code: /*
   * 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 org.apache.skywalking.library.elasticsearch.client;
  
  import com.fasterxml.jackson.core.type.TypeReference;
  import com.linecorp.armeria.client.WebClient;
  import com.linecorp.armeria.common.HttpData;
  import com.linecorp.armeria.common.HttpStatus;
  import com.linecorp.armeria.common.util.Exceptions;
  import java.io.InputStream;
  import java.util.Map;
  import java.util.concurrent.CompletableFuture;
  import lombok.RequiredArgsConstructor;
  import lombok.SneakyThrows;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.skywalking.library.elasticsearch.ElasticSearchVersion;
  import org.apache.skywalking.library.elasticsearch.response.Index;
  
  @Slf4j
  @RequiredArgsConstructor
  public final class AliasClient {
      private final CompletableFuture<ElasticSearchVersion> version;
  
      private final WebClient client;
  
      @SneakyThrows
      public Map<String, Index> indices(String name) {
          final CompletableFuture<Map<String, Index>> future =
              version.thenCompose(
                  v -> client.execute(v.requestFactory().alias().indices(name))
                             .aggregate().thenApply(response -> {
                          final HttpStatus status = response.status();
                          if (status != HttpStatus.OK) {
                              throw new RuntimeException(response.contentUtf8());
                          }
  
                          try (final HttpData content = response.content();
                               final InputStream is = content.toInputStream()) {
                              return v.codec().decode(is, new TypeReference<Map<String, Index>>() {
                              });
                          } catch (Exception e) {
                              return Exceptions.throwUnsafely(e);
                          }
                      }));
          future.whenComplete((result, exception) -> {
              if (exception != null) {
                  log.error("Failed to get indices by alias {}.", name, exception);
                  return;
              }
              if (log.isDebugEnabled()) {
                  log.debug("Indices by alias {}: {}", name, result);
              }
          });
          return future.get();
      }
  }
  