// Pin Definitions
const int dirPin = 2;
const int stepPin = 3;
const int enablePin = 4;

const int stopButtonPin = 5;
const int returnButtonPin = 6;
const int resetButtonPin = 7;

// Motor settings
const int stepDelay = 800; // µs
long stepCount = 0;

// State control
enum Mode { FORWARD, REVERSE, WAIT_RESET };
Mode currentMode = FORWARD;
bool stopped = false;

// Timing for non-blocking step
unsigned long lastStepTime = 0;

// Debounce handling
bool prevReturnButton = LOW;
bool prevResetButton = LOW;
unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

void setup() {
  pinMode(dirPin, OUTPUT);
  pinMode(stepPin, OUTPUT);
  pinMode(enablePin, OUTPUT);

  pinMode(stopButtonPin, INPUT);
  pinMode(returnButtonPin, INPUT);
  pinMode(resetButtonPin, INPUT);

  digitalWrite(enablePin, LOW);   // Enable driver
  digitalWrite(dirPin, HIGH);     // Initial direction: forward
}

void loop() {
  unsigned long currentTime = millis();

  // Read buttons
  bool stopButton = digitalRead(stopButtonPin);
  bool returnButton = digitalRead(returnButtonPin);
  bool resetButton = digitalRead(resetButtonPin);

  // Handle Return Button press (edge detection with debounce)
  if (returnButton == HIGH && prevReturnButton == LOW && (currentTime - lastDebounceTime > debounceDelay)) {
    if (currentMode == FORWARD) {
      currentMode = REVERSE;
      digitalWrite(dirPin, LOW); // Set direction to reverse
    }
    lastDebounceTime = currentTime;
  }
  prevReturnButton = returnButton;

  // Handle Reset Button press
  if (resetButton == HIGH && prevResetButton == LOW && (currentTime - lastDebounceTime > debounceDelay)) {
    if (currentMode == WAIT_RESET) {
      currentMode = FORWARD;
      digitalWrite(dirPin, HIGH); // Set direction to forward
    }
    lastDebounceTime = currentTime;
  }
  prevResetButton = resetButton;

  // Handle Stop Button (live read)
  stopped = (stopButton == HIGH);

  // === Motor control state machine ===
  if (currentMode == FORWARD && !stopped) {
    if (micros() - lastStepTime >= stepDelay * 2) {
      stepMotor();
      stepCount++;
      lastStepTime = micros();
    }
  }

  else if (currentMode == REVERSE) {
    if (stepCount > 0) {
      if (micros() - lastStepTime >= stepDelay * 2) {
        stepMotor();
        stepCount--;
        lastStepTime = micros();
      }
    } else {
      currentMode = WAIT_RESET;
    }
  }

  // WAIT_RESET: motor remains idle until reset button is pressed
}

// Step motor one step
void stepMotor() {
  digitalWrite(stepPin, HIGH);
  delayMicroseconds(stepDelay);
  digitalWrite(stepPin, LOW);
  delayMicroseconds(stepDelay);
}