const int leds[4] = {2, 3, 4, 5};

const int buttons[4] = {6, 7, 8, 9};


int mode = -1;

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(leds[i], OUTPUT);
    pinMode(buttons[i], INPUT_PULLUP);  
  }
}

void loop() {

  for (int i = 0; i < 4; i++) {
    if (digitalRead(buttons[i]) == LOW) {
      mode = i;
    }
  }


  switch (mode) {
    case 0:
      modeOne();
      break;
    case 1:
      modeTwo();
      break;
    case 2:
      modeThree();
      break;
    case 3:
      modeFour();
      break;
    default:
      allOff();
      break;
  }
}


void modeOne() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], HIGH);
  }
  delay(300);
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], LOW);
  }
  delay(300);
}


void modeTwo() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], HIGH);
    delay(150);
    digitalWrite(leds[i], LOW);
  }
}


void modeThree() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], HIGH);
    delay(100);
    digitalWrite(leds[i], LOW);
  }
  for (int i = 2; i > 0; i--) {
    digitalWrite(leds[i], HIGH);
    delay(100);
    digitalWrite(leds[i], LOW);
  }
}


void modeFour() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], i % 2 == 0 ? HIGH : LOW);
  }
  delay(300);
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], i % 2 != 0 ? HIGH : LOW);
  }
  delay(300);
}


void allOff() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(leds[i], LOW);
  }
}