[Move] Implement Grudge (#4794)

* some work

* slay dnr

* Fixed up move mechanics

* bahhh

* yawn

* updated lapse type to correctness

* Test + documentation

* yattt

* Remove some redundant code

* Apply suggestions from code review

Co-authored-by: innerthunder <168692175+innerthunder@users.noreply.github.com>

* Update battler-tags.ts

* Fix `PokemonAnimPhase`

---------

Co-authored-by: frutescens <info@laptop>
Co-authored-by: NightKev <34855794+DayKev@users.noreply.github.com>
Co-authored-by: innerthunder <168692175+innerthunder@users.noreply.github.com>

src/data/battler-tags.ts

@@ -2827,6 +2827,45 @@ export class PowerTrickTag extends BattlerTag {
   }
 }
 
+/**
+ * Tag associated with the move Grudge.
+ * If this tag is active when the bearer faints from an opponent's move, the tag reduces that move's PP to 0.
+ * Otherwise, it lapses when the bearer makes another move.
+ */
+export class GrudgeTag extends BattlerTag {
+  constructor() {
+    super(BattlerTagType.GRUDGE, [ BattlerTagLapseType.CUSTOM, BattlerTagLapseType.PRE_MOVE ], 1, Moves.GRUDGE);
+  }
+
+  onAdd(pokemon: Pokemon) {
+    super.onAdd(pokemon);
+    pokemon.scene.queueMessage(i18next.t("battlerTags:grudgeOnAdd", { pokemonNameWithAffix: getPokemonNameWithAffix(pokemon) }));
+  }
+
+  /**
+   * Activates Grudge's special effect on the attacking Pokemon and lapses the tag.
+   * @param pokemon
+   * @param lapseType
+   * @param sourcePokemon {@linkcode Pokemon} the source of the move that fainted the tag's bearer
+   * @returns `false` if Grudge activates its effect or lapses
+   */
+  override lapse(pokemon: Pokemon, lapseType: BattlerTagLapseType, sourcePokemon?: Pokemon): boolean {
+    if (lapseType === BattlerTagLapseType.CUSTOM && sourcePokemon) {
+      if (sourcePokemon.isActive() && pokemon.isOpponent(sourcePokemon)) {
+        const lastMove = pokemon.turnData.attacksReceived[0];
+        const lastMoveData = sourcePokemon.getMoveset().find(m => m?.moveId === lastMove.move);
+        if (lastMoveData && lastMove.move !== Moves.STRUGGLE) {
+          lastMoveData.ppUsed = lastMoveData.getMovePp();
+          pokemon.scene.queueMessage(i18next.t("battlerTags:grudgeLapse", { pokemonNameWithAffix: getPokemonNameWithAffix(pokemon), moveName: lastMoveData.getName() }));
+        }
+      }
+      return false;
+    } else {
+      return super.lapse(pokemon, lapseType);
+    }
+  }
+}
+
 /**
  * Retrieves a {@linkcode BattlerTag} based on the provided tag type, turn count, source move, and source ID.
  * @param sourceId - The ID of the pokemon adding the tag
@@ -3008,6 +3047,8 @@ export function getBattlerTag(tagType: BattlerTagType, turnCount: number, source
       return new TelekinesisTag(sourceMove);
     case BattlerTagType.POWER_TRICK:
       return new PowerTrickTag(sourceMove, sourceId);
+    case BattlerTagType.GRUDGE:
+      return new GrudgeTag();
     case BattlerTagType.NONE:
     default:
       return new BattlerTag(tagType, BattlerTagLapseType.CUSTOM, turnCount, sourceMove, sourceId);

src/data/move.ts

@@ -8489,7 +8489,7 @@ export function initMoves() {
       .attr(HealStatusEffectAttr, true, StatusEffect.PARALYSIS, StatusEffect.POISON, StatusEffect.TOXIC, StatusEffect.BURN)
       .condition((user, target, move) => !!user.status && (user.status.effect === StatusEffect.PARALYSIS || user.status.effect === StatusEffect.POISON || user.status.effect === StatusEffect.TOXIC || user.status.effect === StatusEffect.BURN)),
     new SelfStatusMove(Moves.GRUDGE, Type.GHOST, -1, 5, -1, 0, 3)
-      .unimplemented(),
+      .attr(AddBattlerTagAttr, BattlerTagType.GRUDGE, true, undefined, 1),
     new SelfStatusMove(Moves.SNATCH, Type.DARK, -1, 10, -1, 4, 3)
       .unimplemented(),
     new AttackMove(Moves.SECRET_POWER, Type.NORMAL, MoveCategory.PHYSICAL, 70, 100, 20, 30, 0, 3)

src/enums/battler-tag-type.ts

@@ -89,5 +89,6 @@ export enum BattlerTagType {
   SYRUP_BOMB = "SYRUP_BOMB",
   ELECTRIFIED = "ELECTRIFIED",
   TELEKINESIS = "TELEKINESIS",
-  COMMANDED = "COMMANDED"
+  COMMANDED = "COMMANDED",
+  GRUDGE = "GRUDGE"
 }

