Refactor UnitSpecific info => AllUnitParams type union (#701)

## Description:

By using a type union we get better type safety, enforcing each unit
type have the appropriate params when initializing

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [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:
evan

---------

Co-authored-by: evan <openfrontio@gmail.com>

src/core/game/Game.ts

@@ -148,6 +148,51 @@ export enum UnitType {
   Construction = "Construction",
 }
 
+export interface UnitParamsMap {
+  [UnitType.TransportShip]: {
+    troops?: number;
+    destination?: TileRef;
+  };
+
+  [UnitType.Warship]: {};
+
+  [UnitType.Shell]: {};
+
+  [UnitType.SAMMissile]: {};
+
+  [UnitType.Port]: {};
+
+  [UnitType.AtomBomb]: {};
+
+  [UnitType.HydrogenBomb]: {};
+
+  [UnitType.TradeShip]: {
+    dstPort: Unit;
+    lastSetSafeFromPirates?: number;
+  };
+
+  [UnitType.MissileSilo]: {
+    cooldownDuration?: number;
+  };
+
+  [UnitType.DefensePost]: {};
+
+  [UnitType.SAMLauncher]: {};
+
+  [UnitType.City]: {};
+
+  [UnitType.MIRV]: {};
+
+  [UnitType.MIRVWarhead]: {};
+
+  [UnitType.Construction]: {};
+}
+
+// Type helper to get params type for a specific unit type
+export type UnitParams<T extends UnitType> = UnitParamsMap[T];
+
+export type AllUnitParams = UnitParamsMap[keyof UnitParamsMap];
+
 export const nukeTypes = [
   UnitType.AtomBomb,
   UnitType.HydrogenBomb,
@@ -276,15 +321,6 @@ export class PlayerInfo {
   }
 }
 
-// Some units have info specific to them
-export interface UnitSpecificInfos {
-  dstPort?: Unit; // Only for trade ships
-  lastSetSafeFromPirates?: number; // Only for trade ships
-  detonationDst?: TileRef; // Only for nukes
-  warshipTarget?: Unit;
-  cooldownDuration?: number;
-}
-
 export interface Unit {
   id(): number;
 
@@ -391,12 +427,12 @@ export interface Player {
   unitsIncludingConstruction(type: UnitType): Unit[];
   buildableUnits(tile: TileRef): BuildableUnit[];
   canBuild(type: UnitType, targetTile: TileRef): TileRef | false;
-  buildUnit(
-    type: UnitType,
-    troops: number,
-    tile: TileRef,
-    unitSpecificInfos?: UnitSpecificInfos,
+  buildUnit<T extends UnitType>(
+    type: T,
+    spawnTile: TileRef,
+    params: UnitParams<T>,
   ): Unit;
+
   captureUnit(unit: Unit): void;
 
   // Relations & Diplomacy

src/core/game/PlayerImpl.ts

@@ -35,7 +35,7 @@ import {
   TerraNullius,
   Tick,
   Unit,
-  UnitSpecificInfos,
+  UnitParams,
   UnitType,
 } from "./Game";
 import { GameImpl } from "./GameImpl";
@@ -703,11 +703,10 @@ export class PlayerImpl implements Player {
     );
   }
 
-  buildUnit(
-    type: UnitType,
-    troops: number,
+  buildUnit<T extends UnitType>(
+    type: T,
     spawnTile: TileRef,
-    unitSpecificInfos: UnitSpecificInfos = {},
+    params: UnitParams<T>,
   ): UnitImpl {
     if (this.mg.config().isUnitDisabled(type)) {
       throw new Error(
@@ -720,14 +719,13 @@ export class PlayerImpl implements Player {
       type,
       this.mg,
       spawnTile,
-      troops,
       this.mg.nextUnitID(),
       this,
-      unitSpecificInfos,
+      params,
     );
     this._units.push(b);
     this.removeGold(cost);
-    this.removeTroops(troops);
+    this.removeTroops("troops" in params ? params.troops : 0);
     this.mg.addUpdate(b.toUpdate());
     this.mg.addUnit(b);
 

src/core/game/UnitImpl.ts

@@ -1,11 +1,11 @@
 import { simpleHash, toInt, withinInt } from "../Util";
 import {
+  AllUnitParams,
   MessageType,
   Player,
   Tick,
   Unit,
   UnitInfo,
-  UnitSpecificInfos,
   UnitType,
 } from "./Game";
 import { GameImpl } from "./GameImpl";
@@ -24,6 +24,7 @@ export class UnitImpl implements Unit {
   private _lastSetSafeFromPirates: number; // Only for trade ships
   private _constructionType: UnitType = undefined;
 
+  private _troops: number;
   private _cooldownTick: Tick | null = null;
   private _dstPort: Unit | null = null; // Only for trade ships
   private _detonationDst: TileRef | null = null; // Only for nukes
@@ -34,21 +35,22 @@ export class UnitImpl implements Unit {
     private _type: UnitType,
     private mg: GameImpl,
     private _tile: TileRef,
-    private _troops: number,
     private _id: number,
     public _owner: PlayerImpl,
-    unitsSpecificInfos: UnitSpecificInfos = {},
+    params: AllUnitParams = {},
   ) {
-    this._health = toInt(this.mg.unitInfo(_type).maxHealth ?? 1);
     this._lastTile = _tile;
-    this._dstPort = unitsSpecificInfos.dstPort;
-    this._detonationDst = unitsSpecificInfos.detonationDst;
-    this._warshipTarget = unitsSpecificInfos.warshipTarget;
-    this._cooldownDuration = unitsSpecificInfos.cooldownDuration;
-    this._lastSetSafeFromPirates = unitsSpecificInfos.lastSetSafeFromPirates;
+    this._health = toInt(this.mg.unitInfo(_type).maxHealth ?? 1);
     this._safeFromPiratesCooldown = this.mg
       .config()
       .safeFromPiratesCooldownMax();
+
+    this._troops = "troops" in params ? params.troops : 0;
+    this._dstPort = "dstPort" in params ? params.dstPort : null;
+    this._cooldownDuration =
+      "cooldownDuration" in params ? params.cooldownDuration : null;
+    this._lastSetSafeFromPirates =
+      "lastSetSafeFromPirates" in params ? params.lastSetSafeFromPirates : 0;
   }
 
   id() {