from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.base import TemplateView
from django.shortcuts import render
from django.db import transaction
from django.contrib.auth import get_user_model
from rest_framework import viewsets, mixins, permissions, status, views
from rest_framework.renderers import TemplateHTMLRenderer
from rest_framework.response import Response
from rest_framework.decorators import action
from rest_framework.reverse import reverse
from rest_framework.decorators import renderer_classes
from vat_validator import validate_vat, vies
from vat_validator.countries import EU_COUNTRY_CODES
from hardcopy import bytestring_to_pdf
from django.core.files.temp import NamedTemporaryFile
from django.http import FileResponse
from django.template.loader import render_to_string
from copy import deepcopy

import json
import logging

from .models import *
from .serializers import *
from .selectors import *

from datetime import datetime
from vat_validator import sanitize_vat
import uncloud_pay.stripe as uncloud_stripe
from django.contrib.auth.decorators import login_required
from django.utils.decorators import method_decorator
from django.http import JsonResponse
import stripe 

logger = logging.getLogger(__name__)

###
# 2020-12 checked code

class RegisterCard(TemplateView):
    template_name = "uncloud_pay/register_stripe.html"

    @method_decorator(login_required)
    def dispatch(self, *args, **kwargs):
        return super().dispatch(*args, **kwargs)


    def get_context_data(self, **kwargs):

        customer_id = uncloud_stripe.get_customer_id_for(self.request.user)
        setup_intent = uncloud_stripe.create_setup_intent(customer_id)
        context = super().get_context_data(**kwargs)
        context['client_secret'] = setup_intent.client_secret
        context['username'] = self.request.user.username
        context['stripe_pk'] = uncloud_stripe.public_api_key
        return context


class CreditCardViewSet(mixins.RetrieveModelMixin,
                        mixins.UpdateModelMixin,
                        mixins.DestroyModelMixin,
                        mixins.ListModelMixin,
                        viewsets.GenericViewSet):

    serializer_class = StripeCreditCardSerializer
    permission_classes = [permissions.IsAuthenticated]

    def list(self, request):
        uncloud_stripe.sync_cards_for_user(self.request.user)
        return super().list(request)

    def get_queryset(self):
        return StripeCreditCard.objects.filter(owner=self.request.user)

class PaymentViewSet(viewsets.ModelViewSet):
    serializer_class = PaymentSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        return Payment.objects.filter(owner=self.request.user)

class BalanceViewSet(viewsets.ViewSet):
    permission_classes = [permissions.IsAuthenticated]

    def list(self, request):
        serializer = BalanceSerializer(data={
            'balance': get_balance_for_user(self.request.user)
        })
        serializer.is_valid()
        return Response(serializer.data)


class ListCards(TemplateView):
    template_name = "uncloud_pay/list_stripe.html"

    @method_decorator(login_required)
    def dispatch(self, *args, **kwargs):
        return super().dispatch(*args, **kwargs)

    def get_context_data(self, **kwargs):
        customer_id = uncloud_stripe.get_customer_id_for(self.request.user)
        cards = uncloud_stripe.get_customer_cards(customer_id)

        context = super().get_context_data(**kwargs)
        context['cards'] = cards
        context['username'] = self.request.user

        return context

###
# Bills and Orders.

class BillViewSet(viewsets.ReadOnlyModelViewSet):
    serializer_class = BillSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        return Bill.objects.filter(owner=self.request.user)


    @action(detail=False, methods=['get'])
    def unpaid(self, request):
        serializer = self.get_serializer(
                Bill.get_unpaid_for(self.request.user),
                many=True)
        return Response(serializer.data)

    @action(detail=True, methods=['get'])
    def download(self, *args, **kwargs):
        """
        Allow to download
        """
        bill = self.get_object()
        provider = UncloudProvider.get_provider()
        output_file = NamedTemporaryFile()
        bill_html = render_to_string("bill.html.j2", {'bill': bill})

        bytestring_to_pdf(bill_html.encode('utf-8'), output_file)
        response = FileResponse(output_file, content_type="application/pdf")
        response['Content-Disposition'] = 'filename="{}_{}.pdf"'.format(
                bill.reference, bill.uuid
        )

        return response


class OrderViewSet(viewsets.ReadOnlyModelViewSet):
    serializer_class = OrderSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        return Order.objects.filter(owner=self.request.user)

class VATRateViewSet(viewsets.ReadOnlyModelViewSet):
    serializer_class = VATRateSerializer
    permission_classes = [permissions.IsAuthenticated]
    queryset = VATRate.objects.all()

class BillingAddressViewSet(mixins.CreateModelMixin,
        mixins.RetrieveModelMixin,
        mixins.UpdateModelMixin,
        mixins.ListModelMixin,
        viewsets.GenericViewSet):
    permission_classes = [permissions.IsAuthenticated]

    def get_serializer_class(self):
        if self.action == 'update':
            return UpdateBillingAddressSerializer
        else:
            return BillingAddressSerializer

    def get_queryset(self):
        return self.request.user.billing_addresses.all()

    def create(self, request):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        # Validate VAT numbers.
        country = serializer.validated_data["country"]

