/*
    * 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.mask.merge.dql;
  
  import org.apache.shardingsphere.infra.binder.context.statement.type.dml.SelectStatementContext;
  import org.apache.shardingsphere.infra.merge.result.MergedResult;
  import org.apache.shardingsphere.infra.merge.result.impl.decorator.DecoratorMergedResult;
  import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.mask.rule.MaskRule;
  import org.apache.shardingsphere.mask.spi.MaskAlgorithm;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.bound.ColumnSegmentBoundInfo;
  
  import java.sql.SQLException;
  import java.util.Optional;
  
  /**
   * Merged result for mask.
   */
  public final class MaskMergedResult extends DecoratorMergedResult {
      
      private final ShardingSphereDatabase database;
      
      private final ShardingSphereMetaData metaData;
      
      private final SelectStatementContext selectStatementContext;
      
      public MaskMergedResult(final ShardingSphereDatabase database, final ShardingSphereMetaData metaData, final SelectStatementContext selectStatementContext, final MergedResult mergedResult) {
          super(mergedResult);
          this.database = database;
          this.metaData = metaData;
          this.selectStatementContext = selectStatementContext;
      }
      
      @SuppressWarnings({"rawtypes", "unchecked"})
      @Override
      public Object getValue(final int columnIndex, final Class<?> type) throws SQLException {
          Optional<ColumnSegmentBoundInfo> columnSegmentBoundInfo = selectStatementContext.findColumnBoundInfo(columnIndex);
          if (!columnSegmentBoundInfo.isPresent()) {
              return getMergedResult().getValue(columnIndex, type);
          }
          String originalTableName = columnSegmentBoundInfo.get().getOriginalTable().getValue();
          String originalColumnName = columnSegmentBoundInfo.get().getOriginalColumn().getValue();
          ShardingSphereDatabase database = metaData.containsDatabase(columnSegmentBoundInfo.get().getOriginalDatabase().getValue())
                  ? metaData.getDatabase(columnSegmentBoundInfo.get().getOriginalDatabase().getValue())
                  : this.database;
          Optional<MaskRule> rule = database.getRuleMetaData().findSingleRule(MaskRule.class);
          if (!rule.isPresent() || !rule.get().findMaskTable(originalTableName).map(optional -> optional.findAlgorithm(originalColumnName).isPresent()).orElse(false)) {
              return getMergedResult().getValue(columnIndex, type);
          }
          Optional<MaskAlgorithm> maskAlgorithm = rule.get().findMaskTable(originalTableName).flatMap(optional -> optional.findAlgorithm(originalColumnName));
          if (!maskAlgorithm.isPresent()) {
              return getMergedResult().getValue(columnIndex, type);
          }
          Object originalValue = getMergedResult().getValue(columnIndex, Object.class);
          return null == originalValue ? null : maskAlgorithm.get().mask(originalValue);
      }
  }