Crystal/tests/battle-ai.test.ts

import { describe, expect, it } from "vitest";
import {
  chooseTrainerMove,
  validateTrainerAI,
  type TrainerAIInput,
  type TrainerAISide,
} from "../src/game/battle/ai";
import { C } from "../src/game/battle/constants";
import { SYMBOLS } from "../src/game/rom/profile";
import type { MoveData } from "../src/game/rom/pokemon";

const move = (
  id: number,
  effect = C.EFFECT_NORMAL_HIT,
  power = 40,
  type = 0,
): MoveData => ({ id, effect, power, type, accuracy: 255, pp: 30, chance: 0 });
const side = (): TrainerAISide => ({
  mon: {
    moves: [1, 2, 0, 0],
    pp: [30, 30, 0, 0],
    status: 0,
    hp: 20,
    maxHp: 20,
    types: [0, 0],
    species: 1,
    dvs: 0x8888,
  },
  sub: [0, 0, 0, 0, 0, 0],
  screens: 0,
  turnsTaken: 0,
  disableCount: 0,
  disabledMove: 0,
});
function fixture(moves = [move(1), move(2)], bytes = [0]): TrainerAIInput {
  let cursor = 0;
  return {
    weights: 0,
    player: side(),
    enemy: side(),
    weather: 0,
    damage: () => {
      throw new Error("Unexpected damage estimate");
    },
    random: () => {
      if (cursor >= bytes.length)
        throw new Error("Unexpected extra random call");
      return bytes[cursor++];
    },
    data: {
      move: (id) => moves.find((m) => m.id === id)!,
      baseData: () => {
        throw new Error("Unexpected base data lookup");
      },
    },
    battleData: {
      byteList: (address) => {
        if (address === SYMBOLS.statusOnlyEffects)
          return [
            C.EFFECT_SLEEP,
            C.EFFECT_TOXIC,
            C.EFFECT_POISON,
            C.EFFECT_PARALYZE,
          ];
        if (address === SYMBOLS.recklessMoves)
          return [
            C.EFFECT_SELFDESTRUCT,
            C.EFFECT_RAMPAGE,
            C.EFFECT_MULTI_HIT,
            C.EFFECT_DOUBLE_HIT,
          ];
        if (address === SYMBOLS.riskyEffects)
          return [C.EFFECT_SELFDESTRUCT, C.EFFECT_OHKO];
        return [1, 2];
      },
      typeMatchups: () => [],
    },
  };
}

