/*
    * 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.infra.connection.kernel;
  
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.checker.SupportedSQLCheckEngine;
  import org.apache.shardingsphere.infra.config.props.ConfigurationProperties;
  import org.apache.shardingsphere.infra.config.props.ConfigurationPropertyKey;
  import org.apache.shardingsphere.infra.executor.sql.context.ExecutionContext;
  import org.apache.shardingsphere.infra.executor.sql.context.ExecutionContextBuilder;
  import org.apache.shardingsphere.infra.executor.sql.log.SQLLogger;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.metadata.database.rule.RuleMetaData;
  import org.apache.shardingsphere.infra.rewrite.SQLRewriteEntry;
  import org.apache.shardingsphere.infra.rewrite.engine.result.SQLRewriteResult;
  import org.apache.shardingsphere.infra.route.context.RouteContext;
  import org.apache.shardingsphere.infra.route.engine.SQLRouteEngine;
  import org.apache.shardingsphere.infra.session.query.QueryContext;
  
  /**
   * Kernel processor.
   */
  @HighFrequencyInvocation
  public final class KernelProcessor {
      
      /**
       * Generate execution context.
       *
       * @param queryContext query context
       * @param globalRuleMetaData global rule meta data
       * @param props configuration properties
       * @return execution context
       */
      public ExecutionContext generateExecutionContext(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ConfigurationProperties props) {
          check(queryContext);
          RouteContext routeContext = route(queryContext, globalRuleMetaData, props);
          SQLRewriteResult rewriteResult = rewrite(queryContext, globalRuleMetaData, props, routeContext);
          ExecutionContext result = createExecutionContext(queryContext, routeContext, rewriteResult);
          logSQL(queryContext, props, result);
          return result;
      }
      
      private void check(final QueryContext queryContext) {
          if (queryContext.getHintValueContext().isSkipMetadataValidate()) {
              return;
          }
          ShardingSphereDatabase database = queryContext.getUsedDatabase();
          new SupportedSQLCheckEngine().checkSQL(database.getRuleMetaData().getRules(), queryContext.getSqlStatementContext(), database);
      }
      
      private RouteContext route(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ConfigurationProperties props) {
          ShardingSphereDatabase database = queryContext.getUsedDatabase();
          return new SQLRouteEngine(database.getRuleMetaData().getRules(), props).route(queryContext, globalRuleMetaData, database);
      }
      
      private SQLRewriteResult rewrite(final QueryContext queryContext, final RuleMetaData globalRuleMetaData, final ConfigurationProperties props, final RouteContext routeContext) {
          SQLRewriteEntry sqlRewriteEntry = new SQLRewriteEntry(queryContext.getUsedDatabase(), globalRuleMetaData, props);
          return sqlRewriteEntry.rewrite(queryContext, routeContext);
      }
      
      private ExecutionContext createExecutionContext(final QueryContext queryContext, final RouteContext routeContext, final SQLRewriteResult rewriteResult) {
          return new ExecutionContext(queryContext, ExecutionContextBuilder.build(queryContext.getUsedDatabase(), rewriteResult, queryContext.getSqlStatementContext()), routeContext);
      }
      
      private void logSQL(final QueryContext queryContext, final ConfigurationProperties props, final ExecutionContext executionContext) {
          if (props.<Boolean>getValue(ConfigurationPropertyKey.SQL_SHOW)) {
              SQLLogger.logSQL(queryContext, props.<Boolean>getValue(ConfigurationPropertyKey.SQL_SIMPLE), executionContext);
          }
      }
  }