        # We ignore empty VAT numbers.
        if 'vat_number' in serializer.validated_data and serializer.validated_data["vat_number"] != "":
            vat_number = serializer.validated_data["vat_number"]

            if not validate_vat(country, vat_number):
                return Response(
                    {'error': 'Malformed VAT number.'},
                    status=status.HTTP_400_BAD_REQUEST)
            elif country in EU_COUNTRY_CODES:
                # XXX: make a synchroneous call to a third patry API here might not be a good idea..
                try:
                    vies_state = vies.check_vat(country, vat_number)
                    if not vies_state.valid:
                        return Response(
                                {'error': 'European VAT number does not exist in VIES.'},
                                status=status.HTTP_400_BAD_REQUEST)
                except Exception as e:
                    logger.warning(e)
                    return Response(
                            {'error': 'Could not validate EU VAT number against VIES. Try again later..'},
                            status=status.HTTP_500_INTERNAL_SERVER_ERROR)


        serializer.save(owner=request.user)
        return Response(serializer.data)

###
# Admin stuff.

class AdminPaymentViewSet(viewsets.ModelViewSet):
    serializer_class = PaymentSerializer
    permission_classes = [permissions.IsAdminUser]

    def get_queryset(self):
        return Payment.objects.all()

    def create(self, request):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.save(timestamp=datetime.now())

        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

# Bills are generated from orders and should not be created or updated by hand.
class AdminBillViewSet(BillViewSet):
    serializer_class = BillSerializer
    permission_classes = [permissions.IsAdminUser]

    def get_queryset(self):
        return Bill.objects.all()

    @action(detail=False, methods=['get'])
    def unpaid(self, request):
        unpaid_bills = []
        # XXX: works but we can do better than number of users + 1 SQL requests...
        for user in get_user_model().objects.all():
            unpaid_bills = unpaid_bills + Bill.get_unpaid_for(self.request.user)

        serializer = self.get_serializer(unpaid_bills, many=True)
        return Response(serializer.data)

    @action(detail=False, methods=['post'])
    def generate(self, request):
        users = get_user_model().objects.all()

        generated_bills = []
        for user in users:
            now = timezone.now()
            generated_bills = generated_bills + Bill.generate_for(
                    year=now.year,
                    month=now.month,
                    user=user)

        return Response(
                map(lambda b: b.reference, generated_bills),
                status=status.HTTP_200_OK)

class AdminOrderViewSet(mixins.ListModelMixin,
        mixins.RetrieveModelMixin,
        mixins.CreateModelMixin,
        mixins.UpdateModelMixin,
        viewsets.GenericViewSet):
    serializer_class = OrderSerializer
    permission_classes = [permissions.IsAdminUser]

    def get_serializer(self, *args, **kwargs):
        return self.serializer_class(*args, **kwargs, admin=True)

    def get_queryset(self):
        return Order.objects.all()

    # Updates create a new order and terminate the 'old' one.
    @transaction.atomic
    def update(self, request, *args, **kwargs):
       order = self.get_object()
       partial = kwargs.pop('partial', False)
       serializer = self.get_serializer(order, data=request.data, partial=partial)
       serializer.is_valid(raise_exception=True)

       # Clone existing order for replacement.
       replacing_order = deepcopy(order)

       # Yes, that's how you make a new entry in DB:
       #   https://docs.djangoproject.com/en/3.0/topics/db/queries/#copying-model-instances
       replacing_order.pk = None

       for attr, value in serializer.validated_data.items():
          setattr(replacing_order, attr, value)

       # Save replacing order and terminate 'previous' one.
       replacing_order.save()
       order.replaced_by = replacing_order
       order.save()
       order.terminate()

       return Response(replacing_order)

    @action(detail=True, methods=['post'])
    def terminate(self, request, pk):
        order = self.get_object()
        if order.is_terminated:
            return Response(
                    {'error': 'Order is already terminated.'},
                    status=status.HTTP_500_INTERNAL_SERVER_ERROR)

        else:
            order.terminate()
            return Response({}, status=status.HTTP_200_OK)