#define BUTTON_PIN PA0
#define LED_PIN PC13

enum Mode {
  MODE_OFF,
  MODE_SLOW,
  MODE_FAST
};

Mode currentMode = MODE_OFF; 
bool buttonState;            
bool lastButtonState = HIGH;  
unsigned long lastDebounceTime = 0;  
unsigned long debounceDelay = 50;   

const unsigned long SLOW_INTERVAL = 1000;    
const unsigned long FAST_INTERVAL = 200;     

unsigned long previousMillis = 0;
bool ledState = HIGH;  

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  pinMode(LED_PIN, OUTPUT);
  
  digitalWrite(LED_PIN, HIGH); 
}

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

  bool reading = digitalRead(BUTTON_PIN);
  
  if (reading != lastButtonState) {
    lastDebounceTime = currentMillis;
  }

  if ((currentMillis - lastDebounceTime) > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;
      
      if (buttonState == LOW) {
        switch(currentMode) {
          case MODE_OFF:
            currentMode = MODE_SLOW;
            break;
          case MODE_SLOW:
            currentMode = MODE_FAST;
            break;
          case MODE_FAST:
            currentMode = MODE_OFF;
            digitalWrite(LED_PIN, HIGH);
            ledState = HIGH;
            break;
        }
      }
    }
  }
  
  lastButtonState = reading;
  
  switch(currentMode) {
    case MODE_OFF:

      break;
      
    case MODE_SLOW:
      if (currentMillis - previousMillis >= SLOW_INTERVAL) {
        previousMillis = currentMillis;
        ledState = !ledState;  
        digitalWrite(LED_PIN, ledState);
      }
      break;
      
    case MODE_FAST:
      if (currentMillis - previousMillis >= FAST_INTERVAL) {
        previousMillis = currentMillis;
        ledState = !ledState;  
        digitalWrite(LED_PIN, ledState);
      }
      break;
  }
}