Refactor structureSpawnTileValue() (#1927)

## Description:

Move `structureSpawnTileValue()` into its own file, as
`FakeHumanExecution.ts` was getting quite large.

## 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

src/core/execution/FakeHumanExecution.ts

@@ -25,6 +25,7 @@ import { PseudoRandom } from "../PseudoRandom";
 import { SpawnExecution } from "./SpawnExecution";
 import { TransportShipExecution } from "./TransportShipExecution";
 import { closestTwoTiles } from "./Util";
+import { structureSpawnTileValue } from "./nation/structureSpawnTileValue";
 
 export class FakeHumanExecution implements Execution {
   private active = true;
@@ -463,6 +464,7 @@ export class FakeHumanExecution implements Execution {
   }
 
   private structureSpawnTile(type: UnitType): TileRef | null {
+    if (this.mg === undefined) throw new Error("Not initialized");
     if (this.player === null) throw new Error("Not initialized");
     const tiles =
       type === UnitType.Port
@@ -471,7 +473,7 @@ export class FakeHumanExecution implements Execution {
         )
         : Array.from(this.player.tiles());
     if (tiles.length === 0) return null;
-    const valueFunction = this.structureSpawnTileValue(type);
+    const valueFunction = structureSpawnTileValue(this.mg, this.player, type);
     let bestTile: TileRef | null = null;
     let bestValue = 0;
     const sampledTiles = this.arraySampler(tiles);
@@ -501,64 +503,6 @@ export class FakeHumanExecution implements Execution {
     }
   }
 
-  private structureSpawnTileValue(type: UnitType): (tile: TileRef) => number {
-    if (this.mg === undefined) throw new Error("Not initialized");
-    if (this.player === null) throw new Error("Not initialized");
-    const borderTiles = this.player.borderTiles();
-    const { mg } = this;
-    const otherUnits = this.player.units(type);
-    // Prefer spacing structures out of atom bomb range
-    const borderSpacing = this.mg.config().nukeMagnitudes(UnitType.AtomBomb).outer;
-    const structureSpacing = borderSpacing * 2;
-    switch (type) {
-      case UnitType.Port:
-        return (tile) => {
-          let w = 0;
-
-          // Prefer to be far away from other structures of the same type
-          const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
-          otherTiles.delete(tile);
-          const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
-          if (closestOther !== null) {
-            const d = mg.manhattanDist(closestOther.x, tile);
-            w += Math.min(d, structureSpacing);
-          }
-
-          return w;
-        };
-      case UnitType.City:
-      case UnitType.Factory:
-      case UnitType.MissileSilo:
-        return (tile) => {
-          let w = 0;
-
-          // Prefer higher elevations
-          w += mg.magnitude(tile);
-
-          // Prefer to be away from the border
-          const closestBorder = closestTwoTiles(mg, borderTiles, [tile]);
-          if (closestBorder !== null) {
-            const d = mg.manhattanDist(closestBorder.x, tile);
-            w += Math.min(d, borderSpacing);
-          }
-
-          // Prefer to be away from other structures of the same type
-          const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
-          otherTiles.delete(tile);
-          const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
-          if (closestOther !== null) {
-            const d = mg.manhattanDist(closestOther.x, tile);
-            w += Math.min(d, structureSpacing);
-          }
-
-          // TODO: Cities and factories should consider train range limits
-          return w;
-        };
-      default:
-        throw new Error(`Value function not implemented for ${type}`);
-    }
-  }
-
   private maybeSpawnWarship(): boolean {
     if (this.mg === undefined) throw new Error("Not initialized");
     if (this.player === null) throw new Error("Not initialized");

src/core/execution/nation/structureSpawnTileValue.ts

@@ -0,0 +1,62 @@
+import { Game, Player, UnitType } from "../../game/Game";
+import { TileRef } from "../../game/GameMap";
+import { closestTwoTiles } from "../Util";
+
+export function structureSpawnTileValue(
+  mg: Game,
+  player: Player,
+  type: UnitType,
+): (tile: TileRef) => number {
+  const borderTiles = player.borderTiles();
+  const otherUnits = player.units(type);
+  // Prefer spacing structures out of atom bomb range
+  const borderSpacing = mg.config().nukeMagnitudes(UnitType.AtomBomb).outer;
+  const structureSpacing = borderSpacing * 2;
+  switch (type) {
+    case UnitType.Port:
+      return (tile) => {
+        let w = 0;
+
+        // Prefer to be far away from other structures of the same type
+        const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
+        otherTiles.delete(tile);
+        const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
+        if (closestOther !== null) {
+          const d = mg.manhattanDist(closestOther.x, tile);
+          w += Math.min(d, structureSpacing);
+        }
+
+        return w;
+      };
+    case UnitType.City:
+    case UnitType.Factory:
+    case UnitType.MissileSilo:
+      return (tile) => {
+        let w = 0;
+
+        // Prefer higher elevations
+        w += mg.magnitude(tile);
+
+        // Prefer to be away from the border
+        const closestBorder = closestTwoTiles(mg, borderTiles, [tile]);
+        if (closestBorder !== null) {
+          const d = mg.manhattanDist(closestBorder.x, tile);
+          w += Math.min(d, borderSpacing);
+        }
+
+        // Prefer to be away from other structures of the same type
+        const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
+        otherTiles.delete(tile);
+        const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
+        if (closestOther !== null) {
+          const d = mg.manhattanDist(closestOther.x, tile);
+          w += Math.min(d, structureSpacing);
+        }
+
+        // TODO: Cities and factories should consider train range limits
+        return w;
+      };
+    default:
+      throw new Error(`Value function not implemented for ${type}`);
+  }
+}