import datetime
import logging
import uuid
from functools import reduce
from decimal import Decimal

from django.conf import settings
from django.db import transaction
from django.http import HttpResponseRedirect
from django.shortcuts import redirect
from django.urls import reverse_lazy
from django.utils.translation import ugettext_lazy as _
from django.views.generic import ListView
from django.contrib import messages

from cart.models import Buying, Discount, Offer
from core.models import City
from core.views import ProtectedListView, ProtectedTemplateView, ProtectedView, ProtectedFormView, ProtectedBaseFormView

from .forms import (
    CartRemoveBuyingForm,
    DiscountForm,
    CartAddInlineForm, CartCheckoutForm,
    CartCheckoutBuyingForm)

logger = logging.getLogger(__name__)


class CartAddView(ProtectedBaseFormView):
    http_method_names = ('post',)
    form_class = CartAddInlineForm

    def get_success_url(self):
        return self.request.META.get('HTTP_REFERRER', reverse_lazy('products:product_list'))

    def form_valid(self, form):
        self.request.cart.add(offer_id=form.cleaned_data['offer'].product_id, quantity=form.cleaned_data['amount'])
        return super().form_valid(form)

    def form_invalid(self, form):
        if form.errors:
            for error in form.errors:
                messages.error(self.request, error)
        return HttpResponseRedirect(self.get_success_url())


class CartRemoveView(ProtectedBaseFormView):
    http_method_names = ('post',)
    model = Offer
    form_class = CartRemoveBuyingForm

    def get_success_url(self):
        return self.request.META.get('HTTP_REFERRER', reverse_lazy('products:product_list'))

    def form_valid(self, form):
        self.request.cart.remove(form.cleaned_data['offer'].product_id)
        return super().form_valid(form)


class CartView(ProtectedListView):
    model = Offer
    paginate_by = settings.DEFAULT_PAGE_AMOUNT
    context_object_name = 'offer_items'
    template_name = 'cart/cart.html'
    ordering = '-create_at'
    title = _('Корзина')

    def get_queryset(self):
        qs = super().get_queryset()
        return qs.filter(product__id__in=self.request.cart.keys())

    def get_total_price(self, object_list):
        return reduce(
            lambda initial, offer: initial + offer.price * Decimal(self.request.cart[offer.product_id]['quantity']),
            object_list,
            Decimal(0)
        )

    def get_total_cashback(self, object_list):
        return reduce(
            lambda initial, offer: initial + offer.cashback * Decimal(self.request.cart[offer.product_id]['quantity']),
            object_list,
            Decimal(0)
        )

    def get_context_data(self, *, object_list=None, **kwargs):
        context = super().get_context_data(object_list=object_list, **kwargs)
        context['title'] = self.title
        context['total_price'] = self.get_total_price(self.object_list)
        context['total_price_currency'] = context[
            'total_cashback_currency'] = self.object_list.first().currency.sign if self.object_list.first() else ''
        context['total_cashback'] = self.get_total_cashback(self.object_list)
        return context


class CartCheckoutView(ProtectedFormView):
    http_method_names = ('get', 'post',)
    template_name = 'cart/checkout.html'
    form_class = CartCheckoutForm
    title = _('Оформление заказа')

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['initial'] = {
            'customer_name': self.request.user.profile.full_name,
            'customer_email': self.request.user.email,
            'phone': self.request.user.profile.phone,
            'customer_address': self.request.user.profile.address,
            'city': City.objects.filter(name=self.request.user.profile.city).first()
        }
        return kwargs


class CartConfirmView(ProtectedFormView):
    http_method_names = ('post',)
    template_name = 'cart/confirm.html'
    form_class = CartCheckoutForm
    title = _('Подтверждение заказа')

    def get_total_price(self, offers):
        return reduce(
            lambda initial, offer: initial + offer.price * Decimal(self.request.cart[offer.product_id]['quantity']),
            offers,
            Decimal(0)
        )

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        data = kwargs['data'].copy()
        data.update({
            'total_price': self.get_total_price(Offer.active.filter(product_id__in=self.request.cart.keys()))
        })
        kwargs['data'] = data
        return kwargs

    def form_valid(self, form):
        if form.is_valid():
            try:
                with transaction.atomic():
                    form.save(self.request.user)
                    for item in self.request.cart:
                        buying_form = CartCheckoutBuyingForm(initial={
                            'offer': item,
                            'order': form.instance.order_code,
                            'amount': self.request.cart[item]['quantity']
                        })
                        buying_form.save(self.request.user)
                form.send_order_invoice(self.request)
                form.send_order_request(self.request)
                self.request.cart.clear()
                return self.render_to_response(self.get_context_data())
            except Exception as e:
                logger.critical(e)

        return self.form_invalid(form)

    def form_invalid(self, form):
        for error in form.errors:
            messages.error(self.request, error)
        return HttpResponseRedirect(self.request.META['HTTP_REFERER'])

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['title'] = self.title
        return context


class BuyingsHistory(ProtectedListView):
    model = Buying
    paginate_by = settings.DEFAULT_PAGE_AMOUNT
    context_object_name = 'bought_item_list'
    ordering = '-create_at'
    template_name = 'cart/bought_history.html'
    title = _('История покупок')

    def get_queryset(self):
        qs = super().get_queryset()
        return qs.filter(user=self.request.user)

    def get_context_data(self, *, object_list=None, **kwargs):
        context = super().get_context_data(object_list=object_list, **kwargs)
        context['title'] = self.title
        return context


class DiscountListView(ListView):
    template_name = 'cart/discount_list.html'
    model = Discount
    title = _('Акции / Cashback')

    def get_context_data(self, *, object_list=None, **kwargs):
        context = super().get_context_data(object_list=object_list, **kwargs)
        context['title'] = self.title
        return context


# Discount views # @TODO: TEST FOR PRODUCTION
class PointsApply(ProtectedTemplateView):
    http_method_names = ('post',)

    def dispatch(self, request, *args, **kwargs):
        super().dispatch(request, *args, **kwargs)
        self.request.session['points'] = True
        return redirect('cart:buyings')


class PointsRevoke(ProtectedView):
    http_method_names = ('post',)

    def dispatch(self, request, *args, **kwargs):
        super().dispatch(request, *args, **kwargs)
        self.request.session.pop('points', None)
        return redirect('cart:buyings')


class DiscountApply(ProtectedFormView):
    http_method_names = ('post',)

    form_class = DiscountForm

    def form_valid(self, form):
        now = datetime.now()
        code = form.cleaned_data['code']
        try:
            discount = Discount.objects.get(code__iexact=code,
                                            valid_from__lte=now,
                                            valid_to__gte=now,
                                            active=True)
            self.request.session['discount_id'] = discount.id
        except Discount.DoesNotExist:
            self.request.session['discount_id'] = None
        return super().form_valid(form)

    def get_success_url(self):
        return reverse_lazy('cart:buyings')


class CreateDiscount(ProtectedFormView):
    http_method_names = ('post',)

    form_class = DiscountForm

    def form_valid(self, form):
        now = datetime.now()
        Discount.objects.update_or_create(
            user=self.request.user,
            defaults={'code': str(uuid.uuid4()),
                      'valid_from': now,
                      'valid_to': now + datetime.timedelta(days=7),
                      'active': True}
        )
        return super().form_valid(form)

    def get_success_url(self):
        return reverse_lazy('cabinet:index')