Crystal/tests/reference-trainer-sight.spec.ts

import { test, expect } from "@playwright/test";
import { existsSync, readFileSync } from "node:fs";
import { romPath, symbolsPath, loadSymbols, openReference } from "./reference-fixture";

test.skip(!existsSync(romPath) || !existsSync(symbolsPath), "Needs private ROM and reference symbols.");

// BurnedTower1F's rival (map object 3) is OBJECTTYPE_TRAINER with sight 3,
// but its script pointer is the generic ObjectEvent (home/map.asm's
// `jumptextfaceplayer ObjectEventText`), not a TrainerHeader: see
// maps/BurnedTower1F.asm's `object_event 8, 9, SPRITE_RIVAL, ..., 0,
// OBJECTTYPE_TRAINER, 3, ObjectEvent, EVENT_RIVAL_BURNED_TOWER`. After
// BurnedTowerRivalBattleScript the rival stands at (9,9) facing right and
// the player at (10,9). _CheckTrainerBattle reads the "beaten" flag from
// the script pointer's first two bytes: jumptextfaceplayer_command ($51)
// and ObjectEventText's low byte ($f2), i.e. flag $f251. EventFlagAction's
// bit math (de >> 3 added to wEventFlags) overflows by $1e4a bytes into
// echo RAM, landing on wNumKeyItems (bank 1, $d8bc) bit 1.
test("CheckTrainerBattle reads BurnedTower1F's rival as beaten only when wNumKeyItems' bit 1 is set", async ({ page }) => {
  const { at, routine } = loadSymbols();
  const a = {
    romBank: at("hROMBank"),
    lastTalked: at("hLastTalked"),
    mapScriptsBank: at("wMapScriptsBank"),
    playerMapX: at("wPlayerMapX"),
    playerMapY: at("wPlayerMapY"),
    map3Object: at("wMap3Object"),
    object1Struct: at("wObject1Struct"),
    numKeyItems: at("wNumKeyItems"),
    seenTrainerDistance: at("wSeenTrainerDistance"),
    seenTrainerDirection: at("wSeenTrainerDirection"),
    tempTrainerEventFlag: at("wTempTrainerEventFlag"),
    tempTrainerClass: at("wTempTrainerClass"),
    tempTrainerID: at("wTempTrainerID"),
    seenTextPointer: at("wSeenTextPointer"),
    winTextPointer: at("wWinTextPointer"),
    lossTextPointer: at("wLossTextPointer"),
    scriptAfterPointer: at("wScriptAfterPointer"),
    runningTrainerBattleScript: at("wRunningTrainerBattleScript"),
  };
  const checkTrainerBattle = routine("CheckTrainerBattle");
  const objectEvent = at("ObjectEvent");
  const mapScriptsBank = routine("BurnedTower1F_MapScripts").bank;

  await openReference(page);
  const result = await page.evaluate(async ({ a, checkTrainerBattle, objectEvent, mapScriptsBank }) => {
    const { BinjgbEmulator } = await import("/src/emulator/binjgb.ts");
    const rom = new Uint8Array(await (document.querySelector("#reference-fixture") as HTMLInputElement).files![0].arrayBuffer());
    const reference = new BinjgbEmulator();
    await reference.load(rom, document.createElement("canvas"));
    const write = (p: number, v: number) => reference.writeMemory(p, v & 255);
    const ptr = (p: number, v: number) => { write(p, v); write(p + 1, v >> 8); };
    const read = (p: number) => reference.readMemory(p);
    const readPtr = (p: number) => read(p) | (read(p + 1) << 8);
    // DI; SP=$c7fe; CheckTrainerBattle is home code, bank is irrelevant;
    // CALL CheckTrainerBattle; branch on carry into $c0f1, then the sentinel
    // at $c0f0, as the other reference fixtures do. Both live away from any
    // battle or trainer variable.
    const program = [
      0xf3, 0x31, 0xfe, 0xc7,
      0x3e, checkTrainerBattle.bank, 0xe0, a.romBank & 255, 0xea, 0, 0x20,
      0xcd, checkTrainerBattle.address & 255, checkTrainerBattle.address >> 8,
      0x38, 3, 0xaf, 0x18, 2, 0x3e, 1, 0xea, 0xf1, 0xc0,
      0x3e, 0x42, 0xea, 0xf0, 0xc0,
      0x18, 0xfe,
    ];

