#include <WiFi.h>
#include <DHTesp.h>
#include <PubSubClient.h>
#include <NTPClient.h>
#include <WiFiUdp.h>

#define DHT_PIN 15
#define BUZZER 12

// making an instance of wificlient class.
// through this the mqttclient is initiated.
WiFiClient espClient;
PubSubClient mqttClient(espClient);

// initializing fetching time from ntpserver.
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP);

// to store the temp data from the sensor.
char tempAr[6];

// creating an instance of dht sensor
DHTesp dhtSensor;

// variable to store wether the sheduling has happened or not.
bool isScheduledON = false;
unsigned long scheduledOnTime;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);

  setupWifi();

  setupMqtt();

  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);

  // initializing updating time with the ntp server.
  timeClient.begin();
  timeClient.setTimeOffset(5.5*3600);

  pinMode(BUZZER, OUTPUT);

  digitalWrite(BUZZER, LOW);
}


void loop() {
  // put your main code here, to run repeatedly:

  // establishing the connection to the broker
  if (!mqttClient.connected()) {
    connectToBroker();
  }

  mqttClient.loop(); // essential to call mqttClient.loop() regularly within the main loop to ensure that the MQTT client functions correctly and maintains a stable connection to the broker.

  updateTemperature();

  Serial.println(tempAr);

  mqttClient.publish("prl-admin-temp", tempAr);

  checkSchedule();

  delay(1000);
}


void buzzerOn(bool on) {
  if (on) {
    tone(BUZZER, 256);
  } 
  else {
    noTone(BUZZER);
  }
}


// setting up the mqtt server
// setting up the receivecallback function to hand calling back from the broker.
void setupMqtt() {
  mqttClient.setServer("test.mosquitto.org", 1883);
  mqttClient.setCallback(receiveCallback);
}


void updateTemperature() {
  TempAndHumidity data = dhtSensor.getTempAndHumidity();
  String(data.temperature, 2).toCharArray(tempAr, 6);
}


// setting up the wifi connection.
void setupWifi() {
  Serial.println();
  Serial.print("connecting to...");
  Serial.println("wokwi-guest");

  WiFi.begin("Wokwi-GUEST", "");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    Serial.println("WiFi connected");
    Serial.println("IP address:");
    Serial.println(WiFi.localIP());
  }
}


void connectToBroker() {
  while (!mqttClient.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (mqttClient.connect("ESP32-4646")) { // random address in this case
      Serial.println("connected");

      // subscribing to topics within the broker.
      mqttClient.subscribe("prl-on-off");
      mqttClient.subscribe("sheduled-out");
    } 
    else {
      Serial.println("failed");
    }
  }
}


void receiveCallback(char* topic, byte* payload, unsigned int length) {
  Serial.print("message arrived [");
  Serial.print(topic);
  Serial.print("]");

  char payloadCharAr[length];
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
    payloadCharAr[i] = (char)payload[i];
  }

  // get content from the subscribed topics by filtering them 
  if (strcmp(topic, "prl-on-off") == 0) {
    buzzerOn(payloadCharAr[0] == '1');
  } 
  // get content from the subscribed topics by filtering them 
  else if (strcmp(topic, "sheduled-out") == 0) {
    if (payloadCharAr[0] == 'N') {
      isScheduledON = false;
    } 
    else {
      isScheduledON = true;
      scheduledOnTime = atol(payloadCharAr); // converting character array to a long integer.
    }
  }
}


unsigned long getTime() {
  timeClient.update();
  return timeClient.getEpochTime();
}


void checkSchedule() {
  if (isScheduledON) {
    unsigned long currentTime = getTime();
    if (currentTime > scheduledOnTime) {
      buzzerOn(true);
      isScheduledON = false;
      mqttClient.publish("main-on-off-esp_medibox", "1");
      mqttClient.publish("main-on-off-esp-shedulSwitch", "0");
      Serial.println("Scheduled ON");
    }
  }
}