/*
    * 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.infra.metadata.database.rule.RuleMetaData;
  import org.apache.shardingsphere.infra.parser.SQLParserEngine;
  import org.apache.shardingsphere.parser.rule.SQLParserRule;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.ddl.column.ColumnDefinitionSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.dml.column.ColumnSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.attribute.type.TableInResultSetSQLStatementAttribute;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.ddl.table.CreateTableStatement;
  
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Optional;
  
  /**
   * Encrypt show create table merged result.
   */
  public final class EncryptShowCreateTableMergedResult extends DecoratorMergedResult {
      
      private static final String COMMA = ", ";
      
      private final EncryptRule rule;
      
      private final String tableName;
      
      private final int tableNameResultSetIndex;
      
      private final SQLParserEngine sqlParserEngine;
      
      public EncryptShowCreateTableMergedResult(final RuleMetaData globalRuleMetaData, final MergedResult mergedResult, final SQLStatementContext sqlStatementContext, final EncryptRule rule) {
          super(mergedResult);
          ShardingSpherePreconditions.checkState(1 == sqlStatementContext.getTablesContext().getSimpleTables().size(),
                  () -> new UnsupportedEncryptSQLException("SHOW CREATE TABLE FOR MULTI TABLES"));
          this.rule = rule;
          tableName = sqlStatementContext.getTablesContext().getSimpleTables().iterator().next().getTableName().getIdentifier().getValue();
          TableInResultSetSQLStatementAttribute attribute = sqlStatementContext.getSqlStatement().getAttributes().getAttribute(TableInResultSetSQLStatementAttribute.class);
          tableNameResultSetIndex = attribute.getNameResultSetIndex();
          sqlParserEngine = globalRuleMetaData.getSingleRule(SQLParserRule.class).getSQLParserEngine(sqlStatementContext.getSqlStatement().getDatabaseType());
      }
      
      @Override
      public Object getValue(final int columnIndex, final Class<?> type) throws SQLException {
          if (tableNameResultSetIndex != columnIndex) {
              return getMergedResult().getValue(columnIndex, type);
          }
          String createTableSQL = getMergedResult().getValue(tableNameResultSetIndex, type).toString();
          Optional<EncryptTable> encryptTable = rule.findEncryptTable(tableName);
          if (!encryptTable.isPresent() || !createTableSQL.contains("(")) {
              return createTableSQL;
          }
          CreateTableStatement createTableStatement = (CreateTableStatement) sqlParserEngine.parse(createTableSQL, false);
          List<ColumnDefinitionSegment> columnDefinitions = new ArrayList<>(createTableStatement.getColumnDefinitions());
          StringBuilder result = new StringBuilder(createTableSQL.substring(0, columnDefinitions.get(0).getStartIndex()));
          for (ColumnDefinitionSegment each : columnDefinitions) {
              findLogicColumnDefinition(each, encryptTable.get(), createTableSQL).ifPresent(optional -> result.append(optional).append(COMMA));
          }
          // TODO decorate encrypt column index when we support index rewrite
          result.delete(result.length() - COMMA.length(), result.length()).append(createTableSQL.substring(columnDefinitions.get(columnDefinitions.size() - 1).getStopIndex() + 1));
          return result.toString();
      }
      
      private Optional<String> findLogicColumnDefinition(final ColumnDefinitionSegment columnDefinition, final EncryptTable encryptTable, final String createTableSQL) {
          ColumnSegment columnSegment = columnDefinition.getColumnName();
          String columnName = columnSegment.getIdentifier().getValue();
          if (encryptTable.isCipherColumn(columnName)) {
              String logicColumn = encryptTable.getLogicColumnByCipherColumn(columnName);
              return Optional.of(createTableSQL.substring(columnDefinition.getStartIndex(), columnSegment.getStartIndex())
                      + columnSegment.getIdentifier().getQuoteCharacter().wrap(logicColumn) + createTableSQL.substring(columnSegment.getStopIndex() + 1, columnDefinition.getStopIndex() + 1));
          }
          if (encryptTable.isDerivedColumn(columnName)) {
              return Optional.empty();
          }
          return Optional.of(createTableSQL.substring(columnDefinition.getStartIndex(), columnDefinition.getStopIndex() + 1));
      }
 }