AKDashboard/tests.py

+import zoneinfo
+
+from django.apps import apps
+from django.test import override_settings, TestCase
+from django.urls import reverse
+from django.utils.timezone import now
+
+from AKDashboard.models import DashboardButton
+from AKModel.models import AK, AKCategory, Event
+from AKModel.tests import BasicViewTests
+
+
+class DashboardTests(TestCase):
+    """
+    Specific Dashboard Tests
+    """
+
+    @classmethod
+    def setUpTestData(cls):
+        """
+        Initialize Test database
+        """
+        super().setUpTestData()
+        cls.event = Event.objects.create(
+                name="Dashboard Test Event",
+                slug="dashboardtest",
+                timezone=zoneinfo.ZoneInfo("Europe/Berlin"),
+                start=now(),
+                end=now(),
+                active=True,
+                plan_hidden=False,
+        )
+        cls.default_category = AKCategory.objects.create(
+                name="Test Category",
+                event=cls.event,
+        )
+
+    def test_dashboard_view(self):
+        """
+        Check that the main dashboard is reachable
+        (would also be covered by generic view testcase below)
+        """
+        url = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+        response = self.client.get(url)
+        self.assertEqual(response.status_code, 200)
+
+    def test_nonexistent_dashboard_view(self):
+        """
+        Make sure there is no dashboard for an non-existing event
+        """
+        url = reverse('dashboard:dashboard_event', kwargs={"slug": "nonexistent-event"})
+        response = self.client.get(url)
+        self.assertEqual(response.status_code, 404)
+
+    @override_settings(DASHBOARD_SHOW_RECENT=True)
+    def test_history(self):
+        """
+        Test displaying of history
+
+        For the sake of that test, the setting to show recent events in dashboard is enforced to be true
+        regardless of the default configuration currently in place
+        """
+        url = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+
+        # History should be empty
+        response = self.client.get(url)
+        self.assertQuerySetEqual(response.context["recent_changes"], [])
+
+        AK.objects.create(
+                name="Test AK",
+                category=self.default_category,
+                event=self.event,
+        )
+
+        # History should now contain one AK (Test AK)
+        response = self.client.get(url)
+        self.assertEqual(len(response.context["recent_changes"]), 1)
+        self.assertEqual(response.context["recent_changes"][0]['text'], "New AK: Test AK.")
+
+    def test_public(self):
+        """
+        Test handling of public and private events
+        (only public events should be part of the standard dashboard,
+        but there should be an individual dashboard for both public and private events)
+        """
+        url_dashboard_index = reverse('dashboard:dashboard')
+        url_event_dashboard = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+
+        # Non-Public event (should not be part of the global dashboard
+        # but should have an individual dashboard page for those knowing the url)
+        self.event.public = False
+        self.event.save()
+        response = self.client.get(url_dashboard_index)
+        self.assertEqual(response.status_code, 200)
+        self.assertFalse(self.event in response.context["active_and_current_events"])
+        self.assertFalse(self.event in response.context["old_events"])
+        response = self.client.get(url_event_dashboard)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context["event"], self.event)
+
+        # Public event -- should be part of the global dashboard
+        self.event.public = True
+        self.event.save()
+        response = self.client.get(url_dashboard_index)
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(self.event in response.context["active_and_current_events"])
+
+    def test_active(self):
+        """
+        Test existence of buttons with regard to activity status of the given event
+        """
+        url_event_dashboard = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+
+        if apps.is_installed('AKSubmission'):
+            # Non-active event -> No submission
+            self.event.active = False
+            self.event.save()
+            response = self.client.get(url_event_dashboard)
+            self.assertNotContains(response, "AK Submission")
+
+            # Active event -> Submission should be open
+            self.event.active = True
+            self.event.save()
+            response = self.client.get(url_event_dashboard)
+            self.assertContains(response, "AK Submission")
+
+    def test_plan_hidden(self):
+        """
+        Test visibility of plan buttons with regard to plan visibility status for a given event
+        """
+        url_event_dashboard = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+
+        if apps.is_installed('AKPlan'):
+            # Plan hidden? No buttons should show up
+            self.event.plan_hidden = True
+            self.event.save()
+            response = self.client.get(url_event_dashboard)
+            self.assertNotContains(response, "Current AKs")
+            self.assertNotContains(response, "AK Wall")
+
+            # Plan not hidden?
+            # Buttons for current AKs and AK Wall should be on the page
+            self.event.plan_hidden = False
+            self.event.save()
+            response = self.client.get(url_event_dashboard)
+            self.assertContains(response, "Current AKs")
+            self.assertContains(response, "AK Wall")
+
+    def test_dashboard_buttons(self):
+        """
+        Make sure manually added buttons are displayed correctly
+        """
+        url_event_dashboard = reverse('dashboard:dashboard_event', kwargs={"slug": self.event.slug})
+
+        response = self.client.get(url_event_dashboard)
+        self.assertNotContains(response, "Dashboard Button Test")
+
+        DashboardButton.objects.create(
+                text="Dashboard Button Test",
+                event=self.event
+        )
+
+        response = self.client.get(url_event_dashboard)
+        self.assertContains(response, "Dashboard Button Test")
+
+
+class DashboardViewTests(BasicViewTests, TestCase):
+    """
+    Generic view tests, based on :class:`AKModel.BasicViewTests` as specified in this class in VIEWS
+    """
+    fixtures = ['model.json', 'dashboard.json']
+
+    APP_NAME = 'dashboard'
+
+    VIEWS = [
+        ('dashboard', {}),
+        ('dashboard_event', {'slug': 'kif42'}),
+    ]

AKDashboard/urls.py

+from django.urls import path
+
+from AKDashboard import views
+
+app_name = "dashboard"
+
+urlpatterns = [
+    path('', views.DashboardView.as_view(), name="dashboard"),
+    path('<slug:slug>/', views.DashboardEventView.as_view(), name='dashboard_event'),
+]

