import java.util.ArrayList;
import java.util.ListIterator;

public class DvdReleaseByCategory {  
   String categoryName; 
   ArrayList subscriberList = new ArrayList();
   ArrayList dvdReleaseList = new ArrayList();   
   
   public DvdReleaseByCategory(String categoryNameIn) {
       categoryName = categoryNameIn;
   }
   
   public String getCategoryName() {
       return this.categoryName;
   }
   
   public boolean addSubscriber(DvdSubscriber dvdSubscriber) {
       return subscriberList.add(dvdSubscriber);
   }
   
   public boolean removeSubscriber(DvdSubscriber dvdSubscriber) {
       ListIterator listIterator = subscriberList.listIterator();
       while (listIterator.hasNext()) {
           if (dvdSubscriber == (DvdSubscriber)(listIterator.next())) {
               listIterator.remove();
               return true;
           }
       }
       return false;
   }
   
   public void newDvdRelease(DvdRelease dvdRelease) {
       dvdReleaseList.add(dvdRelease);
       notifySubscribersOfNewDvd(dvdRelease);
   }
   
   public void updateDvd(DvdRelease dvdRelease) {
       boolean dvdUpdated = false;
       DvdRelease tempDvdRelease;
       ListIterator listIterator = dvdReleaseList.listIterator();
       while (listIterator.hasNext()) {
           tempDvdRelease = (DvdRelease)listIterator.next();
           if (dvdRelease.getSerialNumber().
                 equals(tempDvdRelease.getSerialNumber())) {
               listIterator.remove();
               listIterator.add(dvdRelease);
               dvdUpdated = true;
               break;
           }
       }
       if (dvdUpdated == true) {
           notifySubscribersOfUpdate(dvdRelease);
       } else { 
           this.newDvdRelease(dvdRelease);
       }
   }
   
   private void notifySubscribersOfNewDvd(DvdRelease dvdRelease) {
       ListIterator listIterator = subscriberList.listIterator();
       while (listIterator.hasNext()) {
           ((DvdSubscriber)(listIterator.next())).
               newDvdRelease(dvdRelease, this.getCategoryName());
       }
   }

   private void notifySubscribersOfUpdate(DvdRelease dvdRelease) {
       ListIterator listIterator = subscriberList.listIterator();
       while (listIterator.hasNext()) {
           ((DvdSubscriber)(listIterator.next())).
               updateDvdRelease(dvdRelease, this.getCategoryName() );
       }       
   }
}