// Pin configuration for 74HC595
const int latchPin = 8;
const int clockPin = 12;
const int dataPin = 11;

// Pin configuration for pushbuttons
const int upButtonPin = 2;
const int downButtonPin = 3;
const int stopButtonPin = 4;
const int resetButtonPin = 5;

// Variables
const float TIME = 50; // 350 .... ~1 second
long counter = 0;
int countDirection = 2; // 1 for increment, 0 for decrement

// Define the segments for each digit
const byte segments[] =
{
  B11111100, // 0
  B01100000, // 1
  B11011010, // 2
  B11110010, // 3
  B01100110, // 4
  B10110110, // 5
  B10111110, // 6
  B11100000, // 7
  B11111110, // 8
  B11110110  // 9
};




void setup()
{
  // Set the pins as outputs
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

  // Set the pins as outputs
  pinMode(upButtonPin, INPUT_PULLUP);
  pinMode(downButtonPin, INPUT_PULLUP);
  pinMode(stopButtonPin, INPUT_PULLUP);
  pinMode(resetButtonPin, INPUT_PULLUP);

  // Initialize the display

  updateDisplay();
}


void loop()
{
  // Check the state of the up button
  if (digitalRead(upButtonPin) == LOW)
  {
    countDirection = 1;
  }
  else if (digitalRead(upButtonPin) == HIGH)
  {
    // nothing
  }

  // Check the state of the down button
  if (digitalRead(downButtonPin) == LOW)
  {
    countDirection = 0;
  }
  else if (digitalRead(downButtonPin) == HIGH)
  {
    // nothing
  }

  // Check the state of the stop button
  if (digitalRead(stopButtonPin) == LOW)
  {
    countDirection = 2;
  }
  else if (digitalRead(stopButtonPin) == HIGH)
  {
    // nothing
  }

  // Check the state of the reset button
  if (digitalRead(resetButtonPin) == LOW)
  {
    countDirection = 2;
    counter = 0;
  }
  else if (digitalRead(resetButtonPin) == HIGH)
  {
    // nothing
  }

  // Increment or decrement the counter based on the count direction
  if (countDirection == 1)
  {
    incrementCounter();
  }
  else if (countDirection == 0)
  {
    decrementCounter();
  }

  // delay loop
  for (int i = 0; i <= TIME; i++)
  {
    updateDisplay();
  }
}


// Functions //

void updateDisplay()
{
  // Extract individual digits
  long digitTenMillions = counter / 10000000;
  long digitMillions = (counter / 1000000) % 10;
  long digitHundredThousands = (counter / 100000) % 10;
  long digitTenThousands = (counter / 10000) % 10;
  long digitThousands = (counter / 1000) % 10;
  long digitHundreds = (counter / 100) % 10;
  long digitTens = (counter / 10) % 10;
  long digitOnes = counter % 10;

  // Display each digit on its corresponding display
  // digitOnes
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11111110);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitOnes]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitTens
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11111101);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitTens]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitHundreds
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11111011);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitHundreds]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitThousands
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11110111);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitThousands]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitTenThousands
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11101111);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitTenThousands]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitHundredThousands
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B11011111);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitHundredThousands]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitMillions
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B10111111);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitMillions]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
  // digitTenMillions
  {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, B01111111);
    shiftOut(dataPin, clockPin, LSBFIRST, segments[digitTenMillions]);
    digitalWrite(latchPin, HIGH);
    // Add a delay for persistence of vision
    delayMicroseconds(10);
  }
}


void incrementCounter()
{
  counter = (counter + 1);
}


void decrementCounter()
{
  counter = (counter - 1);
}