# -*- coding: utf-8 -*-
# lingo - basket and payment system
# Copyright (C) 2015  Entr'ouvert
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from decimal import Decimal, ROUND_HALF_UP
import json
import logging
import requests

from django.contrib.auth.models import User
from django.core.exceptions import ObjectDoesNotExist, PermissionDenied
from django.core.urlresolvers import reverse
from django.http import HttpResponse, HttpResponseRedirect, HttpResponseBadRequest
from django.http import HttpResponseForbidden, Http404, JsonResponse
from django.template.response import TemplateResponse
from django.utils import timezone, dateparse
from django.utils.encoding import force_text
from django.views.decorators.csrf import csrf_exempt
from django.views.generic import View, DetailView, ListView, TemplateView
from django.conf import settings
from django.contrib import messages
from django.utils.translation import ugettext_lazy as _
from django.db.transaction import atomic
from django.utils.encoding import smart_text

import eopayment

from combo.data.models import Page
from combo.utils import check_request_signature, aes_hex_decrypt, DecryptionError
from combo.profile.utils import get_user_from_name_id

from .models import (Regie, BasketItem, Transaction, TransactionOperation,
                     LingoBasketCell, SelfDeclaredInvoicePayment, PaymentBackend)

def get_eopayment_object(request, regie_or_payment_backend):
    payment_backend = regie_or_payment_backend
    if isinstance(regie_or_payment_backend, Regie):
        payment_backend = regie_or_payment_backend.payment_backend
    options = payment_backend.service_options
    options.update({
        'automatic_return_url': request.build_absolute_uri(
                reverse('lingo-callback-payment-backend',
                        kwargs={'payment_backend_pk': payment_backend.id})),
        'normal_return_url': request.build_absolute_uri(
                reverse('lingo-return-payment-backend',
                        kwargs={'payment_backend_pk': payment_backend.id})),
    })
    return eopayment.Payment(payment_backend.service, options)


def get_basket_url():
    return LingoBasketCell.objects.all()[0].page.get_online_url()


def lingo_check_request_signature(request):
    keys = []
    if getattr(settings, 'LINGO_API_SIGN_KEY', None):
        keys = [settings.LINGO_API_SIGN_KEY]
    return check_request_signature(request, keys=keys)


class RegiesApiView(ListView):
    model = Regie

    def get(self, request, *args, **kwargs):
        response = HttpResponse(content_type='application/json')
        data = {'data': [x.as_api_dict() for x in self.get_queryset()]}
        json_str = json.dumps(data)
        if 'jsonpCallback' in request.GET:
            json_str = '%s(%s);' % (request.GET['jsonpCallback'], json_str)
        response.write(json_str)
        return response


class AddBasketItemApiView(View):
    http_method_names = ['post', 'options']

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(AddBasketItemApiView, self).dispatch(*args, **kwargs)

    def get_amount(self, amount):
        if isinstance(amount, list):
            d = Decimal(sum([Decimal(a) for a in amount]))
        else:
            d = Decimal(amount)
        return d.quantize(Decimal('0.01'), ROUND_HALF_UP)

    def post(self, request, *args, **kwargs):
        if not lingo_check_request_signature(request):
            return HttpResponseForbidden()

        request_body = json.loads(self.request.body)
        extra = request_body.get('extra', {})

        if not 'amount' in request.GET and not 'amount' in request_body and \
                not 'amount' in extra:
            raise Exception('missing amount parameter')

        item = BasketItem(amount=0)
        item.amount = self.get_amount(request.GET.getlist('amount'))

        if request_body.get('amount'):
            item.amount += self.get_amount(request_body['amount'])

        if extra.get('amount'):
            item.amount += self.get_amount(extra['amount'])

        if 'extra' in request_body:
            item.request_data = request_body.get('extra')
        else:
            item.request_data = request_body

        try:
            if request.GET.get('NameId'):
                user = get_user_from_name_id(request.GET.get('NameId'), raise_on_missing=True)
            elif request.GET.get('email'):
                user = User.objects.get(email=request.GET.get('email'))
            else:
                raise Exception('no user specified')
        except User.DoesNotExist:
            raise Exception('unknown user')

