#
# 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/>.
#
"""
Views for snapshot module.
"""

import json

from django.contrib import messages
from django.shortcuts import redirect
from django.template.response import TemplateResponse
from django.urls import reverse
from django.utils.translation import ugettext as _

from plinth import actions
from plinth.errors import ActionError
from plinth.modules import snapshot as snapshot_module
from plinth.utils import yes_or_no

from . import is_timeline_snapshots_enabled
from .forms import SnapshotForm


def index(request):
    """Show snapshot list."""
    status = get_status()
    if request.method == 'POST':
        form = SnapshotForm(request.POST)
        if 'create' in request.POST:
            actions.superuser_run('snapshot', ['create'])
            messages.success(request, _('Created snapshot.'))
        if 'update' in request.POST and form.is_valid():
            update_configuration(request, status, form.cleaned_data)
            status = get_status()
            form = SnapshotForm(initial=status)
    else:
        form = SnapshotForm(initial=status)

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)

    return TemplateResponse(request, 'snapshot.html', {
        'title': snapshot_module.name,
        'description': snapshot_module.description,
        'snapshots': snapshots,
        'form': form
    })


def update_configuration(request, old_status, new_status):
    """Update configuration of snapshots."""
    try:
        key = 'enable_timeline_snapshots'
        if old_status[key] != new_status[key]:
            enable_timeline = yes_or_no(
                new_status['enable_timeline_snapshots'])
            actions.superuser_run(
                'snapshot',
                ['configure', 'TIMELINE_CREATE={}'.format(enable_timeline)])
            messages.success(request,
                             _('Timeline Snapshots configuration updated'))
    except ActionError as exception:
        messages.error(request,
                       _('Action error: {0} [{1}] [{2}]').format(
                           exception.args[0], exception.args[1],
                           exception.args[2]))


def delete(request, number):
    """Show confirmation to delete a snapshot."""
    if request.method == 'POST':
        actions.superuser_run('snapshot', ['delete', number])
        messages.success(
            request, _('Deleted snapshot #{number}.').format(number=number))
        return redirect(reverse('snapshot:index'))

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)
    snapshot = next(s for s in snapshots if s['number'] == number)

    return TemplateResponse(request, 'snapshot_delete.html', {
        'title': _('Delete Snapshot'),
        'snapshot': snapshot
    })


def delete_all(request):
    """Show confirmation to delete all snapshots."""
    if request.method == 'POST':
        actions.superuser_run('snapshot', ['delete-all'])
        messages.success(request, _('Deleted all snapshots.'))
        return redirect(reverse('snapshot:index'))

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)

    return TemplateResponse(request, 'snapshot_delete_all.html', {
        'title': _('Delete Snapshots'),
        'snapshots': snapshots[1:]
    })


def rollback(request, number):
    """Show confirmation to rollback to a snapshot."""
    if request.method == 'POST':
        actions.superuser_run('snapshot', ['rollback', number])
        messages.success(
            request,
            _('Rolled back to snapshot #{number}.').format(number=number))
        messages.warning(
            request,
            _('The system must be restarted to complete the rollback.'))
        return redirect(reverse('power:restart'))

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)

    snapshot = None
    for current_snapshot in snapshots:
        if current_snapshot['number'] == number:
            snapshot = current_snapshot

    return TemplateResponse(request, 'snapshot_rollback.html', {
        'title': _('Rollback to Snapshot'),
        'snapshot': snapshot
    })


def get_status():
    """Get current status of snapshot configuration."""
    return {'enable_timeline_snapshots': is_timeline_snapshots_enabled()}