class Timer {
  private:
    unsigned long nextChangeTime;
    unsigned long timeOn_;
    boolean overFlow;
  public:
    void TimerSet (unsigned long timeOn) {
      timeOn_ = timeOn;
      unsigned long currentTime = micros();
      nextChangeTime = currentTime + timeOn;
      if (nextChangeTime > currentTime) {
        overFlow = false;
      } else {
        overFlow = true;
      }
   }
    boolean TimerActive() {
      unsigned long currentTime = micros();
      boolean val = false;
      if (! overFlow) {
        if (currentTime < nextChangeTime) {
          val = true;
        }
      } else if ((currentTime + timeOn_)<(nextChangeTime + timeOn_)){
        val = true;
      }
      return val;
    }
};

int LED1 = 7;
int LED2 = 8;
int LED3 = 9;

unsigned long delay1 = 1000000;
unsigned long delay2 = 500000;
unsigned long delay3 = 250000;

int BTN = 4;
unsigned long debounceDuration = 50; // millis
unsigned long lastTimeButtonStateChanged = 0;
byte previousButtonState = LOW;

byte state = 0; // 0: LEDs off, 1: LEDs on, 2: LED1, 3: LED2, 4: LED3

Timer TMR1;
Timer TMR2;
Timer TMR3;

void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);

  pinMode(BTN, INPUT_PULLUP);
}

void loop() {
  // Button debounce
  unsigned long currentMillis = millis();
  if (millis() - lastTimeButtonStateChanged > debounceDuration) {
    byte buttonState = digitalRead(BTN);

    // Check for button press
    if (buttonState != previousButtonState) {
      lastTimeButtonStateChanged = millis();
      previousButtonState = buttonState;

      if (buttonState == LOW) {
        // Cycle through LED states (0-4)
        if (state <= 3) {
          state ++; 
        } else {
          state = 0;
        }
      }
    }
  }

  switch (state) {
  case 0:
    // Turn off all LEDs
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
    break;
  case 1:
    // Turn on all LEDs
    ledBlink(LED1, TMR1, delay1);
    ledBlink(LED2, TMR2, delay2);
    ledBlink(LED3, TMR3, delay3);
    break;
  case 2:
    // Turn on LED1
    ledBlink(LED1, TMR1, delay1);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
    break;
  case 3:
     // Turn on LED2
    ledBlink(LED2, TMR2, delay2);
    digitalWrite(LED1, LOW);
    digitalWrite(LED3, LOW);
    
    break;
  case 4:
     // Turn on LED3
    ledBlink(LED3, TMR3, delay3);
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
    break;
  }
}

void ledBlink(int LED, Timer& TMR, unsigned long delay){
  if (!TMR.TimerActive()) {
      digitalWrite(LED, !digitalRead(LED));
      TMR.TimerSet(delay);
    }
}