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.requests.search;
  
  import com.google.common.base.Strings;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableMap;
  import org.apache.skywalking.library.elasticsearch.requests.search.aggregation.Aggregation;
  import org.apache.skywalking.library.elasticsearch.requests.search.aggregation.AggregationBuilder;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkState;
  import static java.util.Objects.requireNonNull;
  
  public final class SearchBuilder {
      private Integer from;
      private Integer size;
      private QueryBuilder queryBuilder;
      private ImmutableList.Builder<Sort> sort;
      private ImmutableMap.Builder<String, Aggregation> aggregations;
  
      SearchBuilder() {
      }
  
      public SearchBuilder from(Integer from) {
          requireNonNull(from, "from");
          checkArgument(from >= 0, "from must be >= 0, but was %s", from);
          this.from = from;
          return this;
      }
  
      public SearchBuilder size(Integer size) {
          requireNonNull(size, "size");
          checkArgument(size >= 0, "size must be positive, but was %s", size);
          this.size = size;
          return this;
      }
  
      public SearchBuilder sort(String by, Sort.Order order) {
          checkArgument(!Strings.isNullOrEmpty(by), "by cannot be blank");
          requireNonNull(order, "order");
          sort().add(new Sort(by, order));
          return this;
      }
  
      public SearchBuilder query(QueryBuilder queryBuilder) {
          checkState(this.queryBuilder == null, "queryBuilder is already set");
          this.queryBuilder = requireNonNull(queryBuilder, "queryBuilder");
          return this;
      }
  
      public SearchBuilder aggregation(Aggregation aggregation) {
          requireNonNull(aggregation, "aggregation");
          aggregations().put(aggregation.name(), aggregation);
          return this;
      }
  
      public SearchBuilder aggregation(AggregationBuilder builder) {
          requireNonNull(builder, "builder");
          return aggregation(builder.build());
      }
  
      public Search build() {
          final Sorts sorts;
          if (sort == null) {
              sorts = null;
          } else {
              sorts = new Sorts(sort.build());
          }
  
          final ImmutableMap<String, Aggregation> aggregations;
          if (this.aggregations == null) {
              aggregations = null;
          } else {
              aggregations = aggregations().build();
          }
          final Query query;
          if (queryBuilder != null) {
              query = queryBuilder.build();
          } else {
              query = null;
          }
  
          return new Search(
              from, size, query, sorts, aggregations
          );
      }
  
      private ImmutableList.Builder<Sort> sort() {
          if (sort == null) {
              sort = ImmutableList.builder();
          }
          return sort;
      }
  
      private ImmutableMap.Builder<String, Aggregation> aggregations() {
          if (aggregations == null) {
              aggregations = ImmutableMap.builder();
          }
          return aggregations;
      }
  }
  