/*
    * 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.mysql.command.query.binary.prepare;
  
  import lombok.AccessLevel;
  import lombok.NoArgsConstructor;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereColumn;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereSchema;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereTable;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.assignment.InsertValuesSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.ExpressionSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.simple.ParameterMarkerExpressionSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.SQLStatement;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.dml.InsertStatement;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.stream.Collectors;
  
  /**
   * Parameter marker extractor for MySQL COM_STMT_PREPARE.
   */
  @NoArgsConstructor(access = AccessLevel.PRIVATE)
  public final class MySQLComStmtPrepareParameterMarkerExtractor {
      
      /**
       * TODO Support more statements and syntax.
       * Find corresponding columns of parameter markers.
       *
       * @param sqlStatement SQL statement
       * @param schema schema
       * @return corresponding columns of parameter markers
       */
      public static List<ShardingSphereColumn> findColumnsOfParameterMarkers(final SQLStatement sqlStatement, final ShardingSphereSchema schema) {
          return sqlStatement instanceof InsertStatement ? findColumnsOfParameterMarkersForInsert((InsertStatement) sqlStatement, schema) : Collections.emptyList();
      }
      
      private static List<ShardingSphereColumn> findColumnsOfParameterMarkersForInsert(final InsertStatement insertStatement, final ShardingSphereSchema schema) {
          ShardingSphereTable table = schema.getTable(insertStatement.getTable().getTableName().getIdentifier().getValue());
          List<String> columnNamesOfInsert = getColumnNamesOfInsertStatement(insertStatement, table);
          List<ShardingSphereColumn> result = new ArrayList<>(insertStatement.getParameterMarkerSegments().size());
          for (InsertValuesSegment each : insertStatement.getValues()) {
              ListIterator<ExpressionSegment> listIterator = each.getValues().listIterator();
              for (int columnIndex = listIterator.nextIndex(); listIterator.hasNext(); columnIndex = listIterator.nextIndex()) {
                  ExpressionSegment value = listIterator.next();
                  if (!(value instanceof ParameterMarkerExpressionSegment)) {
                      continue;
                  }
                  String columnName = columnNamesOfInsert.get(columnIndex);
                  ShardingSphereColumn column = table.getColumn(columnName);
                  result.add(column);
              }
          }
          return result;
      }
      
      private static List<String> getColumnNamesOfInsertStatement(final InsertStatement insertStatement, final ShardingSphereTable table) {
          return insertStatement.getColumns().isEmpty() ? table.getColumnNames() : insertStatement.getColumns().stream().map(each -> each.getIdentifier().getValue()).collect(Collectors.toList());
      }
  }