import java.util.ArrayList;
public class WaitingLoopArrayImpl<E> implements WaitingArrayInterface<E> {
  private int entryIndex;
  private int exitIndex;
  private int initialCapacity;
  private ArrayList<E> loopArray;

  public WaitingLoopArrayImpl() {
    this.entryIndex = 99;
    this.exitIndex = 0;
    this.initialCapacity = 100;
    this.loopArray = new ArrayList<E>(initialCapacity);
    for(int i = 0; i < 100; i++){
      loopArray.add(null);
    }
  }

  public WaitingLoopArrayImpl(int capacity){
    this.entryIndex = capacity - 1;
    this.exitIndex = 0;
    this.initialCapacity = capacity;
    this.loopArray = new ArrayList<E>();
    for(int i = 0; i < capacity; i++){
      loopArray.add(null);
    }
  }


  private void resizeCapacity(){
    initialCapacity *= 2;
    ArrayList<E> copy = loopArray;
    loopArray = new ArrayList<E>(initialCapacity);
    for(int i = 0; i < initialCapacity; i++){
      loopArray.add(null);
    }
    for(int i = 0; i < copy.size(); i++) {
      loopArray.set(i, copy.get(i));
    }
  }


  @Override
  public void add(E e){
    if(entryIndex == initialCapacity - 1) {
      entryIndex = 0;
    } else { entryIndex += 1; }
    loopArray.set(entryIndex, e);
  }

  @Override
  public void remove() throws EmptyWaitingArrayException {
    if(loopArray.isEmpty() == true){
      throw new EmptyWaitingArrayException("WaitingLoopArrayImpl remove is not working properly");
    }
    if(exitIndex == initialCapacity - 1) {
      loopArray.set(exitIndex, null);
      exitIndex = 0;
    } else {
      loopArray.set(exitIndex, null);
      exitIndex += 1;
    }
  }

  @Override
  public void clear() throws EmptyWaitingArrayException {
    if(loopArray.isEmpty() == true){
      throw new EmptyWaitingArrayException("EWA Exception thrown");
    }
    loopArray = new ArrayList<E>(initialCapacity);
    for(int i = 0; i < initialCapacity; i++){
      loopArray.add(null);
    }

  }

  @Override
  public E getFirst() throws EmptyWaitingArrayException {
    if(loopArray.isEmpty() == true) {
      throw new EmptyWaitingArrayException("EWA Exception thrown");
    } else { return loopArray.get(exitIndex); }
  }

  @Override
  public E getLast() throws EmptyWaitingArrayException {
    if(loopArray.isEmpty() == true) {
      throw new EmptyWaitingArrayException("EWA Exception thrown");
    } else { return loopArray.get(entryIndex); }
  }

  @Override
  public boolean isEmpty(){
    int ctr = 0;
    for(int i = 0; i < loopArray.size(); i++){
      if(loopArray.get(i) == null){
        ctr += 1;
      }
    }
    if(ctr == initialCapacity){
      return true;
    } else { return false; }
  }

  @Override
  public boolean isFull(){
    int ctr = 0;
    for(int i = 0; i < loopArray.size(); i++){
      if(loopArray.get(i) == null){
        ctr += 1;
      }
    }
    if(ctr > 1) {
      return false;
    } else { return true; }
  }

  @Override
  public String toString(){
    String str = "[";
    for(int i = 0; i < loopArray.size() - 1; i++){
      if(loopArray.get(i) == null) {
        str += "";
      } else { str += loopArray.get(i) + ","; }
    }
    if(loopArray.get(loopArray.size() - 1) == null){
      str += "]";
    } else { str += loopArray.get(loopArray.size() - 1) + "]"; }
    return str;
  }
}