#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <MQUnifiedsensor.h>

/************************Hardware Related Macros************************************/
#define         Board                   ("ESP-32")
#define         Pin                     (4)  // Analog input pin for MQ-2 sensor
#define         LED_PIN                 (13) // GPIO pin for the LED
#define         BUZZER_PIN              (12) // GPIO pin for the buzzer

/***********************Software Related Macros************************************/
#define         Type                    ("MQ-2") // MQ2
#define         Voltage_Resolution      (3.3)
#define         ADC_Bit_Resolution      (12) // For ESP32
#define         RatioMQ2CleanAir        (9.83) // RS / R0 = 9.83 ppm 

/*****************************Globals***********************************************/
MQUnifiedsensor MQ2(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin, Type);
LiquidCrystal_I2C lcd(0x27, 20, 4);
int valor_gas = 0; 
bool ledState = LOW; // Variable to store the current state of the LED

void setup() {
  // Initialize the LCD
  lcd.init();
  lcd.begin(20, 4);
  lcd.clear();
  lcd.backlight();
  lcd.print("PRACTICA");
  delay(1000);
   
  lcd.clear();
  lcd.print("SENSADO LM35");
  lcd.setCursor(0,1);
  lcd.print("CURSO 1 ");
  delay(1000);
  lcd.clear();
  
  // Initialize the serial port for debugging
  Serial.begin(9600);

  // Set up the MQ-2 sensor
  MQ2.setRegressionMethod(1); // PPM = a * ratio^b
  MQ2.setA(574.25); MQ2.setB(-2.222); // Configure the equation for LPG concentration

  MQ2.init(); 
  Serial.print("Calibrating please wait.");
  float calcR0 = 0;
  for(int i = 1; i <= 10; i++) {
    MQ2.update(); // Update data
    calcR0 += MQ2.calibrate(RatioMQ2CleanAir);
    Serial.print(".");
  }
  MQ2.setR0(calcR0 / 10);
  Serial.println(calcR0);
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("MQ2 = ");
  lcd.print(calcR0);
  delay(500); // Sampling frequency
  
  if(isinf(calcR0)) { Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected)"); while(1); }
  if(calcR0 == 0) { Serial.println("Warning: Connection issue, R0 is zero (Analog pin shorts to ground)"); while(1); }

  // Set up the LED and buzzer pins as outputs
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW); // Ensure the LED is initially off
  digitalWrite(BUZZER_PIN, LOW); // Ensure the buzzer is initially off
}

void loop() {
  MQ2.update(); // Update data
  MQ2.readSensor(); // Read PPM concentration
  MQ2.serialDebug(); // Print the table on the serial port

  valor_gas = analogRead(Pin);
  valor_gas = map(valor_gas, 0, 4095, 0, 100);
  Serial.println(valor_gas);

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("MQ2 = ");
  lcd.print(valor_gas);
  lcd.setCursor(10,0);
  lcd.print("PPM");

  // Check gas concentration levels
  if (valor_gas >= 90) {
    // Display "URGER" message
    lcd.setCursor(0,1);
    lcd.print("URGENT !");
    lcd.setCursor(0,2);
    lcd.print("Fire Nearby");
    lcd.setCursor(0,3);
    lcd.print("Please Check Area");

    // Flip-flop the LED
    ledState = !ledState; // Toggle the LED state
    digitalWrite(LED_PIN, ledState); // Update the LED

    // Activate the buzzer continuously
    digitalWrite(BUZZER_PIN, HIGH); // Turn on the buzzer
  } else if (valor_gas > 70) {
    // Display "Smoke Detected" message
    lcd.setCursor(0,1);
    lcd.print("Smoke Detected");
    lcd.setCursor(0,2);
    lcd.print("Please Check Area");

    // Flip-flop the LED
    ledState = !ledState; // Toggle the LED state
    digitalWrite(LED_PIN, ledState); // Update the LED

    // Turn off the buzzer
    digitalWrite(BUZZER_PIN, LOW); // Ensure the buzzer is off
  } else {
    // Display "Air Quality OK" message
    lcd.setCursor(0,1);
    lcd.print("Air Quality OK");
    digitalWrite(LED_PIN, LOW); // Turn off the LED
    digitalWrite(BUZZER_PIN, LOW); // Ensure the buzzer is off
  }

  delay(500); // Sampling frequency
}