#    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.conf import settings
from django.contrib.syndication.views import Feed
from django.db.models import Q
from django.template import loader
from django.urls import reverse
from django.utils.feedgenerator import Atom1Feed, SyndicationFeed

from icalendar import Calendar, Event

from .models import Course, Group, LastUpdate
from .templatetags.rooms import format_rooms
from .utils import get_current_or_next_week, get_week, group_courses

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:
            group = Group.objects.get(timetable__year__slug=year_slug, timetable__slug=timetable_slug, 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())}


class RSSFeed(Feed):
    def get_object(self, request, year_slug, timetable_slug, group_slug):
        year, week = get_current_or_next_week()
        try:
            group = Group.objects.get(timetable__year__slug=year_slug, timetable__slug=timetable_slug, slug=group_slug)
            updates = LastUpdate.objects.filter(Q(year=year, week__lte=week) | Q(year__lt=year), timetable__year__slug=year_slug, timetable__slug=timetable_slug).order_by("-year", "-week")[:5]
        except:
            raise ObjectDoesNotExist
        else:
            return group, updates

    def link(self, obj):
        group = obj[0]
        link = reverse("timetable", kwargs={"year_slug": group.timetable.year.slug, "timetable_slug": group.timetable.slug, "group_slug": group.slug})
        return link

    def title(self, obj):
        return "Emploi du temps du groupe {0}".format(obj[0])

    def item_link(self, item):
        group = item.group
        return reverse("timetable", kwargs={"year_slug": group.timetable.year.slug, "timetable_slug": group.timetable.slug, "group_slug": group.slug, "year": item.year, "week": item.week})

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

    def item_updateddate(self, item):
        return item.date

    def items(self, obj):
        template = loader.get_template("timetable_common.html")
        group = obj[0]

        for update in obj[1]:
            start, end = get_week(update.year, update.week)
            courses = Course.objects.get_courses_for_group(group, begin__gte=start, begin__lt=end)
            context = {"group": group, "courses": group_courses(courses), "last_update": update, "year": update.year, "week": update.week}

            update.group = group
            update.description = template.render(context)

        return obj[1]


class AtomFeed(RSSFeed):
    author_name = settings.ADMINS[0][0]
    author_email = settings.ADMINS[0][1]
    feed_type = Atom1Feed