/*
    * 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.readwritesplitting.rule.changed;
  
  import com.google.common.base.Strings;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.rule.event.rule.alter.AlterNamedRuleItemEvent;
  import org.apache.shardingsphere.infra.rule.event.rule.alter.AlterRuleItemEvent;
  import org.apache.shardingsphere.infra.rule.event.rule.drop.DropNamedRuleItemEvent;
  import org.apache.shardingsphere.infra.rule.event.rule.drop.DropRuleItemEvent;
  import org.apache.shardingsphere.infra.util.yaml.YamlEngine;
  import org.apache.shardingsphere.mode.spi.RuleItemConfigurationChangedProcessor;
  import org.apache.shardingsphere.readwritesplitting.api.ReadwriteSplittingRuleConfiguration;
  import org.apache.shardingsphere.readwritesplitting.api.rule.ReadwriteSplittingDataSourceGroupRuleConfiguration;
  import org.apache.shardingsphere.readwritesplitting.api.transaction.TransactionalReadQueryStrategy;
  import org.apache.shardingsphere.readwritesplitting.metadata.nodepath.ReadwriteSplittingRuleNodePathProvider;
  import org.apache.shardingsphere.readwritesplitting.rule.ReadwriteSplittingRule;
  import org.apache.shardingsphere.readwritesplitting.yaml.config.rule.YamlReadwriteSplittingDataSourceGroupRuleConfiguration;
  
  import java.util.LinkedHashMap;
  import java.util.LinkedList;
  import java.util.Optional;
  
  /**
   * Readwrite-splitting data source changed processor.
   */
  public final class ReadwriteSplittingDataSourceChangedProcessor
          implements
              RuleItemConfigurationChangedProcessor<ReadwriteSplittingRuleConfiguration, ReadwriteSplittingDataSourceGroupRuleConfiguration> {
      
      @Override
      public ReadwriteSplittingDataSourceGroupRuleConfiguration swapRuleItemConfiguration(final AlterRuleItemEvent event, final String yamlContent) {
          YamlReadwriteSplittingDataSourceGroupRuleConfiguration yamlDataSourceGroupRuleConfig = YamlEngine.unmarshal(yamlContent, YamlReadwriteSplittingDataSourceGroupRuleConfiguration.class);
          return new ReadwriteSplittingDataSourceGroupRuleConfiguration(((AlterNamedRuleItemEvent) event).getItemName(), yamlDataSourceGroupRuleConfig.getWriteDataSourceName(),
                  yamlDataSourceGroupRuleConfig.getReadDataSourceNames(), getTransactionalReadQueryStrategy(yamlDataSourceGroupRuleConfig), yamlDataSourceGroupRuleConfig.getLoadBalancerName());
      }
      
      private TransactionalReadQueryStrategy getTransactionalReadQueryStrategy(final YamlReadwriteSplittingDataSourceGroupRuleConfiguration yamlDataSourceGroupRuleConfig) {
          return Strings.isNullOrEmpty(yamlDataSourceGroupRuleConfig.getTransactionalReadQueryStrategy())
                  ? TransactionalReadQueryStrategy.DYNAMIC
                  : TransactionalReadQueryStrategy.valueOf(yamlDataSourceGroupRuleConfig.getTransactionalReadQueryStrategy());
      }
      
      @Override
      public ReadwriteSplittingRuleConfiguration findRuleConfiguration(final ShardingSphereDatabase database) {
          Optional<ReadwriteSplittingRule> rule = database.getRuleMetaData().findSingleRule(ReadwriteSplittingRule.class);
          return rule.map(ReadwriteSplittingRule::getConfiguration)
                  .orElseGet(() -> new ReadwriteSplittingRuleConfiguration(new LinkedList<>(), new LinkedHashMap<>()));
      }
      
      @Override
      public void changeRuleItemConfiguration(final AlterRuleItemEvent event, final ReadwriteSplittingRuleConfiguration currentRuleConfig,
                                              final ReadwriteSplittingDataSourceGroupRuleConfiguration toBeChangedItemConfig) {
          // TODO refactor DistSQL to only persist config
          currentRuleConfig.getDataSourceGroups().removeIf(each -> each.getName().equals(toBeChangedItemConfig.getName()));
          currentRuleConfig.getDataSourceGroups().add(toBeChangedItemConfig);
      }
      
      @Override
      public void dropRuleItemConfiguration(final DropRuleItemEvent event, final ReadwriteSplittingRuleConfiguration currentRuleConfig) {
          currentRuleConfig.getDataSourceGroups().removeIf(each -> each.getName().equals(((DropNamedRuleItemEvent) event).getItemName()));
      }
      
      @Override
      public String getType() {
          return ReadwriteSplittingRuleNodePathProvider.RULE_TYPE + "." + ReadwriteSplittingRuleNodePathProvider.DATA_SOURCES;
      }
  }