# Copyright 2014, Tresys Technology, LLC
#
# This file is part of SETools.
#
# SETools is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 2.1 of
# the License, or (at your option) any later version.
#
# SETools 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with SETools.  If not, see
# <http://www.gnu.org/licenses/>.
#
from . import exception
from . import qpol
from . import role
from . import mls
from . import symbol


def user_factory(qpol_policy, name):
    """Factory function for creating User objects."""

    if isinstance(name, User):
        assert name.policy == qpol_policy
        return name
    elif isinstance(name, qpol.qpol_user_t):
        return User(qpol_policy, name)

    try:
        return User(qpol_policy, qpol.qpol_user_t(qpol_policy, str(name)))
    except ValueError:
        raise exception.InvalidUser("{0} is not a valid user".format(name))


class User(symbol.PolicySymbol):

    """A user."""

    @property
    def roles(self):
        """The user's set of roles."""

        roleset = set()

        for role_ in self.qpol_symbol.role_iter(self.policy):
            item = role.role_factory(self.policy, role_)

            # object_r is implicitly added to all roles by the compiler.
            # technically it is incorrect to skip it, but policy writers
            # and analysts don't expect to see it in results, and it
            # will confuse, especially for role set equality user queries.
            if item != "object_r":
                roleset.add(item)

        return roleset

    @property
    def mls_level(self):
        """The user's default MLS level."""
        return mls.level_factory(self.policy, self.qpol_symbol.dfltlevel(self.policy))

    @property
    def mls_range(self):
        """The user's MLS range."""
        return mls.range_factory(self.policy, self.qpol_symbol.range(self.policy))

    def statement(self):
        roles = list(str(r) for r in self.roles)
        stmt = "user {0} roles ".format(self)
        if len(roles) > 1:
            stmt += "{{ {0} }}".format(' '.join(roles))
        else:
            stmt += roles[0]

        try:
            stmt += " level {0.mls_level} range {0.mls_range};".format(self)
        except exception.MLSDisabled:
            stmt += ";"

        return stmt