/**
    *    Copyright 2009-2015 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.session.defaults;
  
  import java.sql.Connection;
  import java.sql.SQLException;
  
  import org.apache.ibatis.exceptions.ExceptionFactory;
  import org.apache.ibatis.executor.ErrorContext;
  import org.apache.ibatis.executor.Executor;
  import org.apache.ibatis.mapping.Environment;
  import org.apache.ibatis.session.Configuration;
  import org.apache.ibatis.session.ExecutorType;
  import org.apache.ibatis.session.SqlSession;
  import org.apache.ibatis.session.SqlSessionFactory;
  import org.apache.ibatis.session.TransactionIsolationLevel;
  import org.apache.ibatis.transaction.Transaction;
  import org.apache.ibatis.transaction.TransactionFactory;
  import org.apache.ibatis.transaction.managed.ManagedTransactionFactory;
  
  /**
   * @author Clinton Begin
   */
  public class DefaultSqlSessionFactory implements SqlSessionFactory {
  
    private final Configuration configuration;
  
    public DefaultSqlSessionFactory(Configuration configuration) {
      this.configuration = configuration;
    }
  
    @Override
    public SqlSession openSession() {
      return openSessionFromDataSource(configuration.getDefaultExecutorType(), null, false);
    }
  
    @Override
    public SqlSession openSession(boolean autoCommit) {
      return openSessionFromDataSource(configuration.getDefaultExecutorType(), null, autoCommit);
    }
  
    @Override
    public SqlSession openSession(ExecutorType execType) {
      return openSessionFromDataSource(execType, null, false);
    }
  
    @Override
    public SqlSession openSession(TransactionIsolationLevel level) {
      return openSessionFromDataSource(configuration.getDefaultExecutorType(), level, false);
    }
  
    @Override
    public SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level) {
      return openSessionFromDataSource(execType, level, false);
    }
  
    @Override
    public SqlSession openSession(ExecutorType execType, boolean autoCommit) {
      return openSessionFromDataSource(execType, null, autoCommit);
    }
  
    @Override
    public SqlSession openSession(Connection connection) {
      return openSessionFromConnection(configuration.getDefaultExecutorType(), connection);
    }
  
    @Override
    public SqlSession openSession(ExecutorType execType, Connection connection) {
      return openSessionFromConnection(execType, connection);
    }
  
    @Override
    public Configuration getConfiguration() {
      return configuration;
    }
  
    private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
      Transaction tx = null;
      try {
        final Environment environment = configuration.getEnvironment();
        final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);
        tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);
        final Executor executor = configuration.newExecutor(tx, execType);
        return new DefaultSqlSession(configuration, executor, autoCommit);
      } catch (Exception e) {
        closeTransaction(tx); // may have fetched a connection so lets call close()
       throw ExceptionFactory.wrapException("Error opening session.  Cause: " + e, e);
     } finally {
       ErrorContext.instance().reset();
     }
   }
 
   private SqlSession openSessionFromConnection(ExecutorType execType, Connection connection) {
     try {
       boolean autoCommit;
       try {
         autoCommit = connection.getAutoCommit();
       } catch (SQLException e) {
         // Failover to true, as most poor drivers
         // or databases won't support transactions
         autoCommit = true;
       }      
       final Environment environment = configuration.getEnvironment();
       final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);
       final Transaction tx = transactionFactory.newTransaction(connection);
       final Executor executor = configuration.newExecutor(tx, execType);
       return new DefaultSqlSession(configuration, executor, autoCommit);
     } catch (Exception e) {
       throw ExceptionFactory.wrapException("Error opening session.  Cause: " + e, e);
     } finally {
       ErrorContext.instance().reset();
     }
   }
 
   private TransactionFactory getTransactionFactoryFromEnvironment(Environment environment) {
     if (environment == null || environment.getTransactionFactory() == null) {
       return new ManagedTransactionFactory();
     }
     return environment.getTransactionFactory();
   }
 
   private void closeTransaction(Transaction tx) {
     if (tx != null) {
       try {
         tx.close();
       } catch (SQLException ignore) {
         // Intentionally ignore. Prefer previous error.
       }
     }
   }
 
 }