Fixes an unlikely bug with JTAC laser code allocation (#1477)

* Fixes an unlikely bug with JTAC laser code allocation, allows for future allocation of codes to a/c with TGPs

* Fixing typing issues

* Changelog

gen/armor.py

@@ -44,6 +44,7 @@ from .airsupport import AirSupport, JtacInfo
 from .callsigns import callsign_for_support_unit
 from .conflictgen import Conflict
 from .ground_forces.combat_stance import CombatStance
+from .lasercoderegistry import LaserCodeRegistry
 from .naming import namegen
 from .radios import MHz, RadioFrequency, RadioRegistry
 
@@ -81,6 +82,7 @@ class GroundConflictGenerator:
         unit_map: UnitMap,
         radio_registry: RadioRegistry,
         air_support: AirSupport,
+        laser_code_registry: LaserCodeRegistry,
     ) -> None:
         self.mission = mission
         self.conflict = conflict
@@ -92,6 +94,7 @@ class GroundConflictGenerator:
         self.unit_map = unit_map
         self.radio_registry = radio_registry
         self.air_support = air_support
+        self.laser_code_registry = laser_code_registry
 
     def generate(self) -> None:
         position = Conflict.frontline_position(
@@ -140,7 +143,7 @@ class GroundConflictGenerator:
         # Add JTAC
         if self.game.blue.faction.has_jtac:
             n = "JTAC" + str(self.conflict.blue_cp.id) + str(self.conflict.red_cp.id)
-            code = 1688 - len(self.air_support.jtacs)
+            code: int = self.laser_code_registry.get_next_laser_code()
             freq = self.radio_registry.alloc_uhf()
 
             utype = self.game.blue.faction.jtac_unit

gen/lasercoderegistry.py

@@ -0,0 +1,37 @@
+from collections import deque
+from typing import Iterator
+
+
+class OutOfLaserCodesError(RuntimeError):
+    def __init__(self) -> None:
+        super().__init__(
+            f"All JTAC laser codes have been allocated.  No available codes."
+        )
+
+
+class LaserCodeRegistry:
+    def __init__(self) -> None:
+        self.allocated_codes: set[int] = set()
+        self.allocator: Iterator[int] = LaserCodeRegistry.__laser_code_generator()
+
+    def get_next_laser_code(self) -> int:
+        try:
+            while (code := next(self.allocator)) in self.allocated_codes:
+                pass
+            self.allocated_codes.add(code)
+            return code
+        except StopIteration:
+            raise OutOfLaserCodesError
+
+    @staticmethod
+    def __laser_code_generator() -> Iterator[int]:
+        # Valid laser codes are as follows
+        # First digit is always 1
+        # Second digit is 5-7
+        # Third and fourth digits are 1 - 8
+        # We iterate backward (reversed()) so that 1687 follows 1688
+        q = deque(int(oct(code)[2:]) + 11 for code in reversed(range(0o1500, 0o2000)))
+
+        # We start with the default of 1688 and wrap around when we reach the end
+        q.rotate(-q.index(1688))
+        return iter(q)