/*
 * Copyright 2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.data.rest.webmvc.support;

import lombok.RequiredArgsConstructor;

import org.springframework.data.projection.ProjectionFactory;
import org.springframework.data.rest.core.mapping.ResourceMappings;
import org.springframework.data.rest.core.mapping.ResourceMetadata;
import org.springframework.util.Assert;

/**
 * {@link DefaultedPageable} implementation of {@link ExcerptProjector} that uses the given {@link ProjectionFactory}
 * and considers the given {@link ResourceMappings}.
 * 
 * @author Oliver Gierke
 * @since 2.5
 */
@RequiredArgsConstructor
public class DefaultExcerptProjector implements ExcerptProjector {

	private final ProjectionFactory factory;
	private final ResourceMappings mappings;

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.rest.webmvc.support.ExcerptProjector#projectExcerpt(java.lang.Object)
	 */
	@Override
	public Object projectExcerpt(Object source) {

		Assert.notNull(source, "Projection source must not be null!");

		ResourceMetadata metadata = mappings.getMetadataFor(source.getClass());
		Class<?> projection = metadata == null ? null : metadata.getExcerptProjection();

		return projection == null || projection.equals(source.getClass()) ? source
				: factory.createProjection(projection, source);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.rest.webmvc.support.ExcerptProjector#hasExcerptProjection(java.lang.Class)
	 */
	@Override
	public boolean hasExcerptProjection(Class<?> type) {

		ResourceMetadata metadata = mappings.getMetadataFor(type);
		return metadata == null ? false : metadata.getExcerptProjection() != null;
	}
}