// Pin Definitions
const int btn1 = 12; // Hold to Activate
const int btn2 = 11; // 3-Minute Constant
const int btn3 = 9;  // 3-Minute Pulse (6s ON, 3s OFF)
const int btn4 = 6;  // CANCEL
const int relayPin = 2;

// Timing Constants (in milliseconds)
const unsigned long THREE_MINUTES = 3UL * 60UL * 1000UL;
const unsigned long PULSE_ON = 6000UL;
const unsigned long PULSE_OFF = 3000UL;

// State Variables
enum Mode { IDLE, CONSTANT, PULSING };
Mode currentMode = IDLE;
unsigned long modeStartTime = 0;
unsigned long lastPulseToggle = 0;
bool relayIsOn = false;

void setup() {
  pinMode(btn1, INPUT_PULLUP);
  pinMode(btn2, INPUT_PULLUP);
  pinMode(btn3, INPUT_PULLUP);
  pinMode(btn4, INPUT_PULLUP);
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW); // Start with relay OFF
}

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

  // --- BUTTON 4: CANCEL (Highest Priority) ---
  if (digitalRead(btn4) == LOW) {
    stopAll();
  }

  // --- BUTTON 1: MOMENTARY HOLD ---
  // Only works if no other cycle is running
  if (currentMode == IDLE) {
    if (digitalRead(btn1) == LOW) {
      digitalWrite(relayPin, HIGH);
      return; // Skip rest of loop to maintain hold
    } else {
      digitalWrite(relayPin, LOW);
    }
  }

  // --- START NEW CYCLES ---
  if (currentMode == IDLE) {
    if (digitalRead(btn2) == LOW) {
      currentMode = CONSTANT;
      modeStartTime = currentMillis;
      digitalWrite(relayPin, HIGH);
    } 
    else if (digitalRead(btn3) == LOW) {
      currentMode = PULSING;
      modeStartTime = currentMillis;
      lastPulseToggle = currentMillis;
      relayIsOn = true;
      digitalWrite(relayPin, HIGH);
    }
  }

  // --- RUN ACTIVE CYCLES ---
  if (currentMode != IDLE) {
    // Check if 3-minute total time is up
    if (currentMillis - modeStartTime >= THREE_MINUTES) {
      stopAll();
    } 
    
    // Logic for Button 3 (Pulsing)
    else if (currentMode == PULSING) {
      unsigned long interval = relayIsOn ? PULSE_ON : PULSE_OFF;
      if (currentMillis - lastPulseToggle >= interval) {
        relayIsOn = !relayIsOn;
        digitalWrite(relayPin, relayIsOn ? HIGH : LOW);
        lastPulseToggle = currentMillis;
      }
    }
  }
}

void stopAll() {
  currentMode = IDLE;
  digitalWrite(relayPin, LOW);
}