AKDashboard/views.py

+from django.apps import apps
+from django.utils.decorators import method_decorator
+from django.views.decorators.csrf import ensure_csrf_cookie
+from django.views.generic import TemplateView, DetailView
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.models import Event, AK, AKSlot
+from AKPlanning import settings
+
+
+class DashboardView(TemplateView):
+    """
+    Index view of dashboard and therefore the main entry point for AKPlanning
+
+    Displays information and buttons for all public events
+    """
+    template_name = 'AKDashboard/dashboard.html'
+
+    @method_decorator(ensure_csrf_cookie)
+    def dispatch(self, *args, **kwargs):
+        return super().dispatch(*args, **kwargs)
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        # Load events and split between active and current/featured events and those that should show smaller below
+        context["active_and_current_events"] = []
+        context["old_events"] = []
+        events = Event.objects.filter(public=True).order_by("-active", "-pk").prefetch_related('dashboardbutton_set')
+        for event in events:
+            if event.active or len(context["active_and_current_events"]) < settings.DASHBOARD_MAX_FEATURED_EVENTS:
+                context["active_and_current_events"].append(event)
+            else:
+                context["old_events"].append(event)
+        context["active_event_count"] = len(context["active_and_current_events"])
+        context["old_event_count"] = len(context["old_events"])
+        context["total_event_count"] = context["active_event_count"] + context["old_event_count"]
+        return context
+
+
+class DashboardEventView(DetailView):
+    """
+    Dashboard view for a single event
+
+    In addition to the basic information and the buttons,
+    an overview over recent events (new and changed AKs, moved AKSlots) for the given event is shown.
+
+    The event dashboard also exists for non-public events (one only needs to know the URL/slug of the event).
+    """
+    template_name = 'AKDashboard/dashboard_event.html'
+    context_object_name = 'event'
+    model = Event
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+
+        # Show feed of recent changes (if activated)
+        if settings.DASHBOARD_SHOW_RECENT:
+            # Create a list of chronically sorted events (both AK and plan changes):
+            recent_changes = []
+
+            # Newest AKs (if AKSubmission is used)
+            if apps.is_installed("AKSubmission"):
+                # Get the latest x changes (if there are that many),
+                # where x corresponds to the entry threshold configured in the settings
+                # (such that the list will be completely filled even if there are no (newer) plan changes)
+                submission_changes = AK.history.filter(event=context['event'])[:int(settings.DASHBOARD_RECENT_MAX)] # pylint: disable=no-member, line-too-long
+                # Create textual representation including icons
+                for s in submission_changes:
+                    if s.history_type == '+':
+                        text = _('New AK: %(ak)s.') % {'ak': s.name}
+                        icon = ('plus-square', 'far')
+                    elif s.history_type == '~':
+                        text = _('AK "%(ak)s" edited.') % {'ak': s.name}
+                        icon = ('pen-square', 'fas')
+                    else:
+                        text = _('AK "%(ak)s" deleted.') % {'ak': s.name}
+                        icon = ('times', 'fas')
+
+                    # Store representation in change list (still unsorted)
+                    recent_changes.append(
+                        {'icon': icon, 'text': text, 'link': s.instance.detail_url, 'timestamp': s.history_date}
+                    )
+
+            # Changes in plan (if AKPlan is used and plan is publicly visible)
+            if apps.is_installed("AKPlan") and not context['event'].plan_hidden:
+                # Get the latest plan changes (again using a threshold, see above)
+                last_changed_slots = AKSlot.objects.select_related('ak').filter(event=context['event'], start__isnull=False).order_by('-updated')[:int(settings.DASHBOARD_RECENT_MAX)] #pylint: disable=line-too-long
+                for changed_slot in last_changed_slots:
+                    # Create textual representation including icons and links and store in list (still unsorted)
+                    recent_changes.append({'icon': ('clock', 'far'),
+                                           'text': _('AK "%(ak)s" (re-)scheduled.') % {'ak': changed_slot.ak.name},
+                                           'link': changed_slot.ak.detail_url,
+                                           'timestamp': changed_slot.updated})
+
+            # Sort by change date...
+            recent_changes.sort(key=lambda x: x['timestamp'], reverse=True)
+            # ... and restrict to the latest 25 changes
+            context['recent_changes'] = recent_changes[:int(settings.DASHBOARD_RECENT_MAX)]
+        else:
+            context['recent_changes'] = []
+
+        return context

AKModel/apps.py

 from django.apps import AppConfig
+from django.contrib.admin.apps import AdminConfig
 
 
 class AkmodelConfig(AppConfig):
+    """
+    App configuration (default, only specifies name of the app)
+    """
     name = 'AKModel'
+
+
+class AKAdminConfig(AdminConfig):
+    """
+    App configuration for admin
+    Loading a custom version here allows to add additional contex and further adapt the behavior of the admin interface
+    """
+    default_site = 'AKModel.site.AKAdminSite'

AKModel/availability/forms.py

+# This part of the code was adapted from pretalx (https://github.com/pretalx/pretalx)
+# Copyright 2017-2019, Tobias Kunze
+# Original Copyrights licensed under the Apache License, Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
+# Documentation was mainly added by us, other changes are marked in the code
+import datetime
+import json
+
+from django import forms
+from django.db import transaction
+from django.db.models.signals import post_save
+from django.utils.dateparse import parse_datetime
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.availability.models import Availability
+from AKModel.availability.serializers import AvailabilitySerializer
+from AKModel.models import Event
+
+
+class AvailabilitiesFormMixin(forms.Form):
+    """
+    Mixin for forms to add availabilities functionality to it
+    Will handle the rendering and population of an availabilities field
+    """
+    availabilities = forms.CharField(
+        label=_('Availability'),
+        help_text=_(
+            'Click and drag to mark the availability during the event, double-click to delete. '
+            'Or use the start and end inputs to add entries to the calendar view.'  # Adapted help text
+        ),
+        widget=forms.TextInput(attrs={'class': 'availabilities-editor-data'}),
+        required=False,
+    )
+
+    def _serialize(self, event, instance):
+        """
+        Serialize relevant availabilities into a JSON format to populate the text field in the form
+
+        :param event: event the availabilities belong to (relevant for start and end times)
+        :param instance: the entity availabilities in this form should belong to (e.g., an AK, or a Room)
+        :return: JSON serializiation of the relevant availabilities
+        :rtype: str
+        """
+        if instance:
+            availabilities = AvailabilitySerializer(
+                instance.availabilities.all(), many=True
+            ).data
+        else:
+            availabilities = []
+
+        return json.dumps(
+            {
+                'availabilities': availabilities,
+                'event': {
+                    # 'timezone': event.timezone,
+                    'date_from': str(event.start),
+                    'date_to': str(event.end),
+                },
+            }
+        )
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Load event information and populate availabilities text field
+        self.event = self.initial.get('event')
+        if isinstance(self.event, int):
+            self.event = Event.objects.get(pk=self.event)
+        initial = kwargs.pop('initial', {})
+        initial['availabilities'] = self._serialize(self.event, kwargs['instance'])
+        if not isinstance(self, forms.BaseModelForm):
+            kwargs.pop('instance')
+        kwargs['initial'] = initial
+
+    def _parse_availabilities_json(self, jsonavailabilities):
+        """
+        Turn raw JSON availabilities into a list of model instances
+
+        :param jsonavailabilities: raw json input
+        :return: a list of availability objects corresponding to the raw input
+        :rtype: List[Availability]
+        """
+        try:
+            rawdata = json.loads(jsonavailabilities)
+        except ValueError as exc:
+            raise forms.ValidationError("Submitted availabilities are not valid json.") from exc
+        if not isinstance(rawdata, dict):
+            raise forms.ValidationError(
+                "Submitted json does not comply with expected format, should be object."
+            )
+        availabilities = rawdata.get('availabilities')
+        if not isinstance(availabilities, list):
+            raise forms.ValidationError(
+                "Submitted json does not comply with expected format, missing or malformed availabilities field"
+            )
+        return availabilities
+
+    def _parse_datetime(self, strdate):
+        """
+        Parse input date string
+        This will try to correct timezone information if needed
+
+        :param strdate: string representing a timestamp
+        :return: a timestamp object
+        """
+        tz = self.event.timezone  # adapt to our event model
+
+        obj = parse_datetime(strdate)
+        if not obj:
+            raise TypeError
+        if obj.tzinfo is None:
+            # Adapt to new python timezone interface
+            obj = obj.replace(tzinfo=tz)
+
+        return obj
+
+    def _validate_availability(self, rawavail):
+        """
+        Validate a raw availability instance input by making sure the relevant fields are present and can be parsed
+        The cleaned up values that are produced to test the validity of the input are stored in-place in the input
+        object for later usage in cleaning/parsing to availability objects
+
+        :param rawavail: object to validate/clean
+        """
+        message = _("The submitted availability does not comply with the required format.")
+        if not isinstance(rawavail, dict):
+            raise forms.ValidationError(message)
+        rawavail.pop('id', None)
+        rawavail.pop('allDay', None)
+        if not set(rawavail.keys()) == {'start', 'end'}:
+            raise forms.ValidationError(message)
+
+        try:
+            rawavail['start'] = self._parse_datetime(rawavail['start'])
+            rawavail['end'] = self._parse_datetime(rawavail['end'])
+        # Adapt: Better error handling
+        except (TypeError, ValueError) as exc:
+            raise forms.ValidationError(
+                _("The submitted availability contains an invalid date.")
+            ) from exc
+
+        timeframe_start = self.event.start  # adapt to our event model
+        if rawavail['start'] < timeframe_start:
+            rawavail['start'] = timeframe_start
+
+        # add 1 day, not 24 hours, https://stackoverflow.com/a/25427822/2486196
+        timeframe_end = self.event.end  # adapt to our event model
+        timeframe_end = timeframe_end + datetime.timedelta(days=1)
+        if rawavail['end'] > timeframe_end:
+            # If the submitted availability ended outside the event timeframe, fix it silently
+            rawavail['end'] = timeframe_end
+
+    def clean_availabilities(self):
+        """
+        Turn raw availabilities into real availability objects
+        :return:
+        """
+        data = self.cleaned_data.get('availabilities')
+        required = (
+                'availabilities' in self.fields and self.fields['availabilities'].required
+        )
+        if not data:
+            if required:
+                raise forms.ValidationError(_('Please fill in your availabilities!'))
+            return None
+
+        rawavailabilities = self._parse_availabilities_json(data)
+        availabilities = []
+
+        for rawavail in rawavailabilities:
+            self._validate_availability(rawavail)
+            availabilities.append(Availability(event_id=self.event.id, **rawavail))
+        if not availabilities and required:
+            raise forms.ValidationError(_('Please fill in your availabilities!'))
+        return availabilities
+
+    def _set_foreignkeys(self, instance, availabilities):
+        """
+        Set the reference to `instance` in each given availability.
+        For example, set the availabilitiy.room_id to instance.id, in
+        case instance of type Room.
+        """
+        reference_name = instance.availabilities.field.name + '_id'
+
+        for avail in availabilities:
+            setattr(avail, reference_name, instance.id)
+
+    def _replace_availabilities(self, instance, availabilities: [Availability]):
+        """
+        Replace the existing list of availabilities belonging to an entity with a new, updated one
+
+        This will trigger a post_save signal for usage in constraint violation checking
+
+        :param instance: entity the availabilities belong to
+        :param availabilities: list of new availabilities
+        """
+        with transaction.atomic():
+            # TODO: do not recreate objects unnecessarily, give the client the IDs, so we can track modifications and
+            #  leave unchanged objects alone
+            instance.availabilities.all().delete()
+            Availability.objects.bulk_create(availabilities)
+            # Adaption:
+            # Trigger post save signal manually to make sure constraints are updated accordingly
+            # Doing this one time is sufficient, since this will nevertheless update all availability constraint
+            # violations of the corresponding AK
+            if len(availabilities) > 0:
+                post_save.send(Availability, instance=availabilities[0], created=True)
+
+    def save(self, *args, **kwargs):
+        """
+        Override the saving method of the (model) form
+        """
+        instance = super().save(*args, **kwargs)
+        availabilities = self.cleaned_data.get('availabilities')
+
+        if availabilities is not None:
+            self._set_foreignkeys(instance, availabilities)
+            self._replace_availabilities(instance, availabilities)
+
+        return instance  # adapt to our forms

