/**
 * The shape of a creature, and the only place that decides whether one is valid.
 *
 * Every actor in this game — pregen, roster agent, NPC, monster — reaches buildActor as
 * a plain object literal hand-written in content.mjs, roster.mjs or a scenario file.
 * Nothing checked those objects. buildActor throws on an unknown skill, weapon, armour,
 * gear or talent key, which catches the loud half; it is silent about everything else.
 *
 * The silent half is the reason this exists:
 *
 *   SPECIES. Every packed actor once shipped as species "hominid" — a Ringworld name
 *   this game does not define — and the sheet falls back to baseline on an unknown key,
 *   so the entire cast was drawn and hit-located as something the rules do not contain.
 *   Nothing failed. See the note in build-packs.mjs where it is now written explicitly.
 *
 *   MISSPELT FIELDS. buildActor reads spec.armour. A spec written with `armours:` is
 *   not an error, it is an actor that silently equips nothing, and there is no way to
 *   tell that apart from a creature that was meant to be unarmoured.
 *
 *   CHOSENSTYLE. styleFor() is `chosen => chosen`, a passthrough, so any string at all
 *   becomes a marksmanship style and the sheet renders whatever it is handed.
 *
 *   SPECIES TALENTS. Unblinking is vesh; Distributed and Quorum are cadence. Nothing
 *   stopped a baseline human being given one.
 *
 *   Out of Step is NOT one of them, though SPECIES.vesh lists it. Two different ideas
 *   share that field: SPECIES[x].talents is what a generated member of the species is
 *   GRANTED, while TALENTS[].species is what only that species may HAVE. Out of Step is
 *   an anomalous talent — five postings and a roster agent offer it to humans — that a
 *   Vesh happens to get for free. Locking it to vesh would take it off all six of them.
 *
 * Everything allowed here is DERIVED from the catalogues rather than retyped, for the
 * reason check-kits gives: a hand-written list of valid values drifts, and the drift is
 * invisible until something rolls 5% with a weapon it should be trained in. Skills come
 * from SKILL_CATALOGUE, kit from the item catalogues, species from SPECIES, stats from
 * CHARACTERISTIC_DICE, and the marksmanship styles from the language file — which
 * check-lang already guarantees is complete.
 *
 * Used by tools/check-creatures.mjs. Kept free of Foundry globals and of node APIs so
 * it stays importable from either side.
 */

import { SKILL_CATALOGUE, TALENTS, GEAR, WEAPONS, ARMOURS, DEVICES } from "./content.mjs";
import { SPECIES, CHARACTERISTIC_DICE } from "../postings.mjs";
import { LOCATION_TABLES } from "../anatomy.mjs";
import EN from "../lang/en.json" with { type: "json" };

/* ---------------------------------------------------------------- vocabularies */

/* Always "family:spec", with an empty spec for unspecialised skills, because that is the
   key buildActor looks up: SKILL_LOOKUP.get(`${s.fam}:${s.spec}`). check-kits builds the
   same vocabulary the other way — bare family when there is no spec — because it is
   matching posting skill lists, which are written that way. Two conventions genuinely
   coexist in this repo; a creature spec uses this one. */
export const SKILLS = new Set(SKILL_CATALOGUE.map(r => `${r[0]}:${r[1] ?? ""}`));
export const WEAPON_KEYS = new Set(WEAPONS.map(w => w.key));
export const ARMOUR_KEYS = new Set(ARMOURS.map(a => a.key));
export const GEAR_KEYS = new Set(GEAR.map(g => g.key));
export const DEVICE_KEYS = new Set((DEVICES ?? []).map(d => d.key));
export const TALENT_KEYS = new Set(TALENTS.map(t => t.key));
export const SPECIES_KEYS = new Set(Object.keys(SPECIES));

/* Which BODY a creature is hit-located as. Separate from species on purpose: species
   is a playable people with characteristic dice and talents, and a bear is not one.
   Without this a four-legged thing could only be authored as a baseline humanoid, so
   every hound and horse in the bestiary had two arms and a chest. */
export const BODY_PLAN_KEYS = new Set(Object.keys(LOCATION_TABLES));
export const STATS = Object.keys(CHARACTERISTIC_DICE);

/** Which species a species-locked talent belongs to; absent means anyone may take it. */
export const TALENT_SPECIES = new Map(
  TALENTS.filter(t => t.species).map(t => [t.key, t.species])
);

/* The two marksmanship styles, read out of the language file rather than written down
   again here. RINGBRP.Style.Reflex and .Deliberate are the only two that exist, and
   check-lang fails the build if either goes missing, so this cannot quietly empty. */
export const STYLES = new Set(
  Object.keys(EN)
    .filter(k => /^RINGBRP\.Style\.[A-Z]/.test(k))
    .map(k => k.split(".").pop().toLowerCase())
);

