/*
    * 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.mask.rule;
  
  import com.cedarsoftware.util.CaseInsensitiveMap;
  import com.cedarsoftware.util.CaseInsensitiveSet;
  import org.apache.shardingsphere.infra.rule.PartialRuleUpdateSupported;
  import org.apache.shardingsphere.infra.rule.attribute.RuleAttributes;
  import org.apache.shardingsphere.infra.rule.scope.DatabaseRule;
  import org.apache.shardingsphere.infra.spi.type.typed.TypedSPILoader;
  import org.apache.shardingsphere.mask.config.MaskRuleConfiguration;
  import org.apache.shardingsphere.mask.config.rule.MaskTableRuleConfiguration;
  import org.apache.shardingsphere.mask.constant.MaskOrder;
  import org.apache.shardingsphere.mask.rule.attribute.MaskTableMapperRuleAttribute;
  import org.apache.shardingsphere.mask.spi.MaskAlgorithm;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.stream.Collectors;
  
  /**
   * Mask rule.
   */
  public final class MaskRule implements DatabaseRule, PartialRuleUpdateSupported<MaskRuleConfiguration> {
      
      private final AtomicReference<MaskRuleConfiguration> configuration = new AtomicReference<>();
      
      private final Map<String, MaskAlgorithm<?, ?>> maskAlgorithms = new CaseInsensitiveMap<>(Collections.emptyMap(), new ConcurrentHashMap<>());
      
      private final Map<String, MaskTable> tables = new CaseInsensitiveMap<>(Collections.emptyMap(), new ConcurrentHashMap<>());
      
      private final AtomicReference<RuleAttributes> attributes = new AtomicReference<>();
      
      public MaskRule(final MaskRuleConfiguration ruleConfig) {
          configuration.set(ruleConfig);
          ruleConfig.getMaskAlgorithms().forEach((key, value) -> maskAlgorithms.put(key, TypedSPILoader.getService(MaskAlgorithm.class, value.getType(), value.getProps())));
          ruleConfig.getTables().forEach(each -> tables.put(each.getName(), new MaskTable(each, maskAlgorithms)));
          attributes.set(new RuleAttributes(new MaskTableMapperRuleAttribute(tables.keySet())));
      }
      
      /**
       * Find mask table.
       *
       * @param tableName table name
       * @return found mask table
       */
      public Optional<MaskTable> findMaskTable(final String tableName) {
          return Optional.ofNullable(tables.get(tableName));
      }
      
      @Override
      public RuleAttributes getAttributes() {
          return attributes.get();
      }
      
      @Override
      public MaskRuleConfiguration getConfiguration() {
          return configuration.get();
      }
      
      @Override
      public void updateConfiguration(final MaskRuleConfiguration toBeUpdatedRuleConfig) {
          configuration.set(toBeUpdatedRuleConfig);
      }
      
      @Override
      public boolean partialUpdate(final MaskRuleConfiguration toBeUpdatedRuleConfig) {
          handleAddedMaskAlgorithm(toBeUpdatedRuleConfig);
          handleRemovedMaskAlgorithm(toBeUpdatedRuleConfig);
          Collection<String> toBeUpdatedTablesNames = toBeUpdatedRuleConfig.getTables().stream().map(MaskTableRuleConfiguration::getName).collect(Collectors.toCollection(CaseInsensitiveSet::new));
          Collection<String> toBeRemovedTableNames = tables.keySet().stream().filter(each -> !toBeUpdatedTablesNames.contains(each)).collect(Collectors.toList());
          if (!toBeRemovedTableNames.isEmpty()) {
              toBeRemovedTableNames.forEach(tables::remove);
          }
          for (MaskTableRuleConfiguration maskTableRuleConfiguration : toBeUpdatedRuleConfig.getTables()) {
              tables.put(maskTableRuleConfiguration.getName(), new MaskTable(maskTableRuleConfiguration, maskAlgorithms));
              attributes.set(new RuleAttributes(new MaskTableMapperRuleAttribute(tables.keySet())));
          }
          return false;
      }
     
     private void handleAddedMaskAlgorithm(final MaskRuleConfiguration toBeUpdatedRuleConfig) {
         toBeUpdatedRuleConfig.getMaskAlgorithms().entrySet().stream()
                 .filter(entry -> !maskAlgorithms.containsKey(entry.getKey()))
                 .forEach(entry -> maskAlgorithms.computeIfAbsent(entry.getKey(), key -> TypedSPILoader.getService(MaskAlgorithm.class, entry.getValue().getType(), entry.getValue().getProps())));
     }
     
     private void handleRemovedMaskAlgorithm(final MaskRuleConfiguration toBeUpdatedRuleConfig) {
         maskAlgorithms.entrySet().stream()
                 .filter(entry -> !toBeUpdatedRuleConfig.getMaskAlgorithms().containsKey(entry.getKey()))
                 .forEach(entry -> maskAlgorithms.remove(entry.getKey()));
     }
     
     @Override
     public int getOrder() {
         return MaskOrder.ORDER;
     }
 }