describe("trainer AI native scoring", () => {
  it("accepts all defined layer bits and rejects invalid layer words", () => {
    for (const weights of [-1, 65536, 1.5, NaN])
      expect(() => validateTrainerAI(weights)).toThrow(/not translated/);
    for (const weights of [16, 0x3d3, 0xffff])
      expect(() => validateTrainerAI(weights)).not.toThrow();
  });
  it.each([C.EFFECT_ATTACK_DOWN, C.EFFECT_DEFENSE_DOWN])(
    "Smart leaves the first rival's attack and stat-lowering effect %i unchanged",
    (effect) => {
      const input = fixture([move(1), move(2, effect, 0)], [3, 1]);
      input.weights = 16;
      expect(chooseTrainerMove(input)).toEqual({
        move: 2,
        index: 1,
        scores: [20, 20, 80, 80],
      });
    },
  );
  it("refuses untranslated Smart effects before any earlier layer consumes randomness", () => {
    const input = fixture(
      [move(1, C.EFFECT_ATTACK_DOWN, 0), move(2, C.EFFECT_REFLECT, 0)],
      [],
    );
    input.weights = 0x3d3;
    input.enemy.mon.pp[1] = 0; // Exhaustion does not bypass scoring or validation.
    expect(() => chooseTrainerMove(input)).toThrow(/Smart AI for move effect/);
  });
  it("validates Smart effects across a supplied full trainer party", () => {
    expect(() =>
      validateTrainerAI(0x3d3, [
        C.EFFECT_NORMAL_HIT,
        C.EFFECT_ATTACK_DOWN,
        C.EFFECT_DEFENSE_DOWN,
      ]),
    ).not.toThrow();
    expect(() =>
      validateTrainerAI(0x3d3, [C.EFFECT_NORMAL_HIT, C.EFFECT_SLEEP]),
    ).toThrow(/Smart AI/);
  });
  it("uses masked random slots and retries blanks without first-slot tie bias", () => {
    const input = fixture(undefined, [3, 6, 253]);
    expect(chooseTrainerMove(input)).toEqual({
      move: 2,
      index: 1,
      scores: [20, 20, 80, 80],
    });
  });
  it("refuses a random source that never produces a candidate", () => {
    const input = fixture();
    input.random = () => 3;
    expect(() => chooseTrainerMove(input)).toThrow(/random source/);
  });
  it("masks PP Ups and discourages disabled/exhausted moves", () => {
    const input = fixture([move(1), move(2), move(3)], [0, 1, 2]);
    input.enemy.mon.moves = [1, 2, 3, 0];
    input.enemy.mon.pp = [30, 0xc0, 0xc1, 0];
    input.enemy.disabledMove = 1;
    expect(chooseTrainerMove(input)).toEqual({
      move: 3,
      index: 2,
      scores: [80, 80, 20, 80],
    });
  });
  it("still scores exhausted moves and consumes randomness before Struggle", () => {
    const input = fixture(
      [move(1, C.EFFECT_ATTACK_UP, 0), move(2)],
      [128, 3, 0],
    );
    input.weights = 2;
    input.enemy.mon.pp.fill(0);
    expect(chooseTrainerMove(input)).toEqual({
      move: 1,
      index: 0,
      scores: [78, 80, 80, 80],
    });
  });
  it("still selects when the only move is disabled", () => {
    const input = fixture([move(1)], [3, 0]);
    input.enemy.mon.moves = [1, 0, 0, 0];
    input.enemy.disabledMove = 1;
    expect(chooseTrainerMove(input)).toEqual({
      move: 1,
      index: 0,
      scores: [80, 20, 80, 80],
    });
  });
  it("refuses empty move lists instead of the cartridge's infinite loop", () => {
    const input = fixture();
    input.enemy.mon.moves.fill(0);
    expect(() => chooseTrainerMove(input)).toThrow(/nonzero move/);
  });
  it("Basic discourages status on a statused or safeguarded target exactly once", () => {
    const input = fixture([move(1, C.EFFECT_SLEEP, 0), move(2)], [1]);
    input.weights = 1;
    input.player.mon.status = 8;
    input.player.screens = 1 << C.SCREENS_SAFEGUARD;
    expect(chooseTrainerMove(input).scores).toEqual([30, 20, 80, 80]);
  });
  it("Basic preserves Nightmare and Future Sight's cartridge redundancy bugs", () => {
    const input = fixture(
      [move(1, C.EFFECT_NIGHTMARE, 0), move(2, C.EFFECT_FUTURE_SIGHT)],
      [0],
    );
    input.weights = 1;
    input.player.mon.status = 8;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
    input.random = () => 1;
    input.enemy.screens = 1 << C.SCREENS_UNUSED;
    input.player.mon.status = 0;
    input.random = () => 0;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([30, 30]);
  });
  it("Setup uses each side's first turn and exact 128/30 byte thresholds", () => {
    const input = fixture(
      [move(1, C.EFFECT_ATTACK_UP, 0), move(2, C.EFFECT_ATTACK_DOWN, 0)],
      [128, 30, 0],
    );
    input.weights = 2;
    input.player.turnsTaken = 1;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([18, 22]);
    input.random = (() => {
      const bytes = [127, 29, 1];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
  });
  it("Types discourages resistance only when another damaging type exists", () => {
    const input = fixture([move(1, 0, 40, 20), move(2, 0, 0, 21)], [0]);
    input.weights = 4;
    input.battleData.typeMatchups = () => [
      { attacker: 20, defender: 0, multiplier: 5 },
    ];
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
    input.data.move = (id) =>
      id === 1 ? move(1, 0, 40, 20) : move(2, 0, 40, 21);
    input.random = () => 1;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([21, 20]);
  });
  it("Types encourages damaging super-effective moves and respects Foresight", () => {
    const input = fixture([move(1, 0, 40, 0), move(2, 0, 40, 20)], [1]);
    input.weights = 4;
    input.player.mon.types = [8, 8];
    input.battleData.typeMatchups = () => [
      { attacker: 20, defender: 8, multiplier: 20 },
      { attacker: 0xfe, defender: 0, multiplier: 0 },
      { attacker: 0, defender: 8, multiplier: 0 },
    ];
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([30, 19]);
    input.player.sub = [0, 1 << C.SUBSTATUS_IDENTIFIED, 0, 0, 0, 0];
    input.random = () => 1;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 19]);
  });
  it("Status discourages poison against Poison and damaging immunities", () => {
    const input = fixture([move(1, C.EFFECT_POISON, 0), move(2)], [0]);
    input.weights = 256;
    input.player.mon.types = [3, 3];
    input.battleData.typeMatchups = () => [
      { attacker: 0, defender: 3, multiplier: 0 },
    ];
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([30, 30]);
  });
  it("Cautious stops the entire layer on its first failed random check", () => {
    const input = fixture(undefined, [230, 1]);
    input.weights = 128;
    input.enemy.turnsTaken = 1;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
    input.random = (() => {
      const bytes = [229, 230, 1];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([21, 20]);
  });
  it("Offensive penalizes non-damaging moves by two", () => {
    const input = fixture([move(1, C.EFFECT_ATTACK_DOWN, 0), move(2)], [1]);
    input.weights = 8;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([22, 20]);
  });
  it("Opportunist discourages stall moves at low HP with the exact half thresholds", () => {
    const input = fixture(undefined, [0]);
    input.weights = 32;
    input.enemy.mon.hp = 11;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);

    input.enemy.mon.hp = 5;
    input.random = () => 0;
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([21, 21]);

    input.enemy.mon.hp = 8;
    input.random = (() => {
      const bytes = [127, 0];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
    input.random = (() => {
      const bytes = [128, 0];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([21, 21]);
  });
  it("Aggressive keeps the last strongest move and spares reckless alternatives", () => {
    const input = fixture(
      [move(1), move(2, C.EFFECT_SELFDESTRUCT), move(3)],
      [1],
    );
    input.weights = 64;
    input.enemy.mon.moves = [1, 2, 3, 0];
    input.enemy.mon.pp = [30, 30, 30, 0];
    input.damage = (id) => (id === 1 ? 5 : 10);
    expect(chooseTrainerMove(input).scores.slice(0, 3)).toEqual([21, 20, 20]);
  });
  it("Risky uses strict KO damage and applies its max-HP and random exclusions", () => {
    const input = fixture([move(1, C.EFFECT_SELFDESTRUCT), move(2)], [1]);
    input.weights = 512;
    input.player.mon.hp = 10;
    input.damage = (id) => (id === 1 ? 100 : 10);
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);

    input.enemy.mon.hp = 19;
    input.random = (() => {
      const bytes = [199, 1];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([20, 20]);
    input.random = (() => {
      const bytes = [200, 1];
      return () => bytes.shift()!;
    })();
    expect(chooseTrainerMove(input).scores.slice(0, 2)).toEqual([15, 20]);
  });
});