/*
    * 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.engine.impl;
  
  import lombok.RequiredArgsConstructor;
  import org.apache.shardingsphere.infra.binder.context.statement.SQLStatementContext;
  import org.apache.shardingsphere.infra.route.context.RouteContext;
  import org.apache.shardingsphere.shadow.api.shadow.ShadowOperationType;
  import org.apache.shardingsphere.shadow.api.shadow.hint.HintShadowAlgorithm;
  import org.apache.shardingsphere.shadow.condition.ShadowDetermineCondition;
  import org.apache.shardingsphere.shadow.route.engine.ShadowRouteEngine;
  import org.apache.shardingsphere.shadow.route.engine.determiner.HintShadowAlgorithmDeterminer;
  import org.apache.shardingsphere.shadow.rule.ShadowRule;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.generic.CommentSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.AbstractSQLStatement;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Map;
  import java.util.Optional;
  import java.util.stream.Collectors;
  
  /**
   * Shadow non-DML statement routing engine.
   */
  @RequiredArgsConstructor
  public final class ShadowNonDMLStatementRoutingEngine implements ShadowRouteEngine {
      
      private final SQLStatementContext sqlStatementContext;
      
      @Override
      public void route(final RouteContext routeContext, final ShadowRule rule) {
          decorateRouteContext(routeContext, rule, findShadowDataSourceMappings(rule));
      }
      
      private Map<String, String> findShadowDataSourceMappings(final ShadowRule rule) {
          Optional<Collection<String>> sqlComments = parseSQLComments();
          if (!sqlComments.isPresent()) {
              return Collections.emptyMap();
          }
          if (isMatchAnyNoteShadowAlgorithms(rule, createShadowDetermineCondition(sqlComments.get()))) {
              return rule.getAllShadowDataSourceMappings();
          }
          return Collections.emptyMap();
      }
      
      private Optional<Collection<String>> parseSQLComments() {
          // TODO use SQLHintUtil to parse SQL comments and remove hint in sql
          Collection<String> result = ((AbstractSQLStatement) sqlStatementContext.getSqlStatement()).getCommentSegments().stream().map(CommentSegment::getText).collect(Collectors.toList());
          return result.isEmpty() ? Optional.empty() : Optional.of(result);
      }
      
      private ShadowDetermineCondition createShadowDetermineCondition(final Collection<String> sqlComments) {
          return new ShadowDetermineCondition("", ShadowOperationType.HINT_MATCH).initSQLComments(sqlComments);
      }
      
      private boolean isMatchAnyNoteShadowAlgorithms(final ShadowRule rule, final ShadowDetermineCondition shadowCondition) {
          for (HintShadowAlgorithm<Comparable<?>> each : rule.getAllHintShadowAlgorithms()) {
              if (HintShadowAlgorithmDeterminer.isShadow(each, shadowCondition, rule)) {
                  return true;
              }
          }
          return false;
      }
  }