/*
    * 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.rewrite.token.generator;
  
  import lombok.Setter;
  import org.apache.shardingsphere.encrypt.exception.syntax.UnsupportedEncryptSQLException;
  import org.apache.shardingsphere.encrypt.rewrite.aware.EncryptRuleAware;
  import org.apache.shardingsphere.encrypt.rule.EncryptRule;
  import org.apache.shardingsphere.encrypt.rule.EncryptTable;
  import org.apache.shardingsphere.infra.binder.context.segment.select.orderby.OrderByItem;
  import org.apache.shardingsphere.infra.binder.context.statement.SQLStatementContext;
  import org.apache.shardingsphere.infra.binder.context.statement.dml.SelectStatementContext;
  import org.apache.shardingsphere.infra.database.core.type.DatabaseTypeRegistry;
  import org.apache.shardingsphere.infra.exception.core.ShardingSpherePreconditions;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereSchema;
  import org.apache.shardingsphere.infra.rewrite.sql.token.generator.CollectionSQLTokenGenerator;
  import org.apache.shardingsphere.infra.rewrite.sql.token.generator.aware.SchemaMetaDataAware;
  import org.apache.shardingsphere.infra.rewrite.sql.token.pojo.SQLToken;
  import org.apache.shardingsphere.infra.rewrite.sql.token.pojo.generic.SubstitutableColumnNameToken;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.column.ColumnSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.order.item.ColumnOrderByItemSegment;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashSet;
  import java.util.LinkedList;
  import java.util.Map;
  import java.util.Optional;
  
  /**
   * Order by item token generator for encrypt.
   */
  @Setter
  public final class EncryptOrderByItemTokenGenerator implements CollectionSQLTokenGenerator<SQLStatementContext>, SchemaMetaDataAware, EncryptRuleAware {
      
      private String databaseName;
      
      private Map<String, ShardingSphereSchema> schemas;
      
      private EncryptRule encryptRule;
      
      @Override
      public boolean isGenerateSQLToken(final SQLStatementContext sqlStatementContext) {
          return sqlStatementContext instanceof SelectStatementContext && containsOrderByItem(sqlStatementContext);
      }
      
      @Override
      public Collection<SQLToken> generateSQLTokens(final SQLStatementContext sqlStatementContext) {
          Collection<SQLToken> result = new LinkedHashSet<>();
          String defaultSchema = new DatabaseTypeRegistry(sqlStatementContext.getDatabaseType()).getDefaultSchemaName(databaseName);
          ShardingSphereSchema schema = sqlStatementContext.getTablesContext().getSchemaName().map(schemas::get).orElseGet(() -> schemas.get(defaultSchema));
          for (OrderByItem each : getOrderByItems(sqlStatementContext)) {
              if (each.getSegment() instanceof ColumnOrderByItemSegment) {
                  ColumnSegment columnSegment = ((ColumnOrderByItemSegment) each.getSegment()).getColumn();
                  Map<String, String> columnTableNames = sqlStatementContext.getTablesContext().findTableNamesByColumnSegment(Collections.singleton(columnSegment), schema);
                  result.addAll(generateSQLTokensWithColumnSegments(Collections.singleton(columnSegment), columnTableNames));
              }
          }
          return result;
      }
      
      private Collection<SubstitutableColumnNameToken> generateSQLTokensWithColumnSegments(final Collection<ColumnSegment> columnSegments, final Map<String, String> columnTableNames) {
          Collection<SubstitutableColumnNameToken> result = new LinkedList<>();
          for (ColumnSegment each : columnSegments) {
              String tableName = columnTableNames.getOrDefault(each.getExpression(), "");
              Optional<EncryptTable> encryptTable = encryptRule.findEncryptTable(tableName);
              String columnName = each.getIdentifier().getValue();
              ShardingSpherePreconditions.checkState(!encryptTable.isPresent() || !encryptTable.get().isEncryptColumn(columnName), () -> new UnsupportedEncryptSQLException("ORDER BY"));
          }
          return result;
      }
      
      private Collection<OrderByItem> getOrderByItems(final SQLStatementContext sqlStatementContext) {
          if (!(sqlStatementContext instanceof SelectStatementContext)) {
              return Collections.emptyList();
          }
          Collection<OrderByItem> result = new LinkedList<>();
          SelectStatementContext statementContext = (SelectStatementContext) sqlStatementContext;
          if (!statementContext.getOrderByContext().isGenerated()) {
              result.addAll(statementContext.getOrderByContext().getItems());
          }
          for (SelectStatementContext each : statementContext.getSubqueryContexts().values()) {
              result.addAll(getOrderByItems(each));
          }
         return result;
     }
     
     private boolean containsOrderByItem(final SQLStatementContext sqlStatementContext) {
         if (!(sqlStatementContext instanceof SelectStatementContext)) {
             return false;
         }
         SelectStatementContext statementContext = (SelectStatementContext) sqlStatementContext;
         if (!statementContext.getOrderByContext().getItems().isEmpty() && !statementContext.getOrderByContext().isGenerated()) {
             return true;
         }
         for (SelectStatementContext each : statementContext.getSubqueryContexts().values()) {
             if (containsOrderByItem(each)) {
                 return true;
             }
         }
         return false;
     }
 }