import datetime import decimal from django.utils import timezone from django.utils.translation import ugettext_lazy as _ from orchestra import plugins class DataMethod(plugins.Plugin, metaclass=plugins.PluginMount): """ filters and computes dataset usage """ def filter(self, dataset): """ Filter the dataset to get the relevant data according to the period """ raise NotImplementedError def compute_usage(self, dataset): """ given a dataset computes its usage according to the method (avg, sum, ...) """ raise NotImplementedError class Last(DataMethod): name = 'last' verbose_name = _("Last value") def filter(self, dataset): try: return dataset.order_by('object_id', '-id').distinct('object_id') except dataset.model.DoesNotExist: return dataset.none() def compute_usage(self, dataset): # FIXME Aggregation of 0s returns None! django bug? # value = dataset.aggregate(models.Sum('value'))['value__sum'] values = dataset.values_list('value', flat=True) if values: return sum(values) return None class MonthlySum(Last): name = 'monthly-sum' verbose_name = _("Monthly Sum") def filter(self, dataset): today = timezone.now() return dataset.filter( created_at__year=today.year, created_at__month=today.month ) class MonthlyAvg(MonthlySum): name = 'monthly-avg' verbose_name = _("Monthly AVG") def get_epoch(self): today = timezone.now() return datetime( year=today.year, month=today.month, day=1, tzinfo=timezone.utc ) def compute_usage(self, dataset): result = 0 try: last = dataset.latest() except dataset.model.DoesNotExist: return result epoch = self.get_epoch() total = (last.created_at-epoch).total_seconds() ini = epoch for data in dataset: slot = (data.created_at-ini).total_seconds() result += data.value * decimal.Decimal(str(slot/total)) ini = data.created_at return result class Last10DaysAvg(MonthlyAvg): name = 'last-10-days-avg' verbose_name = _("Last 10 days AVG") days = 10 def get_epoch(self): today = timezone.now() return today - datetime.timedelta(days=self.days) def filter(self, dataset): return dataset.filter(created_at__gt=self.get_epoch())