src/field/pokemon.ts

@@ -7,7 +7,7 @@ import Move, { HighCritAttr, HitsTagAttr, applyMoveAttrs, FixedDamageAttr, Varia
 import { default as PokemonSpecies, PokemonSpeciesForm, getFusedSpeciesName, getPokemonSpecies, getPokemonSpeciesForm } from "#app/data/pokemon-species";
 import { CLASSIC_CANDY_FRIENDSHIP_MULTIPLIER, getStarterValueFriendshipCap, speciesStarterCosts } from "#app/data/balance/starters";
 import { starterPassiveAbilities } from "#app/data/balance/passives";
-import { Constructor, isNullOrUndefined, randSeedInt } from "#app/utils";
+import { Constructor, isNullOrUndefined, randSeedInt, type nil } from "#app/utils";
 import * as Utils from "#app/utils";
 import { Type, TypeDamageMultiplier, getTypeDamageMultiplier, getTypeRgb } from "#app/data/type";
 import { getLevelTotalExp } from "#app/data/exp";
@@ -2841,6 +2841,7 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
 
       // In case of fatal damage, this tag would have gotten cleared before we could lapse it.
       const destinyTag = this.getTag(BattlerTagType.DESTINY_BOND);
+      const grudgeTag = this.getTag(BattlerTagType.GRUDGE);
 
       const isOneHitKo = result === HitResult.ONE_HIT_KO;
 
@@ -2912,12 +2913,8 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
       if (this.isFainted()) {
         // set splice index here, so future scene queues happen before FaintedPhase
         this.scene.setPhaseQueueSplice();
-        if (!isNullOrUndefined(destinyTag) && dmg) {
-          // Destiny Bond will activate during FaintPhase
-          this.scene.unshiftPhase(new FaintPhase(this.scene, this.getBattlerIndex(), isOneHitKo, destinyTag, source));
-        } else {
-          this.scene.unshiftPhase(new FaintPhase(this.scene, this.getBattlerIndex(), isOneHitKo));
-        }
+        this.scene.unshiftPhase(new FaintPhase(this.scene, this.getBattlerIndex(), isOneHitKo, destinyTag, grudgeTag, source));
+
         this.destroySubstitute();
         this.lapseTag(BattlerTagType.COMMANDED);
         this.resetSummonData();
@@ -3051,19 +3048,19 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
   }
 
   /** @overload */
-  getTag(tagType: BattlerTagType): BattlerTag | null;
+  getTag(tagType: BattlerTagType): BattlerTag | nil;
 
   /** @overload */
-  getTag<T extends BattlerTag>(tagType: Constructor<T>): T | null;
+  getTag<T extends BattlerTag>(tagType: Constructor<T>): T | nil;
 
-  getTag(tagType: BattlerTagType | Constructor<BattlerTag>): BattlerTag | null {
+  getTag(tagType: BattlerTagType | Constructor<BattlerTag>): BattlerTag | nil {
     if (!this.summonData) {
       return null;
     }
     return (tagType instanceof Function
       ? this.summonData.tags.find(t => t instanceof tagType)
       : this.summonData.tags.find(t => t.tagType === tagType)
-    )!; // TODO: is this bang correct?
+    );
   }
 
   findTag(tagFilter: ((tag: BattlerTag) => boolean)) {

src/phases/faint-phase.ts

@@ -1,7 +1,7 @@
 import { BattlerIndex, BattleType } from "#app/battle";
 import BattleScene from "#app/battle-scene";
 import { applyPostFaintAbAttrs, applyPostKnockOutAbAttrs, applyPostVictoryAbAttrs, PostFaintAbAttr, PostKnockOutAbAttr, PostVictoryAbAttr } from "#app/data/ability";
-import { BattlerTagLapseType, DestinyBondTag } from "#app/data/battler-tags";
+import { BattlerTagLapseType, DestinyBondTag, GrudgeTag } from "#app/data/battler-tags";
 import { battleSpecDialogue } from "#app/data/dialogue";
 import { allMoves, PostVictoryStatStageChangeAttr } from "#app/data/move";
 import { SpeciesFormChangeActiveTrigger } from "#app/data/pokemon-forms";
@@ -31,18 +31,24 @@ export class FaintPhase extends PokemonPhase {
   /**
    * Destiny Bond tag belonging to the currently fainting Pokemon, if applicable
    */
-  private destinyTag?: DestinyBondTag;
+  private destinyTag?: DestinyBondTag | null;
 
   /**
-   * The source Pokemon that dealt fatal damage and should get KO'd by Destiny Bond, if applicable
+   * Grudge tag belonging to the currently fainting Pokemon, if applicable
+   */
+  private grudgeTag?: GrudgeTag | null;
+
+  /**
+   * The source Pokemon that dealt fatal damage
    */
   private source?: Pokemon;
 
