// Ấn * để xác nhận
// Ấn D để reset
// Ấn # để hiện x và y


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


const byte ROWS = 4; // four rows
const byte COLS = 4; // four columns

char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; // connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; // connect to the column pinouts of the keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
LiquidCrystal_I2C lcd(0x27, 16, 2);  // Địa chỉ I2C và kích thước LCD

enum CalculatorState {
  MENU,
  INPUT_X,
  INPUT_Y,
  DISPLAY_XY,
  RESULT_A,
  RESULT_B,
  RESULT_C
};

CalculatorState currentState = MENU;
int x = 0;
int y = 0;
int result = 0;

void setup() {
  lcd.begin(16, 2);
  lcd.print("welcome");
  delay(500);
  lcd.print(".");
  delay(200);
  lcd.print(".");
  delay(200);
  lcd.print(".");
  delay(200);
}

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

  switch (currentState) {
    case MENU:
      lcd.setCursor(0, 0);
      lcd.print("1: Input X");
      lcd.setCursor(0, 1);
      lcd.print("2: Input Y");
      if (key == '1') {
        currentState = INPUT_X;
        lcd.clear();
        lcd.print("Enter X: ");
      } else if (key == '2') {
        currentState = INPUT_Y;
        lcd.clear();
        lcd.print("Enter Y: ");
      } else if (key == '#') {
        currentState = DISPLAY_XY;
      } else if (key == 'A') {
        currentState = RESULT_A;
      } else if (key == 'B') {
        currentState = RESULT_B;
      } else if (key == 'C') {
        currentState = RESULT_C;
      } else if (key == 'D') {
        x = 0;
        y = 0;
        lcd.clear();
        lcd.print("reset");
        delay(500);
        lcd.print(".");
        delay(200);
        lcd.print(".");
        delay(200);
        lcd.print(".");
        delay(200);
        //currentState = MENU;
      } 
      break;

    case INPUT_X:
      if (key >= '0' && key <= '9') {
        x = x * 10 + (key - '0');
        lcd.print(key);
      } else if (key == '*') {
        lcd.clear();
        currentState = MENU;
      } 
      break;

    case INPUT_Y:
      if (key >= '0' && key <= '9') {
        y = y * 10 + (key - '0');
        lcd.print(key);
      } else if (key == '*') {
        lcd.clear();
        currentState = MENU;
      } 
      break;

    case DISPLAY_XY:
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("X: ");
      lcd.print(x);
      lcd.setCursor(0, 1);
      lcd.print("Y: ");
      lcd.print(x);
      delay(3000);
      lcd.clear();
      currentState = MENU;
      break;
 
    case RESULT_A:
      result = x + y;
      lcd.clear();
      lcd.print("Result A: ");
      lcd.print(result);
      delay(3000);
      lcd.clear();
      currentState = MENU;
      break;

    case RESULT_B:
      result = x - y;
      lcd.clear();
      lcd.print("Result B: ");
      lcd.print(result);
      delay(3000);
      lcd.clear();
      currentState = MENU;
      break;

    case RESULT_C:
      result = x + x + y + y;
      lcd.clear();
      lcd.print("Result C: ");
      lcd.print(result);
      delay(3000);
      lcd.clear();
      currentState = MENU;
      break;
  }
}