digitalfabrik/integreat-cms

"""
This module contains form views for our models that don't need custom handling.
"""

from __future__ import annotations

from typing import TYPE_CHECKING

from django.contrib import messages
from django.contrib.auth.mixins import PermissionRequiredMixin
from django.core.exceptions import FieldDoesNotExist
from django.urls import reverse
from django.utils.translation import gettext_lazy as _
from django.views.generic.edit import BaseCreateView, BaseUpdateView, ModelFormMixin

if TYPE_CHECKING:
    from typing import Any

    from django.db.models.base import ModelBase
    from django.http import HttpResponse, HttpResponseRedirect

    from ..forms.custom_model_form import CustomModelForm

from .media import MediaContextMixin
from .mixins import ModelConfirmationContextMixin, ModelTemplateResponseMixin


# pylint: disable=too-many-ancestors
class CustomModelFormMixin(
    PermissionRequiredMixin,
    ModelTemplateResponseMixin,
    ModelFormMixin,
    ModelConfirmationContextMixin,
    MediaContextMixin,
):
    """
    This mixin handles error messages in form views of subclasses of
    :class:`~integreat_cms.cms.forms.custom_model_form.CustomModelForm`
    """

    #: The suffix to append to the auto-generated candidate template name.
    template_name_suffix: str = "_form"

    def get_permission_required(self) -> tuple[str]:
        """
        Override this method to override the permission_required attribute.

        :return: The permissions that are required for views inheriting from this Mixin
        """
        # If the form is submitted via POST, require the change permission
        if self.request.method == "POST":
            return (f"cms.change_{self.model._meta.model_name}",)
        # If the form is just retrieved, require the view permission
        return (f"cms.view_{self.model._meta.model_name}",)

    @property
    def model(self) -> ModelBase:
        """
        Return the model class of this form mixin

        :return: The corresponding Django model
        """
        return self.form_class._meta.model

    def get_context_data(self, **kwargs: Any) -> dict[str, Any]:
        r"""
        Returns a dictionary representing the template context
        (see :meth:`~django.views.generic.base.ContextMixin.get_context_data`).

        :param \**kwargs: The given keyword arguments
        :return: The template context
        """
        context = super().get_context_data(**kwargs)
        context.update({"current_menu_item": f"{self.model._meta.model_name}s"})
        return context

    def get_form_kwargs(self) -> dict[str, Any]:
        """
        Return the keyword arguments for instantiating the form

        :return: The form kwargs
        """
        kwargs = super().get_form_kwargs()
        if self.request.region:
            kwargs["additional_instance_attributes"] = {"region": self.request.region}
        return kwargs

    def get_success_url(self) -> str:
        """
        Determine the URL to redirect to when the form is successfully validated

        :return: The url to redirect on success
        """
        kwargs = {}
        try:
            # Check whether the model has a slug field
            self.model._meta.get_field(self.slug_url_kwarg)
            kwargs[self.slug_url_kwarg] = self.object.slug
        except FieldDoesNotExist:
            # If not, use the primary key field as fallback
            kwargs[self.pk_url_kwarg] = self.object.pk
        if self.request.region:
            kwargs["region_slug"] = self.request.region.slug
        return reverse(f"edit_{self.object._meta.model_name}", kwargs=kwargs)

    def form_valid(self, form: CustomModelForm) -> HttpResponseRedirect:
        """
        Saves the form instance, sets the current object for the view, and redirects to :meth:`get_success_url`.

        :param form: The valid form instance
        :return: A redirection to the success url
        """
        if not form.has_changed():
            # Add "no changes" messages
            messages.info(self.request, _("No changes made"))
        elif self.object:
            messages.success(
                self.request,
                _('{} "{}" was successfully saved').format(
                    self.object._meta.verbose_name, self.object
                ),
            )
        else:
            messages.success(
                self.request,
                _('{} "{}" was successfully created').format(
                    form.instance._meta.verbose_name, form.instance
                ),
            )
        return super().form_valid(form)

    def form_invalid(self, form: CustomModelForm) -> HttpResponse:
        """
        Renders a response, providing the invalid form as context.

        :param form: The invalid form instance
        :return: The rendered invalid form
        """
        form.add_error_messages(self.request)
        return super().form_invalid(form)


class CustomCreateView(CustomModelFormMixin, BaseCreateView):
    """
    A view that displays a form for creating a region object, redisplaying the form with validation errors (if
    there are any) and saving the object.
    """


class CustomUpdateView(CustomModelFormMixin, BaseUpdateView):
    """
    A view that displays a form for editing an existing region object, redisplaying the form with validation errors
    (if there are any) and saving changes to the object. This uses a form automatically generated from the object's
    model class (unless a form class is manually specified).
    """