text: import csv
  from decimal import Decimal
  from operator import itemgetter
  
  from django.conf import settings
  from django.contrib import messages
  from django.core import management
  from django.db.models import Count, Q, Sum
  from django.http import FileResponse, HttpResponse
  from django.urls import reverse, reverse_lazy
  from django.views import View
  from django.views.generic import DetailView, FormView, ListView, View
  from django.views.generic.detail import SingleObjectMixin
  from django.views.generic.edit import FormView
  
  from .forms import ImportForm, InitializeForm, SubmitForm
  from .models import Event, ProblemCategory, Solution, Team
  
  
  class SingleObjectFormView(FormView, SingleObjectMixin):
      object_field_name = None
  
      def dispatch(self, request, *args, **kwargs):
          self.object = self.get_object()
  
          return super(SingleObjectFormView, self).dispatch(request, *args, **kwargs)
  
      def get_form_kwargs(self):
          kwargs = super(SingleObjectFormView, self).get_form_kwargs()
  
          if self.request.method in ('POST', 'PUT'):
              data = kwargs['data'].copy()
              data[self.object_field_name] = str(self.object.pk)
              kwargs['data'] = data
  
          if self.request.method == 'GET':
              kwargs['initial'].update({self.object_field_name: self.object})
  
          return kwargs
  
  
  class EventListView(ListView):
      model = Event
      context_object_name = 'events'
  
      template_name = 'competition/index.html'
  
  
  class EventDetailView(DetailView):
      model = Event
      context_object_name = 'event'
  
      template_name = 'competition/event.html'
  
  
  class InitializeView(FormView):
      template_name = 'competition/initialize.html'
  
      form_class = InitializeForm
      success_url = reverse_lazy('competition:index')
  
      def form_valid(self, form):
          event = form.save()
  
          messages.success(self.request, f'{ event } bol úspešne vytvorený!')
  
          return super(InitializeView, self).form_valid(form)
  
  
  class SubmitFormView(SingleObjectFormView):
      model = Event
      context_object_name = 'event'
  
      template_name = 'competition/submit.html'
  
      form_class = SubmitForm
  
      object_field_name = 'event'
  
      def get_success_url(self):
          return reverse('competition:submit', kwargs={'pk': self.kwargs['pk']})
  
      def get_context_data(self, **kwargs):
          context = super(SubmitFormView, self).get_context_data(**kwargs)
  
          context['solutions'] = Solution.objects.filter(
              team__event=self.object).order_by('-time')[:10]
  
          return context
  
      def form_valid(self, form):
          solution = form.save()
  
          messages.success(
              self.request,
              f'Úloha { solution.problem_category.name.lower() } '
              f'{ solution.problem_position } '
              f'bola úspešne odovzdaná tímom { solution.team.name } '
              f'zo školy { solution.team.school }.')
  
          return super(SubmitFormView, self).form_valid(form)
  
      def form_invalid(self, form):
          data = form.data.copy()
          data['code'] = ''
          form.data = data
  
          return super(SubmitFormView, self).form_invalid(form)
  
  
  class ResultsView(DetailView):
      model = Event
      context_object_name = 'event'
  
      template_name = 'competition/results.html'
  
      def get_context_data(self, **kwargs):
          context = super(ResultsView, self).get_context_data(**kwargs)
  
          context['categories'], context['teams'] = generate_results(self.object)
  
          return context
  
  
  class CSVResultsView(View, SingleObjectMixin):
      model = Event
      context_object_name = 'event'
  
      def get(self, request, pk):
          self.object = self.get_object()
  
          response = HttpResponse(content_type='text/csv')
          response['Content-Disposition'] = 'attachment; filename="export.csv"'
  
          categories, teams = generate_results(self.object)
  
          writer = csv.writer(response, delimiter=settings.CSV_DELIMITER)
  
          heading = ['Poradie', 'Názov tímu',
                     'Škola', 'Účastníci', 'Bonifikácia']
          heading.extend([category.name for category in categories])
          heading.extend(['Úlohy', 'Spolu'])
  
          writer.writerow(heading)
  
          for team in teams:
              row = [team['rank'], team['name'], team['school'],
                     team['members'], team['compensation']]
              row.extend(team['solved_by_category'])
              row.extend([team['problem_points'], team['total_points']])
  
              writer.writerow(row)
  
          return response
  
  
  class ImportFormView(FormView):
      form_class = ImportForm
  
      template_name = 'competition/import.html'
  
      def get_success_url(self):
          return reverse('competition:import')
  
      def form_valid(self, form):
          saved = form.save()
  
          messages.success(
              self.request,
              f'Údaje boli úspešne importované. Počet tímov: { saved["teams"] },'
              f' počet účastníkov: { saved["participants"] }')
  
          return super(ImportFormView, self).form_valid(form)
  
  
  class ExportView(View):
      def get(self, request):
          management.call_command('dumpdata', format='json', output='db.json')
  
          return FileResponse(open('db.json', 'rb'), as_attachment=True)
  
  
  def generate_results(event):
      categories = ProblemCategory.objects.filter(
          event=event).order_by('position')
  
      # Pull information about teams from database
      # TODO: use annotate instead of pulling data into a dictionary
      teams = [
          {
              'name': team.name,
              'school': team.school,
              'members': ', '.join([
                  f'{ member.first_name } { member.last_name }'
                  for member in team.participant_set.order_by('last_name', 'first_name')
              ]),
              **team.participant_set.aggregate(compensation=Sum('compensation__points')),
              'solved_by_category': [
                  team.solution_set.filter(problem_category=category).count()
                  for category in categories
              ],
              'total_points': Decimal(0),
              'problem_points': Decimal(0),
              'solved_problems': 0,
          } for team in Team.objects.filter(event=event)
      ]
  
      # Compute points
  
      for team in teams:
          for count, category in zip(team['solved_by_category'], categories):
              if category.multiplicative_compensation:
                  category_points = count * \
                      category.points*team['compensation']
              else:
                  category_points = count * \
                      category.points
  
              team['total_points'] += category_points
  
              if category.is_problem:
                  team['solved_problems'] += count
                  team['problem_points'] += category_points
  
          if event.flat_compensation:
              team['total_points'] += team['compensation']
  
      # Sort teams
      if event.name == 'LOMIHLAV':
          team_key = itemgetter('total_points', 'solved_problems')
      else:
          team_key = itemgetter('total_points', 'problem_points')
  
      teams.sort(key=team_key, reverse=True)
  
      # Generate ranks
      def save_team_ranks(teams, lower_rank):
          upper_rank = lower_rank + len(teams) - 1
  
          if len(teams) == 1:
              teams[0]['rank'] = lower_rank
          else:
              for team_to_rank in teams:
                  team_to_rank['rank'] = f'{ lower_rank } - { upper_rank }'
  
          return upper_rank
  
      lower_rank = 1
      identically_ranked_teams = []
  
      for team in teams:
          if not identically_ranked_teams or\
                  team_key(team) == team_key(identically_ranked_teams[-1]):
              identically_ranked_teams.append(team)
          else:
              lower_rank = save_team_ranks(
                  identically_ranked_teams, lower_rank) + 1
  
              identically_ranked_teams.clear()
              identically_ranked_teams.append(team)
  
      save_team_ranks(identically_ranked_teams, lower_rank)
  
      return (categories, teams)
  