#!/usr/bin/python
# Copyright (C) 2014-2015  Codethink Limited
#
# 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; version 2 of the License.
#
# 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/>.

'''Preparatory checks for Morph 'openstack' write extension'''

import os
import urlparse

import keystoneclient

import writeexts


class OpenStackCheckExtension(writeexts.WriteExtension):

    def process_args(self, args):
        if len(args) != 1:
            raise writeexts.ExtensionError(
                'Wrong number of command line args')

        self.require_btrfs_in_deployment_host_kernel()

        upgrade = self.get_environment_boolean('UPGRADE')
        if upgrade:
            raise writeexts.ExtensionError(
                'Use the `ssh-rsync` write extension to deploy upgrades to an '
                'existing remote system.')

        location = args[0]
        self.check_location(location)

        self.check_imagename()
        self.check_openstack_parameters(self._get_auth_parameters(location))

    def _get_auth_parameters(self, location):
        '''Check the environment variables needed and returns all.

        The environment variables are described in the class documentation.
        '''

        auth_keys = {'OPENSTACK_USER': 'username',
                     'OPENSTACK_TENANT': 'tenant_name',
                     'OPENSTACK_PASSWORD': 'password'}

        for key in auth_keys:
            if os.environ.get(key, '') == '':
                raise writeexts.ExtensionError(key + ' was not given')

        auth_params = {auth_keys[key]: os.environ[key] for key in auth_keys}
        auth_params['auth_url'] = location
        return auth_params

    def check_imagename(self):
        if os.environ.get('OPENSTACK_IMAGENAME', '') == '':
            raise writeexts.ExtensionError(
                'OPENSTACK_IMAGENAME was not given')

    def check_location(self, location):
        x = urlparse.urlparse(location)
        if x.scheme not in ['http', 'https']:
            raise writeexts.ExtensionError(
                'URL schema must be http or https in %s' % location)
        if (x.path != '/v2.0' and x.path != '/v2.0/'):
            raise writeexts.ExtensionError(
                'API version must be v2.0 in %s' % location)

    def check_openstack_parameters(self, auth_params):
        ''' Check that we can connect to and authenticate with openstack '''

        self.status(msg='Checking OpenStack credentials...')

        try:
            keystoneclient.v2_0.Client(**auth_params)
        except keystoneclient.exceptions.Unauthorized:
            errmsg = ('Failed to authenticate with OpenStack '
                      '(are your credentials correct?)')
            raise writeexts.ExtensionError(errmsg)


OpenStackCheckExtension().run()