RingBRP/tools/check-anatomy.mjs

/**
 * check-anatomy — a body plan must be complete, drawable, and consequential.
 *
 * The hit location system was in the game for a long time as a hazards-only
 * subsystem: falling, fire, explosions and automatic fire rolled a location, and
 * every ordinary sword blow and pistol shot did not. Nothing caught that, because
 * every individual piece was correct — the tables, the armour coverage, the
 * disable and destroy thresholds, the effects. They simply were not joined up.
 *
 * This guard covers the part a table notices first:
 *
 *   1. Every table covers 1-20 exactly once in BOTH modes. A gap is a location
 *      roll that returns nothing; an overlap is a location that cannot be hit.
 *   2. Every location has a shape in BODY_ART, and every shape has a location.
 *      The sheet filters shapeless locations out silently, so a missing shape is
 *      a limb that is on the table and not on the drawing.
 *   3. Every `kind` used by any table is one locationEffectsFor actually handles,
 *      has effect text to print, and has a declared destruction outcome. A kind
 *      nobody handles falls through to "body" and quietly does nothing.
 *   4. A wound survives a change of body plan. locationDamage is keyed by location
 *      id, and only the current plan's keys are ever read, so every plan-to-plan
 *      move must land every wound on a location the destination actually has.
 *      Caught live: a Barghest switched to quadruped kept 5 points in `legR` and 7
 *      in `chest` — 12 hit points of damage under keys nothing answers to.
 */

import { readFileSync } from "node:fs";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";
import { LOCATION_TABLES, BODY_ART } from "../anatomy.mjs";
import { locationEffectsFor, destructionOutcomeFor, remapLocationDamage,
         locationDamageReplacement, locationMaxHp, groundedPlanFor,
         naturalArmourOn, exposedHideFor } from "../rules.mjs";

const ROOT = join(dirname(fileURLToPath(import.meta.url)), "..");
const problems = [];

/* The kinds the engine prints effect text for. Read out of the source rather than
   duplicated here, for the same reason rules.mjs exists: one definition. */
const engine = readFileSync(join(ROOT, "ringbrp.mjs"), "utf8");
const effectBlock = engine.slice(engine.indexOf("RINGBRP.locationEffects = {"));
const EFFECT_KINDS = new Set(
  [...effectBlock.slice(0, effectBlock.indexOf("};")).matchAll(/^\s*(\w+):\s*\{/gm)]
    .map(m => m[1]));

/* Kinds locationEffectsFor genuinely acts on — probed rather than parsed, so this
   cannot drift from the function's real behaviour. */
function kindDoesSomething(kind) {
  const base = locationEffectsFor([]);
  const hit  = locationEffectsFor([{ kind, disabled: true, destroyed: false }]);
  return JSON.stringify(base) !== JSON.stringify(hit);
}

let locCount = 0;

for (const [id, table] of Object.entries(LOCATION_TABLES)) {
  const art = BODY_ART[id];
  if (!art) { problems.push(`${id}: no BODY_ART entry — the sheet would draw nothing`); continue; }

  // 1. d20 coverage, both modes
  for (const mode of ["melee", "ranged"]) {
    const faces = new Array(21).fill(0);
    for (const loc of table.locations) {
      const [lo, hi] = loc[mode] ?? [];
      if (!Number.isInteger(lo) || !Number.isInteger(hi) || lo < 1 || hi > 20 || hi < lo) {
        problems.push(`${id}.${loc.id}: ${mode} range [${lo}, ${hi}] is not a 1-20 span`);
        continue;
      }
      for (let f = lo; f <= hi; f++) faces[f]++;
    }
    const gaps = [], dupes = [];
    for (let f = 1; f <= 20; f++) {
      if (faces[f] === 0) gaps.push(f);
      else if (faces[f] > 1) dupes.push(f);
    }
    if (gaps.length)  problems.push(`${id} ${mode}: d20 face(s) ${gaps.join(",")} hit nothing`);
    if (dupes.length) problems.push(`${id} ${mode}: d20 face(s) ${dupes.join(",")} hit two locations`);
  }

