# SPDX-License-Identifier: AGPL-3.0-or-later
"""
Views for snapshot module.
"""

import json
import urllib.parse

from django.contrib import messages
from django.http import HttpResponseRedirect
from django.shortcuts import redirect
from django.template.response import TemplateResponse
from django.urls import reverse, reverse_lazy
from django.utils.translation import gettext as _
from django.utils.translation import gettext_lazy

from plinth import actions
from plinth import app as app_module
from plinth.errors import ActionError
from plinth.modules import snapshot as snapshot_module
from plinth.modules import storage
from plinth.views import AppView

from . import get_configuration
from .forms import SnapshotForm

# i18n for snapshot descriptions
SNAPSHOT_DESCRIPTION_STRINGS = {
    'manually created': gettext_lazy('manually created'),
    'timeline': gettext_lazy('timeline'),
    'apt': gettext_lazy('apt'),
}

subsubmenu = [
    {
        'url': reverse_lazy('snapshot:index'),
        'text': gettext_lazy('Configure')
    },
    {
        'url': reverse_lazy('snapshot:manage'),
        'text': gettext_lazy('Manage Snapshots')
    },
]


def not_supported_view(request):
    """Show that snapshots are not supported on the system."""
    app = app_module.App.get('snapshot')
    template_data = {
        'app_info': app.info,
        'title': app.info.name,
        'fs_type': storage.get_filesystem_type(),
        'fs_types_supported': snapshot_module.fs_types_supported,
    }
    return TemplateResponse(request, 'snapshot_not_supported.html',
                            template_data)


class SnapshotAppView(AppView):
    """Show snapshot app main page."""

    app_id = 'snapshot'
    template_name = 'snapshot.html'
    form_class = SnapshotForm

    def get_initial(self):
        """Return the values to fill in the form."""
        initial = super().get_initial()
        initial.update(get_configuration())
        return initial

    def get_context_data(self, *args, **kwargs):
        """Add additional context data for template."""
        context = super().get_context_data(*args, **kwargs)
        context['subsubmenu'] = subsubmenu
        return context

    def form_valid(self, form):
        """Apply the changes submitted in the form."""
        if 'update' in self.request.POST:
            update_configuration(self.request, form.initial, form.cleaned_data)

        return super().form_valid(form)


def manage(request):
    """Show snapshot list."""
    if not snapshot_module.is_supported():
        return not_supported_view(request)

    if request.method == 'POST':
        if 'create' in request.POST:
            actions.superuser_run('snapshot', ['create'])
            messages.success(request, _('Created snapshot.'))
        if 'delete_selected' in request.POST:
            to_delete = request.POST.getlist('snapshot_list')
            if to_delete:
                # Send values using GET params instead of session variables so
                # that snapshots can be deleted even when disk is full.
                params = [('snapshots', number) for number in to_delete]
                params = urllib.parse.urlencode(params)
                url = reverse('snapshot:delete-selected')
                return HttpResponseRedirect(f'{url}?{params}')

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)
    has_deletable_snapshots = any([
        snapshot for snapshot in snapshots
        if not snapshot['is_default'] and not snapshot['is_active']
    ])

    app = app_module.App.get('snapshot')
    return TemplateResponse(
        request, 'snapshot_manage.html', {
            'title': app.info.name,
            'app_info': app.info,
            'snapshots': snapshots,
            'has_deletable_snapshots': has_deletable_snapshots,
            'subsubmenu': subsubmenu,
        })


def update_configuration(request, old_status, new_status):
    """Update configuration of snapshots."""

    def make_config(args):
        key, stamp = args[0], args[1]
        if old_status[key] != new_status[key]:
            if 'limit' in key:
                return stamp.format('0-{}'.format(new_status[key]))

            return stamp.format(new_status[key])

        return None

    config = filter(
        None,
        map(make_config, [
            ('enable_timeline_snapshots', 'TIMELINE_CREATE={}'),
            ('hourly_limit', 'TIMELINE_LIMIT_HOURLY={}'),
            ('daily_limit', 'TIMELINE_LIMIT_DAILY={}'),
            ('weekly_limit', 'TIMELINE_LIMIT_WEEKLY={}'),
            ('monthly_limit', 'TIMELINE_LIMIT_MONTHLY={}'),
            ('yearly_limit', 'TIMELINE_LIMIT_YEARLY={}'),
            ('free_space', 'FREE_LIMIT={}'),
        ]))

    if old_status['enable_software_snapshots'] != new_status[
            'enable_software_snapshots']:
        if new_status['enable_software_snapshots'] == 'yes':
            actions.superuser_run('snapshot', ['disable-apt-snapshot', 'no'])
        else:
            actions.superuser_run('snapshot', ['disable-apt-snapshot', 'yes'])

    try:
        actions.superuser_run('snapshot', ['set-config', " ".join(config)])

        messages.success(request, _('Storage 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_selected(request):
    """View to delete selected snapshots."""
    if request.method == 'POST':
        to_delete = set(request.POST.getlist('snapshots'))
    else:
        to_delete = set(request.GET.getlist('snapshots'))

    if not to_delete:
        return redirect(reverse('snapshot:manage'))

    output = actions.superuser_run('snapshot', ['list'])
    snapshots = json.loads(output)
    snapshots_to_delete = [
        snapshot for snapshot in snapshots if snapshot['number'] in to_delete
        and not snapshot['is_active'] and not snapshot['is_default']
    ]

    if request.method == 'POST':
        try:
            for snapshot in snapshots_to_delete:
                actions.superuser_run('snapshot',
                                      ['delete', snapshot['number']])

            messages.success(request, _('Deleted selected snapshots'))
        except ActionError as exception:
            if 'Config is in use.' in exception.args[2]:
                messages.error(
                    request,
                    _('Snapshot is currently in use. '
                      'Please try again later.'))
            else:
                raise

        return redirect(reverse('snapshot:manage'))

    return TemplateResponse(request, 'snapshot_delete_selected.html', {
        'title': _('Delete Snapshots'),
        'snapshots': snapshots_to_delete
    })


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
    })