/**
 * Fields buildActor reads. Anything else on a spec is inert — it was either a typo for
 * one of these or a note to the author, and both are worth saying out loud.
 * Kept in sync with build-packs.mjs by check-creatures, which compares the two.
 */
export const KNOWN_FIELDS = new Set([
  "key", "name", "role", "ch", "skills", "species", "bodyPlan", "chosenStyle", "naturalArmour",
  "weapons", "extraWeapons", "armour", "gear", "extraGear", "devices", "talents",
  "tactics", "note", "bio", "portrait", "rank", "trade", "age", "floors", "spotlight",
  "environments", "complication", "formula", "results"
]);

/* ---------------------------------------------------------------- suggestions */

function editDistance(a, b) {
  const m = a.length, n = b.length;
  let prev = Array.from({ length: n + 1 }, (_, j) => j);
  for (let i = 1; i <= m; i++) {
    const cur = [i];
    for (let j = 1; j <= n; j++) {
      cur[j] = Math.min(
        prev[j] + 1,
        cur[j - 1] + 1,
        prev[j - 1] + (a[i - 1] === b[j - 1] ? 0 : 1)
      );
    }
    prev = cur;
  }
  return prev[n];
}

/**
 * The closest candidate, if one is close enough to be worth naming. A wrong suggestion
 * is worse than none — it sends the reader to check something that was never the
 * problem — so the threshold is deliberately tight.
 */
export function nearest(value, candidates) {
  const v = String(value).toLowerCase();
  let best = null, bestD = Infinity;
  for (const c of candidates) {
    const d = editDistance(v, String(c).toLowerCase());
    if (d < bestD) { bestD = d; best = c; }
  }
  const limit = Math.max(2, Math.floor(v.length * 0.34));
  return bestD <= limit ? best : null;
}

/** What a field will accept, for error text and for the forge CLI later. */
export function describe(field) {
  switch (field) {
    case "species":     return [...SPECIES_KEYS];
    case "bodyPlan":    return [...BODY_PLAN_KEYS];
    case "chosenStyle": return [...STYLES];
    case "skills":      return [...SKILLS];
    case "weapons": case "extraWeapons": return [...WEAPON_KEYS];
    case "armour":      return [...ARMOUR_KEYS];
    case "gear": case "extraGear":       return [...GEAR_KEYS];
    case "devices":     return [...DEVICE_KEYS];
    case "talents":     return [...TALENT_KEYS];
    case "ch":          return STATS;
    default:            return null;
  }
}

/* ---------------------------------------------------------------- validation */

const problem = (path, msg, suggestion) => ({
  path, problem: msg,
  nearest: suggestion ?? null,
  toString() { return `${path}: ${msg}${suggestion ? ` — did you mean "${suggestion}"?` : ""}`; }
});

/** A key list field: every entry must resolve against `set`. */
function checkKeys(out, spec, field, set) {
  const raw = spec[field];
  if (raw === undefined) return;
  if (!Array.isArray(raw)) {
    out.push(problem(`${spec.key}.${field}`, `must be an array, got ${typeof raw}`));
    return;
  }
  raw.forEach((entry, i) => {
    // gear may be written as [key, quantity]
    const key = Array.isArray(entry) ? entry[0] : entry;
    if (typeof key !== "string") {
      out.push(problem(`${spec.key}.${field}[${i}]`, `is ${typeof key}, expected a key`));
      return;
    }
    if (!set.has(key)) {
      out.push(problem(`${spec.key}.${field}[${i}]`, `no such entry "${key}"`, nearest(key, set)));
    }
  });
}

/**
 * Every problem with one spec. Returns them ALL rather than throwing on the first,
 * because buildActor already throws on the first and that is precisely what makes
 * fixing a batch of creatures a one-at-a-time slog.
 */
export function validate(spec) {
  const out = [];
  const where = spec?.key ?? "(anonymous)";

  if (!spec || typeof spec !== "object") {
    return [problem("(spec)", "is not an object")];
  }
  if (typeof spec.key !== "string" || !spec.key.trim()) {
    out.push(problem("(spec)", "has no key"));
  }
  if (typeof spec.name !== "string" || !spec.name.trim()) {
    out.push(problem(`${where}.name`, "has no name"));
  }

