Automatic train stations (#1353)

## Description:

Train stations are now built automatically when a factory is
constructed.

Changes:
- When a factory is built, nearby structures are connected to the rail
network
- When a city is built near a factory, it is connected to the rail
network
    - All structures behave the same when a train stops: to be defined
    - Removed station badge
    - Gold income is now related to the structure's level

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

IngloriousTom

src/core/game/Game.ts

@@ -633,6 +633,12 @@ export interface Game extends GameMap {
   // Units
   units(...types: UnitType[]): Unit[];
   unitInfo(type: UnitType): UnitInfo;
+  hasUnitNearby(
+    tile: TileRef,
+    searchRange: number,
+    type: UnitType,
+    playerId: PlayerID,
+  );
   nearbyUnits(
     tile: TileRef,
     searchRange: number,

src/core/game/GameImpl.ts

@@ -715,6 +715,15 @@ export class GameImpl implements Game {
     }
   }
 
+  hasUnitNearby(
+    tile: TileRef,
+    searchRange: number,
+    type: UnitType,
+    playerId: PlayerID,
+  ) {
+    return this.unitGrid.hasUnitNearby(tile, searchRange, type, playerId);
+  }
+
   nearbyUnits(
     tile: TileRef,
     searchRange: number,

src/core/game/RailNetworkImpl.ts

@@ -120,6 +120,7 @@ export class RailNetworkImpl implements RailNetwork {
         newCluster.addStations(stations);
       }
     }
+    station.unit.setTrainStation(false);
   }
 
   /**

src/core/game/TrainStation.ts

@@ -1,4 +1,3 @@
-import { TradeShipExecution } from "../execution/TradeShipExecution";
 import { TrainExecution } from "../execution/TrainExecution";
 import { GraphAdapter } from "../pathfinding/SerialAStar";
 import { PseudoRandom } from "../PseudoRandom";
@@ -14,30 +13,34 @@ interface TrainStopHandler {
   onStop(mg: Game, station: TrainStation, trainExecution: TrainExecution): void;
 }
 
+/**
+ * All stop handlers share the same logic for the time being
+ * Behavior to be defined
+ */
 class CityStopHandler implements TrainStopHandler {
+  private factor: bigint = BigInt(2);
   onStop(
     mg: Game,
     station: TrainStation,
     trainExecution: TrainExecution,
   ): void {
-    const goldBonus = mg.config().trainGold();
+    const level = BigInt(station.unit.level() + 1);
+    const goldBonus = (mg.config().trainGold() * level) / this.factor;
     station.unit.owner().addGold(goldBonus, station.tile());
   }
 }
 
 class PortStopHandler implements TrainStopHandler {
+  private factor: bigint = BigInt(2);
   constructor(private random: PseudoRandom) {}
   onStop(
     mg: Game,
     station: TrainStation,
     trainExecution: TrainExecution,
   ): void {
-    const unit = station.unit;
-    const ports = unit.owner().tradingPorts(unit);
-    if (ports.length === 0) return;
-
-    const port = this.random.randElement(ports);
-    mg.addExecution(new TradeShipExecution(unit.owner(), unit, port));
+    const level = BigInt(station.unit.level() + 1);
+    const goldBonus = (mg.config().trainGold() * level) / this.factor;
+    station.unit.owner().addGold(goldBonus, station.tile());
   }
 }
 
@@ -47,7 +50,15 @@ class FactoryStopHandler implements TrainStopHandler {
     station: TrainStation,
     trainExecution: TrainExecution,
   ): void {
-    trainExecution.loadCargo();
+    const goldBonus = mg.config().trainGold();
+    station.unit.owner().addGold(goldBonus);
+    mg.addUpdate({
+      type: GameUpdateType.BonusEvent,
+      tile: station.tile(),
+      gold: Number(goldBonus),
+      workers: 0,
+      troops: 0,
+    });
   }
 }
 

src/core/game/UnitImpl.ts

@@ -249,6 +249,7 @@ export class UnitImpl implements Unit {
         case UnitType.Port:
         case UnitType.SAMLauncher:
         case UnitType.Warship:
+        case UnitType.Factory:
           this.mg.stats().unitDestroy(destroyer, this._type);
           this.mg.stats().unitLose(this.owner(), this._type);
           break;