/*
    * 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.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.context.RouteContext;
  import org.apache.shardingsphere.infra.route.lifecycle.EntranceSQLRouter;
  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.checker.ShardingRouteContextCheckerFactory;
  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.rule.ShardingRule;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.SQLStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.attribute.type.CursorSQLStatementAttribute;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dml.DMLStatement;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.Optional;
  
  /**
   * Sharding SQL router.
   */
  @HighFrequencyInvocation
  public final class ShardingSQLRouter implements EntranceSQLRouter<ShardingRule> {
      
      @Override
      public RouteContext createRouteContext(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ShardingSphereDatabase database,
                                             final ShardingRule rule, final Collection<String> tableNames, final ConfigurationProperties props) {
          if (rule.isShardingCacheEnabled()) {
              Optional<RouteContext> result = new CachedShardingSQLRouter()
                      .loadRouteContext(this::createRouteContext0, queryContext, globalRuleMetaData, database, rule.getShardingCache(), tableNames, props);
              if (result.isPresent()) {
                  return result.get();
              }
          }
          return createRouteContext0(queryContext, globalRuleMetaData, database, rule, tableNames, props);
      }
      
      private RouteContext createRouteContext0(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ShardingSphereDatabase database, final ShardingRule rule,
                                               final Collection<String> tableNames, final ConfigurationProperties props) {
          Collection<String> logicTableNames = rule.getShardingLogicTableNames(tableNames);
          if (logicTableNames.isEmpty()) {
              return new RouteContext();
          }
          SQLStatement sqlStatement = queryContext.getSqlStatementContext().getSqlStatement();
          ShardingConditions shardingConditions = createShardingConditions(queryContext, globalRuleMetaData, database, rule);
          if (sqlStatement instanceof DMLStatement && shardingConditions.isNeedMerge()) {
              shardingConditions.merge();
          }
          RouteContext result = ShardingRouteEngineFactory.newInstance(rule, database, queryContext, shardingConditions, logicTableNames, props).route(rule);
          checkRouteContext(queryContext, database, rule, props, sqlStatement, shardingConditions, 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().getSqlStatement().getAttributes().findAttribute(CursorSQLStatementAttribute.class).isPresent()) {
              shardingConditions = new ShardingConditionEngine(globalRuleMetaData, database, rule).createShardingConditions(queryContext.getSqlStatementContext(), queryContext.getParameters());
          } else {
              shardingConditions = Collections.emptyList();
          }
          return new ShardingConditions(shardingConditions, queryContext.getSqlStatementContext(), rule);
      }
      
      private void checkRouteContext(final QueryContext queryContext, final ShardingSphereDatabase database, final ShardingRule rule, final ConfigurationProperties props,
                                     final SQLStatement sqlStatement, final ShardingConditions shardingConditions, final RouteContext routeContext) {
          ShardingRouteContextCheckerFactory.newInstance(sqlStatement, shardingConditions).ifPresent(optional -> optional.check(rule, queryContext, database, props, routeContext));
      }
      
      @Override
      public Type getType() {
          return Type.DATA_NODE;
      }
     
     @Override
     public int getOrder() {
         return ShardingOrder.ORDER;
     }
     
     @Override
     public Class<ShardingRule> getTypeClass() {
         return ShardingRule.class;
     }
 }