from __future__ import absolute_import

import rules

# Predicates


@rules.predicate
def is_book_author(user, book):
    if not book:
        return False
    return book.author == user


@rules.predicate
def is_boss(user):
    return user.is_superuser


is_editor = rules.is_group_member("editors")

# Rules

rules.add_rule("change_book", is_book_author | is_editor)
rules.add_rule("delete_book", is_book_author)
rules.add_rule("create_book", is_boss)

# Permissions

rules.add_perm("testapp.change_book", is_book_author | is_editor)
rules.add_perm("testapp.delete_book", is_book_author)