  /* --- characteristics --- */
  if (!spec.ch || typeof spec.ch !== "object") {
    out.push(problem(`${where}.ch`, "has no characteristics"));
  } else {
    for (const stat of STATS) {
      const v = spec.ch[stat];
      if (v === undefined) { out.push(problem(`${where}.ch.${stat}`, "is missing")); continue; }
      if (!Number.isInteger(v)) {
        out.push(problem(`${where}.ch.${stat}`, `is ${JSON.stringify(v)}, expected a whole number`));
      } else if (v < 1 || v > 60) {
        // 60 is far above anything the tiers produce; this is a typo net, not a balance rule.
        out.push(problem(`${where}.ch.${stat}`, `is ${v}, outside 1–60`));
      }
    }
    for (const k of Object.keys(spec.ch)) {
      if (!STATS.includes(k)) {
        out.push(problem(`${where}.ch.${k}`, "is not a characteristic", nearest(k, STATS)));
      }
    }
  }

  /* --- species, and the talents locked to it --- */
  if (spec.species !== undefined && !SPECIES_KEYS.has(spec.species)) {
    out.push(problem(`${where}.species`, `no such species "${spec.species}"`,
      nearest(spec.species, SPECIES_KEYS)));
  }
  if (spec.bodyPlan !== undefined && !BODY_PLAN_KEYS.has(spec.bodyPlan)) {
    out.push(problem(`${where}.bodyPlan`, `no such body plan "${spec.bodyPlan}"`,
      nearest(spec.bodyPlan, BODY_PLAN_KEYS)));
  }
  const species = spec.species ?? "baseline";
  for (const t of spec.talents ?? []) {
    const locked = TALENT_SPECIES.get(t);
    if (locked && locked !== species) {
      out.push(problem(`${where}.talents`,
        `talent "${t}" is ${locked}-only, but this is ${species}`));
    }
  }

  /* --- marksmanship style --- */
  if (spec.chosenStyle !== undefined && !STYLES.has(spec.chosenStyle)) {
    out.push(problem(`${where}.chosenStyle`, `no such style "${spec.chosenStyle}"`,
      nearest(spec.chosenStyle, STYLES)));
  }

  /* --- skills --- */
  if (spec.skills !== undefined) {
    if (!Array.isArray(spec.skills)) {
      out.push(problem(`${where}.skills`, `must be an array, got ${typeof spec.skills}`));
    } else {
      const seen = new Set();
      spec.skills.forEach((s, i) => {
        if (!s || typeof s !== "object") {
          out.push(problem(`${where}.skills[${i}]`, "is not a skill entry"));
          return;
        }
        const id = `${s.fam}:${s.spec ?? ""}`;
        // The lookup key always carries the colon; a reader should not have to. An
        // unspecialised skill is "stealth", not "stealth:".
        const shown = id.endsWith(":") ? id.slice(0, -1) : id;
        if (!SKILLS.has(id)) {
          const near = nearest(id, SKILLS);
          out.push(problem(`${where}.skills[${i}]`, `no such skill "${shown}"`,
            near ? (near.endsWith(":") ? near.slice(0, -1) : near) : null));
        }
        if (seen.has(id)) {
          // buildActor pushes both, and the sheet shows the skill twice at two values.
          out.push(problem(`${where}.skills[${i}]`, `"${shown}" is listed twice`));
        }
        seen.add(id);
        if (!Number.isInteger(s.val)) {
          out.push(problem(`${where}.skills[${i}]`, `"${shown}" value is ${JSON.stringify(s.val)}, expected a whole number`));
        } else if (s.val < 1 || s.val > 100) {
          out.push(problem(`${where}.skills[${i}]`, `"${shown}" is ${s.val}%, outside 1–100`));
        }
      });
    }
  }

  /* --- kit --- */
  checkKeys(out, spec, "weapons", WEAPON_KEYS);
  checkKeys(out, spec, "extraWeapons", WEAPON_KEYS);
  checkKeys(out, spec, "armour", ARMOUR_KEYS);
  checkKeys(out, spec, "gear", GEAR_KEYS);
  checkKeys(out, spec, "extraGear", GEAR_KEYS);
  checkKeys(out, spec, "devices", DEVICE_KEYS);
  checkKeys(out, spec, "talents", TALENT_KEYS);

  /* --- natural armour --- */
  if (spec.naturalArmour !== undefined) {
    const n = Number(spec.naturalArmour);
    if (!Number.isFinite(n) || n < 0) {
      out.push(problem(`${where}.naturalArmour`, `is ${JSON.stringify(spec.naturalArmour)}, expected 0 or more`));
    }
  }

  /* --- fields nothing reads --- */
  for (const k of Object.keys(spec)) {
    if (!KNOWN_FIELDS.has(k)) {
      out.push(problem(`${where}.${k}`, "is not a field buildActor reads — it does nothing",
        nearest(k, KNOWN_FIELDS)));
    }
  }

  return out;
}