class Timer
{
  public:
    void start() {
      timeStamp = millis();
    }
    bool operator() (const unsigned long duration) {
      return (millis() - timeStamp >= duration) ?  true : false;
    }
  private:
    unsigned long timeStamp {0};
};

enum class ButtonState : byte {released, pressed, wait};
enum class DegasState : byte {start, isActive, off, stop};

constexpr unsigned int BUTTON_TIMESPAN {5000};    // 5 Sek. pressed delay
constexpr unsigned int DEGAS_TIMESPANE {10000};   // 10 Sek. Degas change it to 180000
constexpr byte B_PIN {4};
constexpr byte LED_PIN {LED_BUILTIN};             // Use built in LED

Timer bTimer;
Timer dTimer;

ButtonState bState {ButtonState::released};
DegasState dState {DegasState::off};

void button(byte);
bool degas();
void degasAction();

void setup() {
  Serial.begin(115200);
  pinMode(B_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("Start");
}

void loop() {
  button(B_PIN);
  if (degas()) {                // When true do degas for DEGAS_TIMESPAN time
    degasAction(); 
  }
}

void button(byte pin) {
  if (!digitalRead(pin) && dState != DegasState::isActive) {
    if (bState != ButtonState::wait) bState = ButtonState::pressed;
  } else {
    bState = ButtonState::released;
    if (digitalRead(LED_PIN)) digitalWrite(LED_PIN,LOW);  // Indicate button released or off
  }
  switch (bState) {
    case ButtonState::pressed:
      if(!digitalRead(LED_PIN)) digitalWrite(LED_PIN,HIGH); // Indicate button press
      bTimer.start();
      bState = ButtonState::wait;
      break;
    case ButtonState::wait:
      if (bTimer(BUTTON_TIMESPAN)) {
        dState = DegasState::start;
      }
      break;
    default:
      break;
  }
}

bool degas() {
  bool isActive {false};

  switch (dState) {
    case DegasState::start:
      Serial.println("Degas started");
      dState = DegasState::isActive;
      dTimer.start();
      break;
    case DegasState::isActive:
      isActive = true;
      if (dTimer(DEGAS_TIMESPANE )) {
        dState = DegasState::stop;
      }
      break;
    case DegasState::stop:
      Serial.println("Degas ended");
      digitalWrite (2, LOW);
      dState = DegasState::off;
      break;
    default:
      break;
  }
  return isActive;
}

void degasAction() {
  digitalWrite (2, HIGH);

  static unsigned long lastSpam;
  unsigned long onw = millis();

  if (onw - lastSpam > 777) {
    Serial.println("Degas function active");
    lastSpam = onw;
  }
  /*
  TCA9548A(3);
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(35, 5);
  display.println("Degas");
  display.display();

  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(45, 50);
  display.println("mbar");

  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(15, 10);
  display.print(sci(pressure_mbar2, 2));
  display.display();
  */
}