#define STEP_PIN 21
#define DIR_PIN 26

#define CONV_FWD 14
#define CONV_REV 12

#define HOME_SW 35

long stepsPerBin = 50;   // small for simulation
long currentPos = 0;

void setup() {
  Serial.begin(115200);

  pinMode(STEP_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);

  pinMode(CONV_FWD, OUTPUT);
  pinMode(CONV_REV, OUTPUT);

  pinMode(HOME_SW, INPUT_PULLUP);

  Serial.println("VLM READY - Enter Bin (1-20)");
}

void loop() {
  if (Serial.available()) {
    int bin = Serial.parseInt();

    if (bin >= 1 && bin <= 20) {
      moveToBin(bin);
      deliverBin();
      Serial.println("Send R to Return");

      while (true) {
        if (Serial.available()) {
          char c = Serial.read();
          if (c == 'R' || c == 'r') {
            returnBin();
            break;
          }
        }
      }
    }
  }
}

void moveToBin(int bin) {
  long target = bin * stepsPerBin;
  long moveSteps = target - currentPos;

  digitalWrite(DIR_PIN, moveSteps > 0 ? HIGH : LOW);
  moveSteps = abs(moveSteps);

  for (long i = 0; i < moveSteps; i++) {
    stepMotor();
  }

  currentPos = target;
  Serial.print("At Bin ");
  Serial.println(bin);
}

void deliverBin() {
  digitalWrite(CONV_FWD, HIGH);
  delay(2000);
  digitalWrite(CONV_FWD, LOW);
}

void returnBin() {
  digitalWrite(CONV_REV, HIGH);
  delay(2000);
  digitalWrite(CONV_REV, LOW);
}

void stepMotor() {
  digitalWrite(STEP_PIN, HIGH);
  delay(5);
  digitalWrite(STEP_PIN, LOW);
  delay(5);
}