Added basic Scheduling Functionality

A JSON message can now be received on:
'vesper/DEV_ID/control/addSchedule"
Each message, must hold a "file" and "data".
The file is the month's name in 3 letter mode (eg jan, feb, mar)
The data is an entry for each day of the month.
Each day can be an array containing multiple items.

vesper/MQTT_Message_Handling.hpp

@@ -0,0 +1,97 @@
+#pragma once
+
+void setRelayDurations(JsonDocument& doc);
+void updateRelayTimings();
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// Handles the incoming payload. Returns it into a "JsonDocument" format.
+JsonDocument handleJSON(char * payload) {
+	JsonDocument doc;
+	DeserializationError error = deserializeJson(doc, payload);
+	if (error) {
+		Serial.print("deserializeJson() failed: ");
+		Serial.println(error.c_str());
+	}
+	return doc;
+}
+
+// Subscribes to certain topics on the MQTT Server.
+void SuscribeMqtt() {
+
+	  String topicPlayback = String("vesper/") + DEV_ID + "/control/playback";
+    String topicSetMelody = String("vesper/") + DEV_ID + "/control/setMelody";
+    String topicAddMelody = String("vesper/") + DEV_ID + "/control/addMelody";
+		String topicAddSchedule = String("vesper/") + DEV_ID + "/control/addSchedule";
+		String topicRelayTimers = String("vesper/") + DEV_ID + "/control/settings/relayTimers";
+
+    uint16_t control_id = mqttClient.subscribe(topicPlayback.c_str(), 2);
+    Serial.print("Subscribing to Playback Control topic, QoS 2, packetId: ");
+    Serial.println(control_id);
+
+		uint16_t set_melody_id = mqttClient.subscribe(topicSetMelody.c_str(), 2);
+    Serial.print("Subscribing to Set-Melody topic, QoS 2, packetId: ");
+    Serial.println(set_melody_id);
+
+	// doesn't work yet:
+    uint16_t add_melody_id = mqttClient.subscribe(topicAddMelody.c_str(), 2);
+    Serial.print("Subscribing to Add-Melody topic, QoS 2, packetId: ");
+    Serial.println(add_melody_id);
+
+		uint16_t add_schedule_id = mqttClient.subscribe(topicAddSchedule.c_str(), 2);
+		Serial.print("Subscribing to Add-Schedule topic, QoS 2, packetId: ");
+		Serial.println(add_schedule_id);
+
+		uint16_t relay_timers_id = mqttClient.subscribe(topicRelayTimers.c_str(), 2);
+		Serial.print("Subscribing to Relay-Timers topic, QoS 2, packetId: ");
+		Serial.println(relay_timers_id);
+
+}
+
+// Handles incoming MQTT messages on subscribed topics.
+// Could move logic out of this into a dedicated function.
+void OnMqttReceived(char * topic, char * payload, AsyncMqttClientMessageProperties properties, size_t len, size_t index, size_t total) {
+
+	String topicPlayback = String("vesper/") + DEV_ID + "/control/playback";
+  String topicSetMelody = String("vesper/") + DEV_ID + "/control/setMelody";
+  String topicAddMelody = String("vesper/") + DEV_ID + "/control/addMelody";
+	String topicAddSchedule = String("vesper/") + DEV_ID + "/control/addSchedule";
+	String topicRelayTimers = String("vesper/") + DEV_ID + "/control/settings/relayTimers";
+
+	// Don't know what this is. Check it out later.
+	//String payloadContent = String(payload).substring(0, len);
+
+	if (String(topic) == topicPlayback){
+		player.command(payload);
+	}
+
+	else if (String(topic) == topicSetMelody) {
+		player.setMelodyAttributes(handleJSON(payload));
+		player.loadMelodyInRAM(melody_steps);
+	}
+
+	else if (String(topic) == topicAddMelody) {
+		// Handle adding melody
+		Serial.println("Adding melody...");
+		// You can call a function here to handle adding the melody
+	}
+
+	else if (String(topic) == topicAddSchedule) {
+		updateSchedule(handleJSON(payload));
+	}
+
+	else if (String(topic) == topicRelayTimers) {
+		updateRelayTimings(handleJSON(payload));
+	}
+
+	else {
+		// Handle unknown topics
+		Serial.println("Unknown topic received.");
+	}
+}
+
+// Publishes a message on the MQTT server. Message passed as an argument.
+void PublishMqtt(const char * data) {
+    String topicData = String("vesper/") + DEV_ID + "/data";
+    mqttClient.publish(topicData.c_str(), 0, true, data);
+}