Move beacons module.

This isn't related to the missiongenerator, and importing this file from
some places (such as runway data) will cause a circular reference when
importing the rest of the missiongenerator package.

game/dcs/beacons.py

@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import json
+from collections.abc import Iterator
+from dataclasses import dataclass
+from enum import IntEnum, auto
+from pathlib import Path
+from typing import Optional, TYPE_CHECKING
+
+from game.radio.radios import RadioFrequency
+from game.radio.tacan import TacanBand, TacanChannel
+
+if TYPE_CHECKING:
+    from game.theater import ConflictTheater
+
+BEACONS_RESOURCE_PATH = Path("resources/dcs/beacons")
+
+
+class BeaconType(IntEnum):
+    BEACON_TYPE_NULL = auto()
+    BEACON_TYPE_VOR = auto()
+    BEACON_TYPE_DME = auto()
+    BEACON_TYPE_VOR_DME = auto()
+    BEACON_TYPE_TACAN = auto()
+    BEACON_TYPE_VORTAC = auto()
+    BEACON_TYPE_RSBN = auto()
+    BEACON_TYPE_BROADCAST_STATION = auto()
+
+    BEACON_TYPE_HOMER = auto()
+    BEACON_TYPE_AIRPORT_HOMER = auto()
+    BEACON_TYPE_AIRPORT_HOMER_WITH_MARKER = auto()
+    BEACON_TYPE_ILS_FAR_HOMER = auto()
+    BEACON_TYPE_ILS_NEAR_HOMER = auto()
+
+    BEACON_TYPE_ILS_LOCALIZER = auto()
+    BEACON_TYPE_ILS_GLIDESLOPE = auto()
+
+    BEACON_TYPE_PRMG_LOCALIZER = auto()
+    BEACON_TYPE_PRMG_GLIDESLOPE = auto()
+
+    BEACON_TYPE_ICLS_LOCALIZER = auto()
+    BEACON_TYPE_ICLS_GLIDESLOPE = auto()
+
+    BEACON_TYPE_NAUTICAL_HOMER = auto()
+
+
+@dataclass(frozen=True)
+class Beacon:
+    name: str
+    callsign: str
+    beacon_type: BeaconType
+    hertz: int
+    channel: Optional[int]
+
+    @property
+    def frequency(self) -> RadioFrequency:
+        return RadioFrequency(self.hertz)
+
+    @property
+    def is_tacan(self) -> bool:
+        return self.beacon_type in (
+            BeaconType.BEACON_TYPE_VORTAC,
+            BeaconType.BEACON_TYPE_TACAN,
+        )
+
+    @property
+    def tacan_channel(self) -> TacanChannel:
+        assert self.is_tacan
+        assert self.channel is not None
+        return TacanChannel(self.channel, TacanBand.X)
+
+
+class Beacons:
+    _by_terrain: dict[str, dict[str, Beacon]] = {}
+
+    @classmethod
+    def _load_for_theater_if_needed(cls, theater: ConflictTheater) -> None:
+        if theater.terrain.name in cls._by_terrain:
+            return
+
+        beacons_file = BEACONS_RESOURCE_PATH / f"{theater.terrain.name.lower()}.json"
+        if not beacons_file.exists():
+            raise RuntimeError(f"Beacon file {beacons_file.resolve()} is missing")
+
+        beacons = {}
+        for bid, beacon in json.loads(beacons_file.read_text()).items():
+            beacons[bid] = Beacon(**beacon)
+        cls._by_terrain[theater.terrain.name] = beacons
+
+    @classmethod
+    def _dict_for_theater(cls, theater: ConflictTheater) -> dict[str, Beacon]:
+        cls._load_for_theater_if_needed(theater)
+        return cls._by_terrain[theater.terrain.name]
+
+    @classmethod
+    def iter_theater(cls, theater: ConflictTheater) -> Iterator[Beacon]:
+        yield from cls._dict_for_theater(theater).values()
+
+    @classmethod
+    def with_id(cls, beacon_id: str, theater: ConflictTheater) -> Beacon:
+        return cls._dict_for_theater(theater)[beacon_id]