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

// Inisialisasi LCD dengan alamat I2C (sesuaikan dengan modul Anda, biasanya 0x27 atau 0x3F)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Konfigurasi Keypad
const byte ROWS = 4; // empat baris
const byte COLS = 4; // empat kolom

char keys[ROWS][COLS] = {
  {'1', '2', '3', '/'},
  {'4', '5', '6', '*'},
  {'7', '8', '9', '-'},
  {'C', '0', '=', '+'}
};

byte rowPins[ROWS] = {5, 4, 3, 2};   // Pin yang terhubung ke baris keypad
byte colPins[COLS] = {9, 8, 7, 6};   // Pin yang terhubung ke kolom keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Variabel untuk menyimpan input dan hasil
String inputString = "";
float num1 = 0;
float num2 = 0;
char operatorChar = 0;
bool newCalculation = true;

void setup() {
  lcd.init();                      // Inisialisasi LCD
  lcd.backlight();                 // Mengaktifkan backlight LCD
  lcd.setCursor(0, 0);
  lcd.print("Masukkan Volume");
  delay(2000);
  lcd.clear();
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    if (key >= '0' && key <= '9') {                // Jika tombol angka ditekan
      inputString += key;
      lcd.setCursor(0, 0);
      lcd.print(inputString);
    }
    else if (key == '+' || key == '-' || key == '*' || key == '/') {   // Jika tombol operator ditekan
      if (inputString.length() > 0) {
        num1 = inputString.toFloat();
        operatorChar = key;
        inputString = "";
        lcd.setCursor(0, 0);
        lcd.print(num1);
        lcd.print(operatorChar);
      }
    }
    else if (key == '=') {                         // Jika tombol '=' ditekan
      if (inputString.length() > 0 && operatorChar != 0) {
        num2 = inputString.toFloat();
        float result = calculate(num1, num2, operatorChar);
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Hasil:");
        lcd.setCursor(0, 1);
        lcd.print(result);
        newCalculation = true;
        inputString = "";
        operatorChar = 0;
        delay(3000);
        lcd.clear();
      }
    }
    else if (key == 'C') {                         // Jika tombol 'C' ditekan
      clearAll();
    }
  }

  
}

float calculate(float n1, float n2, char op) {
  switch (op) {
    case '+':
      return n1 + n2;
    case '-':
      return n1 - n2;
    case '*':
      return n1 * n2;
    case '/':
      if (n2 != 0)
        return n1 / n2;
      else {
        lcd.clear();
        lcd.print("Error: Div 0");
        delay(2000);
        clearAll();
        return 0;
      }
    default:
      return 0;
  }
}

void clearAll() {
  inputString = "";
  num1 = 0;
  num2 = 0;
  operatorChar = 0;
  lcd.clear();
}