from django.shortcuts import render
from django.http import HttpResponse, JsonResponse
from django.views import generic
from django.template import loader
from django.urls import reverse_lazy
from .models import ArrowCount
from .forms import ArrowCountForm
from django.contrib.auth.decorators import login_required
from django.conf import settings
from django.core.exceptions import SuspiciousOperation
from django.utils.translation import gettext as _
from django.db.models.functions import Extract, ExtractWeek
from django.db.models import Sum
from datetime import datetime, timedelta, date
import json
from django.core.serializers.json import DjangoJSONEncoder

# https://stackoverflow.com/questions/5882405
def tofirstdayinisoweek(year, week):
    ret = datetime.strptime('%04d-%02d-1' % (year, week), '%Y-%W-%w')
    if date(year, 1, 4).isoweekday() > 4:
        ret -= timedelta(days=7)
    return ret

def index(request):
    template = loader.get_template('index.html')
    return HttpResponse(template.render({}, request))

def count_stats(request):
    template = loader.get_template('stats.html')

    # Group counts by week (extract isoyear works only on psql and DB2)
    weeklyArrows = ArrowCount.objects \
        .filter(user = request.user) \
        .annotate(isoyear=Extract('date', lookup_name='isoyear')) \
        .annotate(week=ExtractWeek('date')) \
        .values('isoyear', 'week') \
        .annotate(sum_count=Sum('count')) \
        .order_by('-isoyear', '-week')
    
    for w in weeklyArrows:
        w['weekStarts'] = tofirstdayinisoweek(w['isoyear'], w['week'])
        w['weekEnds'] = w['weekStarts'] + timedelta(days=6)

    return HttpResponse(template.render({
        'weeklyArrows': json.dumps(list(weeklyArrows), cls=DjangoJSONEncoder)
        }, request))

@login_required
def arrow_count_list(request):
    page = request.GET.get('page')

    if not page:
        page = 1
    else:
        page = int(page)

    if page <= 0:
        raise SuspiciousOperation(_("page is negative or 0"))

    start = settings.ITEMS_PER_PAGE * (page - 1)
    finish = settings.ITEMS_PER_PAGE + start
    counts = ArrowCount.objects.order_by('-date') \
        .filter(user = request.user)[start:finish]

    pageCount = ArrowCount.objects.filter(user = request.user).count() / \
        settings.ITEMS_PER_PAGE
    template = loader.get_template('counter/list.html')
    return HttpResponse(template.render({
        'counts': counts,
        'pageCount': pageCount,
        'page': page
        }, request))

class NewArrowCount(generic.CreateView):
    form_class = ArrowCountForm
    success_url = reverse_lazy('count_list')
    template_name = 'counter/new.html'

    def form_valid(self, form):
        form.instance.user = self.request.user
        return super().form_valid(form)

class EditArrowCount(generic.UpdateView):
    form_class = ArrowCountForm
    success_url = reverse_lazy('count_list')
    template_name = 'counter/edit.html'

    def get_object(self, queryset=None):
        obj = ArrowCount.objects.get(id=self.kwargs['id'])
        return obj

    def get(self, request, *args, **kwargs):
        super().get(self, request, *args, **kwargs)
        context_data = self.get_context_data()
        context_data.update(ac_id=self.kwargs['id'])
        return self.render_to_response(context_data) 

class DeleteArrowCount(generic.DeleteView):
    model = ArrowCount
    success_url = reverse_lazy('count_list')

    def get_object(self, queryset=None):
        obj = ArrowCount.objects.get(id=self.kwargs['id'])
        return obj

@login_required
def arrow_count_update_ajax(request, ac_id):
    try:
        count = int(request.POST.get("count", None))
    except ValueError:
        return JsonResponse({
            'success': False,
            'error': _('count is not a number')
        })

    if count == None or count < 0:
        return JsonResponse({
            'success': False,
            'error': _('count is negative or 0')
        })

    arrow_count = ArrowCount.objects.filter(
            id=ac_id, user=request.user)[0]

    if arrow_count == None:
        return JsonResponse({
            'success': False,
            'error': _('ArrowCount instance not found or from different user')
        })

    arrow_count.count = count
    arrow_count.save()

    return JsonResponse({
        'success': True,
        'count': arrow_count.count
    })