from django.shortcuts import render
from django.views import generic
from django.db.models import F, Sum, Q


from django.views.generic import ListView
from inventory.models import Unit, Location


from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.edit import CreateView

from .models import PantryItem, PantryItemLine, Category

class PantryItemLineCreateView(LoginRequiredMixin, CreateView):
    model = PantryItemLine
    fields = '__all__'
    success_url = '.'


class PantryItemCreateView(LoginRequiredMixin, CreateView):
    model = PantryItem
    fields = '__all__'
    success_url = '.'


class CategoryCreateView(LoginRequiredMixin, CreateView):
    model = Category
    fields = '__all__'
    success_url = '.'

class LocationCreateView(LoginRequiredMixin, CreateView):
    model = Location
    fields = '__all__'
    success_url = '.'




class UnitView(ListView):
    model = Unit


# Create your views here.


def index(request):
    return render(request, "inventory/index.html")


class Shoppinglist(generic.ListView):
    template_name = "inventory/shoppinglist.html"
    context_object_name = 'pis'

    def get_queryset(self):
        """
        Return pantryitems for which we have None itemlines or Itemlines whith a total quantitly less than required
        """
        return PantryItem.objects.annotate(
            total_quantity=Sum(F('pantryitemline__quantity') *
                               F('pantryitemline__size'))
        ).filter(Q(min_quantity__gt=F('total_quantity')) | Q(pantryitemline=None, min_quantity__gt=0))


class Expirations(generic.ListView):
    template_name = "inventory/expirations.html"
    context_object_name = 'pis'

    def get_queryset(self):
        return PantryItemLine.objects.exclude(expiry_date__isnull=True).exclude(quantity=0).order_by('expiry_date')


class ConsumeList(generic.ListView):
    template_name = "inventory/consumelist.html"
    context_object_name = 'pis'

    def get_queryset(self):
        return PantryItemLine.objects.exclude(quantity=0).order_by('expiry_date')


class Consume(generic.UpdateView):
    template_name = "inventory/consume.html"
    fields = ['quantity']

    context_object_name = 'pis'

    def get_queryset(self):
        return PantryItemLine.objects.exclude(quantity=0).order_by('expiry_date')


class PantryItemLineView(generic.DetailView):
    model = PantryItemLine