import java.util.*;

public class Airlock implements AirlockInterface {

    List<State> history;
    Map<State, Integer> usageCounters;
    State state;
    Integer tmpInt;

    State lastIn;
    State lastEx;

    Airlock(){
        history = new ArrayList<State>();
        usageCounters = new HashMap<State, Integer>();
        usageCounters.put(State.EXTERNAL_DOOR_CLOSED, 0);
        usageCounters.put(State.INTERNAL_DOOR_CLOSED, 0);
        usageCounters.put(State.EXTERNAL_DOOR_OPENED, 0);
        usageCounters.put(State.INTERNAL_DOOR_OPENED, 0);
    }

    @Override
    public List<State> getHistory() {
        return this.history;
    }

    @Override
    public Map<State, Integer> getUsageCounters() {
        return this.usageCounters;
    }

    @Override
    public State getState() {
        return this.state;
    }

    @Override
    public void setState(State state) {
        this.state = state;

        if(state == State.INTERNAL_DOOR_OPENED || state == State.INTERNAL_DOOR_CLOSED)
            lastIn = state;
        else
            lastEx = state;

        history.add(state);
        tmpInt = usageCounters.get(state);
        usageCounters.replace(state, new Integer(tmpInt.intValue()+1) );
        System.out.println(history.get(history.size()-1));
    }

    @Override
    public Set<State> newStates() {
        Set<State> tmp = new HashSet<State>();
        if(lastEx == State.EXTERNAL_DOOR_OPENED && lastIn == State.INTERNAL_DOOR_OPENED || state == State.DISASTER || lastIn == State.DISASTER || lastEx == State.DISASTER){
            tmp.add(State.DISASTER);
            return tmp;
        }else if(this.state == State.INTERNAL_DOOR_CLOSED || this.state == State.EXTERNAL_DOOR_CLOSED){
            tmp.add(State.EXTERNAL_DOOR_CLOSED);
            tmp.add(State.INTERNAL_DOOR_CLOSED);
            tmp.add(State.INTERNAL_DOOR_OPENED);
            tmp.add(State.EXTERNAL_DOOR_OPENED);
            return tmp;
        }else if(this.state == State.EXTERNAL_DOOR_OPENED){
            tmp.add(State.EXTERNAL_DOOR_CLOSED);
            tmp.add(State.INTERNAL_DOOR_CLOSED);
            tmp.add(State.DISASTER);
            tmp.add(State.EXTERNAL_DOOR_OPENED);
            return tmp;
        }else if(this.state == State.INTERNAL_DOOR_OPENED){
            tmp.add(State.EXTERNAL_DOOR_CLOSED);
            tmp.add(State.INTERNAL_DOOR_CLOSED);
            tmp.add(State.DISASTER);
            tmp.add(State.INTERNAL_DOOR_OPENED);
            return tmp;
        }
        return null;
    }

    @Override
    public void openExternalDoor() {
        State st = State.EXTERNAL_DOOR_OPENED;
        if(lastIn == State.INTERNAL_DOOR_OPENED)
            st = State.DISASTER;
        lastEx = st;
        history.add(st);
        tmpInt = usageCounters.get(st);
        usageCounters.replace(st, new Integer(tmpInt.intValue()+1) );
        System.out.println(history.get(history.size()-1));
    }

    @Override
    public void openInternalDoor() {
        State st = State.INTERNAL_DOOR_OPENED;
        if(lastEx == State.EXTERNAL_DOOR_OPENED)
            st = State.DISASTER;
        lastIn = st;
        history.add(st);
        tmpInt = usageCounters.get(st);
        usageCounters.replace(st, new Integer(tmpInt.intValue()+1) );
        System.out.println(history.get(history.size()-1));
    }

    @Override
    public void closeExternalDoor() {
        State st = State.EXTERNAL_DOOR_CLOSED;
        lastEx = st;
        history.add(st);
        tmpInt = usageCounters.get(st);
        usageCounters.replace(st, new Integer(tmpInt.intValue()+1) );
        System.out.println(history.get(history.size()-1));
    }

    @Override
    public void closeInternalDoor() {
        State st = State.INTERNAL_DOOR_CLOSED;
        lastIn = st;
        history.add(st);
        tmpInt = usageCounters.get(st);
        usageCounters.replace(st, new Integer(tmpInt.intValue()+1) );
        System.out.println(history.get(history.size()-1));
    }
}