#    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/>.

import datetime

from django.db.models import Max
from django.db.models.functions import Length
from django.http import Http404
from django.shortcuts import get_object_or_404, render

from .models import Timetable, Group, Course, Year
from .utils import get_current_week, get_current_or_next_week, get_week, group_courses

import edt

def index(request):
    years = Year.objects.order_by("name")
    return render(request, "index.html", {"elements": years})

def mention_list(request, year_slug):
    year = get_object_or_404(Year, slug=year_slug)
    timetables = Timetable.objects.order_by("name").filter(year=year).select_related("year")

    return render(request, "index.html", {"year": year, "elements": timetables})

def group_list(request, year_slug, timetable_slug):
    timetable = get_object_or_404(Timetable, year__slug=year_slug, slug=timetable_slug)
    groups = Group.objects.filter(timetable=timetable, hidden=False).order_by("name")

    start, _ = get_week(*get_current_week())
    end = start + datetime.timedelta(weeks=4)

    groups_weeks = Course.objects.get_weeks(begin__gte=start, begin__lt=end, groups__in=groups)

    for group in groups:
        for group_week in groups_weeks:
            if group.corresponds_to(group_week["groups__mention"],
                                    group_week["groups__semester"],
                                    group_week["groups__subgroup"]):
                if not hasattr(group, "weeks"):
                    group.weeks = []

                date, _ = get_week(group_week["year"], group_week["week"])
                if date not in group.weeks:
                    group.weeks.append(date)

        if hasattr(group, "weeks"):
            group.weeks.sort()

    return render(request, "group_list.html", {"timetable": timetable, "groups": groups})

def timetable(request, year_slug, timetable_slug, group_slug, year=None, week=None):
    current_year, current_week = get_current_or_next_week()
    is_old_timetable, provided_week = False, True

    if year is None or week is None:
        year, week = current_year, current_week
        provided_week = False
    elif (int(year), int(week)) < (current_year, current_week):
        is_old_timetable = True

    start, end = get_week(year, week)

    timetable = get_object_or_404(Timetable, year__slug=year_slug, slug=timetable_slug)
    group = get_object_or_404(Group, slug=group_slug, timetable=timetable)

    courses = Course.objects.get_courses_for_group(group, begin__gte=start, begin__lt=end)
    if not courses.exists() and provided_week:
        raise Http404

    last_update = courses.aggregate(Max("last_update"))["last_update__max"]
    grouped_courses = group_courses(courses)

    return render(request, "timetable.html", {"group": group, "courses": grouped_courses,
                                              "last_update": last_update,
                                              "year": year, "week": int(week),
                                              "is_old_timetable": is_old_timetable})

def calendars(request, year_slug, timetable_slug, group_slug):
    group = get_object_or_404(Group, timetable__year__slug=year_slug,
                              timetable__slug=timetable_slug, slug=group_slug)
    groups = Group.objects.get_parents(group).annotate(length=Length("subgroup")) \
                                             .order_by("length")

    return render(request, "calendars.html", {"group": group, "groups": groups})

def ctx_processor(request):
    return {"celcatsanitizer_version": edt.VERSION}