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

// Inisialisasi Alamat I2C LCD (0x27 untuk Wokwi / standar)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Definisi Pin Hardware
const int pinTrig   = 9;
const int pinEcho   = 10;
const int pinLED    = 7;
const int pinBuzzer = 8;

void setup() {
  Serial.begin(9600);

  // Konfigurasi Input / Output
  pinMode(pinTrig, OUTPUT);
  pinMode(pinEcho, INPUT);
  pinMode(pinLED, OUTPUT);
  pinMode(pinBuzzer, OUTPUT);

  // Inisialisasi LCD
  lcd.init();
  lcd.backlight();
  
  // Tampilan Awal
  lcd.setCursor(0, 0);
  lcd.print("  SISTEM IOT by Rafn  ");
  lcd.setCursor(0, 1);
  lcd.print("  4 KONDISI OK ");
  delay(2000);
  lcd.clear();
}

void loop() {
  // 1. Memicu Sinyal Ultrasonik
  digitalWrite(pinTrig, LOW);
  delayMicroseconds(2);
  digitalWrite(pinTrig, HIGH);
  delayMicroseconds(10);
  digitalWrite(pinTrig, LOW);

  // 2. Membaca Durasi Pantulan (µs)
  long durasi = pulseIn(pinEcho, HIGH);

  // 3. Menghitung Jarak (cm)
  float jarak = (durasi * 0.0343) / 2;

  // Print ke Serial Monitor
  Serial.print("Jarak: ");
  Serial.print(jarak, 1);
  Serial.println(" cm");

  // 4. Update Tampilan Jarak di Baris 1 LCD
  lcd.setCursor(0, 0);
  lcd.print("Jarak: ");
  lcd.print(jarak, 1);
  lcd.print(" cm   "); // Spasi ekstra untuk menghapus sisa karakter angka lama

  // 5. Percabangan Logika 4 Kondisi
  if (jarak > 0 && jarak <= 2.0) {
    // ==========================================
    // KONDISI 1: DEATH (Jarak <= 2 cm)
    // ==========================================
    lcd.setCursor(0, 1);
    lcd.print("Status: DEATH! ");
    
    digitalWrite(pinLED, HIGH);  // LED menyala penuh
    tone(pinBuzzer, 3000);       // Buzzer berbunyi konstan frekuensi tinggi (1500Hz)
  }
  else if (jarak > 0 && jarak <= 10.0) {
    // ==========================================
    // KONDISI 2: BAHAYA (Jarak <= 10 cm)
    // ==========================================
    lcd.setCursor(0, 1);
    lcd.print("Status: BAHAYA! ");
    
    digitalWrite(pinLED, HIGH);  // LED menyala penuh
    tone(pinBuzzer, 1500);       // Buzzer berbunyi konstan frekuensi tinggi (1500Hz)
  } 
  else if (jarak > 10.0 && jarak <= 30.0) {
    // ==========================================
    // KONDISI 3: WASPADA (10 cm < Jarak <= 30 cm)
    // ==========================================
    lcd.setCursor(0, 1);
    lcd.print("Status: WASPADA ");
    
    // Efek berkedip (Beeping) untuk peringatan sedang
    digitalWrite(pinLED, HIGH);
    tone(pinBuzzer, 800);        // Bunyi nada sedang (800Hz)
    delay(100);
    digitalWrite(pinLED, LOW);
    noTone(pinBuzzer);
    delay(100);
  } 
  else {
    // ==========================================
    // KONDISI 4: AMAN (Jarak > 30 cm)
    // ==========================================
    lcd.setCursor(0, 1);
    lcd.print("Status: AMAN   ");
    
    digitalWrite(pinLED, LOW);   // LED mati
    noTone(pinBuzzer);          // Buzzer mati
  }

  delay(150); // Intervall sampling
}