//note LED dp is not connected in this circuit and the LED initializes at 0
int latchPin = 2; //STCP of the 74HC595 is connected to digitalpin 2, setting the output pin numbers
int dataPin = 3; //DS of the 74HC595 is connected to digitalpin 3, setting the output pin numbers
int clockPin = 4; //SHCP of the 74HC595 is connected to digitalpin 4, setting the output pin numbers

const int upbuttonPin = 15; //initializing pin A2 as the decrement pushbutton, setting the input pin numbers
const int downbuttonPin = 16; //initializing pin A1 as the increment pushbutton, setting the input pin numbers

int number = 0; //for tracking the current number displayed on the 7-segment, initializing "number", first number on LED screen will be "n"
int lastupbuttonState = LOW; //initializing the previous state of the up button
int lastdownbuttonState = LOW; //initializing the previous state of the down button

//note for binary number array, 0b00000000 corresponds to bits 0b 0,0,0,0,0,0,0,0 which corresponds to LED#s 0b dp,f,g,e,d,c,b,a
byte numbersArray[7] = {
  //0b00111111, //LED #0 , for counting purposes in the code this is 0
  0b01010100, //LED #n , for counting purposes in the code this is 0
  0b00000110, //LED #1 , for counting purposes in the code this is 1
  0b01011011, //LED #2
  0b01001111, //LED #3
  0b01100110, //LED #4
  0b01101101, //LED #5
  0b01111101  //LED #6 , for counting purposes in the code this is 6
}; 

void setup() {
  //this will set the digital pins as outputs to the 74HC595 and therefore make the 74HC595 pins output as well
  pinMode(latchPin, OUTPUT); //when held low the data does not display
  pinMode(dataPin, OUTPUT); //datapin
  pinMode(clockPin, OUTPUT); //clock

  //this will set the A pins as inputs for the arduino when the button's connected are pressed and it receives a signal
  pinMode(upbuttonPin, INPUT); //increment button set as input
  pinMode(downbuttonPin, INPUT); //decrement button set as input
  updateDisplay(number);
}

void loop() {
  //for reading the state of the uppushbutton and downpushbutton value:
  bool upbuttonState = digitalRead(upbuttonPin);
  bool downbuttonState = digitalRead(downbuttonPin);

  //check for up button state transitions (check if the up button is pressed)
  if (upbuttonState == HIGH && lastupbuttonState == LOW) {
      if(downbuttonState == LOW) {
        number != 6 ? number += 1: number; 
        delay(250); 
        updateDisplay(number);
      }
      if (downbuttonState == HIGH){
      delay(250);
      number = 0; //change number to n, there will be no other counting
      updateDisplay(number);
      delay(250); //delay for debounce
    }
  }
  
  if (downbuttonState == HIGH && lastdownbuttonState == LOW) {
    if(upbuttonState == LOW) {
        number != 0 ? number -= 1: number; 
        delay(250); 
        updateDisplay(number);
      }
      if (upbuttonState == HIGH){
      delay(250);
      number = 0; //change number to n, there will be no other counting
      updateDisplay(number);
      delay(250); //delay for debounce
    }
  }

  //remember the last button state
  lastupbuttonState = upbuttonState;
  lastdownbuttonState = downbuttonState;

}

void updateDisplay(int num) {
  //This is to make sure that the number is within the range 0-6 and include all the numbers in the array
  num = num % 7;

  //This will hold the latch low, load the bits in the shift register, then open the latch high to send of the bits. Changes the LEDs
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, numbersArray[num]);
  digitalWrite(latchPin, HIGH);
}