/*
    * 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.handler.admin.executor.sysvar.provider;
  
  import org.apache.shardingsphere.proxy.backend.mysql.handler.admin.executor.sysvar.Scope;
  import org.apache.shardingsphere.proxy.backend.mysql.handler.admin.executor.sysvar.MySQLSystemVariable;
  import org.apache.shardingsphere.proxy.backend.mysql.handler.admin.executor.sysvar.MySQLSystemVariableValueProvider;
  import org.apache.shardingsphere.proxy.backend.session.ConnectionSession;
  import org.apache.shardingsphere.sql.parser.sql.common.enums.TransactionIsolationLevel;
  
  import java.util.Optional;
  
  /**
   * Transaction isolation value provider.
   */
  public final class TransactionIsolationValueProvider implements MySQLSystemVariableValueProvider {
      
      @Override
      public String get(final Scope scope, final ConnectionSession connectionSession, final MySQLSystemVariable variable) {
          return Scope.GLOBAL == scope ? variable.getDefaultValue()
                  : Optional.ofNullable(connectionSession.getIsolationLevel()).map(TransactionIsolationLevel::getIsolationLevel).orElseGet(TransactionIsolationLevel.REPEATABLE_READ::getIsolationLevel);
      }
  }