fully implemented spectral thief

src/data/move.ts

@@ -4312,6 +4312,53 @@ export class CueNextRoundAttr extends MoveEffectAttr {
   }
 }
 
+/**
+ * Steals the postitive Stat stages of the target before damage calculation so stat changes
+ * apply to damage calculation (e.g. {@linkcode Moves.SPECTRAL_THIEF})
+ * {@link https://bulbapedia.bulbagarden.net/wiki/Spectral_Thief_(move) | Spectral Thief}
+ */
+export class SpectralThiefAttr extends MoveAttr {
+  constructor() {
+    super();
+  }
+
+  /**
+   * steals max amount of positive stats of the target while not exceeding the limit of max 6 stat stages
+   *
+   * @param user {@linkcode Pokemon} that called {@linkcode move}
+   * @param target {@linkcode Pokemon} that is the target of {@linkcode move}
+   * @param move {@linkcode Move} called by {@linkcode user}
+   * @param args N/A
+   * @returns true if stat stages where correctly stolen
+   */
+  apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
+    if (!super.apply(user, target, move, args)) {
+      return false;
+    }
+
+    // Copy all positive stat stages to user and reduce copied stat stages on target
+    for (const s of BATTLE_STATS) {
+      const statStageValueTarget = target.getStatStage(s);
+      const statStageValueUser = user.getStatStage(s);
+
+      if (statStageValueTarget > 0) {
+        // Only value of up to 6 can be stolen (stat stages don't exceed 6)
+        const availableToSteal = Math.min(statStageValueTarget, 6 - statStageValueUser);
+
+        user.scene.unshiftPhase(new StatStageChangePhase(user.scene, user.getBattlerIndex(), this.selfTarget, [ s ], availableToSteal));
+        target.setStatStage(s, statStageValueTarget - availableToSteal);
+      }
+    }
+
+    target.updateInfo();
+    user.updateInfo();
+    target.scene.queueMessage(i18next.t("moveTriggers:stolePositiveStatChanges", { pokemonName: getPokemonNameWithAffix(user), targetName: getPokemonNameWithAffix(target) }));
+
+    return true;
+  }
+
+}
+
 export class VariableAtkAttr extends MoveAttr {
   constructor() {
     super();
@@ -9872,6 +9919,7 @@ export function initMoves() {
     new AttackMove(Moves.PRISMATIC_LASER, Type.PSYCHIC, MoveCategory.SPECIAL, 160, 100, 10, -1, 0, 7)
       .attr(RechargeAttr),
     new AttackMove(Moves.SPECTRAL_THIEF, Type.GHOST, MoveCategory.PHYSICAL, 90, 100, 10, -1, 0, 7)
+      .attr(SpectralThiefAttr)
       .ignoresSubstitute()
       .partial(), // Does not steal stats
     new AttackMove(Moves.SUNSTEEL_STRIKE, Type.STEEL, MoveCategory.PHYSICAL, 100, 100, 5, -1, 0, 7)

src/field/pokemon.ts

@@ -3,7 +3,7 @@ import BattleScene, { AnySound } from "#app/battle-scene";
 import { Variant, VariantSet, variantColorCache } from "#app/data/variant";
 import { variantData } from "#app/data/variant";
 import BattleInfo, { PlayerBattleInfo, EnemyBattleInfo } from "#app/ui/battle-info";
-import Move, { HighCritAttr, HitsTagAttr, applyMoveAttrs, FixedDamageAttr, VariableAtkAttr, allMoves, MoveCategory, TypelessAttr, CritOnlyAttr, getMoveTargets, OneHitKOAttr, VariableMoveTypeAttr, VariableDefAttr, AttackMove, ModifiedDamageAttr, VariableMoveTypeMultiplierAttr, IgnoreOpponentStatStagesAttr, SacrificialAttr, VariableMoveCategoryAttr, CounterDamageAttr, StatStageChangeAttr, RechargeAttr, IgnoreWeatherTypeDebuffAttr, BypassBurnDamageReductionAttr, SacrificialAttrOnHit, OneHitKOAccuracyAttr, RespectAttackTypeImmunityAttr, MoveTarget, CombinedPledgeStabBoostAttr, VariableMoveTypeChartAttr } from "#app/data/move";
+import Move, { HighCritAttr, HitsTagAttr, applyMoveAttrs, FixedDamageAttr, VariableAtkAttr, allMoves, MoveCategory, TypelessAttr, CritOnlyAttr, getMoveTargets, OneHitKOAttr, VariableMoveTypeAttr, VariableDefAttr, AttackMove, ModifiedDamageAttr, VariableMoveTypeMultiplierAttr, IgnoreOpponentStatStagesAttr, SacrificialAttr, VariableMoveCategoryAttr, CounterDamageAttr, StatStageChangeAttr, RechargeAttr, IgnoreWeatherTypeDebuffAttr, BypassBurnDamageReductionAttr, SacrificialAttrOnHit, OneHitKOAccuracyAttr, RespectAttackTypeImmunityAttr, MoveTarget, CombinedPledgeStabBoostAttr, VariableMoveTypeChartAttr, SpectralThiefAttr } from "#app/data/move";
 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";
@@ -2831,6 +2831,12 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
         isCritical = false;
       }
 
