from django.shortcuts import render
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
        else:
            return PaymentMethodSerializer


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

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

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

    # TODO: find a way to customize serializer for actions.
    # drf-action-serializer module seems to do that.
    @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.data['amount']
        if payment_method.charge(amount):
            return Response({'charged', amount})
        else:
            return Response(status=status.HTTP_500_INTERNAL_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()