#define BLYNK_TEMPLATE_ID "TMPL6GzdM1BTs"
#define BLYNK_TEMPLATE_NAME "ESP32 for Gas Sensor Monitoring"
#define BLYNK_AUTH_TOKEN "2nPzhXmkZhH3wetwSj5Hfv8C2HFLBF8e"
#define BLYNK_PRINT Serial

#define BUTTON_PIN 26
#define RELAY_PIN 22

#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include "DHT.h"
#include <Wire.h>                   // I2C library for LCD
#include <LiquidCrystal_I2C.h>       // LCD library for I2C LCD

// Blynk authentication token
char auth[] = BLYNK_AUTH_TOKEN; // Auth Token

// Your network credentials
char ssid[] = "Wokwi-GUEST"; // WiFi SSID
char pass[] = ""; // WiFi password

BlynkTimer timer;

// DHT sensor setup
#define DHTPIN 15         // DHT22 data pin
#define DHTTYPE DHT22     // DHT sensor type

// Potentiometer setup
#define METHANE_PIN 34    // Potentiometer pin (use this to simulate methane level)
#define CO2_PIN 35        // New Pin for CO2 level
#define LED1_RED 16       // First LED pin (indicates high gas levels)
#define LED2_GREEN 4      // Second LED pin (indicates safe levels)
#define VALVE_LED_PIN 17  // Valve LED pin (open/closed)

DHT dht(DHTPIN, DHTTYPE); // Create a DHT object

// LCD setup
LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address of the LCD, 20 columns and 4 rows

// Blynk virtual pins
#define VIRTUAL_METHANE V0  // Virtual pin for methane percentage
#define VIRTUAL_CO2 V1      // Virtual pin for CO2 percentage
#define VIRTUAL_TEMP V2     // Virtual pin for temperature
#define VIRTUAL_IDEAL V3    // Virtual pin for ideal range status
#define VIRTUAL_OUT_OF_RANGE V4 // Virtual pin for out of range status
#define VIRTUAL_VALVE V5    // Virtual pin for valve status
#define VIRTUAL_BUTTON V6   // Virtual button pin for valve control

const int buttonPin = BUTTON_PIN;  // Pin for push button
const int relayPin = RELAY_PIN;   // Pin for relay

bool valveState = false;   // Track the state of the valve
unsigned long lastButtonPress = 0; // For debouncing button presses

void setup() {
  Serial.begin(115200);    // Initialize serial communication
  dht.begin();             // Initialize the DHT sensor
  pinMode(LED1_RED, OUTPUT); // Set LED1 as output
  pinMode(LED2_GREEN, OUTPUT); // Set LED2 as output
  pinMode(VALVE_LED_PIN, OUTPUT); // Set Valve LED as output
  pinMode(buttonPin, INPUT_PULLUP);  // Set button pin as input with pull-up
  pinMode(relayPin, OUTPUT);          // Set relay pin as output
  digitalWrite(relayPin, LOW);        // Initialize relay to OFF

  // Initialize LCD
  lcd.init();
  lcd.setBacklight(1); // Turn on backlight
  lcd.clear();

  // Connect to WiFi
  Blynk.begin(auth, ssid, pass);
}

// Function to toggle valve state
void toggleValve() {
  valveState = !valveState; // Toggle the valve state

  // Activate the relay based on valve state
  if (valveState) {
    digitalWrite(relayPin, HIGH);  // Open valve (turn relay ON)
    digitalWrite(VALVE_LED_PIN, HIGH); // Turn on Valve LED
  } else {
    digitalWrite(relayPin, LOW);   // Close valve (turn relay OFF)
    digitalWrite(VALVE_LED_PIN, LOW); // Turn off Valve LED
  }

  // Send valve status to Blynk
  Blynk.virtualWrite(VIRTUAL_VALVE, valveState);
  Serial.print("Valve State: ");
  Serial.println(valveState ? "Open" : "Closed");
}

// Blynk function to handle virtual button press
BLYNK_WRITE(VIRTUAL_BUTTON) {
  toggleValve(); // Toggle the valve when the button is pressed in Blynk
}

void loop() {
  // Blynk.run() handles communication with Blynk servers
  Blynk.run();

  // Read methane percentage from potentiometer
  int methaneLevel = analogRead(METHANE_PIN);
  float methanePercentage = map(methaneLevel, 0, 4095, 0, 100); // Map to percentage

