/*
    * 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.encrypt.rule;
  
  import com.cedarsoftware.util.CaseInsensitiveMap;
  import com.cedarsoftware.util.CaseInsensitiveSet;
  import org.apache.shardingsphere.encrypt.config.EncryptRuleConfiguration;
  import org.apache.shardingsphere.encrypt.config.rule.EncryptColumnRuleConfiguration;
  import org.apache.shardingsphere.encrypt.config.rule.EncryptTableRuleConfiguration;
  import org.apache.shardingsphere.encrypt.constant.EncryptOrder;
  import org.apache.shardingsphere.encrypt.exception.metadata.EncryptTableNotFoundException;
  import org.apache.shardingsphere.encrypt.exception.metadata.MismatchedEncryptAlgorithmTypeException;
  import org.apache.shardingsphere.encrypt.rule.attribute.EncryptTableMapperRuleAttribute;
  import org.apache.shardingsphere.encrypt.rule.table.EncryptTable;
  import org.apache.shardingsphere.encrypt.spi.EncryptAlgorithm;
  import org.apache.shardingsphere.infra.algorithm.core.config.AlgorithmConfiguration;
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.exception.ShardingSpherePreconditions;
  import org.apache.shardingsphere.infra.rule.PartialRuleUpdateSupported;
  import org.apache.shardingsphere.infra.rule.attribute.RuleAttribute;
  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 java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  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;
  
  /**
   * Encrypt rule.
   */
  public final class EncryptRule implements DatabaseRule, PartialRuleUpdateSupported<EncryptRuleConfiguration> {
      
      private final String databaseName;
      
      private final AtomicReference<EncryptRuleConfiguration> ruleConfig = new AtomicReference<>();
      
      private final Map<String, EncryptAlgorithm> encryptors;
      
      private final Map<String, EncryptTable> tables = new CaseInsensitiveMap<>(Collections.emptyMap(), new ConcurrentHashMap<>());
      
      private final AtomicReference<RuleAttributes> attributes = new AtomicReference<>();
      
      public EncryptRule(final String databaseName, final EncryptRuleConfiguration ruleConfig) {
          this.databaseName = databaseName;
          this.ruleConfig.set(ruleConfig);
          encryptors = createEncryptors(ruleConfig);
          for (EncryptTableRuleConfiguration each : ruleConfig.getTables()) {
              each.getColumns().forEach(this::checkEncryptorType);
              tables.put(each.getName(), new EncryptTable(each, encryptors));
          }
          attributes.set(buildRuleAttributes());
      }
      
      private RuleAttributes buildRuleAttributes() {
          List<RuleAttribute> ruleAttributes = new LinkedList<>();
          ruleAttributes.add(new EncryptTableMapperRuleAttribute(tables.keySet()));
          return new RuleAttributes(ruleAttributes.toArray(new RuleAttribute[]{}));
      }
      
      private Map<String, EncryptAlgorithm> createEncryptors(final EncryptRuleConfiguration ruleConfig) {
          Map<String, EncryptAlgorithm> result = new CaseInsensitiveMap<>(Collections.emptyMap(), new ConcurrentHashMap<>(ruleConfig.getEncryptors().size(), 1F));
          for (Entry<String, AlgorithmConfiguration> entry : ruleConfig.getEncryptors().entrySet()) {
              result.put(entry.getKey(), TypedSPILoader.getService(EncryptAlgorithm.class, entry.getValue().getType(), entry.getValue().getProps()));
          }
          return result;
      }
      
