from django.core.mail import EmailMessage, EmailMultiAlternatives
from django.shortcuts import render
from django.template.loader import render_to_string
from rest_framework import viewsets, permissions, status
from rest_framework.decorators import action
from rest_framework.response import Response
from bernini import settings
from order.models import SaleOrder, SaleOrderLine, Product
from order.serializers import (
    SaleOrderSerializer,
    SaleOrderLineSerializer,
    ProductSerializer,
)


class SaleOrderViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows orders to be viewed or edited. A `SaleOrder` object will render the general sale
    document that wraps n products a client can buy, using an intermediate model called `SaleOrderLine`, this means:
    a `SaleOrder` object does not interact directly with a product, a `SaleOrderLine` is just a wrap of a product,
    which holds its price-per-unit value, and a quantity for that product; lastly, on the other hand, a `SaleOrder`
    object will hold the total information by doing a sum() operation with all the lines
    """

    queryset = SaleOrder.objects.all().order_by("name")
    serializer_class = SaleOrderSerializer
    permission_classes = [permissions.IsAuthenticated]

    def update(self, request, pk=None, *args, **kwargs):
        order: SaleOrder = self.get_object()

        for field in SaleOrder.ReadonlyMeta.readonly:
            if request.data.get(field) != SaleOrderSerializer(order).data[field]:
                return Response(
                    data=f"You can't manually set the field {field}",
                    status=status.HTTP_400_BAD_REQUEST,
                )

        return super(SaleOrderViewSet, self).update(request, *args, **kwargs)

    def partial_update(self, request, pk=None, *args, **kwargs):
        order: SaleOrder = self.get_object()
        for field in SaleOrder.ReadonlyMeta.readonly:
            if request.data.get(field) != SaleOrderSerializer(order).data[field]:
                return Response(
                    data=f"You can't manually set the field {field}",
                    status=status.HTTP_400_BAD_REQUEST,
                )

        return super(SaleOrderViewSet, self).partial_update(request, *args, **kwargs)

    @action(detail=True, name="Get the total amount")
    def total(self, request, pk=None):
        order: SaleOrder = self.get_object()
        return Response({"amount_total": order.amount_total})

    @action(detail=True)
    def sold(self, request, pk=None):
        """
        Try to sell a `SaleOrder` object, this is, the sale will have assigned
        the user which is doing this operation, the persistent total attribute
        will be set -`total`- and the `sold_at`
        :param request:
        :param pk:
        :return: the object with -possibly- updated values
        """
        return Response(
            SaleOrderSerializer(
                self.get_object().sell(request.user), context={"request": request}
            ).data
        )

    @action(detail=True)
    def sent(self, request, pk=None):
        order: SaleOrder = self.get_object()
        if order.sold_at and order.sold_to.email and settings.EMAIL_HOST_USER:
            mail = EmailMultiAlternatives(
                subject=f"Order {order.name} from Zapatos Bernini",
                from_email=settings.EMAIL_HOST_USER,
                to=[order.sold_to.email],
                reply_to=[settings.EMAIL_HOST_USER],
            )
            mail.attach_alternative(
                render_to_string(
                    template_name="order_sold.html",
                    context={"order": order},
                ),
                mimetype="text/html",
            )
            mail.attach(
                filename=f"Bernini order {order.name}.csv",
                content=order.as_csv(),
                mimetype="text/csv",
            )
            for line in order.saleorderline_set.all():
                mail.attach(
                    filename=f"Bernini order {order.name}/{line.name}.csv",
                    content=line.as_csv(),
                    mimetype="text/csv",
                )
            mail.send()
            return Response(
                status=status.HTTP_200_OK,
                data=f"Email sent! You should receive it at {order.sold_to.email}",
            )
        return Response(
            status=status.HTTP_500_INTERNAL_SERVER_ERROR,
            data="Something went wrong on our end",
        )


class SaleOrderLineViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows orders to be viewed or edited.
    """

    queryset = SaleOrderLine.objects.all().order_by("name")
    serializer_class = SaleOrderLineSerializer
    permission_classes = [permissions.IsAuthenticated]


class ProductViewSet(viewsets.ReadOnlyModelViewSet):
    """
    API endpoint that allows orders to be viewed or edited
    """

    queryset = Product.objects.all().order_by("name")
    serializer_class = ProductSerializer
    permission_classes = [permissions.IsAuthenticatedOrReadOnly]