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

#define PIR_SENSOR 2      
#define LDR_SENSOR A0      
#define NTC_SENSOR A1      
#define LED_PIR 3          //yellow
#define LED_LDR 4         //blue
#define LED_NTC 7         //red
#define LED_READY 5        //green
#define BUZZER 6          

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(PIR_SENSOR, INPUT);
  pinMode(LED_PIR, OUTPUT);
  pinMode(LED_LDR, OUTPUT);
  pinMode(LED_NTC, OUTPUT);
  pinMode(LED_READY, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.print("System Ready");

  // System Ready Signal
  digitalWrite(LED_READY, HIGH);
  tone(BUZZER, 1000, 500);
  delay(2000);
  noTone(BUZZER);
  digitalWrite(LED_READY, LOW);
  lcd.clear();
}

void loop() {
  int pirStatus = digitalRead(PIR_SENSOR); 
  int ldrValue = analogRead(LDR_SENSOR);  
  int ldrThreshold = 500;
  int ntcValue = analogRead(NTC_SENSOR);
  
  // Convert NTC value to temperature (basic estimation)
  float resistance = (1023.0 / ntcValue) - 1;
  resistance = 10000 / resistance;  // Assume 10k pull-down resistor
  float temperature = 1 / (log(resistance / 10000) / 3950 + 1 / 298.15) - 273.15;
  
  lcd.setCursor(0, 0);
  lcd.print("Temp:");
  lcd.setCursor(6, 0);
  lcd.print(temperature);
  lcd.print(" C ");

  if (pirStatus == HIGH) {
    digitalWrite(LED_PIR, HIGH);
    tone(BUZZER, 2000, 500);
    lcd.setCursor(0, 1);
    lcd.print("Motion Detected");
    delay(1000);
  } else {
    digitalWrite(LED_PIR, LOW);
  }

  if (ldrValue < ldrThreshold) {
    digitalWrite(LED_LDR, HIGH);
    tone(BUZZER, 500, 1000);
    lcd.setCursor(0, 1);
    lcd.print("Low Light Alert");
    delay(1000);
  } else {
    digitalWrite(LED_LDR, LOW);
  }

  if (temperature > 40) {
    digitalWrite(LED_NTC, HIGH);
    lcd.setCursor(0, 1);
    lcd.print("High Temp Alert!");
    delay(1000);
    tone(BUZZER, 3000, 1500);
  } else {
    digitalWrite(LED_NTC, LOW);
  }
  delay(500);
}