Add suff drink booking tool with PIN auth

Self-service drink tab at /suff/ for festival attendees. Users log in
with username + 3-digit PIN stored in a separate User.pin field, so
staff/admin accounts can keep their strong password for /admin/ and
also use the drink tool with the same username. PINs for staff users
must be set from the admin panel via a dedicated "PIN setzen" view to
prevent account takeover by name collision.

Time-gated to the festival window (Thu–Sun in Berlin tz) with phases
before/booking/readonly/closed; in non-production mode the tool is
always in booking phase for local testing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

gaehsnitz/admin.py

@@ -1,6 +1,12 @@
-from django.contrib import admin
+from django import forms
+from django.contrib import admin, messages
+from django.contrib.admin.utils import unquote
 from django.contrib.auth import get_user_model
 from django.contrib.auth.admin import UserAdmin
+from django.http import Http404, HttpResponseRedirect
+from django.template.response import TemplateResponse
+from django.urls import path, reverse
+from django.utils.html import format_html
 from django.utils.safestring import mark_safe
 
 from gaehsnitz.models import Donation, Payment, Drink, Consumption
@@ -14,6 +20,20 @@ class ConsumptionInline(admin.TabularInline):
     extra = 0
 
 
+class SetPinForm(forms.Form):
+    pin = forms.CharField(
+        label="Neue PIN (3 Ziffern)",
+        min_length=3,
+        max_length=3,
+    )
+
+    def clean_pin(self):
+        pin = self.cleaned_data["pin"]
+        if not pin.isdigit():
+            raise forms.ValidationError("PIN muss aus genau 3 Ziffern bestehen.")
+        return pin
+
+
 @admin.register(User)
 class CustomUserAdmin(UserAdmin):
     list_display = ("username", "consumed_drinks_price")
@@ -26,17 +46,63 @@ class CustomUserAdmin(UserAdmin):
                 "fields": (
                     "username",
                     "password",
+                    "pin_status",
                 )
             },
         ),
         ("BALANCE", {"fields": ("consumed_drinks_price",)}),
     )
-    readonly_fields = ("consumed_drinks_price",)
+    readonly_fields = ("consumed_drinks_price", "pin_status")
     inlines = (ConsumptionInline,)
 
     def consumed_drinks_price(self, user: User):
         return euro(user.consumed_drinks_price)
 
+    @admin.display(description="PIN")
+    def pin_status(self, user: User):
+        status = "gesetzt" if user.pin else "nicht gesetzt"
+        if user.pk is None:
+            return status
+        url = reverse("admin:gaehsnitz_user_set_pin", args=[user.pk])
+        return format_html('{} &nbsp; <a href="{}">PIN setzen</a>', status, url)
+
+    def get_urls(self):
+        urls = super().get_urls()
+        custom = [
+            path(
+                "<id>/pin/",
+                self.admin_site.admin_view(self.set_pin_view),
+                name="gaehsnitz_user_set_pin",
+            ),
+        ]
+        return custom + urls
+
+    def set_pin_view(self, request, id):
+        if not self.has_change_permission(request):
+            raise Http404
+        user = self.get_object(request, unquote(id))
+        if user is None:
+            raise Http404
+
+        if request.method == "POST":
+            form = SetPinForm(request.POST)
+            if form.is_valid():
+                user.set_pin(form.cleaned_data["pin"])
+                user.save(update_fields=["pin"])
+                messages.success(request, f"PIN für {user.username} gesetzt.")
+                return HttpResponseRedirect(reverse("admin:gaehsnitz_user_change", args=[user.pk]))
+        else:
+            form = SetPinForm()
+
+        context = {
+            **self.admin_site.each_context(request),
+            "title": f"PIN setzen für {user.username}",
+            "opts": self.model._meta,
+            "original": user,
+            "form": form,
+        }
+        return TemplateResponse(request, "admin/gaehsnitz/user/set_pin.html", context)
+
 