  // 2. table and drawing agree, both ways
  const tableIds = new Set(table.locations.map(l => l.id));
  const artIds = new Set(Object.keys(art.parts ?? {}));
  for (const l of tableIds) if (!artIds.has(l)) problems.push(`${id}.${l}: on the table, not on the figure`);
  for (const a of artIds) if (!tableIds.has(a)) problems.push(`${id}.${a}: on the figure, not on the table`);
  if (!/^[\d.\s-]+$/.test(String(art.viewBox ?? ""))) {
    problems.push(`${id}: viewBox "${art.viewBox}" is not four numbers`);
  }

  // 3. every kind is handled, printable and has a destruction outcome
  for (const loc of table.locations) {
    locCount++;
    if (!(Number(loc.frac) > 0)) problems.push(`${id}.${loc.id}: frac ${loc.frac} gives the location no hit points`);
    if (!EFFECT_KINDS.has(loc.kind)) {
      problems.push(`${id}.${loc.id}: kind "${loc.kind}" has no entry in RINGBRP.locationEffects `
        + `— it would fall back to "body" and print the wrong effect`);
    }
    if (!kindDoesSomething(loc.kind)) {
      problems.push(`${id}.${loc.id}: kind "${loc.kind}" changes nothing in locationEffectsFor `
        + `— losing it would be cosmetic`);
    }
    if (typeof destructionOutcomeFor(loc.kind, true) !== "string") {
      problems.push(`${id}.${loc.id}: kind "${loc.kind}" has no destruction outcome`);
    }
  }
}

/* 4. a change of body plan keeps every wound, and keeps what it MEANT --------- *
 * Two separate promises. Every wound must land on a location the destination actually
 * has (the Barghest defect: 12 points under keys nothing answers to). And it must land
 * with the same severity, because severity is what the rules read — a location is
 * disabled at its maximum and destroyed at twice it, and those maxima differ between
 * plans, so carrying the raw number across silently healed destroyed limbs one way and
 * destroyed merely-disabled ones the other.                                           */
const HP = 16;
const lmax = frac => locationMaxHp(HP, frac);
const severity = (taken, max) => taken >= max * 2 ? "destroyed" : taken >= max ? "disabled" : "hurt";
let pairs = 0, carried = 0;

for (const [fromId, fromT] of Object.entries(LOCATION_TABLES)) {
  for (const [toId, toT] of Object.entries(LOCATION_TABLES)) {
    if (fromId === toId) continue;
    pairs++;
    const valid = new Set(toT.locations.map(l => l.id));

    for (const band of ["hurt", "disabled", "destroyed"]) {
      const src = {};
      for (const l of fromT.locations) {
        const m = lmax(l.frac);
        src[l.id] = band === "hurt" ? Math.max(1, m - 1) : band === "disabled" ? m : m * 2;
      }
      const { damage, moved } = remapLocationDamage(src, fromId, toId, HP);

      if (moved.length !== fromT.locations.length) {
        problems.push(`${fromId}->${toId} [${band}]: ${fromT.locations.length} wounds in, `
          + `${moved.length} carried — the rest vanished without being reported`);
      }
      for (const id of Object.keys(damage)) {
        if (!valid.has(id)) {
          problems.push(`${fromId}->${toId} [${band}]: wound placed on "${id}", not a ${toId} `
            + `location — it would be stranded exactly like the Barghest's`);
        }
      }
      // Side and height only mean something between bilateral plans. A vesh has one
      // grasping limb and a cadence is five interchangeable units, so they have fewer
      // parts than a vertebrate has and the last limbs must land wherever there is
      // room. Demanding an anatomical correspondence there would be demanding fiction.
      const sideOf = sl => (/R$/.test(sl) ? "R" : /L$/.test(sl) ? "L" : "");
      const highOf = sl => (/^(upper|wing)/.test(sl) ? "upper" : /^lower/.test(sl) ? "lower" : "");
      const bilateral = t => t.locations.some(l => sideOf(l.slot));
      const paired = bilateral(fromT) && bilateral(toT);