AKModel/availability/models.py

+# This part of the code was adapted from pretalx (https://github.com/pretalx/pretalx)
+# Copyright 2017-2019, Tobias Kunze
+# Original Copyrights licensed under the Apache License, Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
+# Changes are marked in the code
+
+import datetime
+from typing import List
+
+from django.db import models
+from django.utils.functional import cached_property
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.models import Event, AKOwner, Room, AK, AKCategory
+
+zero_time = datetime.time(0, 0)
+
+
+# CHANGES:
+# ScopeManager and LogMixin removed as they are not used in this project
+# adapted to event, people and room models
+# remove serialization as requirements are not covered
+# add translation
+# add meta class
+# enable availabilities for AKs and AKCategories
+# add verbose names and help texts to model attributes
+# adapt or extemd documentation
+
+
+class Availability(models.Model):
+    """The Availability class models when people or rooms are available for.
+
+    The power of this class is not within its rather simple data model,
+    but with the operations available on it. An availability object can
+    span multiple days, but due to our choice of input widget, it will
+    usually only span a single day at most.
+    """
+    # pylint: disable=broad-exception-raised
+
+    event = models.ForeignKey(
+        to=Event,
+        related_name='availabilities',
+        on_delete=models.CASCADE,
+        verbose_name=_('Event'),
+        help_text=_('Associated event'),
+    )
+    person = models.ForeignKey(
+        to=AKOwner,
+        related_name='availabilities',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        verbose_name=_('Person'),
+        help_text=_('Person whose availability this is'),
+    )
+    room = models.ForeignKey(
+        to=Room,
+        related_name='availabilities',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        verbose_name=_('Room'),
+        help_text=_('Room whose availability this is'),
+    )
+    ak = models.ForeignKey(
+        to=AK,
+        related_name='availabilities',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        verbose_name=_('AK'),
+        help_text=_('AK whose availability this is'),
+    )
+    ak_category = models.ForeignKey(
+        to=AKCategory,
+        related_name='availabilities',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        verbose_name=_('AK Category'),
+        help_text=_('AK Category whose availability this is'),
+    )
+    start = models.DateTimeField()
+    end = models.DateTimeField()
+
+    def __str__(self) -> str:
+        person = self.person.name if self.person else None
+        room = getattr(self.room, 'name', None)
+        event = getattr(getattr(self, 'event', None), 'name', None)
+        ak = getattr(self.ak, 'name', None)
+        ak_category = getattr(self.ak_category, 'name', None)
+        return f'Availability(event={event}, person={person}, room={room}, ak={ak}, ak category={ak_category})'
+
+    def __hash__(self):
+        return hash(
+            (getattr(self, 'event', None), self.person, self.room, self.ak, self.ak_category, self.start, self.end))
+
+    def __eq__(self, other: 'Availability') -> bool:
+        """Comparisons like ``availability1 == availability2``.
+
+        Checks if ``event``, ``person``, ``room``, ``ak``, ``ak_category``, ``start`` and ``end``
+        are the same.
+        """
+        return all(
+            (
+                getattr(self, attribute, None) == getattr(other, attribute, None)
+                for attribute in ['event', 'person', 'room', 'ak', 'ak_category', 'start', 'end']
+            )
+        )
+
+    @cached_property
+    def all_day(self) -> bool:
+        """Checks if the Availability spans one (or, technically: multiple)
+        complete day."""
+        return self.start.time() == zero_time and self.end.time() == zero_time
+
+    def overlaps(self, other: 'Availability', strict: bool) -> bool:
+        """Test if two Availabilities overlap.
+
+        :param other:
+        :param strict: Only count a real overlap as overlap, not direct adjacency.
+        """
+
+        if not isinstance(other, Availability):
+            raise Exception('Please provide an Availability object')
+
+        if strict:
+            return (
+                    (self.start <= other.start < self.end)
+                    or (self.start < other.end <= self.end)
+                    or (other.start <= self.start < other.end)
+                    or (other.start < self.end <= other.end)
+            )
+        return (
+                (self.start <= other.start <= self.end)
+                or (self.start <= other.end <= self.end)
+                or (other.start <= self.start <= other.end)
+                or (other.start <= self.end <= other.end)
+        )
+
+    def contains(self, other: 'Availability') -> bool:
+        """Tests if this availability starts before and ends after the
+        other."""
+        return self.start <= other.start and self.end >= other.end
+
+    def merge_with(self, other: 'Availability') -> 'Availability':
+        """Return a new Availability which spans the range of this one and the
+        given one."""
+
+        if not isinstance(other, Availability):
+            raise Exception('Please provide an Availability object.')
+        if not other.overlaps(self, strict=False):
+            raise Exception('Only overlapping Availabilities can be merged.')
+
+        return Availability(
+            start=min(self.start, other.start), end=max(self.end, other.end)
+        )
+
+    def __or__(self, other: 'Availability') -> 'Availability':
+        """Performs the merge operation: ``availability1 | availability2``"""
+        return self.merge_with(other)
+
+    def intersect_with(self, other: 'Availability') -> 'Availability':
+        """Return a new Availability which spans the range covered both by this
+        one and the given one."""
+
+        if not isinstance(other, Availability):
+            raise Exception('Please provide an Availability object.')
+        if not other.overlaps(self, False):
+            raise Exception('Only overlapping Availabilities can be intersected.')
+
+        return Availability(
+            start=max(self.start, other.start), end=min(self.end, other.end)
+        )
+
+    def __and__(self, other: 'Availability') -> 'Availability':
+        """Performs the intersect operation: ``availability1 &
+        availability2``"""
+        return self.intersect_with(other)
+
+    @classmethod
+    def union(cls, availabilities: List['Availability']) -> List['Availability']:
+        """Return the minimal list of Availability objects which are covered by
+        at least one given Availability."""
+        if not availabilities:
+            return []
+
+        availabilities = sorted(availabilities, key=lambda a: a.start)
+        result = [availabilities[0]]
+        availabilities = availabilities[1:]
+
+        for avail in availabilities:
+            if avail.overlaps(result[-1], False):
+                result[-1] = result[-1].merge_with(avail)
+            else:
+                result.append(avail)
+
+        return result
+
+    @classmethod
+    def _pair_intersection(
+            cls,
+            availabilities_a: List['Availability'],
+            availabilities_b: List['Availability'],
+    ) -> List['Availability']:
+        """return the list of Availabilities, which are covered by each of the
+        given sets."""
+        result = []
+
+        # yay for O(b*a) time! I am sure there is some fancy trick to make this faster,
+        # but we're dealing with less than 100 items in total, sooo.. ¯\_(ツ)_/¯
+        for a in availabilities_a:
+            for b in availabilities_b:
+                if a.overlaps(b, True):
+                    result.append(a.intersect_with(b))
+
+        return result
+
+    @classmethod
+    def intersection(
+            cls, *availabilitysets: List['Availability']
+    ) -> List['Availability']:
+        """Return the list of Availabilities which are covered by all of the
+        given sets."""
+
+        # get rid of any overlaps and unmerged ranges in each set
+        availabilitysets = [cls.union(avialset) for avialset in availabilitysets]
+        # bail out for obvious cases (there are no sets given, one of the sets is empty)
+        if not availabilitysets:
+            return []
+        if not all(availabilitysets):
+            return []
+        # start with the very first set ...
+        result = availabilitysets[0]
+        for availset in availabilitysets[1:]:
+            # ... subtract each of the other sets
+            result = cls._pair_intersection(result, availset)
+        return result
+
+    @property
+    def simplified(self):
+        """
+        Get a simplified (only Weekday, hour and minute) string representation of an availability
+        :return: simplified string version
+        :rtype: str
+        """
+        return (f'{self.start.astimezone(self.event.timezone).strftime("%a %H:%M")}-'
+                f'{self.end.astimezone(self.event.timezone).strftime("%a %H:%M")}')
+
+    @classmethod
+    def with_event_length(cls, event, person=None, room=None, ak=None, ak_category=None):
+        """
+        Create an availability covering exactly the time between event start and event end.
+        Can e.g., be used to create default availabilities.
+
+        :param event: relevant event
+        :param person: person, if availability should be connected to a person
+        :param room: room, if availability should be connected to a room
+        :param ak: ak, if availability should be connected to a ak
+        :param ak_category: ak_category, if availability should be connected to a ak_category
+        :return: availability associated to the entity oder entities selected
+        :rtype: Availability
+        """
+        timeframe_start = event.start  # adapt to our event model
+        # add 1 day, not 24 hours, https://stackoverflow.com/a/25427822/2486196
+        timeframe_end = event.end  # adapt to our event model
+        timeframe_end = timeframe_end + datetime.timedelta(days=1)
+        return Availability(start=timeframe_start, end=timeframe_end, event=event, person=person,
+                                    room=room, ak=ak, ak_category=ak_category)
+
+    class Meta:
+        verbose_name = _('Availability')
+        verbose_name_plural = _('Availabilities')
+        ordering = ['event', 'start']

