[mock_uss/scd] Handle retrieval of op intent details when USS is down…

… according to SCD0005+SD0010 (#338)

* [mock_uss/scd] Handle retrieval of op intent details when USS is down according to SCD0005+SD0010

* set US locality highest_priority to 0

monitoring/mock_uss/f3548v21/flight_planning.py

@@ -9,6 +9,7 @@
 from monitoring.monitorlib.clients.flight_planning.flight_info import (
     FlightInfo,
 )
+from monitoring.monitorlib.fetch import QueryError
 from monitoring.uss_qualifier.resources.overrides import apply_overrides
 from uas_standards.astm.f3548.v21 import api as f3548_v21
 from uas_standards.astm.f3548.v21.constants import OiMaxVertices, OiMaxPlanHorizonDays
@@ -281,10 +282,12 @@ def op_intent_from_flightrecord(
 
 
 def query_operational_intents(
+    locality: Locality,
     area_of_interest: f3548_v21.Volume4D,
 ) -> List[f3548_v21.OperationalIntent]:
     """Retrieve a complete set of operational intents in an area, including details.
 
+    :param locality: Locality applicable to this query
     :param area_of_interest: Area where intersecting operational intents must be discovered
     :return: Full definition for every operational intent discovered
     """
@@ -314,10 +317,22 @@ def query_operational_intents(
 
     updated_op_intents = []
     for op_intent_ref in get_details_for:
-        op_intent, _ = scd_client.get_operational_intent_details(
-            utm_client, op_intent_ref.uss_base_url, op_intent_ref.id
-        )
-        updated_op_intents.append(op_intent)
+        try:
+            op_intent, _ = scd_client.get_operational_intent_details(
+                utm_client, op_intent_ref.uss_base_url, op_intent_ref.id
+            )
+            updated_op_intents.append(op_intent)
+        except QueryError as e:
+            if op_intent_ref.uss_availability == f3548_v21.UssAvailabilityState.Down:
+                # if the USS does not respond to request for details, and if it marked as down at the DSS, then we don't
+                # have to fail and can assume specific values for details
+                op_intent = get_down_uss_op_intent(
+                    locality, area_of_interest, op_intent_ref
+                )
+                updated_op_intents.append(op_intent)
+            else:
+                # if the USS is not marked as down we just let the error bubble up
+                raise e
     result.extend(updated_op_intents)
 
     with db as tx:
@@ -327,6 +342,58 @@ def query_operational_intents(
     return result
 
 
+def get_down_uss_op_intent(
+    locality: Locality,
+    area_of_interest: f3548_v21.Volume4D,
+    op_intent_ref: f3548_v21.OperationalIntentReference,
+) -> f3548_v21.OperationalIntent:
+    """This function determines the operational intent to be considered in case its managing USS is determined to be
+     down and does not respond to the requests for details.
+
+    Note: This function will populate volumes (for accepted or activated states) and off_nominal_volumes (for contingent
+     and non-conforming states) with the area of interest that was requested. The reason is that later on the function
+     `check_for_disallowed_conflicts` will need to evaluate again those conflicts to determine pre-existing conflicts.
+    TODO: A better approach to this issue would be to store the area in conflict when a flight is planned with a
+     conflict, that way we can just retrieve the conflicting area instead of having to compute again the intersection
+     between the flight to be planned and the conflicting operational intent.
+    """
+    # USS is declared as down and does not answer for details : minimum - 1
+    if op_intent_ref == f3548_v21.OperationalIntentState.Accepted:
+        return f3548_v21.OperationalIntent(
+            reference=op_intent_ref,
+            details=f3548_v21.OperationalIntentDetails(
+                volumes=[area_of_interest],
+                priority=locality.lowest_bound_priority(),
+            ),
+        )
+
+    elif op_intent_ref == f3548_v21.OperationalIntentState.Activated:
+        return f3548_v21.OperationalIntent(
+            reference=op_intent_ref,
+            details=f3548_v21.OperationalIntentDetails(
+                volumes=[area_of_interest],
+                priority=locality.highest_priority(),
+            ),
+        )
+
+    elif (
+        op_intent_ref == f3548_v21.OperationalIntentState.Contingent
+        or op_intent_ref == f3548_v21.OperationalIntentState.Nonconforming
+    ):
+        return f3548_v21.OperationalIntent(
+            reference=op_intent_ref,
+            details=f3548_v21.OperationalIntentDetails(
+                off_nominal_volumes=[area_of_interest],
+                priority=locality.highest_priority(),
+            ),
+        )
+
+    else:
+        raise ValueError(
+            f"operational intent {op_intent_ref.id}: invalid state {op_intent_ref.state}"
+        )
+
+
 def check_op_intent(
     new_flight: FlightRecord,
     existing_flight: Optional[FlightRecord],
@@ -360,7 +427,7 @@ def check_op_intent(
             + new_flight.op_intent.details.off_nominal_volumes
         )
         vol4 = v1.bounding_volume.to_f3548v21()
-        op_intents = query_operational_intents(vol4)
+        op_intents = query_operational_intents(locality, vol4)
 
         # Check for intersections
         log(

monitoring/monitorlib/locality.py

@@ -27,6 +27,16 @@ def allows_same_priority_intersections(self, priority: int) -> bool:
         """Returns true iff locality allows intersections between two operations at this priority level for ASTM F3548-21"""
         raise NotImplementedError(Locality._NOT_IMPLEMENTED_MSG)
 
+    @abstractmethod
+    def lowest_bound_priority(self) -> int:
+        """Returns the lowest bound priority status for ASTM F3548-21, which is a priority level lower than the lowest priority bound defined by the regulator of this locality"""
+        raise NotImplementedError(Locality._NOT_IMPLEMENTED_MSG)
+
+    @abstractmethod
+    def highest_priority(self) -> int:
+        """Returns the highest priority level for ASTM F3548-21 defined by the regulator of this locality"""
+        raise NotImplementedError(Locality._NOT_IMPLEMENTED_MSG)
+
     def __str__(self):
         return self.__class__.__name__
 
@@ -56,6 +66,12 @@ def is_uspace_applicable(self) -> bool:
     def allows_same_priority_intersections(self, priority: int) -> bool:
         return False
 
+    def lowest_bound_priority(self) -> int:
+        return -1
+
+    def highest_priority(self) -> int:
+        return 100
+
 
 class UnitedStatesIndustryCollaboration(Locality):
     @classmethod
@@ -67,3 +83,9 @@ def is_uspace_applicable(self) -> bool:
 
     def allows_same_priority_intersections(self, priority: int) -> bool:
         return False
+
+    def lowest_bound_priority(self) -> int:
+        return -1
+
+    def highest_priority(self) -> int:
+        return 0  # as of the time of writing this, this value has not been subject to a firm decision