#include <PubSubClient.h>
#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ArduinoJson.h>

class MQTTHelper {
  private: 
    String _group = "homedevice";
    String _identifier = "garagesensor";
    const char* _user = "homedevice";
    const char* _password = "WNzAb4VazNFUPlpkn0ED";

    WiFiClient _espClient;
    PubSubClient _mqttClient;
    String  _will_topic;
    
    void reconnect(int delayMillis = 5000);
    bool connect();
    void announce();
    void callback(char* topic, byte* payload, unsigned int length);
  public:
    MQTTHelper() : _espClient(), _mqttClient(_espClient) {
        auto deviceMac = WiFi.macAddress();
        deviceMac.replace(":","");
        _identifier = "etxean-"+deviceMac.substring(6);
        _will_topic = getTopic("online");
        _mqttClient.setCallback([this] (char* topic, byte* payload, unsigned int length) { this->callback(topic, payload, length); });
    }

    String getIdentifier() { return _identifier; }
    
    String getTopic(String node) {
        return _group + "/" + _identifier + "/" + node;
    }
    
    void Configure(IPAddress server, uint16 port) {
        Serial.println("Configuring MQTT connection to: "+server.toString()+":"+String(port));
        _mqttClient.setServer(server, port);
        if (_mqttClient.connected()) {
            connect();
        }
    }
    
    void loop() {
        static unsigned long lastWill;
        if (!_mqttClient.connected()) {
            reconnect();
        }
        _mqttClient.loop();

        auto now = millis();
        if ((now - lastWill) > 1000)
        {
            lastWill = now;
            _mqttClient.publish(_will_topic.c_str(), "true");
        }
    }

    template<class T>
    void publish(String sensor, T payload, bool retained = false) {
        _mqttClient.publish(getTopic(sensor).c_str(), String(payload).c_str(), retained);
    }
};

void MQTTHelper::callback(char* topic, byte* payload, unsigned int length) {
    Serial.print("Message arrived:");
    Serial.print(topic);
    Serial.print(" = ");
    for (unsigned int i=0;  i<length; i++) {
        Serial.print((char)payload[i]);
    }
    Serial.println();
}

void MQTTHelper::reconnect(int delayMillis) {
  // Loop until we're reconnected
  while (!_mqttClient.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (connect()) {
        Serial.println("connected");
    } else {
        auto reconnectSeconds = (int)round(delayMillis/1000.0);
        Serial.print("failed, rc=");
        Serial.print(_mqttClient.state());
        Serial.println(" try again in "+String(reconnectSeconds)+" seconds");
        // Wait 5 seconds before retrying
        delay(delayMillis);
    }
  }
}

void MQTTHelper::announce() {
    DynamicJsonDocument doc(1024);
    doc["id"] = _identifier;
    doc["ip"] = WiFi.localIP().toString();
    doc["mac"] = WiFi.macAddress();
    String payload;
    serializeJson(doc,payload);
    publish("settings",payload);
}

bool MQTTHelper::connect() {
    // If you do not want to use a username and password, change next line to
    // if (_mqttClient.connect(_identifier.c_str()) {    
    if (_mqttClient.connect(_identifier.c_str(), _user, _password, _will_topic.c_str(), 2, false, "false")) {
        _mqttClient.subscribe((getTopic("settings")+"/get").c_str());
        announce();
        return true;
    } else {
        return false;
    }
}