/*
    * 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.segment.dml.expr.ExpressionSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.complex.ComplexExpressionSegment;
  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.util.SQLUtils;
  import org.apache.shardingsphere.sql.parser.sql.common.value.identifier.IdentifierValue;
  
  import java.util.Optional;
  
  /**
   * Expression projection segment.
   */
  @Getter
  public final class ExpressionProjectionSegment implements ProjectionSegment, ComplexExpressionSegment, AliasAvailable {
      
      private final int startIndex;
      
      private final int stopIndex;
      
      private final String text;
      
      private final ExpressionSegment expr;
      
      @Setter
      private AliasSegment alias;
      
      public ExpressionProjectionSegment(final int startIndex, final int stopIndex, final String text) {
          this.startIndex = startIndex;
          this.stopIndex = stopIndex;
          this.text = SQLUtils.getExpressionWithoutOutsideParentheses(text);
          expr = null;
      }
      
      public ExpressionProjectionSegment(final int startIndex, final int stopIndex, final String text, final ExpressionSegment expr) {
          this.startIndex = startIndex;
          this.stopIndex = stopIndex;
          this.text = SQLUtils.getExpressionWithoutOutsideParentheses(text);
          this.expr = expr;
      }
      
      @Override
      public String getColumnLabel() {
          return getAliasName().orElse(text);
      }
      
      @Override
      public Optional<String> getAliasName() {
          return null == alias ? Optional.empty() : Optional.ofNullable(alias.getIdentifier().getValue());
      }
      
      @Override
      public Optional<IdentifierValue> getAlias() {
          return Optional.ofNullable(alias).map(AliasSegment::getIdentifier);
      }
      
      /**
       * Get alias segment.
       *
       * @return alias segment
       */
      public AliasSegment getAliasSegment() {
          return alias;
      }
      
      @Override
      public int getStartIndex() {
          return null != alias && alias.getStartIndex() < startIndex ? alias.getStartIndex() : startIndex;
      }
      
      @Override
      public int getStopIndex() {
          return null != alias && alias.getStopIndex() > stopIndex ? alias.getStopIndex() : stopIndex;
      }
  }