#include <WiFi.h>
#include <LiquidCrystal_I2C.h>
#include <WiFiClient.h>
#include <PubSubClient.h>

#define sensor 34
#define buzzer 2
#define ADC_REF 3.3
#define ADC_RESOLUTION 4095
int Red_Led = 23;
int Green_Led = 19;

char Green_Led_state = LOW;
char Red_Led_state = LOW;


const char* ssid = "Wokwi-GUEST"; //SSID and password for connecting to the WiFi.
const char* password = "";
const char* hostname = "broker.hivemq.com";

// Initialize the LCD display
LiquidCrystal_I2C lcd(0x27, 16, 2);

WiFiClient espClient;
PubSubClient client(espClient);
const char* espClientName = "esp32Client_4770080G"; // yourStudentID must be unique
int PORTNUM = 1883;

void setup_wifi() 
{
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("Given IP by the router to ESP32 is ");
  Serial.println(WiFi.localIP());
}

void connectMQTT() 
{
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("IOT/group5/project")) 
    {
      Serial.println("connected");
      MQTTSubscribe();
    } 
      else 
    {
      Serial.print("Failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
}

void callback(String topic, byte* payload, unsigned int length)
{
  String messageTemp;
  Serial.print("Message received in topic: ");
  Serial.print(topic);
  Serial.print(" length is: ");
  Serial.println(length);

  Serial.print("Data received from broker: ");
  for (int i = 0; i<length; i++)
  {
    Serial.print( (char)payload[i] );
    messageTemp += (char)payload[i];
  }
 if (topic == "IOT/group5/project")
  {
    Serial.print(" Gas Level == ");
    if (messageTemp == "Normal")
    {
      digitalWrite(Red_Led, LOW);
      Serial.print("Normal");
    }
    else if (messageTemp == "Gas detected")
    {
      
      digitalWrite(Red_Led, HIGH);
      Serial.print(" Gas detected ");
      
    }
  }
}

void MQTTSubscribe() 
{
  client.subscribe("IOT/group5/project");
}

void setup_MQTT() 
{
  client.setServer(hostname, PORTNUM);
  client.setCallback(callback);
}

void setup() 
{
  Serial.begin(115200);
  delay(5000);

  lcd.init();
  lcd.backlight();

  pinMode(buzzer, OUTPUT);
  pinMode(Red_Led, OUTPUT);
  pinMode(Green_Led, OUTPUT);
  
  setup_wifi();
  setup_MQTT();

  lcd.setCursor(1, 0);
  lcd.print("Gas Detector");
  for (int a = 0; a <= 15; a++) 
  {
    lcd.setCursor(a, 1);
    lcd.print(".");
    delay(200);
  }
  lcd.clear();
}

void GASLevel() 
{
  int sensorValue = analogRead(sensor);
  int gasLevel = map(sensorValue, 0, 4095, 0, 100);
  
      //adc_value = analogRead(A5);
      if (sensorValue >= 2457)
  {  // Adjust threshold as needed
    
    digitalWrite(buzzer, HIGH);
    tone(buzzer, 200);
    lcd.setCursor(0, 1);
    lcd.print("Gas detected!");
    client.publish("IOT/group5/project", "Gas detected");
    Red_Led_state = LOW;
    Green_Led_state = LOW;

  } 
    else if ( (sensorValue >= 819) && (sensorValue <= 2048) )
  {
    digitalWrite(buzzer, LOW);
    noTone(buzzer);
    lcd.setCursor(0, 1);
    lcd.print("Normal         ");
    client.publish("IOT/group5/project", "Normal");  
    Red_Led_state = LOW;
    Green_Led_state = HIGH;
  }

    else
  {
    lcd.setCursor(0, 0);
    lcd.print("GAS Level:        ");
  }  
  digitalWrite(Red_Led, Red_Led_state);
  digitalWrite(Green_Led, Green_Led_state);
  

}

  void loop() 
 { 
  
    if (!client.connected()) 
  {
    connectMQTT();
  }
    client.loop();
    GASLevel();
    delay(1000);  // Adjust delay as needed
  }