      for (const mv of moved) {
        carried++;
        const sFrom = sideOf(fromT.locations.find(l => l.id === mv.from)?.slot ?? "");
        const sTo   = sideOf(toT.locations.find(l => l.id === mv.to)?.slot ?? "");
        // A sided wound may lose its side (the destination may have no pair) but must
        // never swap it: the arm you shot must not come back as the other arm.
        if (paired && sFrom && sTo && sFrom !== sTo) {
          problems.push(`${fromId}->${toId} [${band}]: ${mv.from} (${sFrom}) arrives at `
            + `${mv.to} (${sTo}) — a change of shape must not swap left and right`);
        }
        // Nor top and bottom: a wing and an arm are fore limbs and must not come back
        // as hind legs.
        const hFrom = highOf(fromT.locations.find(l => l.id === mv.from)?.slot ?? "");
        const hTo   = highOf(toT.locations.find(l => l.id === mv.to)?.slot ?? "");
        if (paired && hFrom && hTo && hFrom !== hTo) {
          problems.push(`${fromId}->${toId} [${band}]: ${mv.from} (${hFrom}) arrives at `
            + `${mv.to} (${hTo}) — a fore limb must not become a hind one`);
        }
        const S = fromT.locations.find(l => l.id === mv.from);
        const D = toT.locations.find(l => l.id === mv.to);
        if (!D) continue;
        const before = severity(src[mv.from], lmax(S.frac));
        const after  = severity(damage[mv.to], lmax(D.frac));
        if (before !== after) {
          problems.push(`${fromId}->${toId} [${band}]: ${mv.from} was ${before}, `
            + `arrives at ${mv.to} ${after} — a change of shape must not wound or heal`);
        }
      }

      // The update that carries this must not delete a wound it is also setting.
      const upd = locationDamageReplacement(src, damage);
      for (const id of Object.keys(damage)) {
        if (`-=${id}` in upd) {
          problems.push(`${fromId}->${toId}: the update both sets and deletes "${id}" `
            + `— Foundry applies the deletion and the wound is thrown away`);
        }
      }
    }

    // Slots are what make the pairing symmetric; a duplicate would make it arbitrary.
    const slots = toT.locations.map(l => l.slot);
    for (const l of toT.locations) {
      if (!l.slot) problems.push(`${toId}.${l.id}: no slot — it cannot be paired across plans`);
    }
    if (new Set(slots).size !== slots.length) {
      problems.push(`${toId}: duplicate slot(s) ${slots.filter((v, i) => slots.indexOf(v) !== i).join(",")}`);
    }
  }
}

/* 5. a flyer's landing must be somewhere it can survive ---------------------- *
 * A plan that declares `grounded` promises that losing a wing turns the creature into
 * that other plan mid-fight. The landing has to be real: a plan that exists, that has
 * no wings of its own (or the creature would be grounded and still flying), and that
 * can take every wound the flyer was carrying without inventing or losing one. The
 * wings' OWN damage is deliberately dropped by the engine — a ruined wing must not
 * arrive as a ruined foreleg — so it is excluded here too.                           */
let flyers = 0;
for (const [id, table] of Object.entries(LOCATION_TABLES)) {
  const landing = groundedPlanFor(id);
  if (!landing) continue;
  flyers++;
  const dest = LOCATION_TABLES[landing];
  if (!dest) { problems.push(`${id}: grounded plan "${landing}" does not exist`); continue; }
  if (!table.locations.some(l => l.kind === "wing")) {
    problems.push(`${id}: declares a grounded plan but has no wing to lose`);
  }
  if (dest.locations.some(l => l.kind === "wing")) {
    problems.push(`${id}: grounded plan "${landing}" still has wings — it would come `
      + `down and be airborne again`);
  }
  if (groundedPlanFor(landing)) {
    problems.push(`${id}: grounded plan "${landing}" is itself a flyer — landing must end`);
  }
  // The trigger has to be REACHABLE. This is the defect that started all of this: the
  // supporter's wings sat under the same six points of hide as the rest of it, so the
  // eight damage needed to fold one almost never arrived and its written rule fired in
  // 9% of fights. A plan whose whole behaviour turns on losing a wing must not armour
  // that wing with the creature's own hide.
  for (const l of table.locations) {
    if (l.kind === "wing" && !l.bare) {
      problems.push(`${id}.${l.id}: a flyer's wing carries the creature's hide, so the `
        + `grounded rule needs it beaten through full natural armour — mark it bare or `
        + `the rule is decoration`);
    }
    if (l.bare && naturalArmourOn(l, 9) !== 0) {
      problems.push(`${id}.${l.id}: marked bare but still takes natural armour`);
    }
  }

