/*******************************************************************************
 * Copyright (c) 2009 Oracle. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0, which accompanies this distribution
 * and is available at http://www.eclipse.org/legal/epl-v10.html.
 * 
 * Contributors:
 *     Oracle - initial API and implementation
 ******************************************************************************/
package org.eclipse.jpt.utility.internal.model.value;

import java.util.Iterator;

import org.eclipse.jpt.utility.model.value.WritableCollectionValueModel;
import org.eclipse.jpt.utility.model.value.WritablePropertyValueModel;

/**
 * An adapter that allows us to make a {@link WritablePropertyValueModel} behave like
 * a single-element {@link WritableCollectionValueModel}, sorta.
 * <p>
 * If the property's value is null, an empty iterator is returned
 * (i.e. you can't have a collection with a <code>null</code> element).
 * Also, only a single-element collection can be written to the adapter.
 */
public class WritablePropertyCollectionValueModelAdapter<E>
	extends PropertyCollectionValueModelAdapter<E>
	implements WritableCollectionValueModel<E>
{

	// ********** constructor **********

	/**
	 * Convert the specified writable property value model to a writable
	 * collection value model.
	 */
	public WritablePropertyCollectionValueModelAdapter(WritablePropertyValueModel<E> valueHolder) {
		super(valueHolder);
	}


	// ********** WritableCollectionValueModel implementation **********

	public void setValues(Iterable<E> values) {
		Iterator<E> stream = values.iterator();
		if (stream.hasNext()) {
			E newValue = stream.next();
			if (stream.hasNext()) {
				throw new IllegalArgumentException("non-singleton collection: " + values); //$NON-NLS-1$
			}
			this.getValueHolder().setValue(newValue);
		} else {
			this.getValueHolder().setValue(null);
		}
	}

	// our constructor takes only writable property value models
	@SuppressWarnings("unchecked")
	protected WritablePropertyValueModel<E> getValueHolder() {
		return (WritablePropertyValueModel<E>) this.valueHolder;
	}

}