IndexedItemListView.java

package fr.openwide.core.wicket.more.markup.html.collection;

import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.apache.wicket.Component;
import org.apache.wicket.markup.repeater.AbstractPageableView;
import org.apache.wicket.markup.repeater.Item;
import org.apache.wicket.markup.repeater.ReuseIfModelsEqualStrategy;
import org.apache.wicket.model.IModel;

import com.google.common.collect.UnmodifiableIterator;

import fr.openwide.core.wicket.more.markup.html.model.ListItemModel;

public abstract class IndexedItemListView<T>
		extends AbstractPageableView<T> { // Does not implement IGenericComponent<C> in order to allow using IModel<? extends List<T>>, not only IModel<List<T>>

	private static final long serialVersionUID = 6410475416792396400L;

	public IndexedItemListView(String id, IModel<? extends List<T>> model) {
		super(id, model);
	}

	@SuppressWarnings("unchecked")
	public IModel<? extends List<T>> getModel() {
		return (IModel<List<T>>) getDefaultModel();
	}

	@SuppressWarnings("unchecked")
	public List<T> getModelObject() {
		return (List<T>) getDefaultModelObject();
	}
	
	private ListItemModel<T> newItemModel(int index) {
		return new ListItemModel<T>(getModel(), index);
	}

	@Override
	protected Iterator<IModel<T>> getItemModels(final long offset, final long size) {
		final List<T> list = getModelObject();
		if (list == null) {
			return Collections.emptyIterator();
		}
		
		return new UnmodifiableIterator<IModel<T>>() {
			private int index = (int) offset;
			private final int end = (int) (offset + size);
			
			@Override
			public boolean hasNext() {
				return index < end && index < internalGetItemCount();
			}
			
			@Override
			public IModel<T> next() {
				return newItemModel(index++);
			}
		};
	}

	@Override
	protected long internalGetItemCount() {
		return getModelObject().size();
	}
	
	/**
	 * Useful when using a {@link ReuseIfModelsEqualStrategy} : removes the item from the underlying model AND the view
	 * and reorganizes the other items so that their respective indices are up-to-date.
	 */
	public final void removeItem(Item<T> item) {
		removeItemFromView(item);
		removeItemFromModel(item);
	}

	
	/**
	 * Useful when using a {@link ReuseIfModelsEqualStrategy} : removes the item from the view (not the model) and reorganizes
	 * the other items so that their respective indices are up-to-date.
	 */
	protected final void removeItemFromView(Item<T> item) {
		item.remove();
		for (Component child : this) {
			@SuppressWarnings("unchecked")
			Item<T> childItem = (Item<T>) child;
			int childIndex = childItem.getIndex();
			if (childIndex > item.getIndex()) {
				--childIndex;
				childItem.setIndex(childIndex);
				((ListItemModel<?>)childItem.getModel()).getIndexModel().setObject(childIndex);
			}
		}
	}
	
	protected void removeItemFromModel(Item<T> item) {
		getModelObject().remove(item.getIndex());
	}

}