Addresses review comments.

game/event/event.py

@@ -342,8 +342,6 @@ class UnitsDeliveryEvent:
     def __init__(self, control_point: ControlPoint) -> None:
         self.to_cp = control_point
         self.units: Dict[Type[UnitType], int] = {}
-        self.bought_units: Dict[Type[UnitType], int] = {}
-        self.sold_units: Dict[Type[UnitType], int] = {}
 
     def __str__(self) -> str:
         return "Pending delivery to {}".format(self.to_cp)
@@ -372,21 +370,30 @@ class UnitsDeliveryEvent:
                 f"Refunding {count} {unit_type.id} at {self.to_cp.name}")
             game.adjust_budget(price * count, player=self.to_cp.captured)
 
+    def available_next_turn(self, unit_type: Type[UnitType]) -> int:
+        pending_units = self.units.get(unit_type)
+        if pending_units is None:
+            pending_units = 0
+        current_units = self.to_cp.base.total_units_of_type(unit_type)
+        return pending_units + current_units
+
     def process(self, game: Game) -> None:
+        bought_units: Dict[Type[UnitType], int] = {}
+        sold_units: Dict[Type[UnitType], int] = {}
         for unit_type, count in self.units.items():
             coalition = "Ally" if self.to_cp.captured else "Enemy"
             aircraft = unit_type.id
             name = self.to_cp.name
             if count >= 0:
-                self.bought_units[unit_type] = count 
+                bought_units[unit_type] = count 
                 game.message(
                     f"{coalition} reinforcements: {aircraft} x {count} at {name}")
             else:
-                self.sold_units[unit_type] = 0 - count
+                sold_units[unit_type] = -count
                 game.message(
-                    f"{coalition} sold: {aircraft} x {0 - count} at {name}")
-        self.to_cp.base.commision_units(self.bought_units)
-        self.to_cp.base.commit_losses(self.sold_units)
+                    f"{coalition} sold: {aircraft} x {-count} at {name}")
+        self.to_cp.base.commision_units(bought_units)
+        self.to_cp.base.commit_losses(sold_units)
         self.units = {}
-        self.bought_units = {}
-        self.sold_units = {}
+        bought_units = {}
+        sold_units = {}

qt_ui/windows/basemenu/QRecruitBehaviour.py

@@ -136,7 +136,7 @@ class QRecruitBehaviour:
         self.update_available_budget()
 
     def sell(self, unit_type):
-        if self.pending_deliveries.units.get(unit_type, 0) > 0 or self.cp.base.total_units_of_type(unit_type) > 0:
+        if self.pending_deliveries.available_next_turn(unit_type) > 0:
             price = db.PRICES[unit_type]
             self.budget += price
             self.pending_deliveries.sell({unit_type: 1})

qt_ui/windows/basemenu/airfield/QAircraftRecruitmentMenu.py

@@ -92,6 +92,12 @@ class QAircraftRecruitmentMenu(QFrame, QRecruitBehaviour):
                     self, "No space for additional aircraft",
                     f"There is no parking space left at {self.cp.name} to accommodate another plane.", QMessageBox.Ok)
                 return
+            # If we change our mind about selling, we want the aircraft to be put
+            # back in the inventory immediately.
+            elif self.pending_deliveries.units.get(unit_type, 0) < 0:
+                global_inventory = self.game_model.game.aircraft_inventory
+                inventory = global_inventory.for_control_point(self.cp)
+                inventory.add_aircraft(unit_type, 1)
                 
         super().buy(unit_type)
         self.hangar_status.update_label()
@@ -99,13 +105,18 @@ class QAircraftRecruitmentMenu(QFrame, QRecruitBehaviour):
     def sell(self, unit_type: UnitType):
         # Don't need to remove aircraft from the inventory if we're canceling
         # orders.
-        if self.pending_deliveries.units.get(unit_type, 0) <= 0 - self.cp.base.total_units_of_type(unit_type):
-            QMessageBox.critical(
-                self, "Could not sell aircraft",
-                f"Attempted to sell one {unit_type.id} at {self.cp.name} "
-                "but none are available. Are all aircraft currently "
-                "assigned to a mission?", QMessageBox.Ok)
-            return
+        if self.pending_deliveries.units.get(unit_type, 0) <= 0:
+            global_inventory = self.game_model.game.aircraft_inventory
+            inventory = global_inventory.for_control_point(self.cp)
+            try:
+                inventory.remove_aircraft(unit_type, 1)
+            except ValueError:
+                QMessageBox.critical(
+                    self, "Could not sell aircraft",
+                    f"Attempted to sell one {unit_type.id} at {self.cp.name} "
+                    "but none are available. Are all aircraft currently "
+                    "assigned to a mission?", QMessageBox.Ok)
+                return
         super().sell(unit_type)
         self.hangar_status.update_label()
 

qt_ui/windows/basemenu/ground_forces/QArmorRecruitmentMenu.py

@@ -61,13 +61,10 @@ class QArmorRecruitmentMenu(QFrame, QRecruitBehaviour):
         self.setLayout(main_layout)
 
     def sell(self, unit_type: UnitType):
-        # Don't need to remove aircraft from the inventory if we're canceling
-        # orders.
-        if self.pending_deliveries.units.get(unit_type, 0) <= 0 - self.cp.base.total_units_of_type(unit_type):
+        if self.pending_deliveries.available_next_turn(unit_type) <= 0:
             QMessageBox.critical(
                 self, "Could not sell ground unit",
                 f"Attempted to sell one {unit_type.id} at {self.cp.name} "
                 "but none are available.", QMessageBox.Ok)
             return
-        super().sell(unit_type)
-        self.hangar_status.update_label()
+        super().sell(unit_type)