# Copyright (C) 2010  Leonard Thomas
#
# This file is part of Dodai.
#
# Dodai is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Dodai is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Dodai.  If not, see <http://www.gnu.org/licenses/>.

class Sa(object):
    """Callable object that will wire up sqlalchemy engine and
    session objects

    Attributes:
        create_engine:  The sqlalchemy create_engine object
        session_maker:  The sqlalchemy session_maker object
        result_object:  The object that will be populated with
                        all the connection information along with
                        the sqlalchemy objects

    """
    def __init__(self, create_engine, session_maker, result_object):
        self._create_engine = create_engine
        self._session_maker = session_maker
        self._result_object = result_object

    def __call__(self, section, name):
        db = self._result_object()
        db.name = name
        db.protocol = section['protocol']

        if section.has_key('protocol_extra') and section['protocol_extra']:
            db.protocol_extra = section['protocol_extra']

        if section.has_key('filename') and section['filename']:
            db.filename = section['filename']

        if section.has_key('port') and section['port']:
            db.port = int(section['port'])

        if section.has_key('database') and section['database']:
            db.database = section['database']

        if section.has_key('schema') and section['schema']:
            db.schema = section['schema']

        if section.has_key('username') and section['username']:
            db.username = section['username']

        if section.has_key('hostname') and section['hostname']:
            db.hostname = section['hostname']

        db.engine = self._build_engine(section)
        db.session = self._build_session(db.engine)
        return db

    def _build_session(self, engine):
        session = self._session_maker(bind=engine)
        return session()

    def _build_connection_string(self, section):
        out = []
        out.append('{section[protocol]}')
        if section.has_key('protocol_extra') and section['protocol_extra']:
            out.append('+{section[protocol_extra]}')
        out.append('://')
        if section.has_key('filename') and section['filename']:
            out.append('/{section[filename]}')
        else:
            out.append('{section[username]}:{section[password]}@')
            out.append('{section[hostname]}')
            if section.has_key('port') and section['port']:
                out.append(':{section[port]}')
            out.append('/{section[database]}')
        out = ''.join(out)
        out = out.format(section=section)
        return out

    def _build_engine(self, section):
        connection_string = self._build_connection_string(section)
        db_obj = self._create_engine(connection_string)
        return db_obj