## $Id: objecthistory.py 7371 2011-12-18 10:42:19Z henrik $
##
## Copyright (C) 2011 Uli Fouquet & Henrik Bettermann
## This program 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 2 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 General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##
import grok
from datetime import datetime
from persistent.list import PersistentList
from zope.annotation.interfaces import IAnnotations
from waeup.sirp.interfaces import IObjectHistory, ISIRPObject
from waeup.sirp.utils.helpers import get_current_principal

class ObjectHistory(grok.Adapter):
    """A history for objects.

    For any object implementing `ISIRPObject` which is annotatable,
    we provide histories. A history for such an object can be obtained
    by adapting it to `IObjectHistory`.
    """
    grok.context(ISIRPObject)
    grok.implements(IObjectHistory)

    history_key = 'waeup.history'

    def __init__(self, context):
        from zope.security.proxy import removeSecurityProxy
        self.context = removeSecurityProxy(context)
        self._annotations = IAnnotations(self.context)

    def _getMessages(self):
        return self._annotations.get(self.history_key, PersistentList())

    @property
    def messages(self):
        """Get all messages as a persistent list of strings.
        """
        return self._getMessages()

    def addMessage(self, msg):
        """Add the message (history entry) in msg.

        Any message will be stored with a timestamp and the current
        user (principal).
        """
        msgs = self._getMessages()
        timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        user = get_current_principal()
        if user is None:
            user = 'system'
        elif user.id == 'zope.anybody':
            user = 'Anonymous'
        else:
            user = user.title
        msg = '%s - %s by %s' % (timestamp, msg, user)
        msgs.append(msg)
        self._annotations[self.history_key] = msgs
        return