#include <TM1637Display.h>

// Pins for the tm1637 display module
#define CLK 2
#define DIO 3

TM1637Display display(CLK, DIO);



// constants won't change. They're used here to set pin numbers:
const int BUTTON = 4; // the number of the pushbutton pin
const int PRESS_TIME = 1000; // Time for long press 1000 = 1 second


int mm=0, ss=0, ms=0; 
bool timerStart = false;

char Buffer[3] = " ";  // create a buffer to hold the numbers

// Variables will change:
int lastState = LOW;  // the previous state from the input pin
int currentState;     // the current reading from the input pin
unsigned long pressedTime  = 0;
unsigned long releasedTime = 0;
bool isPressing = false;
bool isLongDetected = false;

void setup() {
pinMode(BUTTON, INPUT_PULLUP);
display.setBrightness(0x0f);

noInterrupts();         // disable all interrupts
TCCR1A = 0;             // set entire TCCR1A register to 0  //set timer1 interrupt at 1kHz  // 1 ms
TCCR1B = 0;             // same for TCCR1B
TCNT1  = 0;             // set timer count for 1khz increments
OCR1A = 1999;           // = (16*10^6) / (1000*8) - 1
//had to use 16 bit timer1 for this bc 1999>255, but could switch to timers 0 or 2 with larger prescaler
// turn on CTC mode
TCCR1B |= (1 << WGM12); // Set CS11 bit for 8 prescaler
TCCR1B |= (1 << CS11);  // enable timer compare interrupt
TIMSK1 |= (1 << OCIE1A);
interrupts();           // enable 
unsigned long pressedTime  = PRESS_TIME; 
}

void loop() {
  // read the state of the switch/button:
  currentState = digitalRead(BUTTON);

  if(lastState == HIGH && currentState == LOW) {        // button is pressed
    pressedTime = millis();
    isPressing = true;
    isLongDetected = false;
  } else if(lastState == LOW && currentState == HIGH) { // button is released
    isPressing = false;
    releasedTime = millis();

    long pressDuration = releasedTime - pressedTime;

    if( pressDuration < PRESS_TIME && (timerStart == false)) {
      timerStart = true; // Start stopwatch
      delay(100);
      }
    else if( pressDuration < PRESS_TIME && (timerStart == true)) {
      timerStart = false; // Stop stopwatch
      delay(100);
      }
  }
  if(isPressing == true && isLongDetected == false) {
    long pressDuration = millis() - pressedTime;

    if( pressDuration > PRESS_TIME ) {
      timerStart = false; // Stop stopwatch
      ms=0, ss=0, mm=0; // Reset stopwatch 
      delay(100);
      isLongDetected = true;
    }
  }

display.showNumberDecEx(ss, 0, true, 2, 2);
display.showNumberDecEx(mm, 0b01000000, true, 2, 0);


  // save the the last state
  lastState = currentState;
  
}
ISR(TIMER1_COMPA_vect){
if(timerStart == true)
          {ms=ms+1;}
if(ms>999)
          {ms=0;ss=ss+1;}
if(ss>59)
          {ss=0; mm=mm+1;}
if(mm>89)
      {timerStart = false;} // Stop stopwatch
}