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

// I2C LCD at address 0x27, size 16x2
LiquidCrystal_I2C lcd(0x27, 16, 2);

#define LEDPIN 3
#define LDRPIN A1
#define POTPIN A2
#define BUZZER 8

void setup() {
  lcd.init();
  lcd.backlight();

  pinMode(LEDPIN, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  Serial.begin(9600);

  lcd.setCursor(0, 0);
  lcd.print("LightDetector:ON");
  delay(2000);
  lcd.clear();
}

void loop() {
  int ldrValue = analogRead(LDRPIN);
  int threshold = analogRead(POTPIN);
  int brightness = map(ldrValue, 0, 1023, 255, 0);
  analogWrite(LEDPIN, brightness);

  lcd.setCursor(0, 0);
  lcd.print("LDR: ");
  lcd.print(ldrValue);
  lcd.print("   ");

  lcd.setCursor(0, 1);
  lcd.print("THR: ");
  lcd.print(threshold);
  lcd.print("   ");

  // Serial logging
  Serial.print("LDR: ");
  Serial.print(ldrValue);
  Serial.print(" | THR: ");
  Serial.println(threshold);

  // Buzzer logic
  if (ldrValue > threshold)
  {
   digitalWrite(BUZZER, HIGH);
   
   lcd.setCursor(8, 1);
  lcd.print("BZ:ON ");
  }

  else
   {
    digitalWrite(BUZZER, LOW);
    lcd.setCursor(8, 1);
    lcd.print("BZ:OFF");
   }

  delay(500); // main loop delay
}