#    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 Count, Max
from django.db.models.functions import ExtractWeek, ExtractYear
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
from .templatetags.rooms import format_rooms
from .utils import get_current_or_next_week, get_week, group_courses

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


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

    def write(self, outfile, encoding):
        calendar = Calendar()
        calendar.add("prodid", "-//celcatsanitizer//NONSGML v1.0//EN")
        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)

    def item_extra_kwargs(self, item):
        return {"uid": "{0}@celcatsanitizer".format(item.id),
                "dtstart": item.begin,
                "dtend": item.end,
                "dtstamp": item.last_update,
                "summary": item.name + " (" + item.type + ")",
                "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()
        _, end = get_week(year, week)

        try:
            group = Group.objects.get(timetable__year__slug=year_slug,
                                      timetable__slug=timetable_slug,
                                      slug=group_slug)
        except:
            raise ObjectDoesNotExist
        else:
            updates = Course.objects.get_courses_for_group(group,
                                                           begin__lt=end) \
                                    .annotate(year=ExtractYear("begin"),
                                              week=ExtractWeek("begin")) \
                                    .values("year", "week") \
                                    .annotate(Count("year", distinct=True),
                                              Max("last_update")) \
                                    .order_by("-year", "-week")[:5]
            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_title(self, item):
        return "{0}, semaine {1} de {2}".format(item["group"],
                                                item["week"],
                                                item["year"])

    def item_updateddate(self, item):
        return item["last_update__max"]

    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["last_update__max"],
                       "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