AKModel/availability/serializers.py

+# This part of the code was adapted from pretalx (https://github.com/pretalx/pretalx)
+# Copyright 2017-2019, Tobias Kunze
+# Original Copyrights licensed under the Apache License, Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
+# Documentation was mainly added by us, other changes are marked in the code
+from django.utils import timezone
+from rest_framework.fields import SerializerMethodField
+from rest_framework.serializers import ModelSerializer
+
+from AKModel.availability.models import Availability
+
+
+class AvailabilitySerializer(ModelSerializer):
+    """
+    REST Framework Serializer for Availability
+    """
+    allDay = SerializerMethodField()
+    start = SerializerMethodField()
+    end = SerializerMethodField()
+
+    def get_allDay(self, obj):  # pylint: disable=invalid-name
+        """
+        Bridge between naming conventions of python and fullcalendar by providing the all_day field as allDay, too
+        """
+        return obj.all_day
+
+    def get_start(self, obj):
+        """
+        Get start timestamp
+
+        Use already localized strings in serialized field
+        (default would be UTC, but that would require heavy timezone calculation on client side)
+        """
+        return timezone.localtime(obj.start, obj.event.timezone).strftime("%Y-%m-%dT%H:%M:%S")
+
+    def get_end(self, obj):
+        """
+        Get end timestamp
+
+        Use already localized strings in serialized field
+        (default would be UTC, but that would require heavy timezone calculation on client side)
+        """
+        return timezone.localtime(obj.end, obj.event.timezone).strftime("%Y-%m-%dT%H:%M:%S")
+
+    class Meta:
+        model = Availability
+        fields = ('id', 'start', 'end', 'allDay')

AKModel/environment.py

+"""
+Environment definitions
+Needed for tex compilation
+"""
+import re
+
+from django_tex.environment import environment
+
+# Used to filter all very special UTF-8 chars that are probably not contained in the LaTeX fonts
+# and would hence cause compilation errors
+utf8_replace_pattern = re.compile('[^\u0000-\u206F]', re.UNICODE)
+
+
+def latex_escape_utf8(value):
+    """
+    Escape latex special chars and remove invalid utf-8 values
+
+    :param value: string to escape
+    :type value: str
+    :return: escaped string
+    :rtype: str
+    """
+    return (utf8_replace_pattern.sub('', value).replace('&', r'\&').replace('_', r'\_').replace('#', r'\#').
+            replace('$', r'\$').replace('%', r'\%').replace('{', r'\{').replace('}', r'\}'))
+
+
+def improved_tex_environment(**options):
+    """
+    Encapsulate our improved latex environment for usage
+    """
+    env = environment(**options)
+    env.filters.update({
+        'latex_escape_utf8': latex_escape_utf8,
+    })
+    return env

