#!/usr/bin/python3
# -*- mode: python -*-
#
# This file is part of Plinth.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

"""
Configuration helper for the ejabberd service
"""

import argparse
import os
import shutil
import socket
import subprocess
import re

from plinth import action_utils


JWCHAT_CONFIG = '/etc/jwchat/config.js'
EJABBERD_CONFIG = '/etc/ejabberd/ejabberd.yml'
EJABBERD_BACKUP = '/var/log/ejabberd/ejabberd.dump'
EJABBERD_BACKUP_NEW = '/var/log/ejabberd/ejabberd_new.dump'


def parse_arguments():
    """Return parsed command line arguments as dictionary"""
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(dest='subcommand', help='Sub command')

    # Preseed debconf values before packages are installed.
    pre_install = subparsers.add_parser(
        'pre-install',
        help='Preseed debconf values before packages are installed.')
    pre_install.add_argument(
        '--domainname',
        help='The domain name that will be used by the XMPP service.')

    # Setup jwchat apache conf
    subparsers.add_parser('setup', help='Setup jwchat apache conf')

    subparsers.add_parser('enable', help='Enable XMPP service')
    subparsers.add_parser('disable', help='Disable XMPP service')

    # Prepare ejabberd for hostname change
    pre_hostname_change = subparsers.add_parser(
        'pre-change-hostname',
        help='Prepare ejabberd for nodename change')
    pre_hostname_change.add_argument('--old-hostname',
                                     help='Previous hostname')
    pre_hostname_change.add_argument('--new-hostname',
                                     help='New hostname')

    # Update ejabberd nodename
    hostname_change = subparsers.add_parser('change-hostname',
                                            help='Update ejabberd nodename')
    hostname_change.add_argument('--old-hostname',
                                 help='Previous hostname')
    hostname_change.add_argument('--new-hostname',
                                 help='New hostname')

    # Update ejabberd and jwchat with new domainname
    domainname_change = subparsers.add_parser(
        'change-domainname',
        help='Update ejabberd and jwchat with new domainname')
    domainname_change.add_argument('--domainname', help='New domainname')

    return parser.parse_args()


def subcommand_pre_install(arguments):
    """Preseed debconf values before packages are installed."""
    domainname = arguments.domainname
    if not domainname:
        # If new domainname is blank, use hostname instead.
        domainname = socket.gethostname()

    subprocess.check_output(
        ['debconf-set-selections'],
        input=b'ejabberd ejabberd/hostname string ' + domainname.encode())
    subprocess.check_output(
        ['debconf-set-selections'],
        input=b'jwchat jwchat/ApacheServerName string ' + domainname.encode())


def subcommand_setup(_):
    """Enabled LDAP authentication and setup jwchat apache conf"""
    with open(EJABBERD_CONFIG, 'r') as conffile:
        lines = conffile.readlines()

    with open(EJABBERD_CONFIG, 'w') as conffile:
        for line in lines:
            if re.match(r'^\s*tls:\s+true', line):
                conffile.write('    tls: false\n')
            elif 'auth_method: internal' in line:
                conffile.write('## ' + line)
            elif '## auth_method: ldap' in line:
                conffile.write('auth_method: ldap\n')
            elif '## ldap_servers:' in line:
                conffile.write('ldap_servers:\n')
                conffile.write('  - "localhost"\n')
            elif '## ldap_base:' in line:
                conffile.write('ldap_base: "ou=users,dc=thisbox"\n')
            else:
                conffile.write(line)

    try:
        subprocess.check_output(['ejabberdctl', 'restart'])
    except subprocess.CalledProcessError as err:
        print('Failed to restart ejabberd with new configuration: %s', err)

    with action_utils.WebserverChange() as webserver_change:
        webserver_change.disable('jwchat', kind='site')
        webserver_change.enable('jwchat-plinth')


def subcommand_enable(_):
    """Enable XMPP service"""
    action_utils.service_enable('ejabberd')
    action_utils.webserver_enable('jwchat-plinth')


