/*
    * 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.sharding.distsql.handler.update;
  
  import com.cedarsoftware.util.CaseInsensitiveSet;
  import com.google.common.base.Splitter;
  import lombok.Setter;
  import org.apache.shardingsphere.distsql.handler.engine.update.rdl.rule.spi.database.DatabaseRuleDropExecutor;
  import org.apache.shardingsphere.infra.exception.kernel.metadata.rule.MissingRequiredRuleException;
  import org.apache.shardingsphere.infra.exception.kernel.metadata.rule.InUsedRuleException;
  import org.apache.shardingsphere.distsql.handler.required.DistSQLExecutorCurrentRuleRequired;
  import org.apache.shardingsphere.infra.exception.core.ShardingSpherePreconditions;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.sharding.api.config.ShardingRuleConfiguration;
  import org.apache.shardingsphere.sharding.api.config.rule.ShardingAutoTableRuleConfiguration;
  import org.apache.shardingsphere.sharding.api.config.rule.ShardingTableRuleConfiguration;
  import org.apache.shardingsphere.sharding.distsql.statement.DropShardingTableRuleStatement;
  import org.apache.shardingsphere.sharding.rule.ShardingRule;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedList;
  import java.util.stream.Collectors;
  
  /**
   * Drop sharding table rule executor.
   */
  @DistSQLExecutorCurrentRuleRequired(ShardingRule.class)
  @Setter
  public final class DropShardingTableRuleExecutor implements DatabaseRuleDropExecutor<DropShardingTableRuleStatement, ShardingRule, ShardingRuleConfiguration> {
      
      private ShardingSphereDatabase database;
      
      private ShardingRule rule;
      
      @Override
      public void checkBeforeUpdate(final DropShardingTableRuleStatement sqlStatement) {
          if (!sqlStatement.isIfExists()) {
              checkToBeDroppedShardingTableNames(sqlStatement);
          }
          if (null != rule) {
              checkBindingTables(sqlStatement);
          }
      }
      
      private void checkToBeDroppedShardingTableNames(final DropShardingTableRuleStatement sqlStatement) {
          Collection<String> currentShardingTableNames = getCurrentShardingTableNames();
          Collection<String> notExistedTableNames = getToBeDroppedShardingTableNames(sqlStatement).stream().filter(each -> !currentShardingTableNames.contains(each)).collect(Collectors.toList());
          ShardingSpherePreconditions.checkMustEmpty(notExistedTableNames, () -> new MissingRequiredRuleException("sharding", database.getName(), notExistedTableNames));
      }
      
      private Collection<String> getToBeDroppedShardingTableNames(final DropShardingTableRuleStatement sqlStatement) {
          return sqlStatement.getTableNames().stream().map(each -> each.getIdentifier().getValue()).collect(Collectors.toList());
      }
      
      private Collection<String> getCurrentShardingTableNames() {
          Collection<String> result = new CaseInsensitiveSet<>();
          result.addAll(rule.getConfiguration().getTables().stream().map(ShardingTableRuleConfiguration::getLogicTable).collect(Collectors.toList()));
          result.addAll(rule.getConfiguration().getAutoTables().stream().map(ShardingAutoTableRuleConfiguration::getLogicTable).collect(Collectors.toList()));
          return result;
      }
      
      private void checkBindingTables(final DropShardingTableRuleStatement sqlStatement) {
          Collection<String> bindingTables = getBindingTables();
          Collection<String> usedTableNames = getToBeDroppedShardingTableNames(sqlStatement).stream().filter(bindingTables::contains).collect(Collectors.toList());
          if (!usedTableNames.isEmpty()) {
              throw new InUsedRuleException("Sharding", database.getName(), usedTableNames, "sharding table reference");
          }
      }
      
      private Collection<String> getBindingTables() {
          Collection<String> result = new CaseInsensitiveSet<>();
          rule.getConfiguration().getBindingTableGroups().forEach(each -> result.addAll(Splitter.on(",").splitToList(each.getReference())));
          return result;
      }
      
      @Override
      public boolean hasAnyOneToBeDropped(final DropShardingTableRuleStatement sqlStatement) {
          Collection<String> currentTableNames = new LinkedList<>();
          currentTableNames.addAll(rule.getConfiguration().getTables().stream().map(ShardingTableRuleConfiguration::getLogicTable).collect(Collectors.toSet()));
          currentTableNames.addAll(rule.getConfiguration().getAutoTables().stream().map(ShardingAutoTableRuleConfiguration::getLogicTable).collect(Collectors.toSet()));
          return !Collections.disjoint(currentTableNames, sqlStatement.getTableNames().stream().map(each -> each.getIdentifier().getValue()).collect(Collectors.toSet()));
      }
      
     @Override
     public ShardingRuleConfiguration buildToBeDroppedRuleConfiguration(final DropShardingTableRuleStatement sqlStatement) {
         ShardingRuleConfiguration result = new ShardingRuleConfiguration();
         Collection<String> toBeDroppedShardingTableNames = getToBeDroppedShardingTableNames(sqlStatement);
         for (String each : toBeDroppedShardingTableNames) {
             result.getTables().addAll(rule.getConfiguration().getTables().stream().filter(table -> each.equalsIgnoreCase(table.getLogicTable())).collect(Collectors.toList()));
             result.getAutoTables().addAll(rule.getConfiguration().getAutoTables().stream().filter(table -> each.equalsIgnoreCase(table.getLogicTable())).collect(Collectors.toList()));
             dropShardingTable(rule.getConfiguration(), each);
         }
         UnusedAlgorithmFinder.findUnusedShardingAlgorithm(
                 rule.getConfiguration()).forEach(each -> result.getShardingAlgorithms().put(each, rule.getConfiguration().getShardingAlgorithms().get(each)));
         UnusedAlgorithmFinder.findUnusedKeyGenerator(rule.getConfiguration()).forEach(each -> result.getKeyGenerators().put(each, rule.getConfiguration().getKeyGenerators().get(each)));
         UnusedAlgorithmFinder.findUnusedAuditor(rule.getConfiguration()).forEach(each -> result.getAuditors().put(each, rule.getConfiguration().getAuditors().get(each)));
         return result;
     }
     
     private void dropShardingTable(final ShardingRuleConfiguration currentRuleConfig, final String tableName) {
         currentRuleConfig.getTables().removeAll(currentRuleConfig.getTables().stream().filter(each -> tableName.equalsIgnoreCase(each.getLogicTable())).collect(Collectors.toList()));
         currentRuleConfig.getAutoTables().removeAll(currentRuleConfig.getAutoTables().stream().filter(each -> tableName.equalsIgnoreCase(each.getLogicTable())).collect(Collectors.toList()));
     }
     
     @Override
     public Class<ShardingRule> getRuleClass() {
         return ShardingRule.class;
     }
     
     @Override
     public Class<DropShardingTableRuleStatement> getType() {
         return DropShardingTableRuleStatement.class;
     }
 }