AKModel/fixtures/model.json

+[
+{
+    "model": "AKModel.event",
+    "pk": 1,
+    "fields": {
+        "name": "KIF 23",
+        "slug": "kif23",
+        "place": "Neuland",
+        "timezone": "Europe/Berlin",
+        "start": "2020-10-01T17:41:22Z",
+        "end": "2020-10-04T17:41:30Z",
+        "reso_deadline": "2020-10-03T10:00:00Z",
+        "interest_start": null,
+        "interest_end": null,
+        "public": true,
+        "active": false,
+        "plan_hidden": true,
+        "plan_published_at": null,
+        "base_url": "",
+        "wiki_export_template_name": "",
+        "default_slot": "2.00",
+        "contact_email": "dummy@eyample.org"
+    }
+},
+{
+    "model": "AKModel.event",
+    "pk": 2,
+    "fields": {
+        "name": "KIF 42",
+        "slug": "kif42",
+        "place": "Neuland noch neuer",
+        "timezone": "Europe/Berlin",
+        "start": "2020-11-06T17:51:26Z",
+        "end": "2020-11-10T17:51:27Z",
+        "reso_deadline": "2020-11-08T17:51:42Z",
+        "interest_start": null,
+        "interest_end": null,
+        "public": true,
+        "active": true,
+        "plan_hidden": false,
+        "plan_published_at": "2022-12-01T21:50:01Z",
+        "base_url": "",
+        "wiki_export_template_name": "",
+        "default_slot": "2.00",
+        "contact_email": "dummy@example.org"
+    }
+},
+{
+    "model": "AKModel.akowner",
+    "pk": 1,
+    "fields": {
+        "name": "a",
+        "slug": "a",
+        "institution": "Uni X",
+        "link": "",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akowner",
+    "pk": 2,
+    "fields": {
+        "name": "b",
+        "slug": "b",
+        "institution": "Hochschule Y",
+        "link": "",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akowner",
+    "pk": 3,
+    "fields": {
+        "name": "c",
+        "slug": "c",
+        "institution": "",
+        "link": "",
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akowner",
+    "pk": 4,
+    "fields": {
+        "name": "d",
+        "slug": "d",
+        "institution": "",
+        "link": "",
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akcategory",
+    "pk": 1,
+    "fields": {
+        "name": "Spa▀",
+        "color": "275246",
+        "description": "",
+        "present_by_default": true,
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akcategory",
+    "pk": 2,
+    "fields": {
+        "name": "Ernst",
+        "color": "234567",
+        "description": "",
+        "present_by_default": true,
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akcategory",
+    "pk": 3,
+    "fields": {
+        "name": "Spa▀/Kultur",
+        "color": "333333",
+        "description": "",
+        "present_by_default": true,
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akcategory",
+    "pk": 4,
+    "fields": {
+        "name": "Inhalt",
+        "color": "456789",
+        "description": "",
+        "present_by_default": true,
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akcategory",
+    "pk": 5,
+    "fields": {
+        "name": "Meta",
+        "color": "111111",
+        "description": "",
+        "present_by_default": true,
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.aktrack",
+    "pk": 1,
+    "fields": {
+        "name": "Track 1",
+        "color": "",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akrequirement",
+    "pk": 1,
+    "fields": {
+        "name": "Beamer",
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akrequirement",
+    "pk": 2,
+    "fields": {
+        "name": "Internet",
+        "event": 1
+    }
+},
+{
+    "model": "AKModel.akrequirement",
+    "pk": 3,
+    "fields": {
+        "name": "BBB",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akrequirement",
+    "pk": 4,
+    "fields": {
+        "name": "Mumble",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.akrequirement",
+    "pk": 5,
+    "fields": {
+        "name": "Matrix",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.aktype",
+    "pk": 1,
+    "fields": {
+        "name": "Input",
+        "event": 2
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 1,
+    "fields": {
+        "id": 1,
+        "name": "Test AK Inhalt",
+        "short_name": "test1",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": true,
+        "notes": "",
+        "category": 4,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:28:59.265Z",
+        "history_change_reason": null,
+        "history_type": "+",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 2,
+    "fields": {
+        "id": 1,
+        "name": "Test AK Inhalt",
+        "short_name": "test1",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": true,
+        "notes": "",
+        "category": 4,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:28:59.305Z",
+        "history_change_reason": null,
+        "history_type": "~",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 3,
+    "fields": {
+        "id": 2,
+        "name": "Test AK Meta",
+        "short_name": "test2",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": null,
+        "notes": "",
+        "category": 5,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:29:40.296Z",
+        "history_change_reason": null,
+        "history_type": "+",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 4,
+    "fields": {
+        "id": 2,
+        "name": "Test AK Meta",
+        "short_name": "test2",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": null,
+        "notes": "",
+        "category": 5,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:29:40.355Z",
+        "history_change_reason": null,
+        "history_type": "~",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 5,
+    "fields": {
+        "id": 3,
+        "name": "AK Wish",
+        "short_name": "wish1",
+        "description": "Description of my Wish",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": null,
+        "notes": "We need to find a volunteer first...",
+        "category": 3,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:30:59.469Z",
+        "history_change_reason": null,
+        "history_type": "+",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 6,
+    "fields": {
+        "id": 3,
+        "name": "AK Wish",
+        "short_name": "wish1",
+        "description": "Description of my Wish",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": null,
+        "notes": "We need to find a volunteer first...",
+        "category": 3,
+        "track": null,
+        "event": 2,
+        "history_date": "2021-05-04T10:30:59.509Z",
+        "history_change_reason": null,
+        "history_type": "~",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.historicalak",
+    "pk": 7,
+    "fields": {
+        "id": 2,
+        "name": "Test AK Meta",
