##############################################################################
#
# Copyright (c) 2004 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.
#
##############################################################################
"""Security related configuration fields.
"""
__docformat__ = 'restructuredtext'

from zope.configuration.fields import GlobalObject
from zope.configuration.fields import MessageID
from zope.interface import Interface
from zope.interface import implementer
from zope.schema import Id
from zope.schema.interfaces import IFromUnicode

from zope.security.permission import checkPermission
from zope.security.management import setSecurityPolicy
from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public

@implementer(IFromUnicode)
class Permission(Id):
    r"""This field describes a permission.
    """

    def fromUnicode(self, u):
        u = super(Permission, self).fromUnicode(u)

        map = getattr(self.context, 'permission_mapping', {})
        return map.get(u, u)

    def _validate(self, value):
        super(Permission, self)._validate(value)

        if value != zope_Public:
            self.context.action(
                discriminator=None,
                callable=checkPermission,
                args=(None, value),

                # Delay execution till end. This is an
                # optimization. We don't want to intersperse utility
                # lookup, done when checking permissions, with utility
                # definitions. Utility lookup is expensive after
                # utility definition, as extensive caches have to be
                # rebuilt.
                order=9999999,
            )


class ISecurityPolicyDirective(Interface):
    """Defines the security policy that will be used for Zope."""

    component = GlobalObject(
        title=u"Component",
        description=u"Pointer to the object that will handle the security.",
        required=True)

def securityPolicy(_context, component):
    _context.action(
        discriminator='defaultPolicy',
        callable=setSecurityPolicy,
        args=(component,)
    )

class IPermissionDirective(Interface):
    """Define a new security object."""

    id = Id(
        title=u"ID",
        description=u"ID as which this object will be known and used.",
        required=True)

    title = MessageID(
        title=u"Title",
        description=u"Provides a title for the object.",
        required=True)

    description = MessageID(
        title=u"Description",
        description=u"Provides a description for the object.",
        required=False)

def permission(_context, id, title, description=u''):
    from zope.security.interfaces import IPermission
    from zope.security.permission import Permission
    from zope.component.zcml import utility
    permission = Permission(id, title, description)
    utility(_context, IPermission, permission, name=id)

class IRedefinePermission(Interface):
    """Define a permission to replace another permission."""

    from_ = Permission(
        title=u"Original permission",
        description=u"Original permission ID to redefine.",
        required=True)

    to = Permission(
        title=u"Substituted permission",
        description=u"Substituted permission ID.",
        required=True)

def redefinePermission(_context, from_, to):
    _context = _context.context

    # check if context has any permission mappings yet
    if not hasattr(_context, 'permission_mapping'):
        _context.permission_mapping = {}

    _context.permission_mapping[from_] = to
