/*
  MXENGINEER
  PIN CONNECTIONS:
  - HY-SRF05 VCC  -> Arduino 5V
  - HY-SRF05 GND  -> Arduino GND
  - HY-SRF05 TRIG -> Pin 9
  - HY-SRF05 ECHO -> Pin 10
  - Buzzer (+)    -> Pin 11
  - Buzzer (-)    -> Arduino GND
  - Potentiometer Left  -> Arduino GND
  - Potentiometer Middle -> Arduino A0
  - Potentiometer Right  -> Arduino 5V
*/

const int trigPin = 9;
const int echoPin = 10;
const int buzzerPin = 11;
const int potPin = A0;

long duration;
int distance;
int potValue;
int dangerDistance;
int beepIntensity;
int beepDelay;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  Serial.begin(9600);
}

int readDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH, 30000);
  if (duration == 0) return 999;
  return duration * 0.034 / 2;
}

void loop() {
  distance = readDistance();
  potValue = analogRead(potPin);
  dangerDistance = map(potValue, 0, 1023, 200, 10);
  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.print(" cm  |  Alarm: ");
  Serial.print(dangerDistance);
  Serial.println(" cm");
  
  if (distance > 200) {
    analogWrite(buzzerPin, 0);
    delay(200);
  }
  else if (distance <= dangerDistance) {
    analogWrite(buzzerPin, 255);
    delay(50);
  }
  else if (distance <= 200) {
    beepIntensity = map(distance, dangerDistance, 200, 255, 50);
    beepIntensity = constrain(beepIntensity, 50, 255);
    beepDelay = map(distance, dangerDistance, 200, 100, 600);
    beepDelay = constrain(beepDelay, 100, 600);
    analogWrite(buzzerPin, beepIntensity);
    delay(150);
    analogWrite(buzzerPin, 0);
    delay(beepDelay);
  }
  delay(50);
}