Extend SAM Range to cover Hydros when stacked (#2351)

## Description:

Implements SAM range extension for stacked SAMs to cover hydros as
requested in #2347 and many times from users in discord.
This implementation is as simple as possible: At level 5 and higher,
SAMs extend their range to the range of a hydrogen bomb + 10 for a small
safety margin. Levels 2-4 are interpolated between.

Screenshot to show the sizes compared to a hydro:
<img width="400" alt="image"
src="https://github.com/user-attachments/assets/a857d66c-e3d4-467f-855f-3539cc90b719"
/>

Everything works together with the new range UI, although I might need
to unify with / rebase on #2350. Not yet tested with #2348, but
shouldn't be an issue.

## Input needed:
- Should I add tests for this?
- This is in effect a massive buff to SAMs, might be too strong. Popular
ideas / suggestions from Discord to balance things:
  - Cap the SAM upgrade level at the maximum range (easy to do)
- Alternative, instead of capping the level, decrease the range when
missiles are reloading
- Increase the cost scaling for SAMs per stack, and scale way higher
(e.g. 1.5M > 3M > 4.5M > 6M or something like that) (UI integration
unclear, breaks with existing cost logic)
  - Decrease SAM hit probability for Hydros

I'm happy to implement any of these paths, or just roll with the simple
way it's set up now, just let me know.

## 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

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

newyearnewphil

---------

Co-authored-by: Evan <evanpelle@gmail.com>

src/client/graphics/layers/SAMRadiusLayer.ts

@@ -163,7 +163,7 @@ export class SAMRadiusLayer implements Layer {
       return {
         x: this.game.x(tile),
         y: this.game.y(tile),
-        r: this.game.config().defaultSamRange(),
+        r: this.game.config().samRange(sam.level()),
         owner: sam.owner().smallID(),
       };
     });

src/client/graphics/layers/StructureDrawingUtils.ts

@@ -428,6 +428,7 @@ export class SpriteFactory {
     type: UnitType,
     stage: PIXI.Container,
     pos: { x: number; y: number },
+    level?: number,
   ): PIXI.Container | null {
     if (stage === undefined) throw new Error("Not initialized");
     const parentContainer = new PIXI.Container();
@@ -435,7 +436,7 @@ export class SpriteFactory {
     let radius = 0;
     switch (type) {
       case UnitType.SAMLauncher:
-        radius = this.game.config().defaultSamRange();
+        radius = this.game.config().samRange(level ?? 1);
         break;
       case UnitType.Factory:
         radius = this.game.config().trainStationMaxRange();

src/client/graphics/layers/StructureIconsLayer.ts

@@ -59,6 +59,7 @@ export class StructureIconsLayer implements Layer {
   private ghostUnit: {
     container: PIXI.Container;
     range: PIXI.Container | null;
+    rangeLevel?: number;
     buildableUnit: BuildableUnit;
   } | null = null;
   private pixicanvas: HTMLCanvasElement;
@@ -278,6 +279,9 @@ export class StructureIconsLayer implements Layer {
 
         this.ghostUnit.buildableUnit = unit;
 
+        const targetLevel = this.resolveGhostRangeLevel(unit);
+        this.updateGhostRange(targetLevel);
+
         if (unit.canUpgrade) {
           this.potentialUpgrade = this.renders.find(
             (r) =>
@@ -370,12 +374,11 @@ export class StructureIconsLayer implements Layer {
         { x: localX, y: localY },
         type,
       ),
-      range: this.factory.createRange(type, this.ghostStage, {
-        x: localX,
-        y: localY,
-      }),
+      range: null,
       buildableUnit: { type, canBuild: false, canUpgrade: false, cost: 0n },
     };
+    const baseLevel = this.resolveGhostRangeLevel(this.ghostUnit.buildableUnit);
+    this.updateGhostRange(baseLevel);
   }
 
   private clearGhostStructure() {
@@ -397,6 +400,49 @@ export class StructureIconsLayer implements Layer {
     this.eventBus.emit(new GhostStructureChangedEvent(null));
   }
 
+  private resolveGhostRangeLevel(
+    buildableUnit: BuildableUnit,
+  ): number | undefined {
+    if (buildableUnit.type !== UnitType.SAMLauncher) {
+      return undefined;
+    }
+    if (buildableUnit.canUpgrade !== false) {
+      const existing = this.game.unit(buildableUnit.canUpgrade);
+      if (existing) {
+        return existing.level() + 1;
+      } else {
+        console.error("Failed to find existing SAMLauncher for upgrade");
+      }
+    }
+
+    return 1;
+  }
+
+  private updateGhostRange(level?: number) {
+    if (!this.ghostUnit) {
+      return;
+    }
+
+    if (this.ghostUnit.range && this.ghostUnit.rangeLevel === level) {
+      return;
+    }
+
+    this.ghostUnit.range?.destroy();
+    this.ghostUnit.range = null;
+    this.ghostUnit.rangeLevel = level;
+
+    const position = this.ghostUnit.container.position;
+    const range = this.factory.createRange(
+      this.ghostUnit.buildableUnit.type,
+      this.ghostStage,
+      { x: position.x, y: position.y },
+      level,
+    );
+    if (range) {
+      this.ghostUnit.range = range;
+    }
+  }
+
   private toggleStructures(toggleStructureType: UnitType[] | null): void {
     for (const [structureType, infos] of this.structures) {
       infos.visible =

src/core/configuration/Config.ts

@@ -171,6 +171,8 @@ export interface Config {
   defaultNukeTargetableRange(): number;
   defaultSamMissileSpeed(): number;
   defaultSamRange(): number;
+  samRange(level: number): number;
+  maxSamRange(): number;
   nukeDeathFactor(
     nukeType: NukeType,
     humans: number,

src/core/configuration/DefaultConfig.ts

@@ -920,6 +920,15 @@ export class DefaultConfig implements Config {
     return 70;
   }
 
+  samRange(level: number): number {
+    // rational growth function (level 1 = 70, level 5 just above hydro range, asymptotically approaches 150)
+    return this.maxSamRange() - 480 / (level + 5);
+  }
+
+  maxSamRange(): number {
+    return 150;
+  }
+
   defaultSamMissileSpeed(): number {
     return 12;
   }

src/core/execution/SAMLauncherExecution.ts

@@ -50,7 +50,7 @@ class SAMTargetingSystem {
 
   private isInRange(tile: TileRef) {
     const samTile = this.sam.tile();
-    const range = this.mg.config().defaultSamRange();
+    const range = this.mg.config().samRange(this.sam.level());
     const rangeSquared = range * range;
     return this.mg.euclideanDistSquared(samTile, tile) <= rangeSquared;
   }
@@ -82,7 +82,7 @@ class SAMTargetingSystem {
 
   public getSingleTarget(ticks: number): Target | null {
     // Look beyond the SAM range so it can preshot nukes
-    const detectionRange = this.mg.config().defaultSamRange() * 2;
+    const detectionRange = this.mg.config().maxSamRange() * 2;
     const nukes = this.mg.nearbyUnits(
       this.sam.tile(),
       detectionRange,

tests/util/TestConfig.ts

@@ -54,6 +54,10 @@ export class TestConfig extends DefaultConfig {
     return 20;
   }
 
+  samRange(level: number): number {
+    return 20;
+  }
+
   spawnImmunityDuration(): Tick {
     return 0;
   }