from django.shortcuts import render
from django.db import transaction
from django.contrib.auth import get_user_model
from rest_framework import viewsets, permissions, status
from rest_framework.response import Response
from rest_framework.decorators import action

import json

from .models import *
from .serializers import *
from datetime import datetime

###
# Standard user views:

class BalanceViewSet(viewsets.ViewSet):
    # here we return a number
    # number = sum(payments) - sum(bills)

    #bills = Bill.objects.filter(owner=self.request.user)
    #payments = Payment.objects.filter(owner=self.request.user)

    # sum_paid = sum([ amount for amount payments..,.  ]) # you get the picture
    # sum_to_be_paid = sum([ amount for amount bills..,.  ]) # you get the picture
    pass


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

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

    def unpaid(self, request):
        return Bill.objects.filter(owner=self.request.user, paid=False)

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

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

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

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

class UserViewSet(viewsets.ReadOnlyModelViewSet):
    serializer_class = UserSerializer
    permission_classes = [permissions.IsAuthenticated]

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

class PaymentMethodViewSet(viewsets.ModelViewSet):
    permission_classes = [permissions.IsAuthenticated]

    def get_serializer_class(self):
        if self.action == 'create':
            return CreatePaymentMethodSerializer
        elif self.action == 'charge':
            return ChargePaymentMethodSerializer
        else:
            return PaymentMethodSerializer


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

    # XXX: Handling of errors is far from great down there.
    @transaction.atomic
    def create(self, request):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        # Retrieve Stripe customer ID for user.
        customer_id  = stripe.get_customer_id_for(request.user)
        if customer_id == None:
            return Response(
                    {'error': 'Could not resolve customer stripe ID.'},
                    status=status.HTTP_500_INTERNAL_SERVER_ERROR)

        # Register card under stripe customer.
        credit_card = stripe.CreditCard(**serializer.validated_data.pop('credit_card'))
        card_request = stripe.create_card(customer_id, credit_card)
        if card_request['error']:
            return Response({'stripe_error': card_request['error']}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
        card_id = card_request['response_object']['id']

        # Save payment method locally.
        serializer.validated_data['stripe_card_id'] = card_request['response_object']['id']
        payment_method = PaymentMethod.objects.create(owner=request.user, **serializer.validated_data)

        # We do not want to return the credit card details sent with the POST
        # request.
        output_serializer = PaymentMethodSerializer(payment_method)
        return Response(output_serializer.data)

    @action(detail=True, methods=['post'])
    def charge(self, request, pk=None):
        payment_method = self.get_object()
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        amount = serializer.validated_data['amount']
        try:
            payment = payment_method.charge(amount)
            output_serializer = PaymentSerializer(payment)
            return Response(output_serializer.data)
        except Exception as e:
            return Response({'error': str(e)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)

###
# Admin views.

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

    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)

class AdminBillViewSet(viewsets.ModelViewSet):
    serializer_class = BillSerializer
    permission_classes = [permissions.IsAuthenticated]

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

    def unpaid(self, request):
        return Bill.objects.filter(owner=self.request.user, paid=False)

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

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

class AdminOrderViewSet(viewsets.ModelViewSet):
    serializer_class = OrderSerializer
    permission_classes = [permissions.IsAuthenticated]

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