# Copyright 2013 Hewlett-Packard Development Company, L.P.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

from django.contrib import messages
from django.core.paginator import EmptyPage
from django.core.paginator import Paginator
from django.urls import reverse
from django.urls import reverse_lazy
from django.utils.translation import ugettext as _  # noqa

from horizon import exceptions
from horizon import forms
from horizon import tables
from horizon.utils import functions as utils

from monitoring import api
from monitoring.notifications import constants
from monitoring.notifications import forms as notification_forms
from monitoring.notifications import tables as notification_tables

from openstack_dashboard import policy

PREV_PAGE_LIMIT = 100


class IndexView(tables.DataTableView):
    table_class = notification_tables.NotificationsTable
    template_name = constants.TEMPLATE_PREFIX + 'index.html'

    def dispatch(self, *args, **kwargs):
        return super(IndexView, self).dispatch(*args, **kwargs)

    def get_data(self):
        page_offset = self.request.GET.get('page_offset')
        results = []
        if page_offset is None:
            page_offset = 0
        limit = utils.get_page_size(self.request)
        try:
            results = api.monitor.notification_list(self.request, page_offset, limit)
            paginator = Paginator(results, limit)
            results = paginator.page(1)
        except EmptyPage:
            results = paginator.page(paginator.num_pages)
        except Exception:
            messages.error(self.request, _("Could not retrieve notifications"))
        return results

    def get_context_data(self, **kwargs):
        if not policy.check((('monitoring', 'monitoring:monitoring'), ), self.request):
            raise exceptions.NotAuthorized()
        context = super(IndexView, self).get_context_data(**kwargs)
        contacts = []
        results = []
        num_results = 0
        prev_page_stack = []
        page_offset = self.request.GET.get('page_offset')

        if 'prev_page_stack' in self.request.session:
            prev_page_stack = self.request.session['prev_page_stack']

        if page_offset is None:
            page_offset = 0
            prev_page_stack = []
        else:
            page_offset = int(page_offset)

        limit = utils.get_page_size(self.request)
        try:
            # To judge whether there is next page, get LIMIT + 1
            results = api.monitor.notification_list(self.request, page_offset,
                                                    limit + 1)
            num_results = len(results)
            paginator = Paginator(results, limit)
            contacts = paginator.page(1)
        except EmptyPage:
            contacts = paginator.page(paginator.num_pages)
        except Exception:
            messages.error(self.request, _("Could not retrieve notifications"))
            return context

        context["contacts"] = contacts

        if num_results < limit + 1:
            context["page_offset"] = None
        else:
            context["page_offset"] = page_offset + limit

        if page_offset in prev_page_stack:
            index = prev_page_stack.index(page_offset)
            prev_page_stack = prev_page_stack[0:index]

        prev_page_offset = prev_page_stack[-1] if prev_page_stack else None
        if prev_page_offset is not None:
            context["prev_page_offset"] = prev_page_offset

        if len(prev_page_stack) > PREV_PAGE_LIMIT:
            del prev_page_stack[0]
        prev_page_stack.append(page_offset)
        self.request.session['prev_page_stack'] = prev_page_stack

        return context


class NotificationCreateView(forms.ModalFormView):
    form_class = notification_forms.CreateMethodForm
    template_name = constants.TEMPLATE_PREFIX + 'create.html'
    success_url = reverse_lazy(constants.URL_PREFIX + 'index')

    def get_context_data(self, **kwargs):
        if not policy.check((('monitoring', 'monitoring:monitoring'), ), self.request):
            raise exceptions.NotAuthorized()
        context = super(NotificationCreateView, self). \
            get_context_data(**kwargs)
        context["cancel_url"] = self.get_success_url()
        action = constants.URL_PREFIX + 'notification_create'
        context["action_url"] = reverse(action)
        return context


class NotificationEditView(forms.ModalFormView):
    form_class = notification_forms.EditMethodForm
    template_name = constants.TEMPLATE_PREFIX + 'edit.html'

    def dispatch(self, *args, **kwargs):
        return super(NotificationEditView, self).dispatch(*args, **kwargs)

    def get_object(self):
        id = self.kwargs['id']
        try:
            if hasattr(self, "_object"):
                return self._object
            self._object = None
            self._object = api.monitor.notification_get(self.request, id)
            return self._object
        except Exception:
            redirect = reverse(constants.URL_PREFIX + 'index')
            exceptions.handle(self.request,
                              _('Unable to retrieve notification details.'),
                              redirect=redirect)
        return None

    def get_initial(self):
        self.notification = self.get_object()
        return self.notification

    def get_context_data(self, **kwargs):
        if not policy.check((('monitoring', 'monitoring:monitoring'), ), self.request):
            raise exceptions.NotAuthorized()
        context = super(NotificationEditView, self).get_context_data(**kwargs)
        id = self.kwargs['id']
        context["cancel_url"] = self.get_success_url()
        context["action_url"] = reverse(constants.URL_PREFIX +
                                        'notification_edit', args=(id,))
        return context

    def get_success_url(self):
        return reverse_lazy(constants.URL_PREFIX + 'index',)