#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Inisialisasi OLED display
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// Konfigurasi pin keypad
const byte ROWS = 4;
const byte COLS = 4;
const int debounceDelay = 50;

byte rowPins[ROWS] = {12, 13, 14, 15};
byte colPins[COLS] = {25, 26, 27, 33};

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

bool caps_lock = false;
String text = "";

void setup() {
  Serial.begin(115200);
  
  // Inisialisasi display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);

  // Inisialisasi keypad
  for (byte r = 0; r < ROWS; r++) {
    pinMode(rowPins[r], INPUT_PULLUP);
  }
  for (byte c = 0; c < COLS; c++) {
    pinMode(colPins[c], OUTPUT);
    digitalWrite(colPins[c], HIGH);
  }
}

void loop() {
  char key = getKey();
  if (key) {
    Serial.println(key);
    handleKey(key);
    updateDisplay();
    delay(debounceDelay);
  }
}

char getKey() {
  char key = '\0';
  for (byte c = 0; c < COLS; c++) {
    digitalWrite(colPins[c], LOW);
    for (byte r = 0; r < ROWS; r++) {
      if (digitalRead(rowPins[r]) == LOW) {
        key = keymap[r][c];
      }
    }
    digitalWrite(colPins[c], HIGH);
  }
  return key;
}

void handleKey(char key) {
  if (key >= '0' && key <= '9') {
    text += key;
  } else if (key >= 'A' && key <= 'D') {
    if (caps_lock) {
      text += (key - 'A' + 'a');
    } else {
      text += key;
    }
  } else if (key == '*') {
    caps_lock = !caps_lock;
  } else if (key == '#') {
    text += ' ';
  } else if (key == '<') { // Anda dapat menambahkan lebih banyak simbol opsional di sini
    text += '.';
  }
  // Anda dapat menambahkan fungsi untuk tombol Enter, Backspace, dll.
}

void updateDisplay() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.print(text);
  display.display();
}