admin.py

import json

from typing import Type

from django.contrib import admin
from django.core.exceptions import PermissionDenied
from django.db.models import Model
from django.http import Http404, HttpResponseRedirect
from django.shortcuts import redirect
from django.urls import reverse, path
from django.utils.html import format_html

from cosmogo.utils.gettext import trans
from cosmogo.utils.url import get_absolute_url

DEFAULT_LINK_TEMPLATE = '<a href="{url}">{label}</a>'


def admin_url(model: Type[Model], view: str, *args, site=None, **kwargs) -> str:
    """
    Return an url to an admin view.
    """

    return reverse(admin_url_name(model, view, site=site), args=args, kwargs=kwargs)


def absolute_admin_url(request, model: Type[Model], view: str, *args, site=None, **kwargs):
    return get_absolute_url(request, admin_url_name(model, view, site=site), *args, **kwargs)


def admin_redirect(model: Type[Model], view: str, *args, site=None, **kwargs) -> HttpResponseRedirect:
    return redirect(admin_url_name(model, view, site=site), *args, **kwargs)


def admin_url_name(model: Type[Model], view: str, *, site=None) -> str:
    namespace = (site or admin.site).name
    view_name = admin_view_name(model, view)

    return f'{namespace}:{view_name}'


def admin_view_name(model: Type[Model], view: str) -> str:
    return f'{model._meta.app_label}_{model._meta.model_name}_{view}'


def admin_path(model_admin: admin.ModelAdmin, route, view, name, kwargs=None):
    name = admin_view_name(model_admin.model, name)
    view = model_admin.admin_site.admin_view(view)

    return path(route, view, kwargs=kwargs, name=name)


def admin_link(obj: Model, view='change', site=None, label=None, template=DEFAULT_LINK_TEMPLATE):
    url = admin_url(type(obj), view, obj.pk, site=site)

    return format_link(url, label=label or obj, obj=obj, template=template)


def format_link(url, label=None, *, template=DEFAULT_LINK_TEMPLATE, **kwargs):
    kwargs.setdefault('label', label or url)

    return format_html(template, url=url, **kwargs)


def admin_template_names(model: Type[Model], name: str, *, site=None):
    opts = model._meta
    app_label = opts.app_label
    model_name = opts.model_name
    namespace = (site or admin.site).name

    return [
        f'{namespace}/{app_label}/{model_name}/{name}.html',
        f'{namespace}/{app_label}/{name}.html',
        f'{namespace}/{name}.html',
    ]


def json_display(data):
    content = json.dumps(data, indent=2)

    return format_html('<pre style="padding: 0">{content}</pre>', content=content)


class DefaultTabularInline(admin.TabularInline):
    template = 'admin/inline/tabular-without-original.html'
    extra = 0


class AdminViewMixin:

    def get_object_for(self: admin.ModelAdmin, permission: str, request, object_id):
        obj = self.get_object(request, object_id)

        if not getattr(self, f'has_{permission}_permission')(request, obj=obj):
            raise PermissionDenied

        if obj is None:
            msg = trans('%(name)s object with primary key %(key)r does not exist.')
            context = {'name': self.opts.verbose_name, 'key': object_id}

            raise Http404(msg % context)

        return obj

    def get_object_for_change(self, request, object_id):
        return self.get_object_for('change', request, object_id)

    def get_object_for_delete(self, request, object_id):
        return self.get_object_for('delete', request, object_id)


class ReadOnlyAdminMixin:

    def has_add_permission(self, request, obj=None):
        # For `InlineModelAdmin` the parent object may be passed via `obj`.
        return False

    def has_change_permission(self, request, obj=None):
        return False

    def has_delete_permission(self, request, obj=None):
        return False


class ReadOnlyModelAdmin(ReadOnlyAdminMixin, admin.ModelAdmin):
    """
    Immutable admin for a given model.
    """