+        "short_name": "test2",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "reso": false,
+        "present": null,
+        "notes": "",
+        "category": 5,
+        "track": 1,
+        "event": 2,
+        "history_date": "2022-12-02T12:27:14.277Z",
+        "history_change_reason": null,
+        "history_type": "~",
+        "history_user": null
+    }
+},
+{
+    "model": "AKModel.ak",
+    "pk": 1,
+    "fields": {
+        "name": "Test AK Inhalt",
+        "short_name": "test1",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "category": 4,
+        "track": null,
+        "reso": false,
+        "present": true,
+        "notes": "",
+        "interest": -1,
+        "interest_counter": 0,
+        "include_in_export": false,
+        "event": 2,
+        "owners": [
+            1
+        ],
+        "requirements": [
+            3
+        ],
+        "conflicts": [],
+        "prerequisites": []
+    }
+},
+{
+    "model": "AKModel.ak",
+    "pk": 2,
+    "fields": {
+        "name": "Test AK Meta",
+        "short_name": "test2",
+        "description": "",
+        "link": "",
+        "protocol_link": "",
+        "category": 5,
+        "track": 1,
+        "reso": false,
+        "present": null,
+        "notes": "",
+        "interest": -1,
+        "interest_counter": 0,
+        "event": 2,
+        "owners": [
+            2
+        ],
+        "requirements": [],
+        "conflicts": [],
+        "prerequisites": []
+    }
+},
+{
+    "model": "AKModel.ak",
+    "pk": 3,
+    "fields": {
+        "name": "AK Wish",
+        "short_name": "wish1",
+        "description": "Description of my Wish",
+        "link": "",
+        "protocol_link": "",
+        "category": 3,
+        "track": null,
+        "reso": false,
+        "present": null,
+        "notes": "We need to find a volunteer first...",
+        "interest": -1,
+        "interest_counter": 0,
+        "event": 2,
+        "owners": [],
+        "requirements": [
+            4
+        ],
+        "conflicts": [
+            1
+        ],
+        "prerequisites": [
+            2
+        ]
+    }
+},
+{
+    "model": "AKModel.room",
+    "pk": 1,
+    "fields": {
+        "name": "Testraum",
+        "location": "BBB",
+        "capacity": -1,
+        "event": 2,
+        "properties": [
+            3
+        ]
+    }
+},
+{
+    "model": "AKModel.room",
+    "pk": 2,
+    "fields": {
+        "name": "Testraum 2",
+        "location": "",
+        "capacity": 30,
+        "event": 2,
+        "properties": []
+    }
+},
+{
+    "model": "AKModel.akslot",
+    "pk": 1,
+    "fields": {
+        "ak": 1,
+        "room": 2,
+        "start": "2020-11-06T18:30:00Z",
+        "duration": "2.00",
+        "fixed": false,
+        "event": 2,
+        "updated": "2022-12-02T12:23:11.856Z"
+    }
+},
+{
+    "model": "AKModel.akslot",
+    "pk": 2,
+    "fields": {
+        "ak": 2,
+        "room": 1,
+        "start": "2020-11-08T12:30:00Z",
+        "duration": "2.00",
+        "fixed": false,
+        "event": 2,
+        "updated": "2022-12-02T12:23:18.279Z"
+    }
+},
+{
+    "model": "AKModel.akslot",
+    "pk": 3,
+    "fields": {
+        "ak": 3,
+        "room": null,
+        "start": null,
+        "duration": "1.50",
+        "fixed": false,
+        "event": 2,
+        "updated": "2021-05-04T10:30:59.523Z"
+    }
+},
+{
+    "model": "AKModel.akslot",
+    "pk": 4,
+    "fields": {
+        "ak": 3,
+        "room": null,
+        "start": null,
+        "duration": "3.00",
+        "fixed": false,
+        "event": 2,
+        "updated": "2021-05-04T10:30:59.528Z"
+    }
+},
+{
+    "model": "AKModel.akslot",
+    "pk": 5,
+    "fields": {
+        "ak": 1,
+        "room": null,
+        "start": null,
+        "duration": "2.00",
+        "fixed": false,
+        "event": 2,
+        "updated": "2022-12-02T12:23:11.856Z"
+    }
+},
+{
+    "model": "AKModel.constraintviolation",
+    "pk": 1,
+    "fields": {
+        "type": "soa",
+        "level": 10,
+        "event": 2,
+        "ak_owner": null,
+        "room": null,
+        "requirement": null,
+        "category": null,
+        "comment": "",
+        "timestamp": "2022-12-02T12:23:11.875Z",
+        "manually_resolved": false,
+        "aks": [
+            1
+        ],
+        "ak_slots": [
+            1
+        ]
+    }
+},
+{
+    "model": "AKModel.constraintviolation",
+    "pk": 2,
+    "fields": {
+        "type": "rng",
+        "level": 10,
+        "event": 2,
+        "ak_owner": null,
+        "room": 2,
+        "requirement": 3,
+        "category": null,
+        "comment": "",
+        "timestamp": "2022-12-02T12:23:11.890Z",
+        "manually_resolved": false,
+        "aks": [
+            1
+        ],
+        "ak_slots": [
+            1
+        ]
+    }
+},
+{
+    "model": "AKModel.constraintviolation",
+    "pk": 3,
+    "fields": {
+        "type": "soa",
+        "level": 10,
+        "event": 2,
+        "ak_owner": null,
+        "room": null,
+        "requirement": null,
+        "category": null,
+        "comment": "",
+        "timestamp": "2022-12-02T12:23:18.301Z",
+        "manually_resolved": false,
+        "aks": [
+            2
+        ],
+        "ak_slots": [
+            2
+        ]
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 1,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": null,
+        "ak": 1,
+        "ak_category": null,
+        "start": "2020-11-07T08:00:00Z",
+        "end": "2020-11-07T18:00:00Z"
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 2,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": null,
+        "ak": 1,
+        "ak_category": null,
+        "start": "2020-11-09T10:00:00Z",
+        "end": "2020-11-09T16:30:00Z"
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 3,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": 1,
+        "ak": null,
+        "ak_category": null,
+        "start": "2020-11-06T17:51:26Z",
+        "end": "2020-11-10T23:00:00Z"
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 4,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": 2,
+        "ak": null,
+        "ak_category": null,
+        "start": "2020-11-06T17:51:26Z",
+        "end": "2020-11-06T21:00:00Z"
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 5,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": 2,
+        "ak": null,
+        "ak_category": null,
+        "start": "2020-11-08T15:30:00Z",
+        "end": "2020-11-08T19:30:00Z"
+    }
+},
+{
+    "model": "AKModel.availability",
+    "pk": 6,
+    "fields": {
+        "event": 2,
+        "person": null,
+        "room": 2,
+        "ak": null,
+        "ak_category": null,
+        "start": "2020-11-07T18:30:00Z",
+        "end": "2020-11-07T21:30:00Z"
+    }
+}
+]

