Kochbuch/accounts/views.py

from datetime import timedelta

from django.conf import settings
from django.contrib import messages
from django.contrib.auth import authenticate, login, logout, update_session_auth_hash
from django.contrib.auth.decorators import login_not_required
from django.db import transaction
from django.shortcuts import redirect, render
from django.utils import timezone
from django.utils.http import url_has_allowed_host_and_scheme
from django.views.decorators.cache import never_cache
from django.views.decorators.debug import sensitive_post_parameters
from django.views.decorators.http import require_POST

from core import ratelimit

from .forms import LoginForm, PasswordChangeForm, ProfileForm, RegistrationForm, UserPasswordForm
from .models import Invitation, PasswordResetToken, User


def _login_limits(request, email):
    ip = request.META.get("REMOTE_ADDR", "unknown")
    return [
        (f"login:ip:{ip}", settings.LOGIN_MAX_FAILURES_PER_IP),
        (f"login:email:{email}", settings.LOGIN_MAX_FAILURES_PER_EMAIL),
    ]


def _safe_next(request):
    target = request.POST.get("next") or request.GET.get("next") or ""
    if url_has_allowed_host_and_scheme(target, allowed_hosts={request.get_host()}, require_https=request.is_secure()):
        return target
    return settings.LOGIN_REDIRECT_URL


@login_not_required
@sensitive_post_parameters("password")
@never_cache
def login_view(request):
    if request.user.is_authenticated:
        return redirect("core:home")
    form = LoginForm(request.POST or None)
    status = 200
    if request.method == "POST" and form.is_valid():
        email = form.cleaned_data["email"]
        window = timedelta(minutes=settings.LOGIN_LOCKOUT_MINUTES)
        limits = _login_limits(request, email)
        if any(ratelimit.is_limited(key, limit, window) for key, limit in limits):
            form.add_error(
                None,
                f"Zu viele fehlgeschlagene Anmeldeversuche. Bitte versuche es in "
                f"{settings.LOGIN_LOCKOUT_MINUTES} Minuten erneut.",
            )
            status = 429
        else:
            user = authenticate(request, email=email, password=form.cleaned_data["password"])
            if user is not None:
                ratelimit.reset(limits[1][0])
                login(request, user)
                return redirect(_safe_next(request))
            for key, limit in limits:
                ratelimit.hit(key, limit, window)
            # Same message for unknown e-mail, wrong password and deactivated accounts.
            form.add_error(None, "E-Mail oder Passwort ist falsch.")
            status = 400
    return render(request, "accounts/login.html", {"form": form, "next": request.GET.get("next", "")}, status=status)


@require_POST
def logout_view(request):
    logout(request)
    return redirect(settings.LOGOUT_REDIRECT_URL)


@login_not_required
@sensitive_post_parameters("password1", "password2")
@never_cache
def register(request, token):
    invitation = Invitation.objects.get_usable(token)
    if invitation is None:
        return render(request, "accounts/link_invalid.html", {"kind": "Einladungslink"}, status=404)
    if request.user.is_authenticated:
        return render(request, "accounts/already_logged_in.html", status=409)

    form = RegistrationForm(request.POST or None, invitation=invitation)
    if request.method == "POST" and form.is_valid():
        with transaction.atomic():
            # Re-check under a row lock so one link cannot create two accounts.
            invitation = Invitation.objects.select_for_update().usable().filter(pk=invitation.pk).first()
            if invitation is None:
                return render(request, "accounts/link_invalid.html", {"kind": "Einladungslink"}, status=404)
            user = User.objects.create_user(
                email=form.cleaned_data["email"],
                password=form.cleaned_data["password1"],
                display_name=form.cleaned_data["display_name"],
                role=invitation.role,
            )
            invitation.used_at = timezone.now()
            invitation.used_by = user
            invitation.save(update_fields=["used_at", "used_by"])
        login(request, user, backend="django.contrib.auth.backends.ModelBackend")
        messages.success(request, "Willkommen im Kochbuch!")
        return redirect("core:home")
    return render(request, "accounts/register.html", {"form": form, "invitation": invitation})


@login_not_required
@sensitive_post_parameters("password1", "password2")
@never_cache
def password_reset(request, token):
    reset = PasswordResetToken.objects.get_usable(token)
    if reset is None or not reset.user.is_active:
        return render(request, "accounts/link_invalid.html", {"kind": "Link zum Zurücksetzen"}, status=404)

    form = UserPasswordForm(request.POST or None, user=reset.user)
    if request.method == "POST" and form.is_valid():
        with transaction.atomic():
            reset = PasswordResetToken.objects.select_for_update().usable().filter(pk=reset.pk).first()
            if reset is None:
                return render(request, "accounts/link_invalid.html", {"kind": "Link zum Zurücksetzen"}, status=404)
            user = reset.user
            user.set_password(form.cleaned_data["password1"])
            user.must_change_password = False
            user.save(update_fields=["password", "must_change_password"])
            reset.used_at = timezone.now()
            reset.save(update_fields=["used_at"])
        login(request, user, backend="django.contrib.auth.backends.ModelBackend")
        messages.success(request, "Dein Passwort wurde geändert.")
        return redirect("core:home")
    return render(request, "accounts/password_reset.html", {"form": form, "reset_user": reset.user})


@never_cache
def profile(request):
    form = ProfileForm(request.POST or None, instance=request.user)
    if request.method == "POST" and form.is_valid():
        form.save()
        messages.success(request, "Profil gespeichert.")
        return redirect("accounts:profile")
    return render(request, "accounts/profile.html", {"form": form})


@sensitive_post_parameters("old_password", "password1", "password2")
@never_cache
def password_change(request):
    user = request.user
    form_class = UserPasswordForm if user.must_change_password else PasswordChangeForm
    form = form_class(request.POST or None, user=user)
    if request.method == "POST" and form.is_valid():
        user.set_password(form.cleaned_data["password1"])
        user.must_change_password = False
        user.save(update_fields=["password", "must_change_password"])
        update_session_auth_hash(request, user)
        messages.success(request, "Dein Passwort wurde geändert.")
        return redirect("core:home")
    return render(request, "accounts/password_change.html", {"form": form, "forced": user.must_change_password})