        item.user = user
        if request.GET.get('regie_id'):
            try:
                item.regie = Regie.objects.get(slug=request.GET.get('regie_id'))
            except Regie.DoesNotExist:
                try:
                    item.regie = Regie.objects.get(id=int(request.GET.get('regie_id')))
                except (ValueError, Regie.DoesNotExist):
                    return HttpResponseBadRequest('Unknown regie')
        else:
            try:
                item.regie = Regie.objects.get(is_default=True)
            except Regie.DoesNotExist:
                # if there's no default regie, use the first one we get from
                # the database...
                item.regie = Regie.objects.all()[0]

        if request.GET.get('cancellable') == 'no':
            item.user_cancellable = False

        item.subject = request_body.get('display_name')
        item.source_url = request_body.get('url') or ''

        if 'capture_date' in request_body:
            try:
                # parse_date returns None when the string format is invalid
                capture_date_err = False
                item.capture_date = dateparse.parse_date(request_body['capture_date'])
            except TypeError:
                capture_date_err = True
            if item.capture_date is None or capture_date_err:
                return HttpResponseBadRequest(
                    'Bad format for capture date, it should be yyyy-mm-dd.')

        item.save()
        item.regie.compute_extra_fees(user=item.user)

        payment_url = reverse('basket-item-pay-view', kwargs={'item_id': item.id})
        return JsonResponse({'result': 'success', 'id': str(item.id),
                             'payment_url': request.build_absolute_uri(payment_url)})


class RemoveBasketItemApiView(View):
    http_method_names = ['post', 'options']

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(RemoveBasketItemApiView, self).dispatch(*args, **kwargs)

    def post(self, request, *args, **kwargs):
        if not lingo_check_request_signature(request):
            return HttpResponseForbidden()

        request_body = json.loads(self.request.body)

        if not 'basket_item_id' in request_body:
            raise Exception('missing basket_item_id parameter')

        try:
            if request.GET.get('NameId'):
                user = get_user_from_name_id(request.GET.get('NameId'), raise_on_missing=True)
                if user is None:
                    raise User.DoesNotExist()
            elif request.GET.get('email'):
                user = User.objects.get(email=request.GET.get('email'))
            else:
                raise Exception('no user specified')
        except User.DoesNotExist:
            raise Exception('unknown user')

        item = BasketItem.objects.get(id=request_body.get('basket_item_id'),
                user=user, cancellation_date__isnull=True)
        notify_origin = bool(request_body.get('notify', 'false') == 'true')
        item.notify_cancellation(notify_origin=notify_origin)

        response = HttpResponse(content_type='application/json')
        response.write(json.dumps({'result': 'success'}))
        return response


class ValidateTransactionApiView(View):
    http_method_names = ['post', 'options']

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(ValidateTransactionApiView, self).dispatch(*args, **kwargs)

    def post(self, request, *args, **kwargs):
        if not lingo_check_request_signature(request):
            return HttpResponseForbidden()

        logger = logging.getLogger(__name__)
        try:
            transaction = Transaction.objects.get(id=request.GET['transaction_id'])
        except Transaction.DoesNotExist:
            logger.warning(u'received validate request for unknown transaction %s',
                           request.GET['transaction_id'])
            raise Http404

        payment = get_eopayment_object(request, transaction.regie)
        amount = request.GET['amount']

        logger.info(u'validating amount %s for transaction %s', amount, smart_text(transaction.id))
        try:
            result = payment.backend.validate(Decimal(amount), transaction.bank_data)
        except eopayment.ResponseError as e:
            logger.error(u'failed in validation operation: %s', e)
            response = HttpResponse(content_type='application/json')
            response.write(json.dumps({'err': 1, 'e': force_text(e)}))
            return response

        logger.info(u'bank validation result: %r', result)
        operation = TransactionOperation(transaction=transaction,
                kind='validation', amount=Decimal(amount), bank_result=result)
        operation.save()

        response = HttpResponse(content_type='application/json')
        response.write(json.dumps({'err': 0, 'extra': result}))
        return response


class CancelTransactionApiView(View):
    http_method_names = ['post', 'options']

