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 rest_framework.exceptions import ValidationError

from .models import VMHost, VMProduct, VMSnapshotProduct, VMDiskProduct, VMDiskImageProduct
from uncloud_pay.models import Order

from .serializers import VMHostSerializer, VMProductSerializer, VMSnapshotProductSerializer, VMDiskImageProductSerializer, VMDiskProductSerializer
from uncloud_pay.helpers import ProductViewSet


import datetime

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

class VMDiskImageProductMineViewSet(viewsets.ModelViewSet):
    permission_classes = [permissions.IsAuthenticated]
    serializer_class = VMDiskImageProductSerializer

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

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

        # did not specify size NOR import url?
        if not serializer.validated_data['size_in_gb']:
            if not serializer.validated_data['import_url']:
                raise ValidationError(detail={ 'error_mesage': 'Specify either import_url or size_in_gb' })

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


class VMDiskImageProductPublicViewSet(viewsets.ReadOnlyModelViewSet):
    permission_classes = [permissions.IsAuthenticated]
    serializer_class = VMDiskImageProductSerializer

    def get_queryset(self):
        return VMDiskImageProduct.objects.filter(is_public=True)

class VMDiskProductViewSet(viewsets.ModelViewSet):
    """
    Let a user modify their own VMDisks
    """
    permission_classes = [permissions.IsAuthenticated]
    serializer_class = VMDiskProductSerializer

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

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

        # get disk size from image, if not specified
        if not 'size_in_gb' in serializer.validated_data:
            size_in_gb = serializer.validated_data['image'].size_in_gb
        else:
            size_in_gb = serializer.validated_data['size_in_gb']

        if size_in_gb < serializer.validated_data['image'].size_in_gb:
            raise ValidationError(detail={ 'error_mesage': 'Size is smaller than original image' })


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



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.one_time_price,
                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})

        # This verifies that the VM belongs to the request user
        serializer.is_valid(raise_exception=True)

        disks = VMDiskProduct.objects.filter(vm=serializer.validated_data['vm'])
        ssds_size = sum([d.size_in_gb for d in disks if d.storage_class == 'ssd'])
        hdds_size = sum([d.size_in_gb for d in disks if d.storage_class == 'hdd'])

        recurring_price = serializer.pricing['per_gb_ssd'] * ssds_size + serializer.pricing['per_gb_hdd'] * hdds_size
        recurring_period = serializer.pricing['recurring_period']

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

        serializer.save(owner=request.user,
                        order=order,
                        gb_ssd=ssds_size,
                        gb_hdd=hdds_size)

        return Response(serializer.data)