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package io.ebean.common;

import io.ebean.bean.BeanCollection;

import java.util.Collection;
import java.util.Iterator;

/**
 * Wraps a collection for the purposes of notifying removals and additions to
 * the BeanCollection owner.
 * 
 * This is required for persisting ManyToMany objects. Additions and removals
 * become inserts and deletes to the intersection table.
 * 
 */
class ModifyCollection implements Collection {

  protected final BeanCollection owner;

  protected final Collection c;

  /**
   * Create with an Owner and the underlying collection this wraps.
   * 
   * The owner is notified of the additions and removals.
   * 
   */
  ModifyCollection(BeanCollection owner, Collection c) {
    this.owner = owner;
    this.c = c;
  }

  @Override
  public boolean add(E o) {
    if (c.add(o)) {
      owner.modifyAddition(o);
      return true;
    }
    return false;
  }

  @Override
  public boolean addAll(Collection collection) {
    boolean changed = false;
    for (E o : collection) {
      if (c.add(o)) {
        owner.modifyAddition(o);
        changed = true;
      }
    }
    return changed;
  }

  @Override
  public void clear() {
    c.clear();
  }

  @Override
  public boolean contains(Object o) {
    return c.contains(o);
  }

  @Override
  public boolean containsAll(Collection collection) {
    return c.containsAll(collection);
  }

  @Override
  public boolean isEmpty() {
    return c.isEmpty();
  }

  @Override
  public Iterator iterator() {
    Iterator it = c.iterator();
    return new ModifyIterator<>(owner, it);
  }

  @Override
  public boolean remove(Object o) {
    if (c.remove(o)) {
      owner.modifyRemoval(o);
      return true;
    }
    return false;
  }

  @Override
  public boolean removeAll(Collection collection) {
    boolean changed = false;
    for (Object bean : collection) {
      if (c.remove(bean)) {
        owner.modifyRemoval(bean);
        changed = true;
      }
    }
    return changed;
  }

  @Override
  public boolean retainAll(Collection collection) {
    boolean changed = false;
    Iterator it = c.iterator();
    while (it.hasNext()) {
      Object bean = it.next();
      if (!collection.contains(bean)) {
        // not retaining this bean so add to removals
        it.remove();
        owner.modifyRemoval(bean);
        changed = true;
      }
    }
    return changed;
  }

  @Override
  public int size() {
    return c.size();
  }

  @Override
  public Object[] toArray() {
    return c.toArray();
  }

  @Override
  public  T[] toArray(T[] a) {
    //noinspection SuspiciousToArrayCall
    return c.toArray(a);
  }

}