buttons.h

// Process button inputs and return button activity

#define NUMBUTTONS 2
#define MODEBUTTON 4
#define BRIGHTNESSBUTTON 3

#define BTNIDLE 0
#define BTNDEBOUNCING 1
#define BTNPRESSED 2
#define BTNRELEASED 3
#define BTNLONGPRESS 4
#define BTNLONGPRESSREAD 5

#define BTNDEBOUNCETIME 20
#define BTNLONGPRESSTIME 1000

unsigned long buttonEvents[NUMBUTTONS];
byte buttonStatuses[NUMBUTTONS];
byte buttonmap[NUMBUTTONS] = {BRIGHTNESSBUTTON, MODEBUTTON};

void updateButtons() {
  for (byte i = 0; i < NUMBUTTONS; i++) {
    switch(buttonStatuses[i]) {
      case BTNIDLE:
        if (digitalRead(buttonmap[i]) == LOW) {
          buttonEvents[i] = currentMillis;
          buttonStatuses[i] = BTNDEBOUNCING;
        }
      break;
      
      case BTNDEBOUNCING:
        if (currentMillis - buttonEvents[i] > BTNDEBOUNCETIME) {
          if (digitalRead(buttonmap[i]) == LOW) {
            buttonStatuses[i] = BTNPRESSED;
          }
        }
      break;
      
      case BTNPRESSED:
        if (digitalRead(buttonmap[i]) == HIGH) {
          buttonStatuses[i] = BTNRELEASED;
        } else if (currentMillis - buttonEvents[i] > BTNLONGPRESSTIME) {
            buttonStatuses[i] = BTNLONGPRESS;
        }
      break;
      
      case BTNRELEASED:
      break;
      
      case BTNLONGPRESS:
      break;
 
      case BTNLONGPRESSREAD:
        if (digitalRead(buttonmap[i]) == HIGH) {
          buttonStatuses[i] = BTNIDLE;
        }
      break;     
    }  
  }
}

byte buttonStatus(byte buttonNum) {

  byte tempStatus = buttonStatuses[buttonNum];
  if (tempStatus == BTNRELEASED) {
    buttonStatuses[buttonNum] = BTNIDLE;
  } else if (tempStatus == BTNLONGPRESS) {
    buttonStatuses[buttonNum] = BTNLONGPRESSREAD;
  }
  
  return tempStatus;

}