/*
    *    Copyright 2009-2021 the original author or authors.
    *
    *    Licensed 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.ibatis.executor;
  
  import java.sql.Connection;
  import java.sql.SQLException;
  import java.sql.Statement;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.ibatis.cursor.Cursor;
  import org.apache.ibatis.executor.statement.StatementHandler;
  import org.apache.ibatis.logging.Log;
  import org.apache.ibatis.mapping.BoundSql;
  import org.apache.ibatis.mapping.MappedStatement;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.session.ResultHandler;
  import org.apache.ibatis.session.RowBounds;
  import org.apache.ibatis.transaction.Transaction;
  
  /**
   * @author Clinton Begin
   */
  public class ReuseExecutor extends BaseExecutor {
  
    private final Map<String, Statement> statementMap = new HashMap<>();
  
    public ReuseExecutor(Configuration configuration, Transaction transaction) {
      super(configuration, transaction);
    }
  
    @Override
    public int doUpdate(MappedStatement ms, Object parameter) throws SQLException {
      Configuration configuration = ms.getConfiguration();
      StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null);
      Statement stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.update(stmt);
    }
  
    @Override
    public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
      Configuration configuration = ms.getConfiguration();
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
      Statement stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.query(stmt, resultHandler);
    }
  
    @Override
    protected <E> Cursor<E> doQueryCursor(MappedStatement ms, Object parameter, RowBounds rowBounds, BoundSql boundSql) throws SQLException {
      Configuration configuration = ms.getConfiguration();
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, null, boundSql);
      Statement stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.queryCursor(stmt);
    }
  
    @Override
    public List<BatchResult> doFlushStatements(boolean isRollback) {
      for (Statement stmt : statementMap.values()) {
        closeStatement(stmt);
      }
      statementMap.clear();
      return Collections.emptyList();
    }
  
    private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {
      Statement stmt;
      BoundSql boundSql = handler.getBoundSql();
      String sql = boundSql.getSql();
      if (hasStatementFor(sql)) {
        stmt = getStatement(sql);
        applyTransactionTimeout(stmt);
      } else {
        Connection connection = getConnection(statementLog);
        stmt = handler.prepare(connection, transaction.getTimeout());
        putStatement(sql, stmt);
      }
      handler.parameterize(stmt);
      return stmt;
    }
  
    private boolean hasStatementFor(String sql) {
      try {
        Statement statement = statementMap.get(sql);
        return statement != null && !statement.getConnection().isClosed();
     } catch (SQLException e) {
       return false;
     }
   }
 
   private Statement getStatement(String s) {
     return statementMap.get(s);
   }
 
   private void putStatement(String sql, Statement stmt) {
     statementMap.put(sql, stmt);
   }
 
 }