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

// Inisialisasi LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pin sensor & LED
#define TRIG_PIN 5
#define ECHO_PIN 18
#define LED_HIJAU 13
#define LED_KUNING 12
#define LED_MERAH 14

// Variabel
int pengunjung = 0;
const int KAPASITAS_MAX = 50;
bool orangTerdeteksi = false;
unsigned long waktuTerakhir = 0;

void setup() {
  Serial.begin(115200);
  
  // Setup pin
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_HIJAU, OUTPUT);
  pinMode(LED_KUNING, OUTPUT);
  pinMode(LED_MERAH, OUTPUT);
  
  // Setup LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.print("PERPUSTAKAAN");
  delay(2000);
  
  // LED awal = hijau
  digitalWrite(LED_HIJAU, HIGH);
  updateLCD();
}

void loop() {
  long jarak = bacaSensor();
  
  // Deteksi orang (< 50cm)
  if (jarak > 0 && jarak < 50) {
    unsigned long now = millis();
    
    if (!orangTerdeteksi && (now - waktuTerakhir > 2000)) {
      pengunjung++;
      orangTerdeteksi = true;
      waktuTerakhir = now;
      
      updateLCD();
      updateLED();
      
      Serial.print("Pengunjung: ");
      Serial.println(pengunjung);
    }
  } else {
    orangTerdeteksi = false;
  }
  
  delay(100);
}

long bacaSensor() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  long duration = pulseIn(ECHO_PIN, HIGH, 30000);
  long jarak = duration * 0.034 / 2;
  
  return jarak;
}

void updateLCD() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Pengunjung:");
  lcd.setCursor(0, 1);
  lcd.print(pengunjung);
  lcd.print("/");
  lcd.print(KAPASITAS_MAX);
  
  int persen = (pengunjung * 100) / KAPASITAS_MAX;
  lcd.print(" (");
  lcd.print(persen);
  lcd.print("%)");
}

void updateLED() {
  // Matikan semua LED
  digitalWrite(LED_HIJAU, LOW);
  digitalWrite(LED_KUNING, LOW);
  digitalWrite(LED_MERAH, LOW);
  
  // Nyalakan sesuai kapasitas
  float persen = (float)pengunjung / KAPASITAS_MAX * 100;
  
  if (persen < 50) {
    digitalWrite(LED_HIJAU, HIGH);
  } else if (persen < 80) {
    digitalWrite(LED_KUNING, HIGH);
  } else {
    digitalWrite(LED_MERAH, HIGH);
  }
}