#    Copyright (C) 2017  Alban Gruin
#
#    celcatsanitizer 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.
#
#    celcatsanitizer 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 celcatsanitizer.  If not, see <http://www.gnu.org/licenses/>.

from django.core.exceptions import ObjectDoesNotExist
from django.contrib.syndication.views import Feed
from django.utils.feedgenerator import SyndicationFeed

from icalendar import Calendar, Event

from .models import Course, Group, Timetable, Year
from .templatetags.rooms import format_rooms

ICAL_NAMES = ["summary", "description", "location", "start", "dtstart", "dtend"]


class IcalFeedGenerator(SyndicationFeed):
    content_type = "text/calendar; charset=utf-8"

    def write(self, outfile, encoding):
        calendar = Calendar()
        calendar.add("version", "2.0")

        self.write_events(calendar)
        outfile.write(calendar.to_ical())

    def write_events(self, calendar):
        for item in self.items:
            event = Event()
            for key in ICAL_NAMES:
                if item.get(key) is not None:
                    event.add(key, item[key])
            calendar.add_component(event)


class IcalFeed(Feed):
    feed_type = IcalFeedGenerator
    link = ""

    def get_object(self, request, year_slug, timetable_slug, group_slug):
        try:
            year = Year.objects.get(slug=year_slug)
            timetable = Timetable.objects.get(year=year, slug=timetable_slug)
            group = Group.objects.get(timetable=timetable, slug=group_slug)
        except:
            raise ObjectDoesNotExist
        else:
            return group

    def item_description(self, item):
        return item.notes

    def item_link(self, item):
        return ""

    def items(self, obj):
        return Course.objects.get_courses_for_group(obj).order_by("begin")

    def item_extra_kwargs(self, item):
        return {"dtstart": item.begin,
                "dtend": item.end,
                "summary": item.name,
                "location": format_rooms(item.rooms.all())}