##############################################################################
#
# Copyright (c) 2004-2011 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""
Testing support code.

This module provides some helper/stub objects for setting up interactions.
"""
import contextlib

import zope.security.management
from zope import component
from zope import interface
from zope.security import interfaces
from zope.security.interfaces import PUBLIC_PERMISSION_NAME
from zope.security.permission import Permission


@interface.implementer(interfaces.IPrincipal)
class Principal:
    """
    A trivial implementation of :class:`zope.security.interfaces.IPrincipal`.
    """

    def __init__(self, id, title=None, description='', groups=None):
        self.id = id
        self.title = title or id
        self.description = description
        if groups is not None:
            self.groups = groups
            interface.directlyProvides(self, interfaces.IGroupAwarePrincipal)


@interface.implementer(interfaces.IParticipation)
class Participation:
    """
    A trivial implementation of
    :class:`zope.security.interfaces.IParticipation`.
    """

    def __init__(self, principal):
        self.principal = principal
        self.interaction = None


def addCheckerPublic():
    """
    Add the CheckerPublic permission as :data:`zope.Public
    <zope.security.interfaces.PUBLIC_PERMISSION_NAME>`.
    """

    perm = Permission(
        PUBLIC_PERMISSION_NAME,
        'Public',
        """Special permission used for resources that are always public

        The public permission is effectively an optimization, sine
        it allows security computation to be bypassed.
        """
    )
    gsm = component.getGlobalSiteManager()
    gsm.registerUtility(perm, interfaces.IPermission, perm.id)

    return perm


def create_interaction(principal_id, **kw):
    """
    Create a new interaction for the given principal ID, make it the
    :func:`current interaction
    <zope.security.management.newInteraction>`, and return the
    :class:`Principal` object.
    """
    principal = Principal(principal_id, **kw)
    participation = Participation(principal)
    zope.security.management.newInteraction(participation)
    return principal


@contextlib.contextmanager
def interaction(principal_id, **kw):
    """
    A context manager for running an interaction for the given
    principal ID.
    """
    if zope.security.management.queryInteraction():
        # There already is an interaction. Great. Leave it alone.
        yield
    else:
        principal = create_interaction(principal_id, **kw)
        try:
            yield principal
        finally:
            zope.security.management.endInteraction()