int langs[] = {2,3,4,5};
int leds[] = {6,9,10,11};
bool state[] = {0,0,0,0};
int old = 0;
int current = 0;

void setup() {
  
  Serial.begin(9600);
  
  for(int i=0; i<4; i++) {
    pinMode(langs[i], INPUT);
    pinMode(leds[i], OUTPUT);
  }
}

void loop() {

  checkStatus();
  
  if(current == 0) {
    for(int i=0; i<255; i++) {
      checkStatus();
      for(int x=0; x<4; x++) {
        analogWrite(leds[x], i);
      }
      delay(10);
    }
    for(int i=255; i>0; i--) {
      checkStatus();
      for(int x=0; x<4; x++) {
        analogWrite(leds[x], i);
      }
      delay(10);
    }
  } else {
    for(int i=0; i<100; i++) {
      checkStatus();
      if(current != 0) {
        analogWrite(leds[current-1], i);
      }
      delay(10);
    }
    for(int i=100; i>0; i--) {
      checkStatus();
      if(current != 0) {
        analogWrite(leds[current-1], i);
      }
      delay(10);
    }
  }
}


void checkStatus() {
  
  current = 0;
  for(int i=0; i<4; i++) {
    state[i] = digitalRead(langs[i]);
    //Serial.print(state[i]);
    //Serial.print("\t");
    if(state[i] == LOW) {
      current = i+1;
    }
  }  

  if(old != current) {
    old = current;
    Serial.println(current);
  }
}