[Bug] Fixed Super Fang interaction with Multi Lens (#4914)

Co-authored-by: Jannik Tappert <38758606+CodeTappert@users.noreply.github.com>
Co-authored-by: NightKev <34855794+DayKev@users.noreply.github.com>

src/data/move.ts

@@ -1385,14 +1385,38 @@ export class UserHpDamageAttr extends FixedDamageAttr {
 }
 
 export class TargetHalfHpDamageAttr extends FixedDamageAttr {
+  // the initial amount of hp the target had before the first hit
+  // used for multi lens
+  private initialHp: number;
   constructor() {
     super(0);
   }
 
   apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
-    (args[0] as Utils.IntegerHolder).value = Utils.toDmgValue(target.hp / 2);
+    // first, determine if the hit is coming from multi lens or not
+    const lensCount = user.getHeldItems().find(i => i instanceof PokemonMultiHitModifier)?.getStackCount() ?? 0;
+    if (lensCount <= 0) {
+      // no multi lenses; we can just halve the target's hp and call it a day
+      (args[0] as Utils.NumberHolder).value = Utils.toDmgValue(target.hp / 2);
+      return true;
+    }
 
-    return true;
+    // figure out what hit # we're on
+    switch (user.turnData.hitCount - user.turnData.hitsLeft) {
+      case 0:
+        // first hit of move; update initialHp tracker
+        this.initialHp = target.hp;
+      default:
+        // multi lens added hit; use initialHp tracker to ensure correct damage
+        (args[0] as Utils.NumberHolder).value = Utils.toDmgValue(this.initialHp / 2);
+        return true;
+        break;
+      case lensCount + 1:
+        // parental bond added hit; calc damage as normal
+        (args[0] as Utils.NumberHolder).value = Utils.toDmgValue(target.hp / 2);
+        return true;
+        break;
+    }
   }
 
   getTargetBenefitScore(user: Pokemon, target: Pokemon, move: Move): number {

src/field/pokemon.ts

@@ -2618,8 +2618,8 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
       };
     }
 
-    // If the attack deals fixed damaged, return a result with that much damage
-    const fixedDamage = new Utils.IntegerHolder(0);
+    // If the attack deals fixed damage, return a result with that much damage
+    const fixedDamage = new Utils.NumberHolder(0);
     applyMoveAttrs(FixedDamageAttr, source, this, move, fixedDamage);
     if (fixedDamage.value) {
       const multiLensMultiplier = new Utils.NumberHolder(1);

src/test/items/multi_lens.test.ts

@@ -135,4 +135,57 @@ describe("Items - Multi Lens", () => {
     expect(damageResults[0]).toBe(Math.floor(playerPokemon.level * 0.75));
     expect(damageResults[1]).toBe(Math.floor(playerPokemon.level * 0.25));
   });
+
+  it("should result in correct damage for hp% attacks with 1 lens", async () => {
+    game.override.startingHeldItems([{ name: "MULTI_LENS", count: 1 }])
+      .moveset(Moves.SUPER_FANG)
+      .ability(Abilities.COMPOUND_EYES)
+      .enemyLevel(1000)
+      .enemySpecies(Species.BLISSEY); // allows for unrealistically high levels of accuracy
+
+    await game.classicMode.startBattle([ Species.MAGIKARP ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+
+    game.move.select(Moves.SUPER_FANG);
+    await game.setTurnOrder([ BattlerIndex.PLAYER, BattlerIndex.ENEMY ]);
+    await game.phaseInterceptor.to("MoveEndPhase");
+    expect(enemyPokemon.getHpRatio()).toBeCloseTo(0.5, 5);
+  });
+
+  it("should result in correct damage for hp% attacks with 2 lenses", async () => {
+    game.override.startingHeldItems([{ name: "MULTI_LENS", count: 2 }])
+      .moveset(Moves.SUPER_FANG)
+      .ability(Abilities.COMPOUND_EYES)
+      .enemyMoveset(Moves.SPLASH)
+      .enemyLevel(1000)
+      .enemySpecies(Species.BLISSEY); // allows for unrealistically high levels of accuracy
+
+    await game.classicMode.startBattle([ Species.MAGIKARP ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+
+    game.move.select(Moves.SUPER_FANG);
+    await game.setTurnOrder([ BattlerIndex.PLAYER, BattlerIndex.ENEMY ]);
+    await game.phaseInterceptor.to("MoveEndPhase");
+    expect(enemyPokemon.getHpRatio()).toBeCloseTo(0.5, 5);
+  });
+  it("should result in correct damage for hp% attacks with 2 lenses + Parental Bond", async () => {
+    game.override.startingHeldItems([{ name: "MULTI_LENS", count: 2 }])
+      .moveset(Moves.SUPER_FANG)
+      .ability(Abilities.PARENTAL_BOND)
+      .passiveAbility(Abilities.COMPOUND_EYES)
+      .enemyMoveset(Moves.SPLASH)
+      .enemyLevel(1000)
+      .enemySpecies(Species.BLISSEY); // allows for unrealistically high levels of accuracy
+
+    await game.classicMode.startBattle([ Species.MAGIKARP ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+
+    game.move.select(Moves.SUPER_FANG);
+    await game.setTurnOrder([ BattlerIndex.PLAYER, BattlerIndex.ENEMY ]);
+    await game.phaseInterceptor.to("MoveEndPhase");
+    expect(enemyPokemon.getHpRatio()).toBeCloseTo(0.25, 5);
+  });
 });