#include <LiquidCrystal.h>
#include <Keypad.h>

const int rs = 12, en = 11, d4 = 10, d5 = 9, d6 = 8, d7 = 7;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char key;
char status = 0;
char keys [ROWS] [COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'},
};

uint8_t colPins [COLS] = {5,4,3,2};
uint8_t rowPins [ROWS] = {A0, A1, A2, A3};

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

void setup() {
  lcd.begin(16, 2);
  lcd.print("Kalkulator Siap!");
  delay(1000);
  lcd.clear();
}

int x = 0, y = 0;
float b = 0, c = 0, d = 0;
char e, f;
void loop() { 
  char key = keypad.getKey();
  if (key != NO_KEY){
    if (key >= 48 && key < 58){
      if (y == 0){
          b = b*10 + key-48;
          lcd.setCursor(0,y);
          lcd.print(b);
      } else {
          c = c*10 + key - 48;
          lcd.setCursor(2,y);
          lcd.print(c);
      }
    } else if (key == 'A' || key == 'B' || key == 'C' || key == 'D') {
      lcd.setCursor(0,1);
      e = key;
      switch(e){
        case 'A' : f = '+'; break;
        case 'B' : f = '-'; break;
        case 'C' : f = '*'; break;
        case 'D' : f = '/'; break;
        default : x = 0; y = 0; b = 0; c = 0; d = 0; e = 0; break;
      }
      lcd.print(f);
      y = 1;
    } else if (key == '#'){
      lcd.clear();
      lcd.setCursor(0,0);
      lcd.print("=");
      switch(e){
        case 'A' : d = b+c; break;
        case 'B' : d = b-c; break;
        case 'C' : d = b*c; break;
        case 'D' : d = b/c; break;
        default : x = 0; y = 0; b = 0; c = 0; d = 0; e = 0; break;
      }
      lcd.setCursor(2,0);
      lcd.print(d);
      c = 0;
      b = d;
    }
  }
  //Reset
  if (key == '*'){
    lcd.clear();
    x = 0; 
    y = 0;
    b = 0;
    c = 0;
    d = 0;
    lcd.print("Reset");
    for (int i = 0; i < 5; i++){
      delay(100);
      lcd.setCursor(i,1);
      lcd.print(".");
    }
    lcd.clear();
  } 
}