/*
    * 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.proxy.frontend.postgresql.command.query.extended.parse;
  
  import lombok.RequiredArgsConstructor;
  import org.apache.shardingsphere.db.protocol.packet.DatabasePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.PostgreSQLColumnType;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.parse.PostgreSQLComParsePacket;
  import org.apache.shardingsphere.db.protocol.postgresql.packet.command.query.extended.parse.PostgreSQLParseCompletePacket;
  import org.apache.shardingsphere.distsql.statement.DistSQLStatement;
  import org.apache.shardingsphere.infra.binder.context.statement.SQLStatementContext;
  import org.apache.shardingsphere.infra.binder.engine.SQLBindEngine;
  import org.apache.shardingsphere.infra.database.core.type.DatabaseType;
  import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
  import org.apache.shardingsphere.infra.parser.SQLParserEngine;
  import org.apache.shardingsphere.parser.rule.SQLParserRule;
  import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
  import org.apache.shardingsphere.proxy.backend.distsql.DistSQLStatementContext;
  import org.apache.shardingsphere.proxy.backend.session.ConnectionSession;
  import org.apache.shardingsphere.proxy.frontend.command.executor.CommandExecutor;
  import org.apache.shardingsphere.proxy.frontend.postgresql.command.query.extended.PostgreSQLServerPreparedStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.enums.ParameterMarkerType;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.SQLSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.ParameterMarkerSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.SQLStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dml.DMLStatement;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  
  /**
   * PostgreSQL command parse executor.
   */
  @RequiredArgsConstructor
  public final class PostgreSQLComParseExecutor implements CommandExecutor {
      
      private final PostgreSQLComParsePacket packet;
      
      private final ConnectionSession connectionSession;
      
      @Override
      public Collection<DatabasePacket> execute() {
          ShardingSphereMetaData metaData = ProxyContext.getInstance().getContextManager().getMetaDataContexts().getMetaData();
          DatabaseType databaseType = metaData.getDatabase(connectionSession.getUsedDatabaseName()).getProtocolType();
          SQLParserEngine sqlParserEngine = metaData.getGlobalRuleMetaData().getSingleRule(SQLParserRule.class).getSQLParserEngine(databaseType);
          String sql = packet.getSQL();
          SQLStatement sqlStatement = sqlParserEngine.parse(sql, true);
          String escapedSql = escape(sqlStatement, sql);
          if (!escapedSql.equalsIgnoreCase(sql)) {
              sqlStatement = sqlParserEngine.parse(escapedSql, true);
              sql = escapedSql;
          }
          List<Integer> actualParameterMarkerIndexes = new ArrayList<>(sqlStatement.getParameterMarkers().size());
          if (sqlStatement.getParameterCount() > 0) {
              List<ParameterMarkerSegment> parameterMarkerSegments = new ArrayList<>(sqlStatement.getParameterMarkers());
              for (ParameterMarkerSegment each : parameterMarkerSegments) {
                  actualParameterMarkerIndexes.add(each.getParameterIndex());
              }
              sql = convertSQLToJDBCStyle(parameterMarkerSegments, sql);
              sqlStatement = sqlParserEngine.parse(sql, true);
          }
          List<PostgreSQLColumnType> paddedColumnTypes = paddingColumnTypes(sqlStatement.getParameterCount(), packet.readParameterTypes());
          SQLStatementContext sqlStatementContext = sqlStatement instanceof DistSQLStatement
                  ? new DistSQLStatementContext((DistSQLStatement) sqlStatement)
                  : new SQLBindEngine(metaData, connectionSession.getCurrentDatabaseName(), packet.getHintValueContext()).bind(databaseType, sqlStatement, Collections.emptyList());
          PostgreSQLServerPreparedStatement serverPreparedStatement = new PostgreSQLServerPreparedStatement(
                  sql, sqlStatementContext, packet.getHintValueContext(), paddedColumnTypes, actualParameterMarkerIndexes);
          connectionSession.getServerPreparedStatementRegistry().addPreparedStatement(packet.getStatementId(), serverPreparedStatement);
          return Collections.singleton(PostgreSQLParseCompletePacket.getInstance());
      }
      
      private String escape(final SQLStatement sqlStatement, final String sql) {
          return sqlStatement instanceof DMLStatement ? sql.replace("?", "??") : sql;
      }
      
      private String convertSQLToJDBCStyle(final List<ParameterMarkerSegment> parameterMarkerSegments, final String sql) {
          parameterMarkerSegments.sort(Comparator.comparingInt(SQLSegment::getStopIndex));
          StringBuilder result = new StringBuilder(sql);
          for (int i = parameterMarkerSegments.size() - 1; i >= 0; i--) {
              ParameterMarkerSegment each = parameterMarkerSegments.get(i);
              result.replace(each.getStartIndex(), each.getStopIndex() + 1, ParameterMarkerType.QUESTION.getMarker());
         }
         return result.toString();
     }
     
     private List<PostgreSQLColumnType> paddingColumnTypes(final int parameterCount, final List<PostgreSQLColumnType> specifiedColumnTypes) {
         if (parameterCount == specifiedColumnTypes.size()) {
             return specifiedColumnTypes;
         }
         List<PostgreSQLColumnType> result = new ArrayList<>(parameterCount);
         result.addAll(specifiedColumnTypes);
         int unspecifiedCount = parameterCount - specifiedColumnTypes.size();
         for (int i = 0; i < unspecifiedCount; i++) {
             result.add(PostgreSQLColumnType.UNSPECIFIED);
         }
         return result;
     }
 }