/*
    * 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.encrypt.merge.dal.show;
  
  import org.apache.shardingsphere.encrypt.exception.syntax.UnsupportedEncryptSQLException;
  import org.apache.shardingsphere.encrypt.rule.EncryptRule;
  import org.apache.shardingsphere.encrypt.rule.table.EncryptTable;
  import org.apache.shardingsphere.infra.binder.context.statement.SQLStatementContext;
  import org.apache.shardingsphere.infra.exception.core.ShardingSpherePreconditions;
  import org.apache.shardingsphere.infra.merge.result.MergedResult;
  import org.apache.shardingsphere.infra.merge.result.impl.decorator.DecoratorMergedResult;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.attribute.type.ColumnInResultSetSQLStatementAttribute;
  
  import java.sql.SQLException;
  import java.util.Optional;
  
  /**
   * Encrypt show columns merged result.
   */
  public final class EncryptShowColumnsMergedResult extends DecoratorMergedResult {
      
      private final EncryptRule rule;
      
      private final String tableName;
      
      private final int columnNameResultSetIndex;
      
      public EncryptShowColumnsMergedResult(final MergedResult mergedResult, final SQLStatementContext sqlStatementContext, final EncryptRule rule) {
          super(mergedResult);
          ShardingSpherePreconditions.checkState(1 == sqlStatementContext.getTablesContext().getSimpleTables().size(),
                  () -> new UnsupportedEncryptSQLException("SHOW COLUMNS FOR MULTI TABLES"));
          this.rule = rule;
          tableName = sqlStatementContext.getTablesContext().getSimpleTables().iterator().next().getTableName().getIdentifier().getValue();
          ColumnInResultSetSQLStatementAttribute attribute = sqlStatementContext.getSqlStatement().getAttributes().getAttribute(ColumnInResultSetSQLStatementAttribute.class);
          columnNameResultSetIndex = attribute.getNameResultSetIndex();
      }
      
      @Override
      public boolean next() throws SQLException {
          boolean hasNext = getMergedResult().next();
          Optional<EncryptTable> encryptTable = rule.findEncryptTable(tableName);
          if (hasNext && !encryptTable.isPresent()) {
              return true;
          }
          if (!hasNext) {
              return false;
          }
          return next(encryptTable.get());
      }
      
      private boolean next(final EncryptTable encryptTable) throws SQLException {
          while (encryptTable.isDerivedColumn(getMergedResult().getValue(columnNameResultSetIndex, String.class).toString())) {
              boolean isFinished = !getMergedResult().next();
              if (isFinished) {
                  return false;
              }
          }
          return true;
      }
      
      @Override
      public Object getValue(final int columnIndex, final Class<?> type) throws SQLException {
          if (columnNameResultSetIndex == columnIndex) {
              return getColumnNameValue(type);
          }
          return getMergedResult().getValue(columnIndex, type);
      }
      
      private String getColumnNameValue(final Class<?> type) throws SQLException {
          String columnName = getMergedResult().getValue(columnNameResultSetIndex, type).toString();
          Optional<EncryptTable> encryptTable = rule.findEncryptTable(tableName);
          return encryptTable.isPresent() && encryptTable.get().isCipherColumn(columnName) ? encryptTable.get().getLogicColumnByCipherColumn(columnName) : columnName;
      }
  }