from django.db import transaction
from django.shortcuts import render

from django.contrib.auth.models import User
from django.shortcuts import get_object_or_404

from rest_framework import viewsets, permissions
from rest_framework.response import Response

from .models import VMHost, VMProduct, VMSnapshotProduct
from uncloud_pay.models import Order, RecurringPeriod
from .serializers import VMHostSerializer, VMProductSerializer, VMSnapshotProductSerializer
from uncloud_pay.helpers import ProductViewSet


import datetime

class VMHostViewSet(viewsets.ModelViewSet):
    serializer_class = VMHostSerializer
    queryset = VMHost.objects.all()
    permission_classes = [permissions.IsAdminUser]


class VMProductViewSet(ProductViewSet):
    permission_classes = [permissions.IsAuthenticated]
    serializer_class = VMProductSerializer

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

    # Use a database transaction so that we do not get half-created structure
    # if something goes wrong.
    @transaction.atomic
    def create(self, request):
        # Extract serializer data.
        serializer = VMProductSerializer(data=request.data, context={'request': request})
        serializer.is_valid(raise_exception=True)
        order_recurring_period = serializer.validated_data.pop("recurring_period")

        # Create base order.
        order = Order.objects.create(
                recurring_period=order_recurring_period,
                owner=request.user
                )
        order.save()

        # Create VM.
        vm = serializer.save(owner=request.user, order=order)

        # Add Product record to order (VM is mutable, allows to keep history in order).
        # XXX: Move this to some kind of on_create hook in parent Product class?
        order.add_record(vm.setup_fee,
                vm.recurring_price(order.recurring_period), vm.description)

        return Response(serializer.data)


class VMSnapshotProductViewSet(viewsets.ModelViewSet):
    permission_classes = [permissions.IsAuthenticated]
    serializer_class = VMSnapshotProductSerializer

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

    def create(self, request):
        serializer = VMSnapshotProductSerializer(data=request.data, context={'request': request})
        serializer.is_valid(raise_exception=True)

        # Create order
        now = datetime.datetime.now()
        order = Order(owner=request.user,
                      creation_date=now,
                      starting_date=now,
                      recurring_price=20,
                      one_time_price=0,
                      recurring_period="per_month")
        order.save()

        # FIXME: calculate the gb_* values
        serializer.save(owner=request.user,
                        order=order,
                        gb_ssd=12,
                        gb_hdd=20)

        return Response(serializer.data)