Crystal/tests/battle-driver.ts

import type { CrystalAssets } from "../src/game/rom/assets";
import type { TrainerData } from "../src/game/rom/trainers";
import type {
  Battle,
  BattleEffect,
  BattleInput,
  BattleOptions,
} from "../src/game/battle/battle";
import type { Bag } from "../src/game/party/bag";
import { generatePartyMon, type PartyMon } from "../src/game/party/pokemon";
import { defaultTextContext } from "../src/game/scripts/text";

export const partyMon = (
  assets: CrystalAssets,
  species: number,
  level: number,
): PartyMon =>
  generatePartyMon(assets.pokemon, {
    species,
    level,
    item: 0,
    otId: 1234,
    ot: "CHRIS",
    dvs: 0x823b,
    caughtData: 0,
  });

/** Battle options for a wild Pokémon or a ROM trainer, with a seeded
 * stand-in for the hardware Random routine. */
export function battleOptions(
  assets: CrystalAssets,
  trainers: TrainerData,
  party: PartyMon[],
  enemy:
    | { wild: { species: number; level: number } }
    | { trainer: [number, number] },
  { seed = 1, bag }: { seed?: number; bag?: Bag } = {},
): BattleOptions {
  const base = {
    data: assets.pokemon,
    party,
    bag,
    playerId: 1234,
    playerName: "CHRIS",
    timeOfDay: 1,
    pokedex: { seen: new Set<number>(), caught: new Set<number>() },
    random: () => {
      seed = (seed * 1103515245 + 12345) >>> 0;
      return (seed >>> 16) & 255;
    },
    text: () => defaultTextContext("CHRIS"),
  };
  if ("wild" in enemy) return { ...base, wild: enemy.wild };
  const trainer = trainers.trainer(...enemy.trainer);
  return {
    ...base,
    trainer: {
      name: trainer.name,
      className: trainer.className,
      party: trainers.createParty(trainer),
      aiFlags: trainer.attributes.aiMoveFlags,
      switchFlags: trainer.attributes.aiItemSwitchFlags,
      reward: trainer.reward,
    },
  };
}

/** Run a battle. Menus take queued answers per prompt kind, then the
 * defaults: the first move, YES, cancelling a move to forget, and the
 * first party slot or move slot. */
export function playBattle(
  battle: Battle,
  queued: Partial<Record<BattleEffect["kind"], BattleInput[]>> = {},
) {
  const texts: string[] = [],
    prompts: BattleEffect[] = [];
  const run = battle.run();
  let input: BattleInput;
  for (let step = 0; step < 3000; step++) {
    const next = run.next(input);
    if (next.done) return { texts, prompts, result: next.value.result };
    const effect = next.value;
    input = undefined;
    if (effect.kind === "text") texts.push(effect.text.replace(/\n/g, " "));
    else if (effect.kind !== "hud") {
      prompts.push(effect);
      const answer = queued[effect.kind]?.shift();
      input =
        answer !== undefined
          ? answer
          : effect.kind === "action"
            ? { action: "fight", move: 0 }
            : effect.kind === "yesno"
              ? 1
              : effect.kind === "forget"
                ? 4
                : effect.kind === "party" || effect.kind === "move"
                  ? 0
                  : undefined;
    }
  }
  throw new Error("Battle did not end.");
}

/** Step a battle by hand: texts are collected up to each prompt, and
 * `answer` feeds the current prompt's input. */
export function battleSteps(battle: Battle) {
  const run = battle.run();
  const texts: string[] = [];
  let next = run.next();
  const collect = () => {
    while (
      !next.done &&
      (next.value.kind === "text" || next.value.kind === "hud")
    ) {
      if (next.value.kind === "text")
        texts.push(next.value.text.replace(/\n/g, " "));
      next = run.next();
    }
  };
  collect();
  return {
    texts,
    get prompt(): BattleEffect | undefined {
      return next.done ? undefined : next.value;
    },
    get done() {
      return Boolean(next.done);
    },
    answer(input: BattleInput) {
      next = run.next(input);
      collect();
      return this;
    },
  };
}