#!/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 'distbuild-trove-nfsboot' write extension'''

import logging
import os
import sys

import writeexts


class DistbuildTroveNFSBootCheckExtension(writeexts.WriteExtension):

    nfsboot_root = '/srv/nfsboot'
    remote_user = 'root'

    required_vars = [
        'DISTBUILD_CONTROLLER',
        'DISTBUILD_GIT_SERVER',
        'DISTBUILD_SHARED_ARTIFACT_CACHE',
        'DISTBUILD_TROVE_ID',
        'DISTBUILD_WORKERS',
        'DISTBUILD_WORKER_SSH_KEY',
    ]

    def system_path(self, system_name, version_label=None):
        if version_label:
            return os.path.join(self.nfsboot_root, system_name, 'systems',
                                version_label, 'run')
        else:
            return os.path.join(self.nfsboot_root, system_name)

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

        nfs_host = args[0]
        nfs_netloc = '%s@%s' % (self.remote_user, nfs_host)

        version_label = os.getenv('VERSION_LABEL', 'factory')

        missing_vars = [var for var in self.required_vars
                        if not var in os.environ]
        if missing_vars:
            raise writeexts.ExtensionError(
                'Please set: %s' % ', '.join(missing_vars))

        controllers = os.getenv('DISTBUILD_CONTROLLER').split()
        workers = os.getenv('DISTBUILD_WORKERS').split()

        if len(controllers) != 1:
            raise writeexts.ExtensionError(
                'Please specify exactly one controller.')

        if len(workers) == 0:
            raise writeexts.ExtensionError(
                'Please specify at least one worker.')

        upgrade = self.get_environment_boolean('UPGRADE')

        self.check_good_server(nfs_netloc)

        system_names = set(controllers + workers)
        for system_name in system_names:
            if upgrade:
                self.check_upgradeable(nfs_netloc, system_name, version_label)
            else:
                system_path = self.system_path(system_name)

                if self.remote_directory_exists(nfs_netloc, system_path):
                    if self.get_environment_boolean('OVERWRITE') == False:
                        raise writeexts.ExtensionError(
                            'System %s already exists at %s:%s. Try `morph '
                            'upgrade` instead of `morph deploy`.' % (
                            system_name, nfs_netloc, system_path))

    def check_good_server(self, netloc):
        # FIXME: assumes root
        self.check_ssh_connectivity(netloc.split('@')[-1])

        # Is an NFS server
        try:
            writeexts.ssh_runcmd(
                netloc, ['test', '-e', '/etc/exports'])
        except writeexts.ExtensionError:
            raise writeexts.ExtensionError('server %s is not an nfs server'
                                           % netloc)
        try:
            writeexts.ssh_runcmd(
                netloc, ['systemctl', 'is-enabled', 'nfs-server.service'])

        except writeexts.ExtensionError:
            raise writeexts.ExtensionError('server %s does not control its '
                                           'nfs server by systemd' % netloc)

        # TFTP server exports /srv/nfsboot/tftp
        tftp_root = os.path.join(self.nfsboot_root, 'tftp')
        try:
            writeexts.ssh_runcmd(
                netloc, ['test' , '-d', tftp_root])
        except writeexts.ExtensionError:
            raise writeexts.ExtensionError('server %s does not export %s' %
                                           (netloc, tftp_root))

    def check_upgradeable(self, nfs_netloc, system_name, version_label):
        '''Check that there is already a version of the system present.

        Distbuild nodes are stateless, so an upgrade is actually pretty much
        the same as an initial deployment. This test is just a sanity check.

        '''
        system_path = self.system_path(system_name)
        system_version_path = self.system_path(system_name, version_label)

        if not self.remote_directory_exists(nfs_netloc, system_path):
            raise writeexts.ExtensionError(
                'System %s not found at %s:%s, cannot deploy an upgrade.' % (
                system_name, nfs_netloc, system_path))

        if self.remote_directory_exists(nfs_netloc, system_version_path):
            if self.get_environment_boolean('OVERWRITE'):
                pass
            else:
                raise writeexts.ExtensionError(
                    'System %s version %s already exists at %s:%s.' % (
                    system_name, version_label, nfs_netloc,
                    system_version_path))

    def remote_directory_exists(self, nfs_netloc, path):
        try:
            writeexts.ssh_runcmd(nfs_netloc, ['test', '-d', path])
        except writeexts.ExtensionError as e:
            logging.debug('SSH exception: %s', e)
            return False

        return True


DistbuildTroveNFSBootCheckExtension().run()