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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 zipkin2.server.internal.kafka;

import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.type.AnnotatedTypeMetadata;
import zipkin2.collector.CollectorMetrics;
import zipkin2.collector.CollectorSampler;
import zipkin2.collector.kafka.KafkaCollector;
import zipkin2.storage.StorageComponent;

/**
 * This collector consumes a topic, decodes spans from thrift messages and stores them subject to
 * sampling policy.
 */
@Configuration
@EnableConfigurationProperties(ZipkinKafkaCollectorProperties.class)
@Conditional(ZipkinKafkaCollectorConfiguration.KafkaBootstrapServersSet.class)
public class ZipkinKafkaCollectorConfiguration { // makes simple type name unique for /actuator/conditions

  @Bean(initMethod = "start")
  KafkaCollector kafka(
      ZipkinKafkaCollectorProperties properties,
      CollectorSampler sampler,
      CollectorMetrics metrics,
      StorageComponent storage) {
    return properties.toBuilder().sampler(sampler).metrics(metrics).storage(storage).build();
  }

  /**
   * This condition passes when {@link ZipkinKafkaCollectorProperties#getBootstrapServers()} is set
   * to non-empty.
   *
   * This is here because the yaml defaults this property to empty like this, and spring-boot
   * doesn't have an option to treat empty properties as unset.
   *
   * 
{@code
   * bootstrap-servers: ${KAFKA_BOOTSTRAP_SERVERS:}
   * }
   */
  static final class KafkaBootstrapServersSet implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata a) {
      return !isEmpty(
          context.getEnvironment().getProperty("zipkin.collector.kafka.bootstrap-servers"));
    }

    private static boolean isEmpty(String s) {
      return s == null || s.isEmpty();
    }
  }
}