/*
    * 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.shardingsphere.sql.parser.sql.common.segment.dml.item;
  
  import lombok.Getter;
  import lombok.Setter;
  import org.apache.shardingsphere.sql.parser.sql.common.enums.AggregationType;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.ExpressionSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.generic.AliasAvailable;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.generic.AliasSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.value.identifier.IdentifierValue;
  
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.Optional;
  
  /**
   * Aggregation projection segment.
   */
  @Getter
  public class AggregationProjectionSegment implements ProjectionSegment, AliasAvailable, ExpressionSegment {
      
      private final int startIndex;
      
      private final int stopIndex;
      
      private final AggregationType type;
      
      private final String expression;
      
      private final Collection<ExpressionSegment> parameters = new LinkedList<>();
      
      @Setter
      private AliasSegment alias;
      
      public AggregationProjectionSegment(final int startIndex, final int stopIndex, final AggregationType type, final String expression) {
          this.startIndex = startIndex;
          this.stopIndex = stopIndex;
          this.type = type;
          this.expression = expression;
      }
      
      @Override
      public String getColumnLabel() {
          return getAliasName().orElse(expression);
      }
      
      @Override
      public final Optional<String> getAliasName() {
          return null == alias ? Optional.empty() : Optional.ofNullable(alias.getIdentifier().getValue());
      }
      
      @Override
      public final Optional<IdentifierValue> getAlias() {
          return Optional.ofNullable(alias).map(AliasSegment::getIdentifier);
      }
      
      @Override
      public String getText() {
          return expression;
      }
  }