# Copyright (c) 2012 netzguerilla.net <iro@netzguerilla.net>
# 
# This file is part of Iro.
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
# #Software, and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

from sqlalchemy.orm import sessionmaker

class WithSession(object):
    '''a with statement for a database session connection.'''
    def __init__(self, engine, autocommit=False):
        """
        :param `sqlalchemy.engine.base.Engine` engine: a valid sqlalchemy engine object (normally created via :func:`sqlalchemy.create_engine`).
        :param boolean autocommit: autocommit after running the function.

        .. automethod:: __enter__
        .. automethod:: __exit__
        """
        self.engine = engine
        self.autocommit=autocommit
    
    def __enter__(self):
        """returns a vaild session object."""
        self.session = sessionmaker(bind=self.engine)()
        return self.session
    
    def __exit__(self,exc_type, exc_value, traceback):
        if exc_type is None:
            if self.autocommit:
                self.session.commit()
        else:
            self.session.rollback()
        self.session.close()