TMSS-2823: minor fix, take modulo HALF_SIDEREAL_DAY_LENGTH into account

SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py

@@ -1179,17 +1179,21 @@ class SchedulingUnitCommonPropertiesMixin:
                 transit_window_width_seconds = abs(self.scheduling_constraints_doc['sky']['transit_offset']['to'] - self.scheduling_constraints_doc['sky']['transit_offset']['from'])
                 # ToDo: move get_transit_offset_pointings (and similar) methods to Task/SchedulingUnit
                 from lofar.sas.tmss.services.scheduling.constraints import get_transit_offset_pointings
+                SIDEREAL_DAY_LENGTH = 23*3600 + 56*60 + 4
+                HALF_SIDEREAL_DAY_LENGTH = SIDEREAL_DAY_LENGTH//2
                 for task in self.observation_tasks:
                     if task.is_target_observation:
                         pointings = get_transit_offset_pointings(task)
                         transits = [p.transit_lst for p in pointings if p.direction_type=="J2000"]
                         if transits:
-                            earliest_transit = min(transits)
-                            latest_transit = max(transits)
-                            delta_transit = datetime.datetime.combine(datetime.date.today(), latest_transit) - datetime.datetime.combine(datetime.date.today(), earliest_transit)
-                            delta_transit_seconds = delta_transit.total_seconds()
-                            if delta_transit_seconds > transit_window_width_seconds:
-                                raise RuleValidationException("time between latest and earliest transit for targets in task id=%s name='%s' su_id=%s is larger than the transit_offset window itself: delta_transit=%dsec > transit_window_width=%ssec" % (task.id, task.name, self.id, delta_transit_seconds, transit_window_width_seconds))
+                            # express transit time's into seconds_since_midnight_in_a_local_sideral_day
+                            transits_seconds = [int((datetime.datetime.combine(datetime.date.today(), transit)-datetime.datetime.combine(datetime.date.today(), datetime.time(0,0,0))).total_seconds()) for transit in transits]
+                            # check all delta's (in seconds) between all pairs of transits, raise if too large
+                            for i, transit_a in enumerate(transits_seconds[:-1]):
+                                for transit_b in transits_seconds[i+1:]:
+                                    delta_transit_seconds = abs(transit_a-transit_b)%HALF_SIDEREAL_DAY_LENGTH
+                                    if delta_transit_seconds > transit_window_width_seconds:
+                                        raise RuleValidationException("time between latest and earliest transit for targets in task id=%s name='%s' su_id=%s is larger than the transit_offset window itself: delta_transit=%dsec > transit_window_width=%ssec" % (task.id, task.name, self.id, delta_transit_seconds, transit_window_width_seconds))
 
 
 class SchedulingUnitDraft(TemplateSchemaMixin, ProjectPropertyMixin, SchedulingUnitCommonPropertiesMixin, RefreshFromDbInvalidatesCachedPropertiesMixin, NamedCommon):