-  constructor(scene: BattleScene, battlerIndex: BattlerIndex, preventEndure: boolean = false, destinyTag?: DestinyBondTag, source?: Pokemon) {
+  constructor(scene: BattleScene, battlerIndex: BattlerIndex, preventEndure: boolean = false, destinyTag?: DestinyBondTag | null, grudgeTag?: GrudgeTag | null, source?: Pokemon) {
     super(scene, battlerIndex);
 
     this.preventEndure = preventEndure;
     this.destinyTag = destinyTag;
+    this.grudgeTag = grudgeTag;
     this.source = source;
   }
 
@@ -53,6 +59,10 @@ export class FaintPhase extends PokemonPhase {
       this.destinyTag.lapse(this.source, BattlerTagLapseType.CUSTOM);
     }
 
+    if (!isNullOrUndefined(this.grudgeTag) && !isNullOrUndefined(this.source)) {
+      this.grudgeTag.lapse(this.getPokemon(), BattlerTagLapseType.CUSTOM, this.source);
+    }
+
     if (!this.preventEndure) {
       const instantReviveModifier = this.scene.applyModifier(PokemonInstantReviveModifier, this.player, this.getPokemon()) as PokemonInstantReviveModifier;
 

src/phases/pokemon-anim-phase.ts

@@ -1,8 +1,9 @@
 import BattleScene from "#app/battle-scene";
 import { SubstituteTag } from "#app/data/battler-tags";
-import { PokemonAnimType } from "#enums/pokemon-anim-type";
 import Pokemon from "#app/field/pokemon";
 import { BattlePhase } from "#app/phases/battle-phase";
+import { isNullOrUndefined } from "#app/utils";
+import { PokemonAnimType } from "#enums/pokemon-anim-type";
 import { Species } from "#enums/species";
 
 
@@ -51,7 +52,7 @@ export class PokemonAnimPhase extends BattlePhase {
 
   private doSubstituteAddAnim(): void {
     const substitute = this.pokemon.getTag(SubstituteTag);
-    if (substitute === null) {
+    if (isNullOrUndefined(substitute)) {
       return this.end();
     }
 

src/test/moves/grudge.test.ts

@@ -0,0 +1,90 @@
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import { BattlerIndex } from "#app/battle";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+
+describe("Moves - Grudge", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+    game.override
+      .moveset([ Moves.EMBER, Moves.SPLASH ])
+      .ability(Abilities.BALL_FETCH)
+      .battleType("single")
+      .disableCrits()
+      .enemySpecies(Species.SHEDINJA)
+      .enemyAbility(Abilities.WONDER_GUARD)
+      .enemyMoveset([ Moves.GRUDGE, Moves.SPLASH ]);
+  });
+
+  it("should reduce the PP of the Pokemon's move to 0 when the user has fainted", async () => {
+    await game.classicMode.startBattle([ Species.FEEBAS ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon();
+    game.move.select(Moves.EMBER);
+    await game.forceEnemyMove(Moves.GRUDGE);
+    await game.setTurnOrder([ BattlerIndex.ENEMY, BattlerIndex.PLAYER ]);
+    await game.phaseInterceptor.to("BerryPhase");
+
+    const playerMove = playerPokemon?.getMoveset().find(m => m?.moveId === Moves.EMBER);
+
+    expect(playerMove?.getPpRatio()).toBe(0);
+  });
+
+  it("should remain in effect until the user's next move", async () => {
+    await game.classicMode.startBattle([ Species.FEEBAS ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon();
+    game.move.select(Moves.SPLASH);
+    await game.forceEnemyMove(Moves.GRUDGE);
+    await game.setTurnOrder([ BattlerIndex.PLAYER, BattlerIndex.ENEMY ]);
+    await game.toNextTurn();
+
+    game.move.select(Moves.EMBER);
+    await game.forceEnemyMove(Moves.SPLASH);
+    await game.setTurnOrder([ BattlerIndex.PLAYER, BattlerIndex.ENEMY ]);
+    await game.phaseInterceptor.to("BerryPhase");
+
+    const playerMove = playerPokemon?.getMoveset().find(m => m?.moveId === Moves.EMBER);
+
+    expect(playerMove?.getPpRatio()).toBe(0);
+  });
+
+  it("should not reduce the opponent's PP if the user dies to weather/indirect damage", async () => {
+    // Opponent will be reduced to 1 HP by False Swipe, then faint to Sandstorm
+    game.override
+      .moveset([ Moves.FALSE_SWIPE ])
+      .startingLevel(100)
+      .ability(Abilities.SAND_STREAM)
+      .enemySpecies(Species.RATTATA);
+    await game.classicMode.startBattle([ Species.GEODUDE ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon();
+    const playerPokemon = game.scene.getPlayerPokemon();
+
+    game.move.select(Moves.FALSE_SWIPE);
+    await game.forceEnemyMove(Moves.GRUDGE);
+    await game.setTurnOrder([ BattlerIndex.ENEMY, BattlerIndex.PLAYER ]);
+    await game.phaseInterceptor.to("BerryPhase");
+
+    expect(enemyPokemon?.isFainted()).toBe(true);
+
+    const playerMove = playerPokemon?.getMoveset().find(m => m?.moveId === Moves.FALSE_SWIPE);
+    expect(playerMove?.getPpRatio()).toBeGreaterThan(0);
+  });
+});