# Copyright (C) 2021 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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 unittest

from time import sleep

from vyos.configsession import ConfigSession
from vyos.configsession import ConfigSessionError
from vyos import ConfigError
from vyos.util import cmd

save_config = '/tmp/vyos-smoketest-save'

# This class acts as shim between individual Smoketests developed for VyOS and
# the Python UnitTest framework. Before every test is loaded, we dump the current
# system configuration and reload it after the test - despite the test results.
#
# Using this approach we can not render a live system useless while running any
# kind of smoketest. In addition it adds debug capabilities like printing the
# command used to execute the test.
class VyOSUnitTestSHIM:
    class TestCase(unittest.TestCase):
        # if enabled in derived class, print out each and every set/del command
        # on the CLI. This is usefull to grap all the commands required to
        # trigger the certain failure condition.
        # Use "self.debug = True" in derived classes setUp() method
        debug = False

        @classmethod
        def setUpClass(cls):
            cls._session = ConfigSession(os.getpid())
            cls._session.save_config(save_config)
            pass

        @classmethod
        def tearDownClass(cls):
            # discard any pending changes which might caused a messed up config
            cls._session.discard()
            # ... and restore the initial state
            cls._session.migrate_and_load_config(save_config)

            try:
                cls._session.commit()
            except (ConfigError, ConfigSessionError):
                cls._session.discard()
                cls.fail(cls)

        def cli_set(self, config):
            if self.debug:
                print('set ' + ' '.join(config))
            self._session.set(config)

        def cli_delete(self, config):
            if self.debug:
                print('del ' + ' '.join(config))
            self._session.delete(config)

        def cli_commit(self):
            self._session.commit()

        def getFRRconfig(self, string, end='$', endsection='^!'):
            """ Retrieve current "running configuration" from FRR """
            command = f'vtysh -c "show run" | sed -n "/^{string}{end}/,/{endsection}/p"'

            count = 0
            tmp = ''
            while count < 10 and tmp == '':
                # Let FRR settle after a config change first before harassing it again
                sleep(1)
                tmp = cmd(command)
                count += 1

            if self.debug or tmp == '':
                import pprint
                print(f'\n\ncommand "{command}" returned:\n')
                pprint.pprint(tmp)
            return tmp