 @admin.register(Donation)
 class DonationAdmin(admin.ModelAdmin):

gaehsnitz/auth_backends.py

@@ -0,0 +1,25 @@
+from django.contrib.auth import get_user_model
+from django.contrib.auth.backends import ModelBackend
+
+
+class PinBackend(ModelBackend):
+    """Authenticate festival users by username + 3-digit PIN stored in `pin`.
+
+    Strong passwords stay on the User model for /admin/ via the default
+    ModelBackend. Staff can also set a PIN to use the drink tool with the
+    same username.
+    """
+
+    def authenticate(self, request, username=None, pin=None, **kwargs):
+        if username is None or pin is None:
+            return None
+        User = get_user_model()
+        try:
+            user = User.objects.get(username=username)
+        except User.DoesNotExist:
+            return None
+        if not user.check_pin(pin):
+            return None
+        if not self.user_can_authenticate(user):
+            return None
+        return user

gaehsnitz/migrations/0003_consumption_created_at_user_pin.py

@@ -0,0 +1,22 @@
+# Generated by Django 6.0.5 on 2026-05-14 09:36
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("gaehsnitz", "0002_remove_donation_from_user_remove_payment_from_user_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="consumption",
+            name="created_at",
+            field=models.DateTimeField(auto_now_add=True, null=True),
+        ),
+        migrations.AddField(
+            model_name="user",
+            name="pin",
+            field=models.CharField(blank=True, default="", max_length=128),
+        ),
+    ]

gaehsnitz/models.py

@@ -1,3 +1,4 @@
+from django.contrib.auth.hashers import check_password, make_password
 from django.contrib.auth.models import AbstractUser
 from django.db import models
 from django.db.models import Sum, F
@@ -10,6 +11,16 @@ class PriceField(models.DecimalField):
 
 
 class User(AbstractUser):
+    pin = models.CharField(max_length=128, blank=True, default="")
+
+    def set_pin(self, raw_pin):
+        self.pin = make_password(raw_pin)
+
+    def check_pin(self, raw_pin):
+        if not self.pin:
+            return False
+        return check_password(raw_pin, self.pin)
+
     @property
     def paid_drinks(self):
         return self.consumption_list.filter(for_free=False)
@@ -132,3 +143,4 @@ class Consumption(models.Model):
     amount = models.PositiveSmallIntegerField()
     day = models.PositiveSmallIntegerField(choices=[(1, "Do"), (2, "Fr"), (3, "Sa"), (4, "So")])
     for_free = models.BooleanField(default=False)
+    created_at = models.DateTimeField(auto_now_add=True, null=True)

