/*
    * 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.shadow.route;
  
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.config.props.ConfigurationProperties;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.route.context.RouteContext;
  import org.apache.shardingsphere.infra.route.context.RouteMapper;
  import org.apache.shardingsphere.infra.route.context.RouteUnit;
  import org.apache.shardingsphere.infra.route.lifecycle.DecorateSQLRouter;
  import org.apache.shardingsphere.infra.session.query.QueryContext;
  import org.apache.shardingsphere.shadow.constant.ShadowOrder;
  import org.apache.shardingsphere.shadow.route.retriever.ShadowDataSourceMappingsRetrieverFactory;
  import org.apache.shardingsphere.shadow.rule.ShadowRule;
  
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.Map;
  import java.util.Optional;
  
  /**
   * Shadow SQL router.
   */
  @HighFrequencyInvocation
  public final class ShadowSQLRouter implements DecorateSQLRouter<ShadowRule> {
      
      @Override
      public void decorateRouteContext(final RouteContext routeContext, final QueryContext queryContext, final ShardingSphereDatabase database,
                                       final ShadowRule rule, final Collection<String> tableNames, final ConfigurationProperties props) {
          Collection<RouteUnit> toBeRemovedRouteUnit = new LinkedList<>();
          Collection<RouteUnit> toBeAddedRouteUnit = new LinkedList<>();
          Map<String, String> shadowDataSourceMappings = ShadowDataSourceMappingsRetrieverFactory.newInstance(queryContext).retrieve(rule);
          for (RouteUnit each : routeContext.getRouteUnits()) {
              String logicName = each.getDataSourceMapper().getLogicName();
              String actualName = each.getDataSourceMapper().getActualName();
              Optional<String> productionDataSourceName = rule.findProductionDataSourceName(actualName);
              if (productionDataSourceName.isPresent()) {
                  String shadowDataSourceName = shadowDataSourceMappings.get(productionDataSourceName.get());
                  toBeRemovedRouteUnit.add(each);
                  String dataSourceName = null == shadowDataSourceName ? productionDataSourceName.get() : shadowDataSourceName;
                  toBeAddedRouteUnit.add(new RouteUnit(new RouteMapper(logicName, dataSourceName), each.getTableMappers()));
              }
          }
          routeContext.getRouteUnits().removeAll(toBeRemovedRouteUnit);
          routeContext.getRouteUnits().addAll(toBeAddedRouteUnit);
      }
      
      @Override
      public Type getType() {
          return Type.DATA_SOURCE;
      }
      
      @Override
      public int getOrder() {
          return ShadowOrder.ORDER;
      }
      
      @Override
      public Class<ShadowRule> getTypeClass() {
          return ShadowRule.class;
      }
  }