/*
    * 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.proxy.backend.mysql.response.header.query;
  
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.QueryResultMetaData;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereColumn;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereSchema;
  import org.apache.shardingsphere.infra.rule.attribute.datanode.DataNodeRuleAttribute;
  import org.apache.shardingsphere.proxy.backend.response.header.query.QueryHeader;
  import org.apache.shardingsphere.proxy.backend.response.header.query.QueryHeaderBuilder;
  
  import java.sql.SQLException;
  import java.util.Optional;
  
  /**
   * Query header builder for MySQL.
   */
  public final class MySQLQueryHeaderBuilder implements QueryHeaderBuilder {
      
      @Override
      public QueryHeader build(final QueryResultMetaData queryResultMetaData,
                               final ShardingSphereDatabase database, final String columnName, final String columnLabel, final int columnIndex) throws SQLException {
          String schemaName = null == database ? "" : database.getName();
          String actualTableName = queryResultMetaData.getTableName(columnIndex);
          String tableName;
          boolean primaryKey;
          if (null == actualTableName || null == database) {
              tableName = actualTableName;
              primaryKey = false;
          } else {
              tableName = getLogicTableName(database, actualTableName);
              ShardingSphereSchema schema = database.getSchema(schemaName);
              primaryKey = null != schema
                      && Optional.ofNullable(schema.getTable(tableName)).map(optional -> optional.getColumn(columnName)).map(ShardingSphereColumn::isPrimaryKey).orElse(false);
          }
          int columnType = queryResultMetaData.getColumnType(columnIndex);
          String columnTypeName = queryResultMetaData.getColumnTypeName(columnIndex);
          int columnLength = queryResultMetaData.getColumnLength(columnIndex);
          int decimals = queryResultMetaData.getDecimals(columnIndex);
          boolean signed = queryResultMetaData.isSigned(columnIndex);
          boolean notNull = queryResultMetaData.isNotNull(columnIndex);
          boolean autoIncrement = queryResultMetaData.isAutoIncrement(columnIndex);
          return new QueryHeader(schemaName, tableName, columnLabel, columnName, columnType, columnTypeName, columnLength, decimals, signed, primaryKey, notNull, autoIncrement);
      }
      
      private String getLogicTableName(final ShardingSphereDatabase database, final String actualTableName) {
          for (DataNodeRuleAttribute each : database.getRuleMetaData().getAttributes(DataNodeRuleAttribute.class)) {
              Optional<String> logicTable = each.findLogicTableByActualTable(actualTableName);
              if (logicTable.isPresent()) {
                  return logicTable.get();
              }
          }
          return actualTableName;
      }
      
      @Override
      public String getDatabaseType() {
          return "MySQL";
      }
      
      // TODO to be confirmed, QueryHeaderBuilder should not has default value, just throw unsupported exception if database type missing
      @Override
      public boolean isDefault() {
          return true;
      }
  }