    const results: unknown[] = [];
    for (let numKeyItems = 0; numKeyItems <= 6; numKeyItems++) {
      // The rival: a trainer with sight 3 whose script pointer is the
      // generic ObjectEvent, standing at (9,9) facing right; the player at
      // (10,9), one tile to the right.
      write(a.mapScriptsBank, mapScriptsBank);
      write(a.playerMapX, 10);
      write(a.playerMapY, 9);
      write(a.map3Object + 0, 1); // MAPOBJECT_OBJECT_STRUCT_ID -> wObject1Struct
      write(a.map3Object + 1, 1); // MAPOBJECT_SPRITE (nonzero: has a sprite)
      write(a.map3Object + 8, 2); // MAPOBJECT_TYPE: OBJECTTYPE_TRAINER
      write(a.map3Object + 9, 3); // MAPOBJECT_SIGHT_RANGE
      ptr(a.map3Object + 0xa, objectEvent); // MAPOBJECT_SCRIPT_POINTER -> ObjectEvent
      write(a.object1Struct + 0x10, 9); // OBJECT_MAP_X
      write(a.object1Struct + 0x11, 9); // OBJECT_MAP_Y
      write(a.object1Struct + 0x08, 0x0c); // OBJECT_DIRECTION: facing right (OW_RIGHT)
      write(a.numKeyItems, numKeyItems);
      // Sentinels: only a reported sighting overwrites these.
      write(a.lastTalked, 0xff);
      write(a.seenTrainerDistance, 0xff);
      write(a.seenTrainerDirection, 0xff);
      ptr(a.tempTrainerEventFlag, 0xffff);
      write(a.tempTrainerClass, 0xff);
      write(a.tempTrainerID, 0xff);
      ptr(a.seenTextPointer, 0xffff);
      ptr(a.winTextPointer, 0xffff);
      ptr(a.lossTextPointer, 0xffff);
      ptr(a.scriptAfterPointer, 0xffff);
      write(a.runningTrainerBattleScript, 0xff);
      write(0xc0f0, 0);
      write(0xc0f1, 0xff);
      program.forEach((v, i) => write(0xc000 + i, v));
      reference.setProgramCounter(0xc000);
      for (let frame = 0; frame < 60 && read(0xc0f0) !== 0x42; frame++) reference.advanceFrames(1);
      if (read(0xc0f0) !== 0x42) throw Error("CheckTrainerBattle did not return");
      results.push({
        numKeyItems,
        carry: read(0xc0f1) === 1,
        lastTalked: read(a.lastTalked),
        seenTrainerDistance: read(a.seenTrainerDistance),
        seenTrainerDirection: read(a.seenTrainerDirection),
        tempTrainer: {
          eventFlag: readPtr(a.tempTrainerEventFlag),
          class: read(a.tempTrainerClass),
          id: read(a.tempTrainerID),
          seenText: readPtr(a.seenTextPointer),
          winText: readPtr(a.winTextPointer),
          lossText: readPtr(a.lossTextPointer),
          scriptAfter: readPtr(a.scriptAfterPointer),
          runningTrainerBattleScript: read(a.runningTrainerBattleScript),
        },
      });
    }
    reference.dispose();
    return results;
  }, { a, checkTrainerBattle, objectEvent, mapScriptsBank });

  // Bit 1 of wNumKeyItems (2, 3, 6) makes the overflowed flag read set, so
  // the original treats the rival as already beaten and skips it; every
  // other count reports the sighting, copying ObjectEvent's bytes as a
  // (nonsensical) trainer header into wTempTrainer.
  const sentinelPtr = { eventFlag: 0xffff, class: 0xff, id: 0xff, seenText: 0xffff, winText: 0xffff, lossText: 0xffff, scriptAfter: 0xffff, runningTrainerBattleScript: 0xff };
  const decodedHeader = { eventFlag: 0xf251, class: 0x26, id: 0x16, seenText: 0x46ee, winText: 0x5071, lossText: 0xfa53, scriptAfter: 0x1626, runningTrainerBattleScript: 0 };
  const expected = [0, 1, 2, 3, 4, 5, 6].map((numKeyItems) => {
    const beaten = (numKeyItems & 2) !== 0;
    return {
      numKeyItems,
      carry: !beaten,
      lastTalked: beaten ? 0xff : 3,
      seenTrainerDistance: beaten ? 0xff : 1,
      seenTrainerDirection: beaten ? 0xff : 0x0c,
      tempTrainer: beaten ? sentinelPtr : decodedHeader,
    };
  });
  expect(result).toHaveLength(7);
  expect(result).toEqual(expected);
});

// The battle CheckTrainerBattle reports when it does fire: LoadTrainer_continue
// copies 13 bytes starting at ObjectEvent into wTempTrainer, reading its
// command byte and ObjectEventText's pointer as a trainer class, ID and
// text pointers. Class $26 is SWIMMERM (constants/trainer_constants.asm),
// which has exactly 21 named trainers; ID $16 (22) is one past the last of
// them. ReadTrainerParty's name-skipping loop (engine/battle/
// read_trainer_party.asm) scans forward from SwimmerMGroup's start for 21
// end-of-party ($ff) markers and, since the group tables in data/trainers/
// parties.asm sit back-to-back with no padding, lands exactly on
// SwimmerFGroup's first entry: ELAINE, a single level 21 STARYU. The
// party itself is no garbage: SWIMMERM's sprite, cry and class text with
// SwimmerF's ELAINE as the opponent's name and sole Pokemon, confirmed here
// by running the unmodified ReadTrainerParty and Battle_GetTrainerName
// routines. StartBattleWithMapTrainerScript prints the seen text first,
// though, and the next test shows that is not text.
test("the decoded trainer header resolves to SwimmerF's ELAINE, one past SwimmerM's last trainer", async ({ page }) => {
  const { at, routine } = loadSymbols();
  const a = {
    romBank: at("hROMBank"),
    inBattleTowerBattle: at("wInBattleTowerBattle"),
    linkMode: at("wLinkMode"),
    otherTrainerClass: at("wOtherTrainerClass"),
    otherTrainerID: at("wOtherTrainerID"),
    otPartyCount: at("wOTPartyCount"),
    otPartyMon1Species: at("wOTPartyMon1Species"),
    otPartyMon1Level: at("wOTPartyMon1Level"),
    stringBuffer1: at("wStringBuffer1"),
  };
  const readTrainerParty = routine("ReadTrainerParty");
  const getTrainerName = routine("Battle_GetTrainerName");