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(CancelTransactionApiView, self).dispatch(*args, **kwargs)

    def post(self, request, *args, **kwargs):
        if not lingo_check_request_signature(request):
            return HttpResponseForbidden()

        logger = logging.getLogger(__name__)
        try:
            transaction = Transaction.objects.get(id=request.GET['transaction_id'])
        except Transaction.DoesNotExist:
            logger.warning(u'received validate request for unknown transaction %s',
                           request.GET['transaction_id'])
            raise Http404

        payment = get_eopayment_object(request, transaction.regie)
        amount = request.GET['amount']

        logger.info(u'cancelling amount %s for transaction %s', amount, smart_text(transaction.id))
        try:
            result = payment.backend.cancel(Decimal(amount), transaction.bank_data)
        except eopayment.ResponseError as e:
            logger.error(u'failed in cancel operation: %s', e)
            response = HttpResponse(content_type='application/json')
            response.write(json.dumps({'err': 1, 'e': force_text(e)}))
            return response

        logger.info(u'bank cancellation result: %r', result)
        operation = TransactionOperation(transaction=transaction,
                kind='cancellation', amount=Decimal(amount), bank_result=result)
        operation.save()

        response = HttpResponse(content_type='application/json')
        response.write(json.dumps({'err': 0, 'extra': result}))
        return response


class PayMixin(object):
    @atomic
    def handle_payment(self, request, regie, items, remote_items, next_url='/', email=''):
        if remote_items:
            total_amount = sum([x.amount for x in remote_items])
        else:
            total_amount = sum([x.amount for x in items])

        if total_amount < regie.payment_min_amount:
            messages.warning(request, _(u'Minimal payment amount is %s €.') % regie.payment_min_amount)
            return HttpResponseRedirect(next_url)

        for item in items:
            if item.regie != regie:
                messages.error(request, _(u'Invalid grouping for basket items.'))
                return HttpResponseRedirect(next_url)
        user = request.user if request.user.is_authenticated() else None
        transaction = Transaction()
        if user:
            transaction.user = user
            email = user.email
            firstname = user.first_name
            lastname = user.last_name
        else:
            transaction.user = None
            firstname = ''
            lastname = ''

        transaction.save()
        transaction.regie = regie
        transaction.items = items
        transaction.remote_items = ','.join([x.id for x in remote_items])
        transaction.status = 0
        transaction.amount = total_amount

        payment = get_eopayment_object(request, regie)
        kwargs = {
            'email': email, 'first_name': firstname, 'last_name': lastname
        }
        if items:
            capture_date = items[0].capture_date
            if capture_date:
                kwargs['capture_date'] = capture_date
        if regie.transaction_options:
            kwargs.update(regie.transaction_options)
        (order_id, kind, data) = payment.request(total_amount, **kwargs)
        logger = logging.getLogger(__name__)
        logger.info(u'emitted payment request with id %s', smart_text(order_id), extra={
            'eopayment_order_id': smart_text(order_id), 'eopayment_data': repr(data)})
        transaction.order_id = order_id
        transaction.save()

        # store the next url in session in order to be able to redirect to
        # it if payment is canceled
        request.session.setdefault('lingo_next_url',
                                   {})[order_id] = request.build_absolute_uri(next_url)
        request.session.modified = True

        if kind == eopayment.URL:
            return HttpResponseRedirect(data)
        elif kind == eopayment.FORM:
            return TemplateResponse(request, 'lingo/payment_form.html', {'form': data})

        raise NotImplementedError()


class PayView(PayMixin, View):
    def post(self, request, *args, **kwargs):
        regie_id = request.POST.get('regie')
        next_url = request.POST.get('next_url') or '/'
        user = request.user if request.user.is_authenticated() else None
        remote_items = []
        items = []
        if regie_id and Regie.objects.get(pk=regie_id).is_remote():
            regie = Regie.objects.get(pk=regie_id)
            # get all items data from regie webservice
            for item_id in request.POST.getlist('item'):
                remote_items.append(regie.get_invoice(user, item_id))
        else:
            if user is None:
                messages.error(request, _(u'Payment requires to be logged in.'))
                return HttpResponseRedirect(next_url)