def subcommand_disable(_):
    """Disable XMPP service"""
    action_utils.webserver_disable('jwchat-plinth')
    action_utils.service_disable('ejabberd')


def subcommand_pre_change_hostname(arguments):
    """Prepare ejabberd for hostname change"""
    if not shutil.which('ejabberdctl'):
        print('ejabberdctl not found. Is ejabberd installed?')
        return

    old_hostname = arguments.old_hostname
    new_hostname = arguments.new_hostname

    subprocess.call(['ejabberdctl', 'backup', EJABBERD_BACKUP])
    try:
        subprocess.check_output(['ejabberdctl', 'mnesia-change-nodename',
                                 'ejabberd@' + old_hostname,
                                 'ejabberd@' + new_hostname,
                                 EJABBERD_BACKUP, EJABBERD_BACKUP_NEW])
        os.remove(EJABBERD_BACKUP)
    except subprocess.CalledProcessError as err:
        print('Failed to change hostname in ejabberd backup database: %s', err)


def subcommand_change_hostname(arguments):
    """Update ejabberd and jwchat with new hostname"""
    if not shutil.which('ejabberdctl'):
        print('ejabberdctl not found. Is ejabberd installed?')
        return

    action_utils.service_stop('ejabberd')
    subprocess.call(['pkill', '-u', 'ejabberd'])

    # Make sure there aren't files in the Mnesia spool dir
    os.makedirs('/var/lib/ejabberd/oldfiles', exist_ok=True)
    subprocess.call('mv /var/lib/ejabberd/*.* /var/lib/ejabberd/oldfiles/',
                    shell=True)

    action_utils.service_start('ejabberd')

    # restore backup database
    if os.path.exists(EJABBERD_BACKUP_NEW):
        try:
            subprocess.check_output(['ejabberdctl',
                                     'restore',
                                     EJABBERD_BACKUP_NEW])
            os.remove(EJABBERD_BACKUP_NEW)
        except subprocess.CalledProcessError as err:
            print('Failed to restore ejabberd backup database: %s', err)
    else:
        print('Could not load ejabberd backup database: %s not found'
              % EJABBERD_BACKUP_NEW)


def subcommand_change_domainname(arguments):
    """Update ejabberd and jwchat with new domainname"""
    if not shutil.which('ejabberdctl'):
        print('ejabberdctl not found. Is ejabberd installed?')
        return

    domainname = arguments.domainname
    if not domainname:
        # If new domainname is blank, use hostname instead.
        domainname = socket.gethostname()

    # update jwchat's sitename, if it's installed
    if os.path.exists(JWCHAT_CONFIG):
        with open(JWCHAT_CONFIG, 'r') as conffile:
            lines = conffile.readlines()
        with open(JWCHAT_CONFIG, 'w') as conffile:
            for line in lines:
                if re.match(r'\s*var\s+SITENAME', line):
                    conffile.write('var SITENAME = "' + domainname + '";\n')
                else:
                    conffile.write(line)
    else:
        print('Skipping configuring jwchat sitename: %s not found',
              JWCHAT_CONFIG)

    action_utils.service_stop('ejabberd')
    subprocess.call(['pkill', '-u', 'ejabberd'])

    # Add updated domainname to ejabberd hosts list.
    with open(EJABBERD_CONFIG, 'r') as conffile:
        lines = conffile.readlines()
    with open(EJABBERD_CONFIG, 'w') as conffile:
        in_hosts = False
        for line in lines:
            if in_hosts:
                if re.match(r'\s*-\s*', line):
                    continue

                in_hosts = False

            conffile.write(line)
            if re.match(r'\s*hosts:', line):
                in_hosts = True
                conffile.write('  - "' + domainname + '"\n')

    action_utils.service_start('ejabberd')


def main():
    """Parse arguments and perform all duties"""
    arguments = parse_arguments()

    subcommand = arguments.subcommand.replace('-', '_')
    subcommand_method = globals()['subcommand_' + subcommand]
    subcommand_method(arguments)


if __name__ == '__main__':
    main()
