[change:api] Include reset period in UserRadiusUsageView response

[nemesifier]

Related to openwisp/openwisp-wifi-login-pages#863.

The goal of this ticket is to modify OpenWISP RADIUS to return the counter reset period in the API.

Relevant parts of the code:

openwisp-radius/openwisp_radius/api/views.py

Lines 452 to 470 in 1caa57f

	@method_decorator(
	name="get",
	decorator=swagger_auto_schema(
	operation_description="""
	**Requires the user auth token (Bearer Token).**
	Returns the user's RADIUS usage and limit for the organization.
	It executes the relevant counters and returns returns information that
	shows how much time and/or traffic the user has consumed.
	""",
	),
	)
	class UserRadiusUsageView(ThrottledAPIMixin, DispatchOrgMixin, RetrieveAPIView):
	authentication_classes = (BearerAuthentication, SessionAuthentication)
	permission_classes = (IsAuthenticated,)
	queryset = User.objects.none()
	serializer_class = UserRadiusUsageSerializer
	def get_object(self):
	return self.request.user

openwisp-radius/openwisp_radius/api/serializers.py

Lines 297 to 319 in 1caa57f

	class UserGroupCheckSerializer(serializers.ModelSerializer):
	result = serializers.SerializerMethodField()
	type = serializers.SerializerMethodField()
	class Meta:
	model = RadiusGroupCheck
	fields = ("attribute", "op", "value", "result", "type")
	def get_result(self, obj):
	try:
	Counter = app_settings.CHECK_ATTRIBUTE_COUNTERS_MAP[obj.attribute]
	counter = Counter(
	user=self.context["user"],
	group=self.context["group"],
	group_check=obj,
	)
	consumed = counter.consumed()
	value = int(obj.value)
	if consumed > value:
	consumed = value
	return consumed
	except (SkipCheck, ValueError, KeyError):
	return None

openwisp-radius/openwisp_radius/counters/resets.py

Lines 52 to 58 in 1caa57f

	resets = {
	"daily": _daily,
	"weekly": _weekly,
	"monthly": _monthly,
	"monthly_subscription": _monthly_subscription,
	"never": _never,
	}

I would add a reset property in the API response which returns the date time of the next reset, this means we need to use the "reset" attribute to calculate it.