"""passbook administration overview"""
from typing import Union

from django.conf import settings
from django.contrib.messages.views import SuccessMessageMixin
from django.core.cache import cache
from django.http.request import HttpRequest
from django.http.response import HttpResponse
from django.urls import reverse_lazy
from django.utils.translation import gettext as _
from django.views.generic import FormView, TemplateView
from packaging.version import LegacyVersion, Version, parse
from structlog import get_logger

from passbook import __version__
from passbook.admin.forms.overview import FlowCacheClearForm, PolicyCacheClearForm
from passbook.admin.mixins import AdminRequiredMixin
from passbook.admin.tasks import VERSION_CACHE_KEY, update_latest_version
from passbook.core.models import Provider, User
from passbook.policies.models import Policy

LOGGER = get_logger()


class AdministrationOverviewView(AdminRequiredMixin, TemplateView):
    """Overview View"""

    template_name = "administration/overview.html"

    def get_latest_version(self) -> Union[LegacyVersion, Version]:
        """Get latest version from cache"""
        version_in_cache = cache.get(VERSION_CACHE_KEY)
        if not version_in_cache:
            if not settings.DEBUG:
                update_latest_version.delay()
            return parse(__version__)
        return parse(version_in_cache)

    def get_context_data(self, **kwargs):
        kwargs["policy_count"] = len(Policy.objects.all())
        kwargs["user_count"] = len(User.objects.all()) - 1  # Remove anonymous user
        kwargs["provider_count"] = len(Provider.objects.all())
        kwargs["version"] = parse(__version__)
        kwargs["version_latest"] = self.get_latest_version()
        kwargs["providers_without_application"] = Provider.objects.filter(
            application=None
        )
        kwargs["policies_without_binding"] = len(
            Policy.objects.filter(bindings__isnull=True, promptstage__isnull=True)
        )
        kwargs["cached_policies"] = len(cache.keys("policy_*"))
        kwargs["cached_flows"] = len(cache.keys("flow_*"))
        return super().get_context_data(**kwargs)


class PolicyCacheClearView(AdminRequiredMixin, SuccessMessageMixin, FormView):
    """View to clear Policy cache"""

    form_class = PolicyCacheClearForm

    template_name = "generic/form_non_model.html"
    success_url = reverse_lazy("passbook_admin:overview")
    success_message = _("Successfully cleared Policy cache")

    def post(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
        keys = cache.keys("policy_*")
        cache.delete_many(keys)
        LOGGER.debug("Cleared Policy cache", keys=len(keys))
        return super().post(request, *args, **kwargs)


class FlowCacheClearView(AdminRequiredMixin, SuccessMessageMixin, FormView):
    """View to clear Flow cache"""

    form_class = FlowCacheClearForm

    template_name = "generic/form_non_model.html"
    success_url = reverse_lazy("passbook_admin:overview")
    success_message = _("Successfully cleared Flow cache")

    def post(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
        keys = cache.keys("flow_*")
        cache.delete_many(keys)
        LOGGER.debug("Cleared flow cache", keys=len(keys))
        return super().post(request, *args, **kwargs)