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

// Existing Pins
const int ldrPin = A0;   
const int relayPin = 5;  

// New Pins
const int trigPin = 2;
const int echoPin = 3;
const int buzzerPin = 4;

const int lightThreshold = 500; 

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(ldrPin, INPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  
  digitalWrite(relayPin, LOW); 
  digitalWrite(buzzerPin, LOW);
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Eco-Security OS");
  delay(2000);
  lcd.clear();
}

// Function to calculate distance using the Ultrasonic sensor
long getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2; // Calculate distance in cm
}

void loop() {
  int lightLevel = analogRead(ldrPin);
  long distance = getDistance();
  
  // Update Top Row: Display both Light and Distance
  lcd.setCursor(0, 0);
  lcd.print("Lvl:");
  lcd.print(lightLevel);
  lcd.print(" Dist:");
  lcd.print(distance);
  lcd.print("cm   "); // Extra spaces to clear old text
  
  // Update Bottom Row & System Logic
  lcd.setCursor(0, 1);
  
  if (lightLevel > lightThreshold) { 
    // IT IS DARK - Activate smart zones
    if (distance > 200) {
      // Zone 1: Far away (Save energy)
      digitalWrite(relayPin, LOW);
      digitalWrite(buzzerPin, LOW);
      lcd.print("Mode: ECO-SLEEP ");
    } 
    else if (distance >= 50 && distance <= 200) {
      // Zone 2: Normal presence (Turn on light)
      digitalWrite(relayPin, HIGH);
      digitalWrite(buzzerPin, LOW);
      lcd.print("Mode: AUTO-LAMP ");
    } 
    else if (distance < 50) {
      // Zone 3: Breach (Trigger Alarm)
      lcd.print("Mode: INTRUDER! ");
      digitalWrite(relayPin, HIGH);
      digitalWrite(buzzerPin, HIGH);
      delay(100);
      digitalWrite(relayPin, LOW);
      digitalWrite(buzzerPin, LOW);
      delay(100);
      return; // Skip the normal delay to create a fast strobe/beep effect
    }
  } else { 
    // IT IS DAYTIME - Turn everything off
    digitalWrite(relayPin, LOW);
    digitalWrite(buzzerPin, LOW);
    lcd.print("Mode: DAYTIME   ");
  }
  
  delay(250); 
}