#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;
    String _command_topic;
    String _announce_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");
        _command_topic = _group + "/command";
        _announce_topic = _group+"/announce";
        _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("MQTT: configuring connection to "+server.toString()+":"+String(port));
        _mqttClient.setServer(server, port);
        if (_mqttClient.connected()) {
            connect();
        }
    }
    
    void loop() {
        static unsigned long lastWillTopicSent;
        if (!_mqttClient.connected()) {
            reconnect();
        }
        _mqttClient.loop();

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

    template<class T>
    void publish(String node, T payload, bool retained = false, bool debug = true) {
        auto topic = getTopic(node);
        auto payload_s = String(payload);
        if (debug)
            Serial.println("MQTT: publish: "+topic+" = "+payload_s);
        _mqttClient.publish(topic.c_str(), payload_s.c_str(), retained);
    }
};

void MQTTHelper::callback(char* topic_chars, byte* payload_bytes, unsigned int length) {
    String topic(topic_chars);
    payload_bytes[length] = '\0';
    String payload = (char*)payload_bytes;
    Serial.print("MQTT: callback on: ");
    Serial.println(topic+" = "+payload);
    String commandTopic = getTopic("command");
    
    if (topic == _command_topic && payload == "announce") {
        Serial.println("Announcing");
        announce();
    }
}

void MQTTHelper::reconnect(int delayMillis) {
  // Loop until we're reconnected
  while (!_mqttClient.connected()) {
    Serial.print("MQTT: attempting 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["ip"] = WiFi.localIP().toString();
    doc["mac"] = WiFi.macAddress();
    String payloadSettings;
    serializeJson(doc,payloadSettings);
    // publish to settings topic
    publish("settings", payloadSettings);
    
    doc["id"] = _identifier;
    String payloadAnnounce;
    serializeJson(doc,payloadAnnounce);
    // publish to genneral announce topic
    Serial.println("MQTT: "+_announce_topic+" = "+payloadAnnounce);
    _mqttClient.publish(_announce_topic.c_str(),payloadAnnounce.c_str());
}

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((_command_topic).c_str());
        announce();
        return true;
    } else {
        return false;
    }
}