/*
 * Copyright 2016-2018 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.mongodb.core.aggregation;

import org.bson.Document;
import org.springframework.util.Assert;

/**
 * Encapsulates the {@code $out}-operation.
 * <p>
 * We recommend to use the static factory method {@link Aggregation#out(String)} instead of creating instances of this
 * class directly.
 *
 * @author Nikolay Bogdanov
 * @author Christoph Strobl
 * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/out/">MongoDB Aggregation Framework: $out</a>
 */
public class OutOperation implements AggregationOperation {

	private final String collectionName;

	/**
	 * @param outCollectionName Collection name to export the results. Must not be {@literal null}.
	 */
	public OutOperation(String outCollectionName) {
		Assert.notNull(outCollectionName, "Collection name must not be null!");
		this.collectionName = outCollectionName;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mongodb.core.aggregation.AggregationOperation#toDocument(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
	 */
	@Override
	public Document toDocument(AggregationOperationContext context) {
		return new Document("$out", collectionName);
	}
}
