/*
    * 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.sharding.rewrite.token.generator.impl;
  
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.binder.context.statement.SQLStatementContext;
  import org.apache.shardingsphere.infra.binder.context.statement.type.dml.SelectStatementContext;
  import org.apache.shardingsphere.infra.rewrite.sql.token.common.generator.CollectionSQLTokenGenerator;
  import org.apache.shardingsphere.infra.rewrite.sql.token.common.pojo.SQLToken;
  import org.apache.shardingsphere.infra.rewrite.sql.token.common.pojo.generic.RemoveToken;
  import org.apache.shardingsphere.sharding.rewrite.token.generator.IgnoreForSingleRoute;
  
  import java.util.Collection;
  import java.util.LinkedList;
  
  /**
   * Sharding remove token generator.
   */
  @HighFrequencyInvocation
  public final class ShardingRemoveTokenGenerator implements CollectionSQLTokenGenerator<SelectStatementContext>, IgnoreForSingleRoute {
      
      @Override
      public boolean isGenerateSQLToken(final SQLStatementContext sqlStatementContext) {
          return isContainsAggregationDistinctProjection(sqlStatementContext);
      }
      
      private boolean isContainsAggregationDistinctProjection(final SQLStatementContext sqlStatementContext) {
          return sqlStatementContext instanceof SelectStatementContext && !((SelectStatementContext) sqlStatementContext).getProjectionsContext().getAggregationDistinctProjections().isEmpty();
      }
      
      @Override
      public Collection<SQLToken> generateSQLTokens(final SelectStatementContext sqlStatementContext) {
          Collection<SQLToken> result = new LinkedList<>();
          sqlStatementContext.getSqlStatement().getGroupBy().ifPresent(optional -> result.add(new RemoveToken(optional.getStartIndex(), optional.getStopIndex())));
          return result;
      }
  }