#
#  Copyright (c) 2004 Helmut Merz helmutm@cy55.de
#
#  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
#

"""
Definition of the ResourceConstraint class.

$Id$
"""

from zope.interface import implements

from interfaces import IResourceConstraint


class ResourceConstraint(object):

    implements(IResourceConstraint)

    explanation = u''
    constraintType = 'select'
    referenceType = 'explicit'
    referenceKey = None


    def __init__(self, task):
        self.referenceValues = []
        self._task = task


    def isResourceAllowed(self, resource):
        if self.referenceType == 'parent':
            for r in self.referenceValues:
                m = getattr(r, self.referenceKey)
                if resource in m():
                    return True
            return False
        elif self.referenceType == 'explicit':
            return resource in self.referenceValues
        else:
            return False


    def getAllowedResources(self, candidates=None):
        if self.referenceType == 'parent':
            result = []
            for r in self.referenceValues:
                m = getattr(r, self.referenceKey)
                result.extend(m())
            return tuple(result)
        elif self.referenceType == 'explicit':
            return tuple(self.referenceValues)
        else:
            return ()