text: import json
  from collections import OrderedDict
  from io import BytesIO
  from typing import Tuple
  
  from django import forms
  from django.conf import settings
  from django.contrib.staticfiles import finders
  from django.core.files import File
  from django.core.files.base import ContentFile
  from django.core.files.storage import default_storage
  from django.db.models import Exists, OuterRef
  from django.db.models.functions import Coalesce
  from django.utils.translation import ugettext as _
  from jsonfallback.functions import JSONExtract
  from PyPDF2 import PdfFileMerger
  from reportlab.lib import pagesizes
  from reportlab.pdfgen import canvas
  
  from pretix.base.exporter import BaseExporter
  from pretix.base.i18n import language
  from pretix.base.models import Order, OrderPosition
  from pretix.base.pdf import Renderer
  from pretix.base.services.orders import OrderError
  from pretix.base.settings import PERSON_NAME_SCHEMES
  from pretix.plugins.badges.models import BadgeItem, BadgeLayout
  
  
  def _renderer(event, layout):
      if layout is None:
          return None
      if isinstance(layout.background, File) and layout.background.name:
          bgf = default_storage.open(layout.background.name, "rb")
      else:
          bgf = open(finders.find('pretixplugins/badges/badge_default_a6l.pdf'), "rb")
      return Renderer(event, json.loads(layout.layout), bgf)
  
  
  def render_pdf(event, positions):
      Renderer._register_fonts()
  
      renderermap = {
          bi.item_id: _renderer(event, bi.layout)
          for bi in BadgeItem.objects.select_related('layout').filter(item__event=event)
      }
      try:
          default_renderer = _renderer(event, event.badge_layouts.get(default=True))
      except BadgeLayout.DoesNotExist:
          default_renderer = None
      merger = PdfFileMerger()
  
      any = False
      for op in positions:
          r = renderermap.get(op.item_id, default_renderer)
          if not r:
              continue
          any = True
  
          with language(op.order.locale):
              buffer = BytesIO()
              p = canvas.Canvas(buffer, pagesize=pagesizes.A4)
              r.draw_page(p, op.order, op)
              p.save()
              outbuffer = r.render_background(buffer, 'Badge')
              merger.append(ContentFile(outbuffer.read()))
  
      outbuffer = BytesIO()
      merger.write(outbuffer)
      merger.close()
      outbuffer.seek(0)
      if not any:
          raise OrderError(_("None of the selected products is configured to print badges."))
      return outbuffer
  
  
  class BadgeExporter(BaseExporter):
      identifier = "badges"
      verbose_name = _("Attendee badges")
  
      @property
      def export_form_fields(self):
          name_scheme = PERSON_NAME_SCHEMES[self.event.settings.name_scheme]
          d = OrderedDict(
              [
                  ('items',
                   forms.ModelMultipleChoiceField(
                       queryset=self.event.items.annotate(
                           no_badging=Exists(BadgeItem.objects.filter(item=OuterRef('pk'), layout__isnull=True))
                       ).exclude(no_badging=True),
                       label=_('Limit to products'),
                       widget=forms.CheckboxSelectMultiple(
                           attrs={'class': 'scrolling-multiple-choice'}
                       ),
                       initial=self.event.items.filter(admission=True)
                   )),
                  ('include_pending',
                   forms.BooleanField(
                       label=_('Include pending orders'),
                       required=False
                   )),
                  ('order_by',
                   forms.ChoiceField(
                       label=_('Sort by'),
                       choices=[
                           ('name', _('Attendee name')),
                           ('code', _('Order code')),
                       ] + ([
                           ('name:{}'.format(k), _('Attendee name: {part}').format(part=label))
                           for k, label, w in name_scheme['fields']
                       ] if settings.JSON_FIELD_AVAILABLE and len(name_scheme['fields']) > 1 else []),
                   )),
              ]
          )
          return d
  
      def render(self, form_data: dict) -> Tuple[str, str, str]:
          qs = OrderPosition.objects.filter(
              order__event=self.event, item_id__in=form_data['items']
          ).prefetch_related(
              'answers', 'answers__question'
          ).select_related('order', 'item', 'variation', 'addon_to')
  
          if form_data.get('include_pending'):
              qs = qs.filter(order__status__in=[Order.STATUS_PAID, Order.STATUS_PENDING])
          else:
              qs = qs.filter(order__status__in=[Order.STATUS_PAID])
  
          if form_data.get('order_by') == 'name':
              qs = qs.order_by('attendee_name_cached', 'order__code')
          elif form_data.get('order_by') == 'code':
              qs = qs.order_by('order__code')
          elif form_data.get('order_by', '').startswith('name:'):
              part = form_data['order_by'][5:]
              qs = qs.annotate(
                  resolved_name=Coalesce('attendee_name_parts', 'addon_to__attendee_name_parts', 'order__invoice_address__name_parts')
              ).annotate(
                  resolved_name_part=JSONExtract('resolved_name', part)
              ).order_by(
                  'resolved_name_part'
              )
  
          outbuffer = render_pdf(self.event, qs)
          return 'badges.pdf', 'application/pdf', outbuffer.read()
  