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

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define GAS_PIN    A0
#define FLAME_PIN  D2

#define GREEN_LED  D3
#define YELLOW_LED D4   // FIXED: was D5
#define RED_LED    D5   // FIXED: was D4

#define BUZZER D6
#define BUTTON D7

int threshold = 500;
String currentState = "";

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

  pinMode(FLAME_PIN, INPUT_PULLUP);
  pinMode(BUTTON, INPUT_PULLUP);

  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("FIRE & GAS");
  lcd.setCursor(0, 1);
  lcd.print("DETECTION SYS");
  delay(2000);
  lcd.clear();
}

void loop() {
  int gas = analogRead(GAS_PIN);
  bool flame = digitalRead(FLAME_PIN) == LOW;

  Serial.print("Gas Value: ");
  Serial.println(gas);

  if (flame) {
    digitalWrite(RED_LED, HIGH);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER, HIGH);

    if (currentState != "FIRE") {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("FIRE ALERT!");
      lcd.setCursor(0, 1);
      lcd.print("FLAME FOUND");
      currentState = "FIRE";
    }

  } else if (gas > threshold) {
    digitalWrite(YELLOW_LED, HIGH);
    digitalWrite(RED_LED, LOW);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER, HIGH);

    if (currentState != "GAS") {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("GAS LEAK!");
      lcd.setCursor(0, 1);
      lcd.print("HIGH GAS");
      currentState = "GAS";
    }

  } else {
    digitalWrite(GREEN_LED, HIGH);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(RED_LED, LOW);
    digitalWrite(BUZZER, LOW);

    if (currentState != "SAFE") {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("SYSTEM SAFE");
      lcd.setCursor(0, 1);
      lcd.print("MONITORING");
      currentState = "SAFE";
    }
  }

  if (digitalRead(BUTTON) == LOW) {
    digitalWrite(BUZZER, LOW);
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("RESET DONE");
    lcd.setCursor(0, 1);
    lcd.print("SYSTEM READY");
    delay(1000);
    currentState = "";
  }

  delay(300);
}