  await openReference(page);
  const result = await page.evaluate(async ({ a, readTrainerParty, getTrainerName }) => {
    const { BinjgbEmulator } = await import("/src/emulator/binjgb.ts");
    const rom = new Uint8Array(await (document.querySelector("#reference-fixture") as HTMLInputElement).files![0].arrayBuffer());
    const reference = new BinjgbEmulator();
    await reference.load(rom, document.createElement("canvas"));
    const write = (p: number, v: number) => reference.writeMemory(p, v & 255);
    const read = (p: number) => reference.readMemory(p);
    write(a.inBattleTowerBattle, 0);
    write(a.linkMode, 0);
    write(a.otherTrainerClass, 0x26); // SWIMMERM
    write(a.otherTrainerID, 0x16); // 22: one past SWIMMERM's last trainer (21)
    // DI; SP=$c7fe; both routines share engine/battle/core.asm's bank;
    // CALL ReadTrainerParty (ends in a party of OT mons), then
    // CALL Battle_GetTrainerName (copies the name into wStringBuffer1).
    const program = [
      0xf3, 0x31, 0xfe, 0xc7,
      0x3e, readTrainerParty.bank, 0xe0, a.romBank & 255, 0xea, 0, 0x20,
      0xcd, readTrainerParty.address & 255, readTrainerParty.address >> 8,
      0xcd, getTrainerName.address & 255, getTrainerName.address >> 8,
      0x3e, 0x42, 0xea, 0xf0, 0xc0,
      0x18, 0xfe,
    ];
    write(0xc0f0, 0);
    program.forEach((v, i) => write(0xc000 + i, v));
    reference.setProgramCounter(0xc000);
    for (let frame = 0; frame < 60 && read(0xc0f0) !== 0x42; frame++) reference.advanceFrames(1);
    if (read(0xc0f0) !== 0x42) throw Error("ReadTrainerParty/Battle_GetTrainerName did not return");
    const outcome = {
      partyCount: read(a.otPartyCount),
      species: read(a.otPartyMon1Species),
      level: read(a.otPartyMon1Level),
      name: Array.from({ length: 11 }, (_, i) => read(a.stringBuffer1 + i)),
    };
    reference.dispose();
    return outcome;
  }, { a, readTrainerParty, getTrainerName });

  const STARYU = 0x78;
  // "ELAINE@" in the game's charmap, followed by SwimmerFGroup's next three
  // bytes (TRAINERTYPE_NORMAL, level 21, STARYU) and the party's $ff end
  // marker: the exact 11 (NAME_LENGTH) bytes CopyTrainerName copies.
  expect(result).toEqual({
    partyCount: 1,
    species: STARYU,
    level: 21,
    name: [0x84, 0x8b, 0x80, 0x88, 0x8d, 0x84, 0x50, 0x00, 0x15, 0x78, 0xff],
  });
});

// StartBattleWithMapTrainerScript's `trainertext TRAINERTEXT_SEEN` prints
// the decoded seen text ($46ee in the map scripts' bank) before the battle.
// It points into the middle of SproutTower1FStatueText: its first byte is
// the space character $7f, which DoTextUntilTerminator dispatches as a text
// command. TextCommands has NUM_TEXT_CMDS (23) entries, so command $7f reads
// its pointer from home code beyond the table and jumps into the middle of
// the VBlank handlers. What happens next depends on the whole CPU state, so
// the native port keeps skipping the sighting (see checkTrainers).
test("the decoded seen text dispatches text command $7f, beyond TextCommands", () => {
  const { at, routine } = loadSymbols();
  const rom = readFileSync(romPath);
  const bank = routine("BurnedTower1F_MapScripts").bank;
  const seenText = 0x46ee;
  const first = rom[bank * 0x4000 + seenText - 0x4000];
  const NUM_TEXT_CMDS = 23;
  const entry = at("TextCommands") + first * 2;
  const target = rom[entry] | (rom[entry + 1] << 8);
  expect(first).toBe(0x7f);
  expect(first).toBeGreaterThanOrEqual(NUM_TEXT_CMDS);
  expect(entry).toBeGreaterThan(at("TextCommands") + NUM_TEXT_CMDS * 2);
  expect(target).toBe(0x0428);
  expect(target).toBeGreaterThan(at("VBlank_Credits"));
  expect(target).toBeLessThan(at("TextCommands"));
});