const int button_1_pin = 2;
const int button_2_pin = 3;
const int led_pin = 4;

int led_state = LOW;
int button_1_state_last = LOW;
int button_1_state_current;
int button_2_state_last = LOW;
int button_2_state_current;

int button_1_mode = 0;
int button_2_mode = 0;
int last_button = 1;
int t = 0;

unsigned long last_debounce_time = 0;
const unsigned long debounce_delay = 10;
const unsigned int delta_t_fast = 200;
const unsigned int delta_t_slow = 400;

void setup() {
  // put your setup code here, to run once:
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  // https://docs.arduino.cc/built-in-examples/digital/Button
  // https://docs.arduino.cc/built-in-examples/digital/Debounce

  // Debounce button 1
  int button_1_reading = digitalRead(button_1_pin);
  if(button_1_reading != button_1_state_last) {
    last_debounce_time = millis();
  }
  if((millis() - last_debounce_time) > debounce_delay) {
    if(button_1_reading != button_1_state_current) {
      button_1_state_current = button_1_reading;
      if (button_1_state_current == HIGH) {
        // led_state = !led_state;
        button_1_mode = !button_1_mode;
        last_button = 1;
      }
    }
  }
  button_1_state_last = button_1_reading;

  // Debounce button 2
  int button_2_reading = digitalRead(button_2_pin);
  if(button_2_reading != button_2_state_last) {
    last_debounce_time = millis();
  }
  if((millis() - last_debounce_time) > debounce_delay) {
    if(button_2_reading != button_2_state_current) {
      button_2_state_current = button_2_reading;
      if (button_2_state_current == HIGH) {
        // led_state = !led_state;
        button_2_mode = !button_2_mode;
        last_button = 2;
        t = millis();
      }
    }
  }
  button_2_state_last = button_2_reading;

  switch(last_button) {
    case 1:
      if(button_1_mode == 0) {
        digitalWrite(led_pin, LOW);
      } else {
        digitalWrite(led_pin, HIGH);
      }
      break;
    case 2:
      if(button_2_mode == 0) {
        // t = millis();
        // led_state = !led_state;
        if(millis() - t >= delta_t_slow) {
          led_state = !led_state;
          digitalWrite(led_pin, led_state);
          t = millis();
        }
      } else {
        // t = millis();
        // led_state = !led_state;
        if(millis() - t >= delta_t_fast) {
          led_state = !led_state;
          digitalWrite(led_pin, led_state);
          t = millis();
        }
      }
      break;
  }
  // digitalWrite(led_pin, led_state);
}