/*
    * 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.sharding.route.engine;
  
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.binder.context.type.CursorAvailable;
  import org.apache.shardingsphere.infra.config.props.ConfigurationProperties;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.metadata.database.rule.RuleMetaData;
  import org.apache.shardingsphere.infra.route.SQLRouter;
  import org.apache.shardingsphere.infra.route.context.RouteContext;
  import org.apache.shardingsphere.infra.session.connection.ConnectionContext;
  import org.apache.shardingsphere.infra.session.query.QueryContext;
  import org.apache.shardingsphere.sharding.cache.route.CachedShardingSQLRouter;
  import org.apache.shardingsphere.sharding.constant.ShardingOrder;
  import org.apache.shardingsphere.sharding.route.engine.condition.ShardingCondition;
  import org.apache.shardingsphere.sharding.route.engine.condition.ShardingConditions;
  import org.apache.shardingsphere.sharding.route.engine.condition.engine.ShardingConditionEngine;
  import org.apache.shardingsphere.sharding.route.engine.type.ShardingRouteEngineFactory;
  import org.apache.shardingsphere.sharding.route.engine.validator.ShardingStatementValidator;
  import org.apache.shardingsphere.sharding.route.engine.validator.ShardingStatementValidatorFactory;
  import org.apache.shardingsphere.sharding.rule.ShardingRule;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.SQLStatement;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.dml.DMLStatement;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Optional;
  
  /**
   * Sharding SQL router.
   */
  @HighFrequencyInvocation
  public final class ShardingSQLRouter implements SQLRouter<ShardingRule> {
      
      @Override
      public RouteContext createRouteContext(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ShardingSphereDatabase database, final ShardingRule rule,
                                             final ConfigurationProperties props, final ConnectionContext connectionContext) {
          if (rule.isShardingCacheEnabled()) {
              Optional<RouteContext> result = new CachedShardingSQLRouter()
                      .loadRouteContext(this::createRouteContext0, queryContext, globalRuleMetaData, database, rule.getShardingCache(), props, connectionContext);
              if (result.isPresent()) {
                  return result.get();
              }
          }
          return createRouteContext0(queryContext, globalRuleMetaData, database, rule, props, connectionContext);
      }
      
      private RouteContext createRouteContext0(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ShardingSphereDatabase database, final ShardingRule rule,
                                               final ConfigurationProperties props, final ConnectionContext connectionContext) {
          SQLStatement sqlStatement = queryContext.getSqlStatementContext().getSqlStatement();
          ShardingConditions shardingConditions = createShardingConditions(queryContext, globalRuleMetaData, database, rule);
          Optional<ShardingStatementValidator> validator = ShardingStatementValidatorFactory.newInstance(sqlStatement, shardingConditions, globalRuleMetaData);
          validator.ifPresent(optional -> optional.preValidate(rule, queryContext.getSqlStatementContext(), queryContext.getParameters(), database, props));
          if (sqlStatement instanceof DMLStatement && shardingConditions.isNeedMerge()) {
              shardingConditions.merge();
          }
          RouteContext result = ShardingRouteEngineFactory.newInstance(rule, database, queryContext, shardingConditions, props, connectionContext, globalRuleMetaData).route(rule);
          validator.ifPresent(optional -> optional.postValidate(rule, queryContext.getSqlStatementContext(), queryContext.getHintValueContext(), queryContext.getParameters(), database, props, result));
          return result;
      }
      
      private ShardingConditions createShardingConditions(final QueryContext queryContext,
                                                          final RuleMetaData globalRuleMetaData, final ShardingSphereDatabase database, final ShardingRule rule) {
          List<ShardingCondition> shardingConditions;
          if (queryContext.getSqlStatementContext().getSqlStatement() instanceof DMLStatement || queryContext.getSqlStatementContext() instanceof CursorAvailable) {
              shardingConditions = new ShardingConditionEngine(globalRuleMetaData, database, rule).createShardingConditions(queryContext.getSqlStatementContext(), queryContext.getParameters());
          } else {
              shardingConditions = Collections.emptyList();
          }
          return new ShardingConditions(shardingConditions, queryContext.getSqlStatementContext(), rule);
      }
      
      @Override
      public void decorateRouteContext(final RouteContext routeContext, final QueryContext queryContext, final ShardingSphereDatabase database, final ShardingRule rule,
                                       final ConfigurationProperties props, final ConnectionContext connectionContext) {
          // TODO
      }
      
      @Override
      public int getOrder() {
          return ShardingOrder.ORDER;
      }
      
     @Override
     public Class<ShardingRule> getTypeClass() {
         return ShardingRule.class;
     }
 }