Splitting the code into single files is done. \o/

src/mqtt.cpp

@@ -0,0 +1,71 @@
+#include "my_mqtt.h"
+#include "config.h"
+#include <ESP8266WiFi.h>
+#include <PubSubClient.h>
+#include "EffectEntry.h"
+#include "Effect.h"
+#include "effects.h"
+#include "functions.h"
+
+WiFiClient wifi;
+PubSubClient mqtt_client(wifi);
+long mqtt_last_reconnect_attempt = 0;
+
+void mqtt_callback(char* complete_topic, byte* pl, unsigned int length) {
+  pl[length] = '\0';
+  char* payload = (char*)pl;
+  char* topic = complete_topic + strlen(MQTT_TOPIC); // Strip MQTT_TOPIC from the beginning
+
+  // Here, payload is a char* (but has to be casted).
+  if(strcmp(topic, "mode")==0) {
+    for (int i=0; i<effects->size(); i++) {
+      EffectEntry e = effects->get(i);
+      if (strcmp(e.name, payload)==0) {
+        //Serial.printf("Effect found in mqtt_callback: %p\n", (void *)&e->effect);
+        current_effect = e.effect;
+        clear();
+        return;
+      }
+    }
+  } else if (strcmp(topic, "reboot")==0) {
+    ESP.restart();
+  }
+
+  long value = atol(payload);
+
+  if (strcmp(topic, "brightness")==0 && value > 0 && value <= 255) {
+    FastLED.setBrightness(value);
+  }
+}
+
+boolean mqtt_connect() {
+  char client_id[30];
+  snprintf(client_id, 30, HOSTNAME, ESP.getChipId());
+  LOG("MQTT * Connecting to MQTT server with client id "); LOGln(client_id);
+  if (mqtt_client.connect(client_id, MQTT_USER, MQTT_PASS)) {
+    LOGln("MQTT * Connected.");
+    mqtt_client.publish(MQTT_TOPIC "status", "ONLINE");
+    mqtt_client.subscribe(MQTT_TOPIC "+");
+  }
+  return mqtt_client.connected();
+}
+
+void mqtt_setup() {
+  mqtt_client.setServer(MQTT_SERVER, MQTT_PORT);
+  mqtt_client.setCallback(mqtt_callback);
+  mqtt_last_reconnect_attempt = 0;
+}
+
+void mqtt_loop() {
+  if (!mqtt_client.connected()) {
+    long now = millis();
+    if (now - mqtt_last_reconnect_attempt > 5000) {
+      mqtt_last_reconnect_attempt = now;
+      if (mqtt_connect()) {
+        mqtt_last_reconnect_attempt = 0;
+      }
+    }
+  } else {
+    mqtt_client.loop();
+  }
+}