#include <TimerOne.h>
#define STOP_STATE 0
#define UP_STATE 1
#define DOWN_STATE 2

char state;
char floor_button[5] = {2,3,4,5,6};
char floor_light[5] = {12,11,10,9,8};
char index,current_floor,target_floor;


void setup() {
  // put your setup code here, to run once:
  for (index=0;index<5;index++){
    pinMode(floor_button[index], INPUT_PULLUP);
    pinMode(floor_light[index], OUTPUT);
  }
  state = DOWN_STATE;
  current_floor = 0;
  target_floor = 0;
  Timer1.initialize(1000000);
  Timer1.attachInterrupt(onesecond);
}

void loop() {
  // put your main code here, to run repeatedly:
  switch(state){
    case STOP_STATE: 
      for (index=0;index<5;index++){
        if (digitalRead(floor_button[index])==0){
          target_floor = index;
          digitalWrite(floor_light, HIGH);
          break;
        }
      }    
      if (current_floor<target_floor){
        state = UP_STATE;
        Timer1.start();      
      }
      else if (current_floor>target_floor){
        state = DOWN_STATE; 
        Timer1.start();       
      }
      break;
   case UP_STATE: if (current_floor == target_floor){
      state = STOP_STATE;
      Timer1.stop();
      break;    
   }
   case DOWN_STATE: if (current_floor == target_floor){
      state = STOP_STATE;
      Timer1.stop();
      break;    
   }   
  }
  for (index=0;index<5;index++){
    if (index == current_floor)
      digitalWrite(floor_light[index], HIGH);
    else digitalWrite(floor_light[index], LOW);
  }  
}


void onesecond(){
  switch(state){
    case STOP_STATE: 
      break;
   case UP_STATE:current_floor++ ;
      break;    
   case DOWN_STATE:current_floor--; 
      break;      
  }
}