AKModel/forms.py

+"""
+Central and admin forms
+"""
+
+import csv
+import io
+
+from django import forms
+from django.forms.utils import ErrorList
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.availability.forms import AvailabilitiesFormMixin
+from AKModel.models import Event, AKCategory, AKRequirement, Room, AKType
+
+
+class DateTimeInput(forms.DateInput):
+    """
+    Simple widget for datetime input fields using the HTML5 datetime-local input type
+    """
+    input_type = 'datetime-local'
+
+
+class NewEventWizardStartForm(forms.ModelForm):
+    """
+    Initial view of new event wizard
+
+    This form is a model form for Event, but only with a subset of the required fields.
+    It is therefore not possible to really create an event using this form, but only to enter
+    information, in particular the timezone, that is needed to correctly handle/parse the user
+    inputs for further required fields like start and end of the event.
+
+    The form will be used for this partial input, the input of the remaining required fields
+    will then be handled by :class:`NewEventWizardSettingsForm` (see below).
+    """
+    class Meta:
+        model = Event
+        fields = ['name', 'slug', 'timezone', 'plan_hidden']
+        widgets = {
+            'plan_hidden': forms.HiddenInput(),
+        }
+
+    # Special hidden field for wizard state handling
+    is_init = forms.BooleanField(initial=True, widget=forms.HiddenInput)
+
+
+class NewEventWizardSettingsForm(forms.ModelForm):
+    """
+    Form for second view of the event creation wizard.
+
+    Will handle the input of the remaining required as well as some optional fields.
+    See also :class:`NewEventWizardStartForm`.
+    """
+    class Meta:
+        model = Event
+        fields = "__all__"
+        exclude = ['plan_published_at']
+        widgets = {
+            'name': forms.HiddenInput(),
+            'slug': forms.HiddenInput(),
+            'timezone': forms.HiddenInput(),
+            'active': forms.HiddenInput(),
+            'start': DateTimeInput(),
+            'end': DateTimeInput(),
+            'interest_start': DateTimeInput(),
+            'interest_end': DateTimeInput(),
+            'reso_deadline': DateTimeInput(),
+            'plan_hidden': forms.HiddenInput(),
+        }
+
+
+class NewEventWizardPrepareImportForm(forms.Form):
+    """
+    Wizard form for choosing an event to import/copy elements (requirements, categories, etc) from.
+    Is used to restrict the list of elements to choose from in the next step (see :class:`NewEventWizardImportForm`).
+    """
+    import_event = forms.ModelChoiceField(
+        queryset=Event.objects.all(),
+        label=_("Copy ak requirements and ak categories of existing event"),
+        help_text=_("You can choose what to copy in the next step")
+    )
+
+
+class NewEventWizardImportForm(forms.Form):
+    """
+    Wizard form for excaclty choosing which elemments to copy/import for the newly created event.
+    Possible elements are categories, requirements, and dashboard buttons if AKDashboard is active.
+    The lists are restricted to elements from the event selected in the previous step
+    (see :class:`NewEventWizardPrepareImportForm`).
+    """
+    import_categories = forms.ModelMultipleChoiceField(
+        queryset=AKCategory.objects.all(),
+        widget=forms.CheckboxSelectMultiple,
+        label=_("Copy ak categories"),
+        required=False,
+    )
+
+    import_requirements = forms.ModelMultipleChoiceField(
+        queryset=AKRequirement.objects.all(),
+        widget=forms.CheckboxSelectMultiple,
+        label=_("Copy ak requirements"),
+        required=False,
+    )
+
+    import_types = forms.ModelMultipleChoiceField(
+        queryset=AKType.objects.all(),
+        widget=forms.CheckboxSelectMultiple,
+        label=_("Copy types"),
+        required=False,
+    )
+
+    # pylint: disable=too-many-arguments
+    def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None, initial=None, error_class=ErrorList,
+                 label_suffix=None, empty_permitted=False, field_order=None, use_required_attribute=None,
+                 renderer=None):
+        super().__init__(data, files, auto_id, prefix, initial, error_class, label_suffix, empty_permitted, field_order,
+                         use_required_attribute, renderer)
+        self.fields["import_categories"].queryset = self.fields["import_categories"].queryset.filter(
+            event=self.initial["import_event"])
+        self.fields["import_requirements"].queryset = self.fields["import_requirements"].queryset.filter(
+            event=self.initial["import_event"])
+        self.fields["import_types"].queryset = self.fields["import_types"].queryset.filter(
+            event=self.initial["import_event"])
+
+        # pylint: disable=import-outside-toplevel
+        # Local imports used to prevent cyclic imports and to only import when AKDashboard is available
+        from django.apps import apps
+        if apps.is_installed("AKDashboard"):
+            # If AKDashboard is active, allow to copy dashboard buttons, too
+            from AKDashboard.models import DashboardButton
+            self.fields["import_buttons"] = forms.ModelMultipleChoiceField(
+                queryset=DashboardButton.objects.filter(event=self.initial["import_event"]),
+                widget=forms.CheckboxSelectMultiple,
+                label=_("Copy dashboard buttons"),
+                required=False,
+            )
+
+
+class NewEventWizardActivateForm(forms.ModelForm):
+    """
+    Wizard form to activate the newly created event
+    """
+    class Meta:
+        fields = ["active"]
+        model = Event
+
+
+class AdminIntermediateForm(forms.Form):
+    """
+    Base form for admin intermediate views (forms used there should inherit from this,
+    by default, the form is empty since it is only needed for the confirmation button)
+    """
+
+
+class AdminIntermediateActionForm(AdminIntermediateForm):
+    """
+    Form for Admin Action Confirmation views -- has a pks field needed to handle the serialization/deserialization of
+    the IDs of the entities the user selected for the admin action to be performed on
+    """
+    pks = forms.CharField(widget=forms.HiddenInput)
+
+
+class SlideExportForm(AdminIntermediateForm):
+    """
+    Form to control the slides generated from the AK list of an event
+
+    The user can select how many upcoming AKs are displayed at the footer to inform people that it is their turn soon,
+    whether the AK list should be restricted to those AKs that where marked for presentation, and whether ther should
+    be a symbol and empty space to take notes on for wishes
+    """
+    num_next = forms.IntegerField(
+        min_value=0,
+        max_value=6,
+        initial=3,
+        label=_("# next AKs"),
+        help_text=_("How many next AKs should be shown on a slide?"))
+    presentation_mode = forms.TypedChoiceField(
+        initial=False,
+        label=_("Presentation only?"),
+        widget=forms.RadioSelect,
+        choices=((True, _('Yes')), (False, _('No'))),
+        coerce=lambda x: x == "True",
+        help_text=_("Restrict AKs to those that asked for chance to be presented?"))
+    wish_notes = forms.TypedChoiceField(
+        initial=False,
+        label=_("Space for notes in wishes?"),
+        widget=forms.RadioSelect,
+        choices=((True, _('Yes')), (False, _('No'))),
+        coerce=lambda x: x == "True",
+        help_text=_("Create symbols indicating space to note down owners and timeslots for wishes, e.g., to be filled "
+                    "out on a touch screen while presenting?"))
+
+
+class DefaultSlotEditorForm(AdminIntermediateForm):
+    """
+    Form for default slot editor
+    """
+    availabilities = forms.CharField(
+        label=_('Default Slots'),
+        help_text=_(
+            'Click and drag to add default slots, double-click to delete. '
+            'Or use the start and end inputs to add entries to the calendar view.'
+        ),
+        widget=forms.TextInput(attrs={'class': 'availabilities-editor-data'}),
+        required=True,
+    )
+
+
+class RoomBatchCreationForm(AdminIntermediateForm):
+    """
+    Form for room batch creation
+
+    Allows to input a list of room details and choose whether default availabilities should be generated for these
+    rooms. Will check that the input follows a CSV format with at least a name column present.
+    """
+    rooms = forms.CharField(
+        label=_('New rooms'),
+        help_text=_('Enter room details in CSV format. Required colum is "name", optional colums are "location", '
+                    '"capacity", and "url" for online/hybrid rooms. Delimiter: Semicolon'),
+        widget=forms.Textarea,
+        required=True,
+    )
+    create_default_availabilities = forms.BooleanField(
+        label=_('Default availabilities?'),
+        help_text=_('Create default availabilities for all rooms?'),
+        required=False
+    )
+
+    def clean_rooms(self):
+        """
+        Validate and transform the input for the rooms textfield
+        Treat the input as CSV and turn it into a dict containing the relevant information.
+
+        :return: a dict containing the raw room information
+        :rtype: dict[str, str]
+        """
+        rooms_raw_text = self.cleaned_data["rooms"]
+        rooms_raw_dict = csv.DictReader(io.StringIO(rooms_raw_text), delimiter=";")
+
+        if "name" not in rooms_raw_dict.fieldnames:
+            raise forms.ValidationError(_("CSV must contain a name column"))
+
+        return rooms_raw_dict
+
+
+class RoomForm(forms.ModelForm):
+    """
+    Room (creation) form (basic), will be extended for handling of availabilities
+    (see :class:`RoomFormWithAvailabilities`) and also for creating hybrid rooms in AKOnline (if active)
+    """
+    class Meta:
+        model = Room
+        fields = ['name',
+                  'location',
+                  'capacity',
+                  'event',
+                  ]
+
+
+class RoomFormWithAvailabilities(AvailabilitiesFormMixin, RoomForm):
+    """
+    Room (update) form including handling of availabilities, extends :class:`RoomForm`
+    """
+    class Meta:
+        model = Room
+        fields = ['name',
+                  'location',
+                  'capacity',
+                  'properties',
+                  'event',
+                  ]
+
+        widgets = {
+            'properties': forms.CheckboxSelectMultiple,
+        }
+
+    def __init__(self, *args, **kwargs):
+        # Init availability mixin
+        kwargs['initial'] = {}
+        super().__init__(*args, **kwargs)
+        self.initial = {**self.initial, **kwargs['initial']}
+        # Filter possible values for m2m when event is specified
+        if hasattr(self.instance, "event") and self.instance.event is not None:
+            self.fields["properties"].queryset = AKRequirement.objects.filter(event=self.instance.event)

AKModel/management/commands/makemessages.py

+import os
+
+from django.core.management.commands.makemessages import Command as MakeMessagesCommand
+
+
+class Command(MakeMessagesCommand):
+    """
+    Adapted version of the :class:`MakeMessagesCommand`
+    Ensure PO files are generated using forward slashes in the location comments on all operating systems
+    """
+    def find_files(self, root):
+        # Replace backward slashes with forward slashes if necessary in file list
+        all_files = super().find_files(root)
+        if os.sep != "\\":
+            return all_files
+
+        for file_entry in all_files:
+            if file_entry.dirpath == ".":
+                file_entry.dirpath = ""
+            elif file_entry.dirpath.startswith(".\\"):
+                file_entry.dirpath = file_entry.dirpath[2:].replace("\\", "/")
+
+        return all_files
+
+    def build_potfiles(self):
+        # Replace backward slashes with forward slashes if necessary in the files itself
+        pot_files = super().build_potfiles()
+        if os.sep != "\\":
+            return pot_files
+
+        for filename in pot_files:
+            with open(filename, "r", encoding="utf-8") as f:
+                lines = f.readlines()
+                fixed_lines = []
+                for line in lines:
+                    if line.startswith("#: "):
+                        line = line.replace("\\", "/")
+                    fixed_lines.append(line)
+
+            with open(filename, "w", encoding="utf-8") as f:
+                f.writelines(fixed_lines)
+
+        return pot_files

AKModel/metaviews/__init__.py

+from AKModel.metaviews.status import StatusManager
+
+# create on instance of the :class:`AKModel.metaviews.status.StatusManager`
+# that can then be accessed everywhere (singleton pattern)
+status_manager = StatusManager()