+      /**
+       * Steals positive stat stages from {@linkcode this} and gives it to {@linkcode source}
+       * before damage calculation
+       */
+      applyMoveAttrs(SpectralThiefAttr, source, this, move);
+
       const { cancelled, result, damage: dmg } = this.getAttackDamage(source, move, false, false, isCritical, false);
 
       const typeBoost = source.findTag(t => t instanceof TypeBoostTag && t.boostedType === source.getMoveType(move)) as TypeBoostTag;

src/test/moves/spectral_thief.test.ts

@@ -0,0 +1,125 @@
+import { Abilities } from "#enums/abilities";
+import { Stat } from "#enums/stat";
+import { allMoves } from "#app/data/move";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import { TurnEndPhase } from "#app/phases/turn-end-phase";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+
+describe("Moves - Spectral Thief", () => {
+  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
+      .enemySpecies(Species.SHUCKLE)
+      .enemyLevel(100)
+      .enemyMoveset(Moves.SPLASH)
+      .enemyAbility(Abilities.BALL_FETCH)
+      .moveset([ Moves.SPECTRAL_THIEF, Moves.SPLASH ])
+      .ability(Abilities.BALL_FETCH)
+      .disableCrits;
+  });
+
+  it("should steal max possible positive stat changes and ignore negative ones.", async () => {
+    await game.classicMode.startBattle();
+
+    const player = game.scene.getPlayerPokemon()!;
+    const enemy = game.scene.getEnemyPokemon()!;
+
+    enemy.setStatStage(Stat.ATK, 6);
+    enemy.setStatStage(Stat.DEF, -6);
+    enemy.setStatStage(Stat.SPATK, 6);
+    enemy.setStatStage(Stat.SPDEF, -6);
+    enemy.setStatStage(Stat.SPD, 3);
+
+    player.setStatStage(Stat.ATK, 4);
+    player.setStatStage(Stat.DEF, 1);
+    player.setStatStage(Stat.SPATK, 0);
+    player.setStatStage(Stat.SPDEF, 0);
+    player.setStatStage(Stat.SPD, -2);
+
+    game.move.select(Moves.SPECTRAL_THIEF);
+    await game.phaseInterceptor.to(TurnEndPhase);
+
+    /**
+     * enemy has +6 ATK and player +4 => player only steals +2
+     * enemy has -6 DEF and player 1 => player should not steal
+     * enemy has +6 SPATK and player 0 => player only steals +6
+     * enemy has -6 SPDEF and player 0 => player should not steal
+     * enemy has +3 SPD and player -2 => player only steals +3
+     */
+    expect(player.getStatStages()).toEqual([ 6, 1, 6, 0, 1, 0, 0 ]);
+    expect(enemy.getStatStages()).toEqual([ 4, -6, 0, -6, 0, 0, 0 ]);
+  });
+
+  it("should steal stat stages before dmg calculation", async () => {
+    game.override
+      .enemySpecies(Species.MAGIKARP)
+      .enemyLevel(50);
+    await game.classicMode.startBattle();
+
+    const player = game.scene.getPlayerPokemon()!;
+    const enemy = game.scene.getEnemyPokemon()!;
+    const moveToCheck = allMoves[Moves.SPECTRAL_THIEF];
+    const dmgBefore = enemy.getAttackDamage(player, moveToCheck, false, false, false, false).damage;
+
+    enemy.setStatStage(Stat.ATK, 6);
+
+    player.setStatStage(Stat.ATK, 0);
+
+    game.move.select(Moves.SPECTRAL_THIEF);
+    await game.phaseInterceptor.to(TurnEndPhase);
+
+    expect(dmgBefore).toBeLessThan(enemy.getAttackDamage(player, moveToCheck, false, false, false, false).damage);
+  });
+
+  it("should steal stat stages as a negative value with Contrary.", async () => {
+    game.override
+      .ability(Abilities.CONTRARY);
+    await game.classicMode.startBattle();
+
+    const player = game.scene.getPlayerPokemon()!;
+    const enemy = game.scene.getEnemyPokemon()!;
+
+    enemy.setStatStage(Stat.ATK, 6);
+
+    player.setStatStage(Stat.ATK, 0);
+
+    game.move.select(Moves.SPECTRAL_THIEF);
+    await game.phaseInterceptor.to(TurnEndPhase);
+
+    expect(player.getStatStage(Stat.ATK)).toEqual(-6);
+    expect(enemy.getStatStage(Stat.ATK)).toEqual(0);
+  });
+
+  it("should steal double the stat stages with Simple.", async () => {
+    game.override
+      .ability(Abilities.SIMPLE);
+    await game.classicMode.startBattle();
+
+    const player = game.scene.getPlayerPokemon()!;
+    const enemy = game.scene.getEnemyPokemon()!;
+
+    enemy.setStatStage(Stat.ATK, 3);
+
+    player.setStatStage(Stat.ATK, 0);
+
+    game.move.select(Moves.SPECTRAL_THIEF);
+    await game.phaseInterceptor.to(TurnEndPhase);
+
+    expect(player.getStatStage(Stat.ATK)).toEqual(6);
+    expect(enemy.getStatStage(Stat.ATK)).toEqual(0);
+  });
+});