// ================= PIN DEFINITIONS =================
#define STEP_PIN 25
#define DIR_PIN  26
#define EN_PIN   27

#define TOP_LIMIT     32
#define BOTTOM_LIMIT  33

// ================= BIN SETTINGS =================
const int stepsPerBin = 800;   // Adjust based on belt & pulley
int currentBin = 0;
int targetBin = 0;

// ================= SETUP =================
void setup() {
  Serial.begin(115200);

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

  pinMode(TOP_LIMIT, INPUT_PULLUP);
  pinMode(BOTTOM_LIMIT, INPUT_PULLUP);

  digitalWrite(EN_PIN, LOW); // Enable A4988 (LOW = enabled)

  homing();
}

// ================= LOOP =================
void loop() {
  if (Serial.available()) {
    targetBin = Serial.parseInt();
    moveToBin(targetBin);
  }
}

// ================= FUNCTIONS =================

void stepMotor(int steps, bool direction) {
  digitalWrite(DIR_PIN, direction);
  for (int i = 0; i < steps; i++) {
    digitalWrite(STEP_PIN, HIGH);
    delayMicroseconds(800);
    digitalWrite(STEP_PIN, LOW);
    delayMicroseconds(800);
  }
}

void homing() {
  Serial.println("Homing started...");

  digitalWrite(DIR_PIN, LOW); // Move down
  while (digitalRead(BOTTOM_LIMIT) == HIGH) {
    digitalWrite(STEP_PIN, HIGH);
    delayMicroseconds(900);
    digitalWrite(STEP_PIN, LOW);
    delayMicroseconds(900);
  }

  currentBin = 0;
  Serial.println("Homing complete");
}

void moveToBin(int bin) {
  if (bin < 0 || bin > 10) {
    Serial.println("Invalid bin number");
    return;
  }

  int diff = bin - currentBin;
  int steps = abs(diff) * stepsPerBin;

  if (diff > 0) {
    stepMotor(steps, HIGH);  // Up
  } else if (diff < 0) {
    stepMotor(steps, LOW);   // Down
  }

  currentBin = bin;
  Serial.print("Reached Bin: ");
  Serial.println(currentBin);
}