/*
    * 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.google.common.base.Preconditions;
  import org.apache.shardingsphere.infra.algorithm.core.config.AlgorithmConfiguration;
  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.api.config.MaskRuleConfiguration;
  import org.apache.shardingsphere.mask.api.config.rule.MaskTableRuleConfiguration;
  import org.apache.shardingsphere.mask.rule.attribute.MaskTableMapperRuleAttribute;
  import org.apache.shardingsphere.mask.spi.MaskAlgorithm;
  
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Map.Entry;
  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 ConcurrentHashMap<String, MaskAlgorithm<?, ?>> maskAlgorithms;
      
      private final ConcurrentHashMap<String, MaskTable> tables;
      
      private final AtomicReference<RuleAttributes> attributes = new AtomicReference<>();
      
      @SuppressWarnings("unchecked")
      public MaskRule(final MaskRuleConfiguration ruleConfig) {
          configuration.set(ruleConfig);
          maskAlgorithms = ruleConfig.getMaskAlgorithms().entrySet().stream()
                  .collect(Collectors.toMap(Entry::getKey, entry -> TypedSPILoader.getService(MaskAlgorithm.class, entry.getValue().getType(), entry.getValue().getProps()),
                          (oldValue, currentValue) -> oldValue, ConcurrentHashMap::new));
          tables = ruleConfig.getTables().stream()
                  .collect(Collectors.toMap(each -> each.getName().toLowerCase(), each -> new MaskTable(each, maskAlgorithms), (oldValue, currentValue) -> oldValue, ConcurrentHashMap::new));
          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) {
          Collection<String> toBeAddedTableNames = toBeUpdatedRuleConfig.getTables().stream().map(MaskTableRuleConfiguration::getName).collect(Collectors.toList());
          toBeAddedTableNames.removeAll(tables.keySet());
          if (!toBeAddedTableNames.isEmpty()) {
              toBeAddedTableNames.forEach(each -> addTableRule(each, toBeUpdatedRuleConfig));
              attributes.set(new RuleAttributes(new MaskTableMapperRuleAttribute(tables.keySet())));
              return true;
          }
          Collection<String> toBeRemovedTableNames = new HashSet<>(tables.keySet());
          toBeRemovedTableNames.removeAll(toBeUpdatedRuleConfig.getTables().stream().map(MaskTableRuleConfiguration::getName).collect(Collectors.toList()));
          if (!toBeRemovedTableNames.isEmpty()) {
             toBeRemovedTableNames.stream().map(String::toLowerCase).forEach(tables::remove);
             attributes.set(new RuleAttributes(new MaskTableMapperRuleAttribute(tables.keySet())));
             // TODO check and remove unused INLINE mask algorithms
             return true;
         }
         // TODO Process update table
         // TODO Process CRUD mask algorithms
         return false;
     }
     
     private void addTableRule(final String tableName, final MaskRuleConfiguration toBeUpdatedRuleConfig) {
         MaskTableRuleConfiguration tableRuleConfig = getTableRuleConfiguration(tableName, toBeUpdatedRuleConfig);
         for (Entry<String, AlgorithmConfiguration> entry : toBeUpdatedRuleConfig.getMaskAlgorithms().entrySet()) {
             maskAlgorithms.computeIfAbsent(entry.getKey(), key -> TypedSPILoader.getService(MaskAlgorithm.class, entry.getValue().getType(), entry.getValue().getProps()));
         }
         tables.put(tableName.toLowerCase(), new MaskTable(tableRuleConfig, maskAlgorithms));
     }
     
     private MaskTableRuleConfiguration getTableRuleConfiguration(final String tableName, final MaskRuleConfiguration toBeUpdatedRuleConfig) {
         Optional<MaskTableRuleConfiguration> result = toBeUpdatedRuleConfig.getTables().stream().filter(table -> table.getName().equals(tableName)).findFirst();
         Preconditions.checkState(result.isPresent());
         return result.get();
     }
 }