"""some utilities to define schema permissions

:organization: Logilab

:copyright: 2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

"""

__docformat__ = "restructuredtext en"

from rql.utils import quote

# permissions for "meta" entity type (readable by anyone, can only be

# added/deleted by managers)

# permissions for "meta" relation type (readable by anyone, can only be

# added/deleted by managers)

# permissions for relation type that should only set by hooks using unsafe

# execute, readable by anyone

def _perm(names):

    if isinstance(names, (list, tuple)):

        if len(names) == 1:

            names = quote(names[0])

        else:

            names = 'IN (%s)' % (','.join(quote(name) for name in names))

    else:

        names = quote(names)

    #return u' require_permission P, P name %s, U in_group G, P require_group G' % names

    return u' require_permission P, P name %s, U has_group_permission P' % names

def xperm(*names):

    return 'X' + _perm(names)

def xexpr(*names):

    return ERQLExpression(xperm(*names))

def xrexpr(relation, *names):

    return ERQLExpression('X %s Y, Y %s' % (relation, _perm(names)))

def xorexpr(relation, etype, *names):

    return ERQLExpression('Y %s X, X is %s, Y %s' % (relation, etype, _perm(names)))

def sexpr(*names):

    return RRQLExpression('S' + _perm(names), 'S')

def restricted_sexpr(restriction, *names):

    rql = '%s, %s' % (restriction, 'S' + _perm(names))

    return RRQLExpression(rql, 'S')

def restricted_oexpr(restriction, *names):

    rql = '%s, %s' % (restriction, 'O' + _perm(names))

    return RRQLExpression(rql, 'O')

def oexpr(*names):

    return RRQLExpression('O' + _perm(names), 'O')

# def supdate_perm():

#     return RRQLExpression('U has_update_permission S', 'S')

# def oupdate_perm():

#     return RRQLExpression('U has_update_permission O', 'O')

def relxperm(rel, role, *names):

    assert role in ('subject', 'object')

    if role == 'subject':

        zxrel = ', X %s Z' % rel

    else:

        zxrel = ', Z %s X' % rel

    return 'Z' + _perm(names) + zxrel

def relxexpr(rel, role, *names):

    return ERQLExpression(relxperm(rel, role, *names))