from copy import deepcopy

from django.contrib import admin
from django.contrib.admin import site
from django.contrib.auth import get_user_model
from django.contrib.auth.admin import UserAdmin
from django.contrib.sites.models import Site
from django.db import OperationalError
from django.utils.translation import gettext_lazy as _

from cms.admin.forms import (
    GlobalPagePermissionAdminForm,
    PagePermissionInlineAdminForm,
    ViewRestrictionInlineAdminForm,
)
from cms.exceptions import NoPermissionsException
from cms.models import GlobalPagePermission, PagePermission
from cms.utils import page_permissions, permissions
from cms.utils.conf import get_cms_setting
from cms.utils.helpers import classproperty

PERMISSION_ADMIN_INLINES = []

user_model = get_user_model()
admin_class = UserAdmin
for model, admin_instance in site._registry.items():
    if model == user_model:
        admin_class = admin_instance.__class__


class TabularInline(admin.TabularInline):
    pass


def users_exceed_threshold():
    """
    Check if the number of users exceeds the configured threshold. Only bother
    counting the users when using an integer threshold, otherwise return the
    truthy value of the setting to avoid a potentially expensive DB query.
    """
    threshold = get_cms_setting('RAW_ID_USERS')

    # Don't bother counting the users when not using an integer threshold
    if threshold is True or threshold is False or not isinstance(threshold, int):
        return (threshold)

    # Given a fresh django-cms install and a django settings with the
    # CMS_RAW_ID_USERS = CMS_PERMISSION = True
    # django throws an OperationalError when running
    # ./manage migrate
    # because auth_user doesn't exists yet
    try:
        return get_user_model().objects.count() > threshold
    except OperationalError:
        return False


class PagePermissionInlineAdmin(TabularInline):
    model = PagePermission
    # use special form, so we can override of user and group field
    form = PagePermissionInlineAdminForm
    classes = ['collapse', 'collapsed']
    extra = 0  # edit page load time boost
    show_with_view_permissions = False

    def has_change_permission(self, request, obj=None):
        if not obj:
            return False
        return page_permissions.user_can_change_page_permissions(
            request.user,
            page=obj,
            site=obj.node.site,
        )

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

    @classproperty
    def raw_id_fields(cls):
        # Dynamically set raw_id_fields based on settings
        return ['user'] if users_exceed_threshold() else []

    def get_queryset(self, request):
        """
        Queryset change, so user with global change permissions can see
        all permissions. Otherwise user can see only permissions for
        peoples which are under him (he can't see his permissions, because
        this will lead to violation, when he can add more power to himself)
        """
        site = Site.objects.get_current(request)

        try:
            # can see only permissions for users which are under him in tree
            qs = self.model.objects.subordinate_to_user(request.user, site)
        except NoPermissionsException:
            return self.model.objects.none()
        return qs.filter(can_view=self.show_with_view_permissions)

    def get_formset(self, request, obj=None, **kwargs):
        """
        Some fields may be excluded here. User can change only
        permissions which are available for them. E.g. if user does not have
        can_publish flag, they can't change assign can_publish permissions.
        """
        exclude = self.exclude or []
        if obj:
            user = request.user
            if not obj.has_add_permission(user):
                exclude.append('can_add')
            if not obj.has_delete_permission(user):
                exclude.append('can_delete')
            if not obj.has_publish_permission(user):
                exclude.append('can_publish')
            if not obj.has_advanced_settings_permission(user):
                exclude.append('can_change_advanced_settings')
            if not obj.has_move_page_permission(user):
                exclude.append('can_move_page')

        kwargs['exclude'] = exclude
        formset_cls = super().get_formset(request, obj=obj, **kwargs)
        qs = self.get_queryset(request)
        if obj is not None:
            qs = qs.filter(page=obj)
        formset_cls._queryset = qs
        return formset_cls


class ViewRestrictionInlineAdmin(PagePermissionInlineAdmin):
    extra = 0  # edit page load time boost
    form = ViewRestrictionInlineAdminForm
    verbose_name = _("View restriction")
    verbose_name_plural = _("View restrictions")
    show_with_view_permissions = True


class GlobalPagePermissionAdmin(admin.ModelAdmin):
    list_display = ['user', 'group', 'can_change', 'can_delete', 'can_publish', 'can_change_permissions']
    list_filter = ['sites', 'user', 'group', 'can_change', 'can_delete', 'can_publish', 'can_change_permissions']
    list_display_links = ['user', 'group']

    form = GlobalPagePermissionAdminForm
    search_fields = []
    for field in admin_class.search_fields:
        search_fields.append("user__%s" % field)
    search_fields.append('group__name')

    list_display.append('can_change_advanced_settings')
    list_filter.append('can_change_advanced_settings')

    def METHOD_NAME(self, request):
        filter_copy = deepcopy(self.list_filter)
        if users_exceed_threshold():
            filter_copy.remove('user')
        return filter_copy

    def has_add_permission(self, request):
        site = Site.objects.get_current(request)
        return permissions.user_can_add_global_permissions(request.user, site)

    def has_change_permission(self, request, obj=None):
        site = Site.objects.get_current(request)
        return permissions.user_can_change_global_permissions(request.user, site)

    def has_delete_permission(self, request, obj=None):
        site = Site.objects.get_current(request)
        return permissions.user_can_delete_global_permissions(request.user, site)

    @classproperty
    def raw_id_fields(cls):
        # Dynamically set raw_id_fields based on settings
        return ['user'] if users_exceed_threshold() else []


if get_cms_setting('PERMISSION'):
    admin.site.register(GlobalPagePermission, GlobalPagePermissionAdmin)
    PERMISSION_ADMIN_INLINES.extend([
        ViewRestrictionInlineAdmin,
        PagePermissionInlineAdmin,
    ])