/*
    * 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.statement.dml;
  
  import lombok.Getter;
  import lombok.Setter;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.assignment.InsertValuesSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.column.ColumnSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.column.InsertColumnsSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.subquery.SubquerySegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.generic.table.SimpleTableSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.AbstractSQLStatement;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedList;
  import java.util.Optional;
  
  /**
   * Insert statement.
   */
  @Getter
  @Setter
  public abstract class InsertStatement extends AbstractSQLStatement implements DMLStatement {
      
      private SimpleTableSegment table;
      
      private InsertColumnsSegment insertColumns;
      
      private SubquerySegment insertSelect;
      
      private final Collection<InsertValuesSegment> values = new LinkedList<>();
      
      private final Collection<ColumnSegment> derivedInsertColumns = new LinkedList<>();
      
      /**
       * Get insert columns segment.
       * 
       * @return insert columns segment
       */
      public Optional<InsertColumnsSegment> getInsertColumns() {
          return Optional.ofNullable(insertColumns);
      }
      
      /**
       * Get columns.
       * 
       * @return columns
       */
      public Collection<ColumnSegment> getColumns() {
          return null == insertColumns ? Collections.emptyList() : insertColumns.getColumns();
      }
      
      /**
       * Get insert select segment.
       *
       * @return insert select segment
       */
      public Optional<SubquerySegment> getInsertSelect() {
          return Optional.ofNullable(insertSelect);
      }
  }