//IOT project:MQ2 senor simulation on ESP32 
//Member name: Jayson Tham, Afif,Isaac Xin 



//Libraries and Definitions
//Includes necessary libraries for WiFi, LCD display, and MQTT.

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

// Defines sensor pin, buzzer pin, ADC reference voltage, ADC resolution, and LED pin.
#define POT_PIN 34  // Analog pin where the potentiometer is connected
#define BUZZER_PIN 2  // Pin number where the buzzer is connected
#define RED_LED_PIN 23  // Pin number where the red LED is connected
#define ADC_REF 3.3  // ADC reference voltage
#define ADC_RESOLUTION 4095  // ADC resolution for ESP32

// Declares various variables including adc_value and Red_Led_state.
int adc_value;
float ppm;
char Red_Led_state = LOW;

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

// Initializes the LCD display with I2C address 0x27 and 16x2 dimensions.
LiquidCrystal_I2C lcd(0x27, 16, 2);

WiFiClient espClient;
PubSubClient client(espClient);
const char* espClientName = "esp32Client_4770080G"; // Unique client ID for MQTT broker
int PORTNUM = 1883;

// Connects the ESP32 to the specified WiFi network.
// It keeps retrying until it gets connected, then prints the assigned IP address.
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("IP address: ");
  Serial.println(WiFi.localIP());
}

// Attempts to connect to the MQTT broker. It keeps retrying until it gets connected.
void connectMQTT() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("esp32Client_4770080G")) {
      Serial.println("connected");
    } else {
      Serial.print("Failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
}

// Sets the MQTT broker's server and port.
void setup_MQTT() {
  client.setServer(hostname, PORTNUM);
}

// Main setup function
// Initializes serial communication, LCD display, and pins for the buzzer and LED.
// Calls WiFi and MQTT setup functions. Displays "Gas Detector" message on the LCD.
void setup() {
  Serial.begin(115200);
  delay(5000);

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

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RED_LED_PIN, 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();
}

// Function to convert ADC value to ppm (assuming a linear relationship for demonstration)
// You may need to adjust the calibration values based on your sensor's datasheet and environment.
float convertToPPM(int adc_value) {
  float voltage = adc_value * (ADC_REF / ADC_RESOLUTION);
  // Assuming a linear relationship: ppm = k * voltage (you should calibrate this properly)
  float ppm = voltage * 1000; // Adjust the factor based on calibration
  return ppm;
}

// Function to read gas level, update the LCD, and handle MQTT communication
void GASLevel() {
  adc_value = analogRead(POT_PIN);  // Read the analog value from the potentiometer
  Serial.print("ADC Value: ");  // Print the ADC value for debugging
  Serial.println(adc_value);

  ppm = convertToPPM(adc_value);
  Serial.print("PPM Value: ");  // Print the PPM value for debugging
  Serial.println(ppm);

  lcd.clear();  // Clear the LCD
  lcd.setCursor(0, 0);
  lcd.print("GAS Level: ");
  lcd.print(ppm);
  lcd.print(" ppm");

  if (ppm >= 500) {  // Adjust threshold as needed
    digitalWrite(BUZZER_PIN, HIGH);
    tone(BUZZER_PIN, 200);
    lcd.setCursor(0, 1);
    lcd.print("Gas detected!");
    Red_Led_state = HIGH;
    Serial.println("Gas detected");
    client.publish("IOT/group5/project", "Gas detected");
  } else if (ppm > 500 && ppm < 3000) {
    digitalWrite(BUZZER_PIN, LOW);
    noTone(BUZZER_PIN);
    lcd.setCursor(0, 1);
    lcd.print("Normal         ");
    Red_Led_state = LOW;
    Serial.println("Normal");
    client.publish("IOT/group5/project", "Normal");
  } else {
    lcd.setCursor(0, 1);
    lcd.print("Safe           ");
  }

  digitalWrite(RED_LED_PIN, Red_Led_state);
}

// Main loop
void loop() {
  if (!client.connected()) {
    connectMQTT();
  }
  client.loop();
  GASLevel();
  delay(2000);  // Adjust delay as needed
}