gaehsnitz/suff.py

@@ -0,0 +1,207 @@
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+from django.conf import settings
+from django.contrib.auth import authenticate, login, logout
+from django.contrib.auth.decorators import login_required
+from django.contrib.auth import get_user_model
+from django.db.models import F, Sum
+from django.http import Http404, HttpResponseRedirect
+from django.shortcuts import render
+from django.urls import reverse
+from django.utils import timezone
+from django.utils.text import slugify
+from django.views.decorators.http import require_http_methods
+
+from gaehsnitz.models import Consumption, Drink
+
+User = get_user_model()
+
+BERLIN = ZoneInfo("Europe/Berlin")
+BOOKING_START = datetime(2026, 6, 11, 0, 0, 0, tzinfo=BERLIN)
+BOOKING_END = datetime(2026, 6, 14, 23, 59, 59, tzinfo=BERLIN)
+READONLY_END = datetime(2026, 6, 21, 23, 59, 59, tzinfo=BERLIN)
+
+DAY_BY_WEEKDAY = {3: 1, 4: 2, 5: 3, 6: 4}
+
+
+def _now():
+    return timezone.now().astimezone(BERLIN)
+
+
+def _phase():
+    if not settings.PRODUCTION:
+        return "booking"
+    now = _now()
+    if now < BOOKING_START:
+        return "before"
+    if now <= BOOKING_END:
+        return "booking"
+    if now <= READONLY_END:
+        return "readonly"
+    return "closed"
+
+
+def _require_open(request):
+    """Raise 404 once tool is fully closed. Return current phase otherwise."""
+    phase = _phase()
+    if phase == "closed":
+        raise Http404
+    return phase
+
+
+def _current_festival_day():
+    weekday = _now().weekday()
+    return DAY_BY_WEEKDAY.get(weekday, 4)
+
+
+def _normalize_name(raw):
+    return slugify(raw or "")[:150]
+
+
+def _tab_context(user):
+    consumption = user.consumption_list.select_related("drink").order_by("-created_at", "-id")
+    paid = (
+        user.paid_drinks.annotate(cost=F("amount") * F("drink__sale_price_per_bottle")).aggregate(total=Sum("cost"))[
+            "total"
+        ]
+        or 0
+    )
+    return {
+        "tab_user": user,
+        "consumption_list": consumption,
+        "total": paid,
+    }
+
+
+@require_http_methods(["GET", "POST"])
+def name_view(request):
+    phase = _require_open(request)
+    if request.user.is_authenticated:
+        return HttpResponseRedirect(reverse("suff:me"))
+
+    error = None
+    if request.method == "POST":
+        raw_name = request.POST.get("name", "")
+        username = _normalize_name(raw_name)
+        if not username:
+            error = "Bitte einen Namen eingeben."
+        else:
+            try:
+                existing = User.objects.get(username=username)
+            except User.DoesNotExist:
+                existing = None
+
+            if existing is None:
+                request.session["pending_username"] = username
+                request.session["pending_mode"] = "create"
+                return HttpResponseRedirect(reverse("suff:pin"))
+
+            if not existing.pin:
+                return render(
+                    request,
+                    "suff/no_pin.html",
+                    {"phase": phase, "username": username},
+                )
+
+            request.session["pending_username"] = username
+            request.session["pending_mode"] = "login"
+            return HttpResponseRedirect(reverse("suff:pin"))
+
+    return render(request, "suff/name.html", {"phase": phase, "error": error})
+
+
+@require_http_methods(["GET", "POST"])
+def pin_view(request):
+    phase = _require_open(request)
+    username = request.session.get("pending_username")
+    mode = request.session.get("pending_mode")
+    if not username or mode not in ("create", "login"):
+        return HttpResponseRedirect(reverse("suff:name"))
+
+    error = None
+    if request.method == "POST":
+        pin = request.POST.get("pin", "")
+        if not (pin.isdigit() and len(pin) == 3):
+            error = "PIN muss aus genau 3 Ziffern bestehen."
+        elif mode == "create":
+            if User.objects.filter(username=username).exists():
+                error = "Name bereits vergeben."
+                return HttpResponseRedirect(reverse("suff:name"))
+            user = User(username=username)
+            user.set_pin(pin)
+            user.save()
+            authed = authenticate(request, username=username, pin=pin)
+            if authed is None:
+                error = "Login nach Anlegen fehlgeschlagen."
+            else:
+                login(request, authed, backend="gaehsnitz.auth_backends.PinBackend")
+                request.session.pop("pending_username", None)
+                request.session.pop("pending_mode", None)
+                return HttpResponseRedirect(reverse("suff:me"))
+        else:
+            authed = authenticate(request, username=username, pin=pin)
+            if authed is None:
+                error = "Falsche PIN."
+            else:
+                login(request, authed, backend="gaehsnitz.auth_backends.PinBackend")
+                request.session.pop("pending_username", None)
+                request.session.pop("pending_mode", None)
+                return HttpResponseRedirect(reverse("suff:me"))
+
+    return render(
+        request,
+        "suff/pin.html",
+        {
+            "phase": phase,
+            "error": error,
+            "mode": mode,
+            "username": username,
+        },
+    )
+
+
+@login_required
+@require_http_methods(["GET"])
+def me_view(request):
+    phase = _require_open(request)
+    drinks = Drink.objects.order_by("name") if phase == "booking" else Drink.objects.none()
+    context = _tab_context(request.user)
+    context.update(
+        {
+            "phase": phase,
+            "drinks": drinks,
+            "current_day": _current_festival_day(),
+        }
+    )
+    return render(request, "suff/me.html", context)
+
+
+@login_required
+@require_http_methods(["POST"])
+def book_view(request):
+    phase = _require_open(request)
+    if phase != "booking":
+        raise Http404
+
+    drink_id = request.POST.get("drink_id")
+    try:
+        drink = Drink.objects.get(pk=int(drink_id))
+    except (Drink.DoesNotExist, TypeError, ValueError):
+        return HttpResponseRedirect(reverse("suff:me"))
+
+    Consumption.objects.create(
+        user=request.user,
+        drink=drink,
+        amount=1,
+        day=_current_festival_day(),
+        for_free=False,
+    )
+    return HttpResponseRedirect(reverse("suff:me"))
+
+
+@require_http_methods(["POST"])
+def logout_view(request):
+    _require_open(request)
+    logout(request)
+    return HttpResponseRedirect(reverse("suff:name"))

