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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later
 * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
 */
package org.hibernate.sql.results.internal.domain.entity;

import java.util.Collections;
import java.util.List;
import java.util.function.Consumer;

import org.hibernate.metamodel.model.domain.internal.SingularPersistentAttributeEntity;
import org.hibernate.metamodel.model.domain.spi.EntityValuedNavigable;
import org.hibernate.metamodel.model.domain.spi.NavigableContainer;
import org.hibernate.sql.results.spi.AssemblerCreationContext;
import org.hibernate.sql.results.spi.AssemblerCreationState;
import org.hibernate.sql.results.spi.DomainResult;
import org.hibernate.sql.results.spi.DomainResultAssembler;
import org.hibernate.sql.results.spi.EntityFetch;
import org.hibernate.sql.results.spi.EntityInitializer;
import org.hibernate.sql.results.spi.Fetch;
import org.hibernate.sql.results.spi.FetchParent;
import org.hibernate.sql.results.spi.FetchParentAccess;
import org.hibernate.sql.results.spi.Initializer;
import org.hibernate.type.descriptor.java.spi.JavaTypeDescriptor;

/**
 * The Fetch generated for {@link SingularPersistentAttributeEntity#generateFetch}
 * for lazy loading
 *
 * @author Steve Ebersole
 */
public class DelayedEntityFetch implements EntityFetch {
	private final FetchParent fetchParent;
	private final EntityValuedNavigable fetchedNavigable;
	private final DomainResult fkResult;

	public DelayedEntityFetch(
			FetchParent fetchParent,
			EntityValuedNavigable fetchedNavigable,
			DomainResult fkResult) {
		this.fetchParent = fetchParent;
		this.fetchedNavigable = fetchedNavigable;
		this.fkResult = fkResult;
	}

	@Override
	public EntityValuedNavigable getEntityValuedNavigable() {
		return fetchedNavigable;
	}

	@Override
	public FetchParent getFetchParent() {
		return fetchParent;
	}

	@Override
	public EntityValuedNavigable getFetchedNavigable() {
		return fetchedNavigable;
	}

	@Override
	public boolean isNullable() {
		return fetchedNavigable.isNullable();
	}

	@Override
	public DomainResultAssembler createAssembler(
			FetchParentAccess parentAccess,
			Consumer collector,
			AssemblerCreationContext creationContext,
			AssemblerCreationState creationState) {
		// todo (6.0) : create and register an Initializer that generates proper lazy representation for a specific entity of the given type
		//		generally a proxy.  should handle registering batch / subselect fetch
		final EntityInitializer initializer = new DelayedEntityFetchInitializer(
				fetchedNavigable,
				parentAccess,
				fkResult.createResultAssembler( collector, creationState, creationContext )
		);

		collector.accept( initializer );

		return new EntityAssembler(
				getFetchedNavigable().getJavaTypeDescriptor(),
				initializer
		);
	}

	@Override
	public JavaTypeDescriptor getJavaTypeDescriptor() {
		return getFetchedNavigable().getJavaTypeDescriptor();
	}

	@Override
	public NavigableContainer getNavigableContainer() {
		return fetchedNavigable.getContainer();
	}

	@Override
	public List getFetches() {
		return Collections.emptyList();
	}
}