            if not regie_id:
                # take all items but check they're from the same regie
                items = BasketItem.get_items_to_be_paid(user=user)
                regie_id = items[0].regie_id
                for item in items:
                    if item.regie_id != regie_id:
                        messages.error(request, _(u'Invalid grouping for basket items.'))
                        return HttpResponseRedirect(next_url)

            regie = Regie.objects.get(id=regie_id)
            regie.compute_extra_fees(user=user)
            items = BasketItem.get_items_to_be_paid(user=user).filter(regie=regie)

        if items:
            capture_date = items[0].capture_date
            for item in items:
                if item.capture_date != capture_date:
                    messages.error(
                        request,
                        _(u'Invalid grouping for basket items: different capture dates.'))
                    return HttpResponseRedirect(next_url)

        if not user and not request.POST.get('email'):
            messages.warning(request, _(u'You must give an email address.'))
            return HttpResponseRedirect(request.POST.get('item_url'))
        email = request.POST.get('email')

        # XXX: mark basket items as being processed (?)
        return self.handle_payment(request, regie, items, remote_items, next_url, email)


class BasketItemPayView(PayMixin, View):
    def get(self, request, *args, **kwargs):
        next_url = request.GET.get('next_url') or '/'
        if not (request.user and request.user.is_authenticated()):
            return HttpResponseForbidden(_('No item payment allowed for anonymous users.'))

        item = BasketItem.objects.get(pk=kwargs['item_id'])
        regie = item.regie
        if regie.extra_fees_ws_url:
            return HttpResponseForbidden(_('No item payment allowed as extra fees set.'))

        if item.user != request.user:
            return HttpResponseForbidden(_('Wrong item: payment not allowed.'))

        return self.handle_payment(request, regie, [item], [], next_url)


class PaymentException(Exception):
    pass


class UnsignedPaymentException(PaymentException):
    pass


class UnknownPaymentException(PaymentException):
    pass


class PaymentView(View):
    def handle_response(self, request, backend_response, **kwargs):
        if 'regie_pk' in kwargs:
            payment_backend = Regie.objects.get(id=kwargs['regie_pk']).payment_backend
        elif 'payment_backend_pk' in kwargs:
            payment_backend = PaymentBackend.objects.get(id=kwargs['payment_backend_pk'])
        else:
            raise Exception("A payment backend or regie primary key must be specified")

        payment = get_eopayment_object(request, payment_backend)
        logger = logging.getLogger(__name__)
        logger.info(u'received payment response: %r', backend_response)
        try:
            payment_response = payment.response(backend_response)
        except eopayment.ResponseError as e:
            logger.error(u'failed to process payment response: %s', e,
                         extra={'eopayment_raw_response': repr(backend_response)})
            raise PaymentException('Failed to process payment response')

        extra_info = {
            'eopayment_order_id': smart_text(payment_response.order_id),
            'eopayment_response': repr(payment_response),
        }
        for k, v in payment_response.bank_data.items():
            extra_info['eopayment_bank_data_' + k] = smart_text(v)
        if not payment_response.signed and not payment_response.result == eopayment.CANCELLED:
            # we accept unsigned cancellation requests as some platforms do
            # that :/
            logger.warning(u'received unsigned payment response with id %s',
                           smart_text(payment_response.order_id), extra=extra_info)
            raise UnsignedPaymentException('Received unsigned payment response')

        try:
            transaction = Transaction.objects.get(order_id=payment_response.order_id)
        except Transaction.DoesNotExist:
            logger.warning(u'received unknown payment response with id %s',
                           smart_text(payment_response.order_id), extra=extra_info)
            raise UnknownPaymentException('Received unknown payment response')
        else:
            extra_info['lingo_transaction_id'] = transaction.pk
            if transaction.user:
                # let hobo logger filter handle the extraction of user's infos
                extra_info['user'] = transaction.user
            logger.info(u'received known payment response with id %s',
                           smart_text(payment_response.order_id), extra=extra_info)

        if transaction.status == payment_response.result:
            # return early if transaction status didn't change (it means the
            # payment service sent the response both as server to server and
            # via the user browser and we already handled one).
            return transaction

        if transaction.status and transaction.status != payment_response.result:
            logger.info(u'received payment notification on existing transaction '
                            '(status: %s, new status: %s)' % (
                        transaction.status, payment_response.result))

