from django.contrib import admin, messages
from django.contrib.auth.admin import UserAdmin
from django.http import HttpResponseRedirect
from django.urls import reverse

from accounts.models import ApiToken, PushSubscription, User

TEST_PAYLOAD = {
    "title": "Osiris — test",
    "body": "Reminders are working. This is what a dose reminder looks like.",
    "url": "/admin/today/",
    "tag": "test",
}


def send_test_push(request, subscription: PushSubscription) -> bool:
    """Push a test notification and report the outcome as an admin message."""
    # Imported here rather than at module scope: tracker.push imports this module's
    # models, so a top-level import would be circular.
    from tracker.push import push_is_configured, send_to_subscription

    if not push_is_configured():
        messages.error(
            request,
            "VAPID keys are not set on the server — run manage.py generate_vapid_keys.",
        )
        return False

    pk = subscription.pk
    if send_to_subscription(subscription, TEST_PAYLOAD):
        messages.success(request, f"Test notification sent to {subscription}.")
        return True

    # send_to_subscription deletes the row on a 404/410, which is the single most
    # useful thing to know here: the device is gone, not merely unreachable.
    if not PushSubscription.objects.filter(pk=pk).exists():
        messages.warning(
            request,
            "That device had discarded its subscription (the push service returned "
            "404/410), so it has been removed. Re-enable reminders on the device.",
        )
    else:
        messages.error(
            request, "The push service rejected the message. See the server log."
        )
    return False


@admin.register(User)
class OsirisUserAdmin(UserAdmin):
    pass


@admin.register(PushSubscription)
class PushSubscriptionAdmin(admin.ModelAdmin):
    """Devices receiving reminders. Delete a row to stop pushing to that device."""

    list_display = ["user", "user_agent", "created_at", "last_success_at"]
    readonly_fields = ["endpoint", "p256dh", "auth", "created_at", "last_success_at"]
    actions = ["send_test_notification"]
    change_form_template = "admin/accounts/pushsubscription/change_form.html"

    @admin.action(description="Send a test notification to the selected devices")
    def send_test_notification(self, request, queryset):
        for subscription in queryset:
            send_test_push(request, subscription)

    def change_view(self, request, object_id, form_url="", extra_context=None):
        """Handle the 'Send test notification' button.

        Intercepted before the form is validated or saved: sending a test is not an
        edit, and it should not be blocked by an unrelated validation error.
        """
        if request.method == "POST" and "_send_test" in request.POST:
            subscription = self.get_object(request, object_id)
            if subscription is None:
                return self._get_obj_does_not_exist_redirect(
                    request, self.opts, object_id
                )

            send_test_push(request, subscription)

            # Back to this object so the message is read in context — unless the push
            # came back 404/410, in which case the row was deleted as dead.
            if PushSubscription.objects.filter(pk=subscription.pk).exists():
                return HttpResponseRedirect(request.get_full_path())
            return HttpResponseRedirect(
                reverse("admin:accounts_pushsubscription_changelist")
            )

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


@admin.register(ApiToken)
class ApiTokenAdmin(admin.ModelAdmin):
    """Tokens are created by the Flutter app via /api/auth/login; this is for revoking."""

    list_display = ["name", "user", "key", "created_at", "last_used_at"]
    readonly_fields = ["key", "created_at", "last_used_at"]
    list_filter = ["user"]