#!/usr/bin/env python
#
#    PivotChroot.py: this file is part of the GRS suite
#    Copyright (C) 2015  Anthony G. Basile
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program 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 General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

import os
import shutil

from grs.Constants import CONST
from grs.Rotator import Rotator


class PivotChroot(Rotator):
    """ Move an inner chroot out to the new system portage configroot.  """

    def __init__(
            self, tmpdir=CONST.TMPDIR, portage_configroot=CONST.PORTAGE_CONFIGROOT,
            logfile=CONST.LOGFILE
    ):
        self.tmpdir = tmpdir
        self.portage_configroot = portage_configroot
        self.logfile = logfile


    def pivot(self, subchroot, _md):
        # If any directories are mounted, unmount them before pivoting.
        some_mounted, all_mounted = _md.are_mounted()
        if some_mounted:
            _md.umount_all()

        # Move the system's portage configroot out of the way to system.0,
        # then pivot the inner chroot to system.
        self.full_rotate(self.portage_configroot)
        inner_chroot = os.path.join('%s.0' % self.portage_configroot, subchroot)
        shutil.move(inner_chroot, os.path.join(self.tmpdir, 'system'))

        # Be conservative: only if all the directories were mounted on the old
        # system portage configroot to we remount on the newly pivoted root.
        if all_mounted:
            _md.mount_all()