#include <Keypad.h>
#include <SevSeg.h>

// Keypad setup
const byte ROWS = 4; // Number of rows
const byte COLS = 4; // Number of 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);

// 7-Segment Display setup
SevSeg sevseg;

char displayBuffer[5] = "    "; // Holds 4 digits plus null terminator
int bufferIndex = 0;

void setup() {
  // SevSeg setup
  byte numDigits = 4;
  byte digitPins[] = {10, 11, 12, 13};    // Pins for the digits
  byte segmentPins[] = {A0, A1, A2, A3, A4, A5, 0}; // Pins for the segments
  bool resistorsOnSegments = true;       // 'true' means resistors are on segment pins
  bool updateWithDelays = false;
  bool leadingZeros = false;
  bool disableDecPoint = true;

  sevseg.begin(COMMON_ANODE, numDigits, digitPins, segmentPins, resistorsOnSegments,
               updateWithDelays, leadingZeros, disableDecPoint);
  sevseg.setBrightness(90); // Set display brightness
}

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

  if (key) {
    // Handle key press
    if (key >= '0' && key <= '9') {
      // Add digit to buffer
      if (bufferIndex < 4) {
        displayBuffer[bufferIndex] = key;
        bufferIndex++;
      }
    } else if (key == '*') {
      // Clear buffer
      for (int i = 0; i < 4; i++) {
        displayBuffer[i] = ' ';
      }
      bufferIndex = 0;
    }

    // Display the buffer
    sevseg.setChars(displayBuffer);
  }

  sevseg.refreshDisplay(); // Must be called repeatedly
}