  // every wound it could be carrying, wings excluded, must survive the drop
  const src = {};
  for (const l of table.locations) if (l.kind !== "wing") src[l.id] = locationMaxHp(16, l.frac);
  const { damage, moved } = remapLocationDamage(src, id, landing, 16);
  const valid = new Set(dest.locations.map(l => l.id));
  if (moved.length !== Object.keys(src).length) {
    problems.push(`${id}->${landing}: ${Object.keys(src).length} wounds in, ${moved.length} carried`);
  }
  for (const k of Object.keys(damage)) {
    if (!valid.has(k)) problems.push(`${id}->${landing}: wound stranded on "${k}"`);
  }
  // and the landing must have room: two wounds collapsing onto one location loses a
  // distinction the creature had, even when the severity survives.
  const targets = new Set(moved.map(m => m.to));
  if (targets.size !== moved.length) {
    const collapsed = moved.length - targets.size;
    problems.push(`${id}->${landing}: ${collapsed} wound(s) collapse onto a location `
      + `already taken — the landing has ${dest.locations.length} places for `
      + `${moved.length} wounds`);
  }

  // and it must not be a healing: a disabled location stays disabled across the drop
  for (const mv of moved) {
    const D = dest.locations.find(l => l.id === mv.to);
    if (D && damage[mv.to] < locationMaxHp(16, D.frac)) {
      problems.push(`${id}->${landing}: ${mv.from} was disabled and arrives at ${mv.to} `
        + `merely hurt — coming down must not heal it`);
    }
  }
}

/* 6. coming down must not be a reward for the creature ----------------------- *
 * The defect this exists to catch shipped twice before anyone measured it. R-95 made a
 * lost wing change the animal; R-96 took the hide off the wing so the wing could be lost
 * at all. Together they gave the party a soft target and then deleted it the moment the
 * party hit it: six of twenty ranged faces land on a bare wing while it flies and none
 * do once it is grounded, so the creature's own "disable either wing and it is the
 * fight you can actually win" was worth minus forty-three points of win rate.
 *
 * So: measure what an average round of ordinary fire gets through, before and after.
 * A flyer that is HARDER to hurt on the ground than in the air fails, whatever the
 * fiction says about it.                                                              */
{
  /* Averaged across the whole range a round in this game can do — 1d3 to 1d10+2, before
     and after the borough halves it — because the answer genuinely changes with the size
     of the round and a single probe picks its own conclusion. A 4-point round does more
     through a bare wing than through a halved hide; a 9-point round does far less. The
     first version of this check measured only at 4 and duly reported that the fix had
     failed. Small arms prefer it airborne; anything heavier wants it down. */
  const HIDE = 7, RANGE = 12;
  const through = (planId, grounded) => {
    const t = LOCATION_TABLES[planId];
    let total = 0;
    for (let shot = 1; shot <= RANGE; shot++) {
      for (let face = 1; face <= 20; face++) {
        const loc = t.locations.find(l => face >= l.ranged[0] && face <= l.ranged[1]);
        if (!loc) continue;
        total += Math.max(0, shot - naturalArmourOn(loc, exposedHideFor(HIDE, grounded)));
      }
    }
    return total / (20 * RANGE);
  };
  for (const [id] of Object.entries(LOCATION_TABLES)) {
    const landing = groundedPlanFor(id);
    if (!landing || !LOCATION_TABLES[landing]) continue;
    const air = through(id, false), ground = through(landing, true);
    if (ground < air) {
      problems.push(`${id}: an average round gets ${air.toFixed(2)} through it flying and only `
        + `${ground.toFixed(2)} once grounded — putting it on the ground would make it HARDER `
        + `to kill, and its own tactics tell the GM the opposite`);
    }
  }
}

if (problems.length) {
  console.error("check-anatomy: FAILED");
  for (const p of [...new Set(problems)]) console.error("  " + p);
  process.exit(1);
}

console.log(`check-anatomy: OK — ${Object.keys(LOCATION_TABLES).length} body plans, `
  + `${locCount} locations, d20 complete in both modes, every location drawn, `
  + `every kind handled and destructible, ${pairs} plan changes carried ${carried} `
  + `wounds with their severity intact, `
  + `${flyers} flyer(s) with a survivable landing`);