# copyright 2003-2014 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
""" undoable transaction objects. """
__docformat__ = "restructuredtext en"
_ = unicode

from cubicweb import RepositoryError


ACTION_LABELS = {
    'C': _('entity creation'),
    'U': _('entity update'),
    'D': _('entity deletion'),
    'A': _('relation add'),
    'R': _('relation removal'),
    }


class NoSuchTransaction(RepositoryError):
    # Used by CubicWebException
    msg = _("there is no transaction #%s")

    def __init__(self, txuuid):
        super(NoSuchTransaction, self).__init__(txuuid)
        self.txuuid = txuuid

class Transaction(object):
    """an undoable transaction"""

    def __init__(self, cnx, uuid, time, ueid):
        self.cnx = cnx
        self.uuid = uuid
        self.datetime = time
        self.user_eid = ueid

    def _execute(self, *args, **kwargs):
        """execute a query using either the req or the cnx"""
        return self.cnx.execute(*args, **kwargs)


    def __repr__(self):
        return '<Transaction %s by %s on %s>' % (
            self.uuid, self.user_eid, self.datetime)

    def user(self):
        """return the user entity which has done the transaction,
        none if not found.
        """
        return self.cnx.find('CWUser', eid=self.user_eid).one()

    def actions_list(self, public=True):
        """return an ordered list of action effectued during that transaction

        if public is true, return only 'public' action, eg not ones triggered
        under the cover by hooks.
        """
        return self.cnx.transaction_actions(self.uuid, public)


class AbstractAction(object):

    def __init__(self, action, public, order):
        self.action = action
        self.public = public
        self.order = order

    @property
    def label(self):
        return ACTION_LABELS[self.action]

    @property
    def ertype(self):
        """ Return the entity or relation type this action is related to"""
        raise NotImplementedError(self)


class EntityAction(AbstractAction):

    def __init__(self, action, public, order, etype, eid, changes):
        super(EntityAction, self).__init__(action, public, order)
        self.etype = etype
        self.eid = eid
        self.changes = changes

    def __repr__(self):
        return '<%s: %s %s (%s)>' % (
            self.label, self.eid, self.changes,
            self.public and 'dbapi' or 'hook')

    @property
    def ertype(self):
        """ Return the entity or relation type this action is related to"""
        return self.etype


class RelationAction(AbstractAction):

    def __init__(self, action, public, order, rtype, eidfrom, eidto):
        super(RelationAction, self).__init__(action, public, order)
        self.rtype = rtype
        self.eid_from = eidfrom
        self.eid_to = eidto

    def __repr__(self):
        return '<%s: %s %s %s (%s)>' % (
            self.label, self.eid_from, self.rtype, self.eid_to,
            self.public and 'dbapi' or 'hook')

    @property
    def ertype(self):
        """ Return the entity or relation type this action is related to"""
        return self.rtype