JWT(project_id, (const char *)gcp_jwt_private_pem_key_start, gcp_jwt_private_pem_key_end - gcp_jwt_private_pem_key_start);
}

void app_main() {
   /* initializers 
    ....
   */

   gcp_device_identifiers_t default_gcp_device_identifiers = {
        .registery = REGISTERY,
        .region = REGION,
        .project_id = PROJECT_ID,
        .device_id = DEVICE_ID};

   gcp_app_config_t gcp_app_config = { 
        .cmd_callback = &app_command_callback, /* wildcard command topic messages will be delivered to this callback from MQTT_TASK thread */
        .config_callback = &app_config_callback, /* called from MQTT_TASK thread when config is received from GCP */
        .state_callback = &app_get_state_callback, /* called from GCP_APP thread and new state will be sent on if there is change from the previous state */
        .device_identifiers = &default_gcp_device_identifiers,
        .jwt_callback = &jwt_callback};

   gcp_app_handle_t petit_app = gcp_app_init(&gcp_app_config);
   gcp_app_start(petit_app);
}  

static void app_command_callback(gcp_app_handle_t client, char *topic, char *command, void *user_context)
{
    gcp_app_logf(client, "love is %s", command);
    gcp_app_log(client, "Love is giving something you don't have to someone who doesn't want it.");
}