gaehsnitz/suff_urls.py

@@ -0,0 +1,19 @@
+from django.urls import path
+
+from gaehsnitz.suff import (
+    book_view,
+    logout_view,
+    me_view,
+    name_view,
+    pin_view,
+)
+
+app_name = "suff"
+
+urlpatterns = [
+    path("", name_view, name="name"),
+    path("pin/", pin_view, name="pin"),
+    path("me/", me_view, name="me"),
+    path("book/", book_view, name="book"),
+    path("logout/", logout_view, name="logout"),
+]

gaehsnitz/templates/admin/gaehsnitz/user/set_pin.html

@@ -0,0 +1,23 @@
+{% extends "admin/base_site.html" %}
+
+{% block breadcrumbs %}
+<div class="breadcrumbs">
+    <a href="{% url 'admin:index' %}">Home</a>
+    &rsaquo; <a href="{% url 'admin:app_list' app_label=opts.app_label %}">{{ opts.app_config.verbose_name }}</a>
+    &rsaquo; <a href="{% url 'admin:gaehsnitz_user_changelist' %}">Users</a>
+    &rsaquo; <a href="{% url 'admin:gaehsnitz_user_change' original.pk %}">{{ original }}</a>
+    &rsaquo; PIN setzen
+</div>
+{% endblock %}
+
+{% block content %}
+<form method="post">
+    {% csrf_token %}
+    <div>
+        {{ form.as_p }}
+    </div>
+    <div class="submit-row">
+        <input type="submit" value="PIN setzen" class="default" />
+    </div>
+</form>
+{% endblock %}

gaehsnitz/templates/suff/base.html

@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="de">
+    <head>
+        <meta name="viewport" content="width=device-width, initial-scale=1" />
+        <meta charset="utf-8" />
+        <title>Suff - Gähsnitz Open Air</title>
+    </head>
+    <body>
+        <h1>Suff</h1>
+        {% block content %}{% endblock %}
+    </body>
+</html>

gaehsnitz/templates/suff/me.html

@@ -0,0 +1,50 @@
+{% extends "suff/base.html" %}
+
+{% block content %}
+<h2>Hallo {{ tab_user.username }}</h2>
+
+{% if phase == "readonly" %}
+    <p><i>Festival vorbei. Buchungen geschlossen, nur noch Anzeige.</i></p>
+{% endif %}
+
+<h3>Deine Rechnung: {{ total|floatformat:2 }} €</h3>
+
+<h3>Bisher gebucht</h3>
+{% if consumption_list %}
+    <ul>
+    {% for c in consumption_list %}
+        <li>
+            {{ c.get_day_display }}{% if c.created_at %} {{ c.created_at|date:"H:i" }}{% endif %}:
+            {{ c.amount }}× {{ c.drink.name }}
+            {% if c.for_free %}
+                (gratis)
+            {% else %}
+                à {{ c.drink.sale_price_per_bottle|floatformat:2 }} €
+            {% endif %}
+        </li>
+    {% endfor %}
+    </ul>
+{% else %}
+    <p>Noch nichts gebucht.</p>
+{% endif %}
+
+{% if phase == "booking" %}
+    <h3>Neues Getränk buchen</h3>
+    <p>Heutiger Tag: {{ current_day }}</p>
+    {% for drink in drinks %}
+        <form method="post" action="{% url 'suff:book' %}" style="display:inline">
+            {% csrf_token %}
+            <input type="hidden" name="drink_id" value="{{ drink.id }}" />
+            <button type="submit">
+                +1 {{ drink.name }} ({{ drink.sale_price_per_bottle|floatformat:2 }} €)
+            </button>
+        </form>
+    {% endfor %}
+{% endif %}
+
+<hr />
+<form method="post" action="{% url 'suff:logout' %}">
+    {% csrf_token %}
+    <button type="submit">Logout</button>
+</form>
+{% endblock %}