        # check if transaction belongs to right regie
        if not transaction.regie.payment_backend == payment_backend:
            logger.warning(u'received payment for inappropriate payment backend '
                            '(expecteds: %s, received: %s)' % (
                                transaction.regie.payment_backend, payment_backend))
            raise PaymentException('Invalid payment regie')

        transaction.status = payment_response.result
        transaction.bank_transaction_id = payment_response.transaction_id
        transaction.bank_data = payment_response.bank_data
        transaction.end_date = timezone.now()
        transaction.save()

        if payment_response.result == eopayment.WAITING:
            # mark basket items as waiting for payment confirmation
            transaction.items.all().update(waiting_date=timezone.now())
            return transaction

        if payment_response.result == eopayment.CANCELLED:
            # mark basket items as no longer waiting so the user can restart a
            # payment.
            transaction.items.all().update(waiting_date=None)
            return transaction

        if payment_response.result not in (eopayment.PAID, eopayment.ACCEPTED):
            return transaction

        transaction.items.update(payment_date=transaction.end_date)

        for item in transaction.items.all():
            try:
                item.notify_payment()
            except:
                # ignore errors, it will be retried later on if it fails
                logger.exception('error in sync notification for basket item %s', item.id)

        if transaction.remote_items:
            transaction.first_notify_remote_items_of_payments()

        return transaction


class CallbackView(PaymentView):
    def handle_callback(self, request, backend_response, **kwargs):
        try:
            self.handle_response(request, backend_response, **kwargs)
        except UnknownPaymentException as e:
            raise Http404(force_text(e))
        except PaymentException as e:
            return HttpResponseBadRequest(force_text(e))
        return HttpResponse()

    def get(self, request, *args, **kwargs):
        return self.handle_callback(request, request.environ['QUERY_STRING'], **kwargs)

    def post(self, request, *args, **kwargs):
        return self.handle_callback(request, request.body, **kwargs)

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(CallbackView, self).dispatch(*args, **kwargs)


class ReturnView(PaymentView):
    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(ReturnView, self).dispatch(*args, **kwargs)

    def get(self, request, *args, **kwargs):
        if not request.environ['QUERY_STRING']:
            return HttpResponseBadRequest('Missing query string')
        return self.handle_return(request, request.environ['QUERY_STRING'], **kwargs)

    def post(self, request, *args, **kwargs):
        return self.handle_return(request, request.body, **kwargs)

    def handle_return(self, request, backend_response, **kwargs):
        transaction = None
        try:
            transaction = self.handle_response(request, backend_response, **kwargs)
        except UnsignedPaymentException as e:
            # some payment backends do not sign return URLs, don't mark this as
            # an error, they will provide a notification to the callback
            # endpoint.
            pass
        except PaymentException as e:
            messages.error(request, _('We are sorry but the payment service '
                                      'failed to provide a correct answer.'))
            return HttpResponseRedirect(get_basket_url())

        if transaction and transaction.status in (eopayment.PAID, eopayment.ACCEPTED):
            messages.info(request, transaction.regie.get_text_on_success())

        if transaction and request.session.get('lingo_next_url'):
            redirect_url = request.session['lingo_next_url'].get(transaction.order_id)
            if redirect_url:
                return HttpResponseRedirect(redirect_url)

        # return to basket page if there are still items to pay
        if request.user.is_authenticated():
            remaining_basket_items = BasketItem.get_items_to_be_paid(
                user=self.request.user).count()
            if remaining_basket_items:
                return HttpResponseRedirect(get_basket_url())
        return HttpResponseRedirect('/')


class ItemDownloadView(View):
    http_method_names = [u'get']

    def get(self, request, *args, **kwargs):
        try:
            regie = Regie.objects.get(pk=kwargs['regie_id'])
        except Regie.DoesNotExist:
            raise Http404()

        try:
            item_id = aes_hex_decrypt(settings.SECRET_KEY, kwargs['item_crypto_id'])
        except DecryptionError:
            raise Http404()

