#
# 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/>.
#

"""
Plinth views for basic system configuration
"""
from django.utils import translation
from django.utils.translation import ugettext as _
from django.template.response import TemplateResponse
from django.contrib import messages

from plinth.modules import config
from .forms import ConfigurationForm
from plinth.signals import pre_hostname_change, post_hostname_change
from plinth import actions
from plinth.signals import domain_added, domain_removed, domainname_change
from plinth.modules import firewall
from plinth.modules.names import SERVICES

import logging
import socket

LOGGER = logging.getLogger(__name__)


def get_hostname():
    """Return the hostname"""
    return socket.gethostname()


def get_language(request):
    """Return the current language setting"""
    # TODO: Store the language per user in kvstore,
    # taking care of setting language on login, and adapting kvstore when
    # renaming/deleting users

    # The information from the session is more accurate but not always present
    return request.session.get(translation.LANGUAGE_SESSION_KEY,
                               request.LANGUAGE_CODE)


def index(request):
    """Serve the configuration form"""
    status = get_status(request)

    if request.method == 'POST':
        form = ConfigurationForm(request.POST, initial=status,
                                 prefix='configuration')
        # pylint: disable-msg=E1101
        if form.is_valid():
            _apply_changes(request, status, form.cleaned_data)
            status = get_status(request)
            form = ConfigurationForm(initial=status,
                                     prefix='configuration')
    else:
        form = ConfigurationForm(initial=status, prefix='configuration')

    return TemplateResponse(request, 'config.html',
                            {'title': _('General Configuration'),
                             'form': form})


def get_status(request):
    """Return the current status"""
    return {'hostname': get_hostname(),
            'domainname': config.get_domainname(),
            'language': get_language(request)}


def _apply_changes(request, old_status, new_status):
    """Apply the form changes"""
    if old_status['hostname'] != new_status['hostname']:
        try:
            set_hostname(new_status['hostname'])
        except Exception as exception:
            messages.error(request, _('Error setting hostname: {exception}')
                           .format(exception=exception))
        else:
            messages.success(request, _('Hostname set'))

    if old_status['domainname'] != new_status['domainname']:
        try:
            set_domainname(new_status['domainname'])
        except Exception as exception:
            messages.error(request, _('Error setting domain name: {exception}')
                           .format(exception=exception))
        else:
            messages.success(request, _('Domain name set'))

    if old_status['language'] != new_status['language']:
        language = new_status['language']
        try:
            translation.activate(language)
            request.session[translation.LANGUAGE_SESSION_KEY] = language
        except Exception as exception:
            messages.error(request, _('Error setting language: {exception}')
                           .format(exception=exception))
        else:
            messages.success(request, _('Language changed'))


def set_hostname(hostname):
    """Sets machine hostname to hostname"""
    old_hostname = get_hostname()
    domainname = config.get_domainname()

    # Hostname should be ASCII. If it's unicode but passed our
    # valid_hostname check, convert to ASCII.
    hostname = str(hostname)

    pre_hostname_change.send_robust(sender='config',
                                    old_hostname=old_hostname,
                                    new_hostname=hostname)

    LOGGER.info('Changing hostname to - %s', hostname)
    actions.superuser_run('hostname-change', [hostname])

    post_hostname_change.send_robust(sender='config',
                                     old_hostname=old_hostname,
                                     new_hostname=hostname)

    LOGGER.info('Setting domain name after hostname change - %s', domainname)
    actions.superuser_run('domainname-change', [domainname])


def set_domainname(domainname):
    """Sets machine domain name to domainname"""
    old_domainname = config.get_domainname()

    # Domain name should be ASCII. If it's unicode, convert to ASCII.
    domainname = str(domainname)

    LOGGER.info('Changing domain name to - %s', domainname)
    actions.superuser_run('domainname-change', [domainname])

    domainname_change.send_robust(sender='config',
                                  old_domainname=old_domainname,
                                  new_domainname=domainname)

    # Update domain registered with Name Services module.
    domain_removed.send_robust(sender='config', domain_type='domainname')
    if domainname:
        try:
            domainname_services = firewall.get_enabled_services(
                zone='external')
        except actions.ActionError:
            # This happens when firewalld is not installed.
            # TODO: Are these services actually enabled?
            domainname_services = [service[0] for service in SERVICES]

        domain_added.send_robust(sender='config', domain_type='domainname',
                                 name=domainname, description=_('Domain Name'),
                                 services=domainname_services)