gaehsnitz/templates/suff/name.html

@@ -0,0 +1,19 @@
+{% extends "suff/base.html" %}
+
+{% block content %}
+<h2>Wer bist du?</h2>
+<p>
+    Gib deinen Namen ein. Sonderzeichen, Leerzeichen und Großbuchstaben werden
+    entfernt (z.B. wird aus "Flo Hä!" → "flo-ha"). Merk dir den Namen so,
+    wie er hier nach dem Anlegen angezeigt wird.
+</p>
+{% if error %}<p><b>{{ error }}</b></p>{% endif %}
+<form method="post" action="{% url 'suff:name' %}">
+    {% csrf_token %}
+    <label>
+        Name:
+        <input type="text" name="name" autofocus required />
+    </label>
+    <button type="submit">Weiter</button>
+</form>
+{% endblock %}

gaehsnitz/templates/suff/no_pin.html

@@ -0,0 +1,21 @@
+{% extends "suff/base.html" %}
+
+{% block content %}
+<h2>Keine PIN gesetzt</h2>
+<p>
+    Für den Namen <b>{{ username }}</b> ist noch keine PIN hinterlegt.
+</p>
+<p>
+    Das ist ein Staff-Account. Aus Sicherheitsgründen kann die PIN für solche
+    Accounts nicht selbst gesetzt werden – sonst könnte sich jeder mit dem
+    Namen eines Admins eine eigene PIN anlegen und damit hier einloggen.
+</p>
+<p>
+    Bitte einen Admin bitten, die PIN über das Admin-Panel zu setzen.
+</p>
+<p>
+    <a href="{% url 'suff:name' %}">Zurück</a>
+    &middot;
+    <a href="/admin/">Admin-Panel</a>
+</p>
+{% endblock %}

gaehsnitz/templates/suff/pin.html

@@ -0,0 +1,31 @@
+{% extends "suff/base.html" %}
+
+{% block content %}
+{% if mode == "create" %}
+    <h2>Neuer Account: {{ username }}</h2>
+    <p>Merk dir diesen Namen: <b>{{ username }}</b>. Du brauchst ihn beim nächsten Login.</p>
+    <p>Wähl eine 3-stellige PIN.</p>
+{% else %}
+    <h2>Hallo {{ username }}</h2>
+    <p>Gib deine 3-stellige PIN ein.</p>
+{% endif %}
+
+{% if error %}<p><b>{{ error }}</b></p>{% endif %}
+
+<form method="post" action="{% url 'suff:pin' %}">
+    {% csrf_token %}
+    <label>
+        PIN:
+        <input type="text" name="pin" inputmode="numeric" pattern="[0-9]{3}" maxlength="3"
+               minlength="3" required autofocus autocomplete="off" />
+    </label>
+    <button type="submit">
+        {% if mode == "create" %}Account anlegen{% else %}Login{% endif %}
+    </button>
+</form>
+
+<p>
+    Nicht du / keine PIN / vergessen?
+    <a href="{% url 'suff:name' %}">Zurück und neuen Namen wählen</a>
+</p>
+{% endblock %}

gaehsnitz/views.py

@@ -56,7 +56,6 @@ class NewsView(GaehsnitzTemplateView):
         return context
 
 
-
 class Archive2022View(GaehsnitzTemplateView):
     template_name = "gaehsnitz/archive-2022.html"