        try:
            data = regie.get_invoice_pdf(request.user, item_id)
        except PermissionDenied:
            return HttpResponseForbidden()
        except DecryptionError as e:
            return Http404(str(e))

        if data.status_code != 200:
            logging.error('failed to retrieve invoice (%r)', data.status_code)
            messages.error(request, _('We are sorry but an error occured when retrieving the invoice.'))
            if self.request.META.get('HTTP_REFERER'):
                return HttpResponseRedirect(self.request.META.get('HTTP_REFERER'))
            return HttpResponseRedirect('/')

        r = HttpResponse(data, content_type='application/pdf')
        r['Content-Disposition'] = 'attachment; filename="%s.pdf"' % item_id
        return r


class ItemView(TemplateView):
    http_method_names = [u'get']

    def get_context_data(self, **kwargs):
        ret = {'item_url': self.request.get_full_path()}

        try:
            regie = Regie.objects.get(pk=kwargs['regie_id'])
        except Regie.DoesNotExist:
            raise Http404()

        try:
            item_id = aes_hex_decrypt(settings.SECRET_KEY, kwargs['item_crypto_id'])
        except DecryptionError:
            raise Http404()

        item = regie.get_invoice(self.request.user, item_id)
        if not item:
            raise Http404(_('No item was found.'))
        if self.request.GET.get('page'):
            try:
                ret['page'] = Page.objects.get(pk=self.request.GET['page'])
            except (Page.DoesNotExist, ValueError):
                pass
        ret.update({'item': item, 'regie': regie})
        return ret

    def get_template_names(self):
        if self.request.is_ajax:
            return ['lingo/combo/item.html']
        return ['lingo/combo/invoice_fullpage.html']


class CancelItemView(DetailView):
    model = BasketItem
    template_name = 'lingo/combo/cancel-item.html'

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

    def get_queryset(self):
        user = self.request.user if self.request.user.is_authenticated() else None
        return BasketItem.get_items_to_be_paid(user=user)

    def post(self, request, *args, **kwargs):
        if not request.user.is_authenticated():
            messages.error(request, _('An error occured when removing the item. '
                                      '(no authenticated user)'))
            return HttpResponseRedirect(get_basket_url())
        if not self.get_object().user_cancellable:
            messages.error(request, _('This item cannot be removed.'))
            return HttpResponseRedirect(get_basket_url())
        try:
            self.get_object().notify_cancellation(notify_origin=True)
        except requests.exceptions.HTTPError:
            messages.error(request, _('An error occured when removing the item.'))
        return HttpResponseRedirect(get_basket_url())


class SelfInvoiceView(View):
    http_method_names = ['get',  'options']

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(SelfInvoiceView, self).dispatch(*args, **kwargs)

    def get(self, request, *args, **kwargs):
        try:
            obj = SelfDeclaredInvoicePayment.objects.get(id=kwargs['cell_id'])
        except SelfDeclaredInvoicePayment.DoesNotExist:
            raise Http404()
        invoice_id = request.GET.get('invoice-number', '')
        invoice_amount = request.GET.get('invoice-amount', '').replace(',', '.')
        msg = None
        url = None
        try:
            invoice_amount = Decimal(invoice_amount)
        except ArithmeticError:
            invoice_amount = '-'
            msg = _('Sorry, the provided amount is invalid.')
        else:
            for regie in obj.get_regies():
                try:
                    invoice = regie.get_invoice(None, invoice_id, log_errors=False)
                except ObjectDoesNotExist:
                    continue
                if invoice.total_amount != invoice_amount:
                    continue
                url = reverse('view-item', kwargs={
                    'regie_id': regie.id, 'item_crypto_id': invoice.crypto_id})
                break
            else:
                msg = _('Sorry, no invoice were found with that number and amount.')
        if request.GET.get('ajax') == 'on':
            response = HttpResponse(content_type='application/json')
            response.write(json.dumps({'url': url, 'msg': msg and force_text(msg)}))
            return response
        if url:
            return HttpResponseRedirect(url)
        messages.warning(request, msg)
        return HttpResponseRedirect(request.GET.get('page_path') or '/')