#include <LiquidCrystal_I2C.h>
#define LED 2

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 20, 4);

// PIR Sensor
int ledPin = 2;
int inputPin = 3;
int pirState = LOW;
int val = 0;


void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);

  lcd.init();
  lcd.backlight();


  // PIR Sensor
  pinMode(ledPin, OUTPUT);
  pinMode(inputPin, INPUT);

  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int analogValue = analogRead(A0);
  float voltage = analogValue /1024. * 5;
  float resistance = 200 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  lcd.setCursor(3, 0);
  lcd.print("Cahaya: ");
  if (lux > 50) {
    lcd.print("Terang!");
    digitalWrite(LED, LOW);
    lcd.setCursor(0,2);
    lcd.println("PIR sensor aktif");
    lcd.setCursor(0,3);
    lcd.println("=> di malam hari ...");
  }
  else {
    lcd.print("Gelap...");
    digitalWrite(LED, HIGH);
    // lcd.setCursor(0,2);
    // lcd.print("  Mulai mendeteksi  ");
    // lcd.setCursor(0,3);
    // lcd.print("  Gerakan...        ");

    // PIR Sensor
    val = digitalRead(inputPin);
    if (val == HIGH) {
      digitalWrite(ledPin, HIGH);
      if (pirState == LOW) {
        lcd.setCursor(0, 2);
        lcd.println("    Ada Gerakan!    ");
        lcd.setCursor(0, 3);
        lcd.println("    ------------    ");
        pirState = HIGH;
      }
    }
    else {
      digitalWrite(ledPin, LOW);
      if (pirState == HIGH) {
        lcd.setCursor(0, 2);
        lcd.println(" Belum ada gerakan ");
        lcd.setCursor(0, 3);
        lcd.println(" ----------------- ");
        pirState = LOW;
      }
    }
  }

  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");
  
  delay(100);
}