const int TRIG = 7;         
const int ECHO = 6;         
const int DIR1 = 12;        
const int STEP1 = 13;       
const int DIR2 = 2;        
const int STEP2 = 3;        
const int REV = 200;        
const int DIS_THRESHOLD = 10;  // Distance threshold for obstacle detection (in cm)
const int SAFETY_MARGIN = 2;   // Safety margin for obstacle distance

float duration_us, distance_cm;

void setup() {
  Serial.begin(9600);         
  pinMode(TRIG, OUTPUT);      
  pinMode(ECHO, INPUT);      
  pinMode(STEP1, OUTPUT);     
  pinMode(DIR1, OUTPUT);      
  pinMode(STEP2, OUTPUT);     
  pinMode(DIR2, OUTPUT);      
}

// Loop function
void loop() {
  distance_cm = getUltrasonicDistance();

  if (distance_cm < DIS_THRESHOLD + SAFETY_MARGIN) {
    avoidObstacle();
  } else {
    moveForward(1000);   
  }

}

float getUltrasonicDistance() {
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  duration_us = pulseIn(ECHO, HIGH);
  float distance = duration_us * 0.017;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  return distance;
}

void moveForward(int speed) {
  digitalWrite(DIR1, HIGH);   
  digitalWrite(DIR2, HIGH);   
  for (int x = 0; x < REV; x++) {
    digitalWrite(STEP1, HIGH);
    digitalWrite(STEP2, HIGH);
    delayMicroseconds(speed);    
    digitalWrite(STEP1, LOW);
    digitalWrite(STEP2, LOW);
    delayMicroseconds(speed);
  }
}

void avoidObstacle() {
  turnLeft(500);   
  delay(500);      
  moveForward(1000);
}

void turnLeft(int speed) {
  digitalWrite(DIR1, HIGH);
  digitalWrite(DIR2, LOW);
  
  for (int x = 0; x < REV / 2; x++) { 
    digitalWrite(STEP1, HIGH);
    digitalWrite(STEP2, HIGH);
    delayMicroseconds(speed);
    digitalWrite(STEP1, LOW);
    digitalWrite(STEP2, LOW);
    delayMicroseconds(speed);
  }
}