#define trigPin 3
#define echoPin 4
#define vibrationPin 1
#define potentiometrIn A1
#define buttonPin 0

#define minDist 2
#define maxDist 100
const int t = 200;

long duration;
long distance;
long t1;
long t2;
long multiplier;
long currentMax;

bool isOn = false;
int buttonState = LOW;

int currentButtonState;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(vibrationPin, OUTPUT);
  pinMode(potentiometrIn, INPUT);
}


void loop() {

  currentButtonState = digitalRead(buttonPin);
  if (currentButtonState != buttonState) {
    buttonState = currentButtonState;
    if (buttonState == HIGH) {
      isOn = !isOn;
    }
  }

  if (isOn) {
    multiplier = analogRead(potentiometrIn);
    multiplier = constrain(multiplier, 0, 1023);
    currentMax = (maxDist * multiplier) / 1023 + 2*minDist;

    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    duration = pulseIn(echoPin, HIGH);
    distance = duration / 58;
    distance = constrain(distance, minDist, currentMax);



    t2 = (long(t)*(distance-minDist))/(currentMax-minDist);
    t1 = t - t2;

    if (t1 >= 3) {
      digitalWrite(vibrationPin, HIGH);
      delay(t1);
    }

    if (t2 >= 3) {
      digitalWrite(vibrationPin, LOW);
      delay(t2);
    }
  } else {
    digitalWrite(vibrationPin, LOW);
  }
}