from django.contrib.auth.mixins import LoginRequiredMixin
from django.http import Http404
from django.shortcuts import get_object_or_404
from django.views.generic import DetailView, ListView

from .markdown import render_markdown
from .models import GuidePage, allowed_audiences


class GuideAccessMixin:
    """Scope the help centre by PORTAL first, then by role.

    Being an admin does not mean seeing every guide in every portal: the buyer
    portal lists buyer guides (the audience of its readers), the ops portal
    lists ops guides, and the admin guides only appear in the ops portal for
    admin/superuser accounts. See apps.guides.models.allowed_audiences.
    """

    def get_portal(self):
        return getattr(self.request.resolver_match, "namespace", None) or "portal"

    def get_allowed_audiences(self):
        user = self.request.user
        return allowed_audiences(
            self.get_portal(),
            role=getattr(user, "role", None),
            is_superuser=user.is_superuser,
        )

    def get_help_root(self):
        return f"/{self.get_portal()}/help/"


class GuideIndexView(LoginRequiredMixin, GuideAccessMixin, ListView):
    model = GuidePage
    context_object_name = "guides"

    def get_queryset(self):
        return GuidePage.objects.filter(audience__in=self.get_allowed_audiences())

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx["help_root"] = self.get_help_root()
        return ctx


class GuideDetailView(LoginRequiredMixin, GuideAccessMixin, DetailView):
    model = GuidePage
    # the templates read {{ guide.title }}; without this the object arrives as
    # "object" and every guide detail page renders a blank browser title
    context_object_name = "guide"

    def get_object(self, queryset=None):
        path = f"user-guides/{self.kwargs['page_path']}"
        page = get_object_or_404(GuidePage, path=path)
        if page.audience not in self.get_allowed_audiences():
            raise Http404("This guide is not available in this portal.")
        return page

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        help_root = self.get_help_root()
        ctx["help_root"] = help_root
        ctx["guide_html"] = render_markdown(self.object.content, self.object.path, help_root)
        ctx["guides"] = GuidePage.objects.filter(audience__in=self.get_allowed_audiences())
        return ctx