  // Read CO2 percentage from another potentiometer
  int co2Level = analogRead(CO2_PIN);
  float co2Percentage = map(co2Level, 0, 4095, 0, 100); // Map to percentage

  // Read temperature from DHT sensor
  float t = dht.readTemperature(); // Read temperature in Celsius

  // Check if DHT sensor reading is valid
  if (isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Send data to Blynk app
  Blynk.virtualWrite(VIRTUAL_METHANE, methanePercentage); // Send methane percentage
  Blynk.virtualWrite(VIRTUAL_CO2, co2Percentage);       // Send CO2 percentage
  Blynk.virtualWrite(VIRTUAL_TEMP, t); // Send temperature

  // Print the values to the Serial Monitor
  Serial.print("Methane Percentage: ");
  Serial.print(methanePercentage);
  Serial.print(" CO2 Percentage: ");
  Serial.print(co2Percentage);
  Serial.print(" Temperature: ");
  Serial.print(t);
  Serial.println(" °C");

  // Update the LCD every second to avoid flickering
  static unsigned long lastLcdUpdate = 0;
  if (millis() - lastLcdUpdate >= 1000) {
    lastLcdUpdate = millis();  // Update time

    // Display temperature on the first row
    lcd.setCursor(0, 0); // Set cursor to the first row
    lcd.print("Temp: ");
    lcd.print(t);
    if (t > 35) { // Temperature warning (above 35°C)
      lcd.print(" !!HIGH!!");
    } else if (t < 30) { // Temperature warning (below 30°C)
      lcd.print(" !!LOW!!");
    } else { // Ideal range
      lcd.print(" --OK--");
    }

    // Display CO2 on the second row
    lcd.setCursor(0, 1); // Set cursor to the second row
    lcd.print("CO2: ");
    lcd.print(co2Percentage);
    if (co2Percentage > 40) { // CO2 warning (above 40%)
      lcd.print(" !!HIGH!!");
    } else if (co2Percentage < 30) { // CO2 warning (below 30%)
      lcd.print(" !!LOW!!");
    } else { // Ideal range
      lcd.print(" --OK--");
    }   
    
     // Display methane on the third row
    lcd.setCursor(0, 2); // Set cursor to the third row
    lcd.print("CH4: ");
    lcd.print(methanePercentage);
    if (methanePercentage > 75) { // Methane warning (above 75%)
      lcd.print(" !!HIGH!!");
    } else if (methanePercentage < 50) { // Methane warning (below 50%)
      lcd.print(" !!LOW!!");
    } else { // Ideal range
      lcd.print(" --OK--");
    }



    // Display valve state on the fourth row
    lcd.setCursor(0, 3); // Set cursor to the fourth row
    lcd.print("Valve: ");
    if (valveState) {
      lcd.print("Open");
    } else {
      lcd.print("Closed");
    }
  }

   // Define the thresholds for gas levels and temperature
  float methaneThresholdHigh = 75.0; // Methane high threshold
  float methaneThresholdLow = 50.0; // Methane low threshold
  float co2ThresholdHigh = 40.0; // CO2 high threshold
  float co2ThresholdLow = 30.0; // CO2 low threshold
  float tempThresholdHigh = 35.0; // Temperature high threshold
  float tempThresholdLow = 30.0; // Temperature low threshold

  // Control LEDs based on methane, CO2, and temperature values
  if (methanePercentage >= methaneThresholdLow && methanePercentage <= methaneThresholdHigh &&
      co2Percentage >= co2ThresholdLow && co2Percentage <= co2ThresholdHigh &&
      t >= tempThresholdLow && t <= tempThresholdHigh) {
    // All conditions met for green LED (safe state)
    digitalWrite(LED1_RED, LOW);   // Turn off Red LED
    digitalWrite(LED2_GREEN, HIGH); // Turn on Green LED
  } else {
    // Conditions violated, turn on red LED (alarm state)
    digitalWrite(LED1_RED, HIGH);  // Turn on Red LED
    digitalWrite(LED2_GREEN, LOW); // Turn off Green LED
  }

  // Check if the button is pressed (with debouncing)
  if (digitalRead(buttonPin) == LOW && (millis() - lastButtonPress) > 300) {
    toggleValve(); // Toggle the valve when the physical button is pressed
    lastButtonPress = millis(); // Update the time of last press
    Serial.println("Physical button pressed.");
  }

  delay(100); // Wait for a small amount of time to reduce CPU load
}