const int button = 0;
const int led = 16;
int buttonState = false;
int ledState = HIGH;
int buttonDownTime = 0;
bool buttonDownBit = false;
unsigned long currentTime = 0;
unsigned long previousTime = 0;
unsigned long delayTime = 100;

void setup() {
  pinMode(button, INPUT);
  pinMode(led, OUTPUT);
}

void loop() {
  getDelay();
  blink();
  delay(1);
}

void getDelay() {
  // get buttonDownTim
  buttonState = digitalRead(button);
  // buttonState LOW means button is pressed
  if ((buttonState == LOW) && (buttonDownBit == false)) {
    buttonDownTime = millis();
    buttonDownBit = true;
  }
  if ((buttonState == HIGH) && (buttonDownBit == true)) {
    delayTime = millis() - buttonDownTime;
    buttonDownBit = false;
  }
}

void blink() {
  currentTime = millis();
  if ((currentTime - previousTime) >= delayTime) {
    ledState = (ledState == LOW) ? HIGH : LOW;
    digitalWrite(led, ledState);
    previousTime = currentTime;
  }
}