AKModel/metaviews/admin.py

+from abc import ABC, abstractmethod
+
+from django.contrib import admin, messages
+from django.shortcuts import get_object_or_404
+from django.urls import reverse
+from django.utils.translation import gettext_lazy as _
+from django.views.generic import FormView
+
+from AKModel.forms import AdminIntermediateForm, AdminIntermediateActionForm
+from AKModel.models import Event
+
+
+class EventSlugMixin:
+    """
+    Mixin to handle views with event slugs
+
+    This will make the relevant event available as self.event in all kind types of requests
+    (generic GET and POST views, list views, dispatching, create views)
+    """
+    # pylint: disable=no-member
+    event = None
+
+    def _load_event(self):
+        """
+        Perform the real loading of the event data (as specified by event_slug in the URL) into self.event
+        """
+        # Find event based on event slug
+        if self.event is None:
+            self.event = get_object_or_404(Event, slug=self.kwargs.get("event_slug", None))
+
+    def get(self, request, *args, **kwargs):
+        """
+        Override GET request handling to perform loading event first
+        """
+        self._load_event()
+        return super().get(request, *args, **kwargs)
+
+    def post(self, request, *args, **kwargs):
+        """
+        Override POST request handling to perform loading event first
+        """
+        self._load_event()
+        return super().post(request, *args, **kwargs)
+
+    def list(self, request, *args, **kwargs):
+        """
+        Override list view request handling to perform loading event first
+        """
+        self._load_event()
+        return super().list(request, *args, **kwargs)
+
+    def create(self, request, *args, **kwargs):
+        """
+        Override create view request handling to perform loading event first
+        """
+        self._load_event()
+        return super().create(request, *args, **kwargs)
+
+    def dispatch(self, request, *args, **kwargs):
+        """
+        Override dispatch which is called in many generic views to perform loading event first
+        """
+        if self.event is None:
+            self._load_event()
+        return super().dispatch(request, *args, **kwargs)
+
+    def get_context_data(self, *, object_list=None, **kwargs):
+        """
+        Override `get_context_data` to make the event information available in the rendering context as `event`. too
+        """
+        context = super().get_context_data(object_list=object_list, **kwargs)
+        # Add event to context (to make it accessible in templates)
+        context["event"] = self.event
+        return context
+
+
+class FilterByEventSlugMixin(EventSlugMixin):
+    """
+    Mixin to filter different querysets based on a event slug from the request url
+    """
+
+    def get_queryset(self):
+        """
+        Get adapted queryset:
+        Filter current queryset based on url event slug or return 404 if event slug is invalid
+        :return: Queryset
+        """
+        return super().get_queryset().filter(event=self.event)
+
+
+class AdminViewMixin:
+    """
+    Mixin to provide context information needed in custom admin views
+
+    Will either use default information for `site_url` and `title` or allows to set own values for that
+    """
+    # pylint: disable=too-few-public-methods
+
+    site_url = ''
+    title = ''
+
+    def get_context_data(self, **kwargs):
+        """
+        Extend context
+        """
+        extra = admin.site.each_context(self.request)
+        extra.update(super().get_context_data(**kwargs))
+
+        if self.site_url != '':
+            extra["site_url"] = self.site_url
+        if self.title != '':
+            extra["title"] = self.title
+
+        return extra
+
+
+class IntermediateAdminView(AdminViewMixin, FormView):
+    """
+    Metaview: Handle typical "action but with preview and confirmation step before" workflow
+    """
+    template_name = "admin/AKModel/action_intermediate.html"
+    form_class = AdminIntermediateForm
+
+    def get_preview(self):
+        """
+        Render a preview of the action to be performed.
+        Default is empty
+        :return: preview (html)
+        :rtype: str
+        """
+        return ""
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        context["title"] = self.title
+        context["preview"] = self.get_preview()
+        return context
+
+
+class WizardViewMixin:
+    """
+    Mixin to create wizard-like views.
+    This visualizes the progress of the user in the creation process and provides the interlinking to the next step
+
+    In the current implementation, the steps of the wizard are hardcoded here,
+    hence this mixin can only be used for the event creation wizard
+    """
+    # pylint: disable=too-few-public-methods
+    def get_context_data(self, **kwargs):
+        """
+        Extend context
+        """
+        context = super().get_context_data(**kwargs)
+        context["wizard_step"] = self.wizard_step
+        context["wizard_steps"] = [
+            _("Start"),
+            _("Settings"),
+            _("Event created, Prepare Import"),
+            _("Import categories & requirements"),
+            _("Activate?"),
+            _("Finish")
+        ]
+        context["wizard_step_text"] = context["wizard_steps"][self.wizard_step - 1]
+        context["wizard_steps_total"] = len(context["wizard_steps"])
+        return context
+
+
+class IntermediateAdminActionView(IntermediateAdminView, ABC):
+    """
+    Abstract base view: Intermediate action view (preview & confirmation see :class:`IntermediateAdminView`)
+    for custom admin actions (marking multiple objects in a django admin model instances list with a checkmark and then
+    choosing an action from the dropdown).
+
+    This will automatically handle the decoding of the URL encoding of the list of primary keys django does to select
+    which objects the action should be run on, then display a preview, perform the action after confirmation and
+    redirect again to the object list including display of a confirmation message
+    """
+    # pylint: disable=no-member
+    form_class = AdminIntermediateActionForm
+    entities = None
+
+    def get_queryset(self, pks=None):
+        """
+        Get the queryset of objects to perform the action on
+        """
+        if pks is None:
+            pks = self.request.GET['pks']
+        return self.model.objects.filter(pk__in=pks.split(","))
+
+    def get_initial(self):
+        initial = super().get_initial()
+        initial['pks'] = self.request.GET['pks']
+        return initial
+
+    def get_preview(self):
+        self.entities = self.get_queryset()
+        joined_entities = '\n'.join(str(e) for e in self.entities)
+        return f"{self.confirmation_message}:\n\n {joined_entities}"
+
+    def get_success_url(self):
+        return reverse(f"admin:{self.model._meta.app_label}_{self.model._meta.model_name}_changelist")
+
+    @abstractmethod
+    def action(self, form):
+        """
+        The real action to perform
+        :param form: form holding the data probably needed for the action
+        """
+
+    def form_valid(self, form):
+        self.entities = self.get_queryset(pks=form.cleaned_data['pks'])
+        self.action(form)
+        messages.add_message(self.request, messages.SUCCESS, self.success_message)
+        return super().form_valid(form)
+
+
+class LoopActionMixin(ABC):
+    """
+    Mixin for the typical kind of action where one needs to loop over all elements
+    and perform a certain function on each of them
+
+    The action is performed by overriding `perform_action(self, entity)`
+    further customization can be reached with the two callbacks `pre_action()` and `post_action()`
+    that are called before and after performing the action loop
+    """
+    def action(self, form):  # pylint: disable=unused-argument
+        """
+        The real action to perform.
+        Will perform the loop, perform the action on each aelement and call the callbacks
+
+        :param form: form holding the data probably needed for the action
+        """
+        self.pre_action()
+        for entity in self.entities:
+            self.perform_action(entity)
+            entity.save()
+        self.post_action()
+
+    @abstractmethod
+    def perform_action(self, entity):
+        """
+        Action to perform on each entity
+
+        :param entity: entity to perform the action on
+        """
+
+    def pre_action(self):
+        """
+        Callback for custom action before loop starts
+        """
+
+    def post_action(self):
+        """
+        Callback for custom action after loop finished
+        """

AKModel/migrations/0001_event.py

+# Generated by Django 2.2.6 on 2019-10-11 16:58
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Event',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(help_text='Name or iteration of the event', max_length=64, unique=True, verbose_name='Name')),
+                ('start', models.DateTimeField(help_text='Time the event begins', verbose_name='Start')),
+                ('end', models.DateTimeField(help_text='Time the event ends', verbose_name='End')),
+                ('place', models.CharField(help_text='City etc. where the event takes place', max_length=128, verbose_name='Place')),
+                ('active', models.BooleanField(help_text='Marks currently active events', verbose_name='Active State')),
+            ],
+        ),
+    ]