      // TODO How to process changed encryptors and tables if check failed? It should check before rule change
      private void checkEncryptorType(final EncryptColumnRuleConfiguration columnRuleConfig) {
          ShardingSpherePreconditions.checkState(encryptors.containsKey(columnRuleConfig.getCipher().getEncryptorName())
                  && encryptors.get(columnRuleConfig.getCipher().getEncryptorName()).getMetaData().isSupportDecrypt(),
                  () -> new MismatchedEncryptAlgorithmTypeException(databaseName, "Cipher", columnRuleConfig.getCipher().getEncryptorName(), "decrypt"));
          columnRuleConfig.getAssistedQuery().ifPresent(optional -> ShardingSpherePreconditions.checkState(encryptors.containsKey(optional.getEncryptorName())
                  && encryptors.get(optional.getEncryptorName()).getMetaData().isSupportEquivalentFilter(),
                  () -> new MismatchedEncryptAlgorithmTypeException(databaseName, "Assisted query", columnRuleConfig.getCipher().getEncryptorName(), "equivalent filter")));
          columnRuleConfig.getLikeQuery().ifPresent(optional -> ShardingSpherePreconditions.checkState(encryptors.containsKey(optional.getEncryptorName())
                 && encryptors.get(optional.getEncryptorName()).getMetaData().isSupportLike(),
                 () -> new MismatchedEncryptAlgorithmTypeException(databaseName, "Like query", columnRuleConfig.getCipher().getEncryptorName(), "like")));
     }
     
     /**
      * Get all table names.
      *
      * @return all table names
      */
     public Collection<String> getAllTableNames() {
         return tables.keySet();
     }
     
     /**
      * Find encrypt table.
      *
      * @param tableName table name
      * @return encrypt table
      */
     @HighFrequencyInvocation
     public Optional<EncryptTable> findEncryptTable(final String tableName) {
         return Optional.ofNullable(tables.get(tableName));
     }
     
     /**
      * Get encrypt table.
      *
      * @param tableName table name
      * @return encrypt table
      */
     @HighFrequencyInvocation
     public EncryptTable getEncryptTable(final String tableName) {
         return findEncryptTable(tableName).orElseThrow(() -> new EncryptTableNotFoundException(tableName));
     }
     
     /**
      * Find query encryptor.
      *
      * @param tableName table name
      * @param columnName column name
      * @return query encryptor
      */
     @HighFrequencyInvocation
     public Optional<EncryptAlgorithm> findQueryEncryptor(final String tableName, final String columnName) {
         return findEncryptTable(tableName).flatMap(optional -> optional.findQueryEncryptor(columnName));
     }
     
     @Override
     public RuleAttributes getAttributes() {
         return attributes.get();
     }
     
     @Override
     public EncryptRuleConfiguration getConfiguration() {
         return ruleConfig.get();
     }
     
     @Override
     public void updateConfiguration(final EncryptRuleConfiguration toBeUpdatedRuleConfig) {
         ruleConfig.set(toBeUpdatedRuleConfig);
     }
     
     @Override
     public boolean partialUpdate(final EncryptRuleConfiguration toBeUpdatedRuleConfig) {
         if (handleAddedEncryptors(toBeUpdatedRuleConfig) || handleRemovedEncryptors(toBeUpdatedRuleConfig)) {
             return false;
         }
         Collection<String> toBeUpdatedTablesNames = toBeUpdatedRuleConfig.getTables().stream().map(EncryptTableRuleConfiguration::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 (EncryptTableRuleConfiguration encryptTableRuleConfiguration : toBeUpdatedRuleConfig.getTables()) {
             encryptTableRuleConfiguration.getColumns().forEach(this::checkEncryptorType);
             tables.put(encryptTableRuleConfiguration.getName(), new EncryptTable(encryptTableRuleConfiguration, encryptors));
             attributes.set(buildRuleAttributes());
         }
         return true;
     }
     
     private boolean handleAddedEncryptors(final EncryptRuleConfiguration toBeUpdatedRuleConfig) {
         return toBeUpdatedRuleConfig.getEncryptors().entrySet().stream()
                 .filter(entry -> !encryptors.containsKey(entry.getKey()))
                 .peek(entry -> encryptors.computeIfAbsent(entry.getKey(), key -> TypedSPILoader.getService(EncryptAlgorithm.class, entry.getValue().getType(), entry.getValue().getProps())))
                 .findAny().isPresent();
     }
     
     private boolean handleRemovedEncryptors(final EncryptRuleConfiguration toBeUpdatedRuleConfig) {
         return encryptors.entrySet().stream()
                 .filter(entry -> !toBeUpdatedRuleConfig.getEncryptors().containsKey(entry.getKey()))
                 .peek(entry -> encryptors.remove(entry.getKey())).findAny().isPresent();
     }
     
     @Override
     public int getOrder() {
         return EncryptOrder.ORDER;
     }
 }