Add AI convoy attack planning.

Like the comment says this rarely has any effect due to the ordering of
flight planning and convoy creation. Could be separated, but opfor will
still not be able to target any convoys that the player creates in the
UI on that turn because they planning is done before the player can use
the UI.

Multi-turn transfers will be targetable, however.

game/transfers.py

@@ -126,6 +126,11 @@ class ConvoyMap:
     def departing_from(self, origin: ControlPoint) -> Iterator[Convoy]:
         yield from self.convoys[origin].values()
 
+    def travelling_to(self, destination: ControlPoint) -> Iterator[Convoy]:
+        for destination_dict in self.convoys.values():
+            if destination in destination_dict:
+                yield destination_dict[destination]
+
     def disband_convoy(self, convoy: Convoy) -> None:
         del self.convoys[convoy.origin][convoy.destination]
 

gen/flights/ai_flight_planner.py

@@ -39,6 +39,7 @@ from game.theater.theatergroundobject import (
     NavalGroundObject,
     VehicleGroupGroundObject,
 )
+from game.transfers import Convoy
 from game.utils import Distance, nautical_miles
 from gen import Conflict
 from gen.ato import Package
@@ -444,6 +445,15 @@ class ObjectiveFinder:
                 airfields.append(control_point)
         return self._targets_by_range(airfields)
 
+    def convoys(self) -> Iterator[Convoy]:
+        for front_line in self.front_lines():
+            if front_line.control_point_a.is_friendly(self.is_player):
+                enemy_cp = front_line.control_point_a
+            else:
+                enemy_cp = front_line.control_point_b
+
+            yield from self.game.transfers.convoys.travelling_to(enemy_cp)
+
     def friendly_control_points(self) -> Iterator[ControlPoint]:
         """Iterates over all friendly control points."""
         return (
@@ -605,6 +615,34 @@ class CoalitionMissionPlanner:
                 ],
             )
 
+        # These will only rarely get planned. When a convoy is travelling multiple legs,
+        # they're targetable after the first leg. The reason for this is that
+        # procurement happens *after* mission planning so that the missions that could
+        # not be filled will guide the procurement process. Procurement is the stage
+        # that convoys are created (because they're created to move ground units that
+        # were just purchased), so we haven't created any yet. Any incomplete transfers
+        # from the previous turn (multi-leg journeys) will still be present though so
+        # they can be targeted.
+        #
+        # Even after this is fixed, the player's convoys that were created through the
+        # UI will never be targeted on the first turn of their journey because the AI
+        # stops planning after the start of the turn. We could potentially fix this by
+        # moving opfor mission planning until the takeoff button is pushed.
+        for convoy in self.objective_finder.convoys():
+            yield ProposedMission(
+                convoy,
+                [
+                    ProposedFlight(FlightType.BAI, 2, self.MAX_BAI_RANGE),
+                    # TODO: Max escort range.
+                    ProposedFlight(
+                        FlightType.ESCORT, 2, self.MAX_BAI_RANGE, EscortType.AirToAir
+                    ),
+                    ProposedFlight(
+                        FlightType.SEAD, 2, self.MAX_BAI_RANGE, EscortType.Sead
+                    ),
+                ],
+            )
+
         for group in self.objective_finder.threatening_ships():
             yield ProposedMission(
                 group,