/*
 * Copyright 2013-2022 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
 *
 *      https://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.data.mongodb.core.query.CriteriaDefinition;
import org.springframework.util.Assert;

/**
 * Encapsulates the {@code $match}-operation.
 * <p>
 * We recommend to use the static factory method
 * {@link Aggregation#match(org.springframework.data.mongodb.core.query.Criteria)} instead of creating instances of this
 * class directly.
 *
 * @author Sebastian Herold
 * @author Thomas Darimont
 * @author Oliver Gierke
 * @author Divya Srivastava
 * @since 1.3
 * @see <a href="https://docs.mongodb.com/manual/reference/operator/aggregation/match/">MongoDB Aggregation Framework:
 *      $match</a>
 */
public class MatchOperation implements AggregationOperation {

	private final CriteriaDefinition criteriaDefinition;
	private final AggregationExpression expression;

	/**
	 * Creates a new {@link MatchOperation} for the given {@link CriteriaDefinition}.
	 *
	 * @param criteriaDefinition must not be {@literal null}.
	 */
	public MatchOperation(CriteriaDefinition criteriaDefinition) {

		Assert.notNull(criteriaDefinition, "Criteria must not be null");

		this.criteriaDefinition = criteriaDefinition;
		this.expression = null;
	}

	/**
	 * Creates a new {@link MatchOperation} for the given {@link AggregationExpression}.
	 *
	 * @param expression must not be {@literal null}.
	 * @since 3.3
	 */
	public MatchOperation(AggregationExpression expression) {

		Assert.notNull(expression, "Expression must not be null");

		this.criteriaDefinition = null;
		this.expression = expression;
	}

	@Override
	public Document toDocument(AggregationOperationContext context) {

		return new Document(getOperator(),
				context.getMappedObject(expression != null ? expression.toDocument() : criteriaDefinition.getCriteriaObject()));
	}

	@Override
	public String getOperator() {
		return "$match";
	}
}