from django.conf import settings
from django.contrib.admin.views.decorators import staff_member_required
from django.contrib.staticfiles import finders
from django.http import FileResponse, Http404
from django.middleware.csrf import get_token
from django.shortcuts import render

from tracker.models import ScheduledDose


def service_worker(request):
    """The built worker (frontend/src/sw.ts), from the root so its scope covers /admin/.

    Served by a view rather than the staticfiles machinery because the URL must
    stay stable and unhashed — a renamed worker would be a brand-new worker.
    """
    path = finders.find("sw.js")
    if path is None:
        raise Http404("Frontend not built yet — run: make frontend")

    response = FileResponse(open(path, "rb"), content_type="application/javascript")
    # Browsers cap service-worker caching anyway; make updates immediate.
    response["Cache-Control"] = "no-cache"
    return response


@staff_member_required
def app(request):
    """The single-page app shell: Vue routes between Today and Recap client-side.

    All data flows through the API; the shell only carries the per-page-load
    facts the frontend cannot fetch (CSRF token) or that feed the reminder
    diagnostics.
    """
    active_doses = ScheduledDose.objects.filter(
        is_active=True, medication__is_active=True
    )

    return render(
        request,
        "tracker/app.html",
        {
            "config": {
                "vapidPublicKey": settings.VAPID_PUBLIC_KEY,
                # get_token also sets the CSRF cookie for the session.
                "csrfToken": get_token(request),
                "activeDoses": active_doses.count(),
                "dosesWithReminders": active_doses.filter(
                    reminder_time__isnull=False
                ).count(),
                "subscribedDevices": request.user.push_subscriptions.count(),
            }
        },
    )