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/*
 * Copyright 2019-2020 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.kafka.config;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import org.apache.kafka.clients.admin.NewTopic;
import org.apache.kafka.common.config.TopicConfig;

/**
 * Builder for a {@link NewTopic}. Since 2.6 partitions and replicas default to
 * {@link Optional#empty()} indicating the broker defaults will be applied.
 *
 * @author Gary Russell
 * @since 2.3
 *
 */
public final class TopicBuilder {

	private final String name;

	private Optional partitions = Optional.empty();

	private Optional replicas = Optional.empty();

	private Map> replicasAssignments;

	private final Map configs = new HashMap<>();

	private TopicBuilder(String name) {
		this.name = name;
	}

	/**
	 * Set the number of partitions (default broker 'num.partitions').
	 * @param partitionCount the partitions.
	 * @return the builder.
	 */
	public TopicBuilder partitions(int partitionCount) {
		this.partitions = Optional.of(partitionCount);
		return this;
	}

	/**
	 * Set the number of replicas (default broker 'default.replication.factor').
	 * @param replicaCount the replicas (which will be cast to short).
	 * @return the builder.
	 */
	public TopicBuilder replicas(int replicaCount) {
		this.replicas = Optional.of((short) replicaCount);
		return this;
	}

	/**
	 * Set the replica assignments.
	 * @param replicaAssignments the assignments.
	 * @return the builder.
	 * @see NewTopic#replicasAssignments()
	 */
	public TopicBuilder replicasAssignments(Map> replicaAssignments) {
		replicaAssignments.forEach((part, list) -> assignReplicas(part, list));
		return this;
	}

	/**
	 * Add an individual replica assignment.
	 * @param partition the partition.
	 * @param replicaList the replicas.
	 * @return the builder.
	 * @see NewTopic#replicasAssignments()
	 */
	public TopicBuilder assignReplicas(int partition, List replicaList) {
		if (this.replicasAssignments == null) {
			this.replicasAssignments = new HashMap<>();
		}
		this.replicasAssignments.put(partition, new ArrayList<>(replicaList));
		return this;
	}

	/**
	 * Set the configs.
	 * @param configProps the configs.
	 * @return the builder.
	 * @see NewTopic#configs()
	 */
	public TopicBuilder configs(Map configProps) {
		this.configs.putAll(configProps);
		return this;
	}

	/**
	 * Set a configuration option.
	 * @param configName the name.
	 * @param configValue the value.
	 * @return the builder
	 * @see TopicConfig
	 */
	public TopicBuilder config(String configName, String configValue) {
		this.configs.put(configName, configValue);
		return this;
	}

	/**
	 * Set the {@link TopicConfig#CLEANUP_POLICY_CONFIG} to
	 * {@link TopicConfig#CLEANUP_POLICY_COMPACT}.
	 * @return the builder.
	 */
	public TopicBuilder compact() {
		this.configs.put(TopicConfig.CLEANUP_POLICY_CONFIG, TopicConfig.CLEANUP_POLICY_COMPACT);
		return this;
	}

	public NewTopic build() {
		NewTopic topic = this.replicasAssignments == null
				? new NewTopic(this.name, this.partitions, this.replicas)
				: new NewTopic(this.name, this.replicasAssignments);
		if (this.configs.size() > 0) {
			topic.configs(this.configs);
		}
		return topic;
	}

	/**
	 * Create a TopicBuilder with the supplied name.
	 * @param name the name.
	 * @return the builder.
	 */
	public static TopicBuilder name(String name) {
		return new TopicBuilder(name);
	}

}