#    This file is part of rhizi, a collaborative knowledge graph editor.
#    Copyright (C) 2014-2015  Rhizi
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program 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 Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.


#!/usr/bin/python

import logging

from db_driver import DB_Driver_REST, DB_Driver_Base
from db_op import DB_composed_op
from db_op import DB_op
from neo4j_util import Neo4JException


log = logging.getLogger('rhizi')

class DB_Controller(object):
    """
    neo4j DB controller
    """
    def __init__(self, rest_api_base_url, db_driver_class=None):
        if not db_driver_class:
            self.db_driver = DB_Driver_REST(rest_api_base_url)
        else:
            self.db_driver = db_driver_class()
        assert isinstance(self.db_driver, DB_Driver_Base)

    def exec_op(self, op):
        """
        execute operation within a DB transaction
        """
        if isinstance(op, DB_composed_op):  # composed DB op
            log.debug('exec_composed-op:' + op.name)

            for sub_op in op.iter__sub_op():
                sub_op_ret = self.exec_op(sub_op)  # recursive call
                op.post_sub_op_exec_hook(sub_op, sub_op_ret)

            op_ret = op.process_result_set()
            return op_ret

        try:  # non-composed DB op
            self.db_driver.begin_tx(op)
            self.db_driver.exec_query_set(op)
            self.db_driver.commit_tx(op)

            op_ret = op.process_result_set()
            log.debug('exec_op: ' + op.name + ': return value: ' + unicode(op_ret)[:256])  # trim verbose return values
            return op_ret

        except Neo4JException as e:
            log.exception(e)  # Neo4JException may be composed of several sub errors, defer to class __str__
            raise e
        except Exception as e:
            # here we watch for IOExecptions, etc - not db errors
            # these are returned in the db response itself

            log.exception('op: %r' % (op))
            raise e

    def create_db_op(self, f_work, f_cont):
        ret = DB_op(f_work, f_cont)
        return ret