from __future__ import annotations

from typing import Any

from django.contrib import admin
from django.db.models import Model
from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
from django.urls import URLPattern, re_path
from django.utils.encoding import force_str
from django.utils.translation import gettext as _

from django_solo import settings as solo_settings
from django_solo.models import DEFAULT_SINGLETON_INSTANCE_ID


class SingletonModelAdmin(admin.ModelAdmin):  # type: ignore[type-arg]
    object_history_template = "admin/solo/object_history.html"
    change_form_template = "admin/solo/change_form.html"

    def has_add_permission(self, request: HttpRequest) -> bool:
        return False

    def has_delete_permission(self, request: HttpRequest, obj: Model | None = None) -> bool:
        return False

    def get_urls(self) -> list[URLPattern]:
        urls = super().get_urls()

        if not solo_settings.SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE:
            return urls

        # _meta.model_name only exists on Django>=1.6 -
        # on earlier versions, use module_name.lower()
        try:
            model_name = self.model._meta.model_name
        except AttributeError:
            model_name = self.model._meta.module_name.lower()

        self.model._meta.verbose_name_plural = self.model._meta.verbose_name
        url_name_prefix = f"{self.model._meta.app_label}_{model_name}"
        custom_urls = [
            re_path(
                r"^history/$",
                self.admin_site.admin_view(self.history_view),
                {"object_id": str(self.singleton_instance_id)},
                name=f"{url_name_prefix}_history",
            ),
            re_path(
                r"^$",
                self.admin_site.admin_view(self.change_view),
                {"object_id": str(self.singleton_instance_id)},
                name=f"{url_name_prefix}_change",
            ),
        ]

        # By inserting the custom URLs first, we overwrite the standard URLs.
        return custom_urls + urls

    def response_change(self, request: HttpRequest, obj: Model) -> HttpResponseRedirect:
        msg = _("{obj} was changed successfully.").format(obj=force_str(obj))
        if "_continue" in request.POST:
            self.message_user(request, msg + " " + _("You may edit it again below."))
            return HttpResponseRedirect(request.path)
        else:
            self.message_user(request, msg)
            return HttpResponseRedirect("../../")

    def change_view(
        self,
        request: HttpRequest,
        object_id: str,
        form_url: str = "",
        extra_context: dict[str, Any] | None = None,
    ) -> HttpResponse:
        if object_id == str(self.singleton_instance_id):
            self.model.objects.get_or_create(pk=self.singleton_instance_id)

        if not extra_context:
            extra_context = {}
        extra_context["skip_object_list_page"] = solo_settings.SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE

        return super().change_view(
            request,
            object_id,
            form_url=form_url,
            extra_context=extra_context,
        )

    def history_view(
        self, request: HttpRequest, object_id: str, extra_context: dict[str, Any] | None = None
    ) -> HttpResponse:
        if not extra_context:
            extra_context = {}
        extra_context["skip_object_list_page"] = solo_settings.SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE

        return super().history_view(
            request,
            object_id,
            extra_context=extra_context,
        )

    @property
    def singleton_instance_id(self) -> int:
        return getattr(self.model, "singleton_instance_id", DEFAULT_SINGLETON_INSTANCE_ID)