#define A  13
#define B  12
#define C  11
#define D  10
#define E  9
#define F  8
#define G  7

#define CLK 2
#define DT 3
#define SW 4

boolean ledCathode = false; //if you using anode 7 segment display, Make it true 

int currentStateCLK, lastStateCLK, start;
unsigned long lastButtonPress = 0;
unsigned int counter = 0;

int countDelay = 1000; // Countdown delay

byte numeral[11] = {
  B0000001,//0
  B1001111,//1
  B0010010,//2
  B0000110,//3
  B1001100,//4
  B0100100,//5
  B0100000,//6
  B0001111,//7
  B0000000,//8
  B0001100,//9
  B0111000 //F
};

const int segmentPins[7] = {G, F, E, D, C, B, A};

void setup()
{
  Serial.begin(9600);
  for (int i = 0; i < 7; i++)
  {
    pinMode(segmentPins[i], OUTPUT);
  }

  pinMode(CLK, INPUT);
  pinMode(DT, INPUT);
  pinMode(SW, INPUT_PULLUP);
  lastStateCLK = digitalRead(CLK);
  counter = 0;
}

void loop()
{
  currentStateCLK = digitalRead(CLK);
  if (currentStateCLK != lastStateCLK  && currentStateCLK == 1) {
    if (digitalRead(DT) != currentStateCLK) {
      counter --;
    } else {
      counter ++;
    }
  }
  lastStateCLK = currentStateCLK;
  Serial.println(counter);
  if (counter > 0 && counter <= 10) {
    showDigit(counter);
  } else if (counter == 11) {
    counter = 0;
    showDigit(counter);
  } else {
    counter = 0;
    showDigit(counter);
  }
  
  int btnState = digitalRead(SW);
  if (btnState == LOW) {
    if (millis() - lastButtonPress > 50) {
      Serial.println("Button pressed!");
      for (start = counter; start >= 0; start -- ) {
        showDigit(start);
        delay(countDelay);
      }
      counter = 0;
      showDigit(counter);
    }
    lastButtonPress = millis();
  }
  delay(1);
}

void showDigit( int number)
{
  boolean isBitSet;
  for (int segment = 0; segment < 7; segment++)
  {
    isBitSet = bitRead(numeral[number], segment);
    if (ledCathode == true) {
      isBitSet = ! isBitSet;
    }
    digitalWrite( segmentPins[segment], isBitSet);
  }
}