AbstractCollectionPropertyGetMethod.java

package com.buschmais.xo.impl.proxy.entity.property;

import java.util.Collection;

import com.buschmais.xo.api.XOException;
import com.buschmais.xo.impl.AbstractPropertyManager;
import com.buschmais.xo.impl.SessionContext;
import com.buschmais.xo.impl.proxy.collection.AbstractCollectionProxy;
import com.buschmais.xo.impl.proxy.collection.ListProxy;
import com.buschmais.xo.impl.proxy.collection.SetProxy;
import com.buschmais.xo.impl.proxy.common.property.AbstractPropertyMethod;
import com.buschmais.xo.spi.metadata.method.AbstractRelationPropertyMethodMetadata;

/**
 * Abstract base implementation for get methods returning collections of
 * datastore types.
 *
 * @param <DatastoreType>
 *            The datastore type.
 * @param <Entity>
 *            The entity type.
 * @param <Relation>
 *            The relation type.
 * @param <PropertyManager>
 *            The property manager.
 * @param <M>
 *            The method metadata.
 */
public abstract class AbstractCollectionPropertyGetMethod<DatastoreType, Entity, Relation, PropertyManager extends AbstractPropertyManager<DatastoreType>, M extends AbstractRelationPropertyMethodMetadata<?>>
		extends AbstractPropertyMethod<DatastoreType, PropertyManager, M> {

	private final SessionContext<?, Entity, ?, ?, ?, Relation, ?, ?, ?> sessionContext;

	private CollectionPropertyType collectionPropertyType;

	/**
	 * Constructor.
	 *
	 * @param sessionContext
	 *            The session context.
	 * @param propertyManager
	 *            The property manager.
	 * @param metadata
	 *            The metadata.
	 */
	public AbstractCollectionPropertyGetMethod(SessionContext<?, Entity, ?, ?, ?, Relation, ?, ?, ?> sessionContext,
			PropertyManager propertyManager, M metadata) {
		super(propertyManager, metadata);
		this.sessionContext = sessionContext;
		this.collectionPropertyType = CollectionPropertyType.getCollectionPropertyType(metadata.getAnnotatedMethod().getType());
	}

	@Override
	public Object invoke(DatastoreType entity, Object instance, Object[] args) {
		AbstractCollectionProxy<?, ?, ?, ?> collectionProxy = createCollectionProxy(entity, sessionContext);
		Collection<?> collection;
		switch (collectionPropertyType) {
		case List:
			collection = new ListProxy<>(collectionProxy);
			break;
		case Set:
			collection = new SetProxy<>(collectionProxy);
			break;
		case Collection:
			collection = collectionProxy;
			break;
		default:
			throw new XOException("Unsupported collection type " + collectionPropertyType);
		}
		return sessionContext.getInterceptorFactory().addInterceptor(collection, collectionPropertyType.getCollectionType());
	}

	/**
	 * Create the collection proxy instance.
	 *
	 * @param datastoreType
	 *            The datastore type (i.e. representing the instance holding the
	 *            collection property).
	 * @param sessionContext
	 *            The session context.
	 * @return The collection proxy.
	 */
	protected abstract AbstractCollectionProxy<?, ?, ?, ?> createCollectionProxy(DatastoreType datastoreType,
			SessionContext<?, Entity, ?, ?, ?, Relation, ?, ?, ?> sessionContext);

}