// ── Chat titles, as rules and as a set (phase 17, D135–D137) ───────────────
//
// An operator writes rules per server — "#1 kills", "top 3 playtime" — and the
// site works out who holds each title from the CURRENT wipe's standings. The
// same answer goes to three places: BetterChat in the game (`titles.set`), the
// web leaderboard and the app's. So it is worked out here, once, as pure
// functions of the rules and the standings, and every consumer reads it.
//
// Four readings shape it (§33.4):
//
//   1. a rule counts only a stat above zero — a fresh wipe gives no titles,
//      rather than #1 kills to somebody with none
//   2. ties follow the leaderboard's own order, so a rule's top N is the first
//      N rows the web shows for that stat
//   3. a title's text is at most 24 characters, with markup characters taken
//      out, and its colour is `#rrggbb`
//   4. the rule order is precedence: `first` shows the first rule a player meets

const crypto = require('node:crypto')

/**
 * The categories a rule may rank (PLAN_REDESIGNS §5, D172): the twenty-three
 * conditions and their shipped titles, plus `playtime`, which predates them and
 * has no default title, so a playtime rule always carries its own text.
 *
 * `source` says where the standing is read from (`titles.db.js`):
 *   `sum`      a column of `rust_player_wipe_stats`, summed
 *   `diff`     one column less another — human NPCs are every NPC kill less the
 *              animals (§5.2, D209), so the public NPC column keeps its meaning
 *   `best`     a column's MAX: the longest single kill (D174)
 *   `weapons`  a named list's kills in `rust_weapon_kills` (§5.3)
 *   `gathered` a named list's amount in `rust_gather_totals` (D159)
 *
 * An admin may rename any category that has a default (D175); the ids are what
 * a rule stores, so they never change.
 */
const STATS = {
  kills: { label: 'Players killed', title: 'Reaper', source: { sum: 'kills' } },
  npckills: { label: 'NPC kills', title: 'Exterminator', source: { diff: ['npc_kills', 'animal_kills'] } },
  animalkills: { label: 'Animal kills', title: 'Beastbane', source: { sum: 'animal_kills' } },
  bowkills: { label: 'Bow kills', title: 'Fletcher', source: { weapons: 'bow' } },
  meleekills: { label: 'Melee kills', title: 'Brawler', source: { weapons: 'melee' } },
  bladekills: { label: 'Blade kills', title: 'Duelist', source: { weapons: 'blade' } },
  revolverkills: { label: 'Revolver kills', title: 'Outlaw', source: { weapons: 'revolver' } },
  headshots: { label: 'Headshots', title: 'Crownbreaker', source: { sum: 'headshots' } },
  pvpdistance: { label: 'Longest player kill', title: 'Longshot', source: { best: 'best_pvp_m' } },
  pvedistance: { label: 'Longest NPC or animal kill', title: 'Marksman', source: { best: 'best_pve_m' } },
  apckills: { label: 'APC kills', title: 'Tankbreaker', source: { sum: 'apc_kills' } },
  helikills: { label: 'Helicopter kills', title: 'Rotorbane', source: { sum: 'heli_kills' } },
  wood: { label: 'Wood gathered', title: 'Timberwright', source: { gathered: 'wood' } },
  ore: { label: 'Ore gathered', title: 'Prospector', source: { gathered: 'ore' } },
  plants: { label: 'Plants gathered', title: 'Greenhand', source: { gathered: 'plants' } },
  attire: { label: 'Clothes crafted', title: 'Seamster', source: { sum: 'crafted_attire' } },
  weapons: { label: 'Weapons crafted', title: 'Armorer', source: { sum: 'crafted_weapons' } },
  built: { label: 'Structures built', title: 'Mason', source: { sum: 'built' } },
  repaired: { label: 'Structures repaired', title: 'Tinkerer', source: { sum: 'repaired' } },
  healed: { label: 'Players healed', title: 'Mender', source: { sum: 'healed' } },
  rockets: { label: 'Rockets fired', title: 'Artillerist', source: { sum: 'rockets' } },
  explosives: { label: 'Explosives thrown', title: 'Demolitionist', source: { sum: 'explosives' } },
  missions: { label: 'Missions completed', title: 'Wayfarer', source: { sum: 'missions' } },
  playtime: { label: 'Playtime', title: null, source: { sum: 'playtime_sec' } },
}

/** The categories an admin can rename: every one with a shipped title (D175). */
const CATEGORY_IDS = Object.keys(STATS).filter((id) => STATS[id].title)

const MODES = ['first', 'all', 'upto']

const MAX_RULES = 10
const MAX_TOP_N = 10
const TEXT_MAX = 24
const MAX_UPTO = 5

/**
 * An operator's title text, made safe to put in a chat line: the characters
 * BetterChat's markup and its placeholders are built from are taken out, then
 * the whitespace is collapsed. `{` and `}` go too, beyond reading 3's four: a
 * title is substituted into `{Title}` before `{Message}` is, so a title reading
 * `{Message}` would print the player's words twice.
 */
function cleanText(raw) {
  return String(raw === undefined || raw === null ? '' : raw)
    .replace(/[[\]<>{}]/g, '')
    .replace(/\s+/g, ' ')
    .trim()
}

/** A mode word, or `first` — the fewest — for one this build does not know. */
function normaliseMode(mode) {
  return MODES.includes(mode) ? mode : 'first'
}

/**
 * A server's title settings as the admin form sends them, checked whole.
 *
 * Resolves `{ ok: true, value: { mode, max, rules } }` with every rule cleaned,
 * or `{ ok: false, errors }`, one sentence per problem. A text that is empty
 * AFTER cleaning is refused rather than saved blank, so a title made entirely of
 * brackets is a sentence on the form and not an empty chip in the game.
 */
function validateSettings(body) {
  const errors = []
  const input = body || {}
  const mode = input.mode === undefined ? 'first' : input.mode

  if (!MODES.includes(mode)) errors.push(`mode must be one of ${MODES.join(', ')}`)

  const max = input.max === undefined || input.max === null || input.max === '' ? 2 : Number(input.max)
  if (!Number.isInteger(max) || max < 1 || max > MAX_UPTO) errors.push(`max must be a whole number from 1 to ${MAX_UPTO}`)

  const rules = Array.isArray(input.rules) ? input.rules : null
  if (!rules) errors.push('rules must be a list')
  else if (rules.length > MAX_RULES) errors.push(`a server has at most ${MAX_RULES} title rules`)

  const clean = []

  for (const [i, rule] of (rules || []).entries()) {
    const n = i + 1
    const r = rule || {}
    if (!STATS[r.stat]) errors.push(`rule ${n}: stat must be one of ${Object.keys(STATS).join(', ')}`)

    const topN = Number(r.topN)
    if (!Number.isInteger(topN) || topN < 1 || topN > MAX_TOP_N) errors.push(`rule ${n}: top must be from 1 to ${MAX_TOP_N}`)

    // Empty means "the category's title" (D175) — for a category that has one.
    // A text that was typed and cleaned down to nothing is still refused: a
    // title made entirely of brackets is a mistake, not a request for the default.
    const typed = String(r.text === undefined || r.text === null ? '' : r.text).trim()
    const text = cleanText(r.text)
    const stat = STATS[r.stat]
    if (!text && (typed || !stat || !stat.title)) errors.push(`rule ${n}: the title needs some text`)
    else if (text.length > TEXT_MAX) errors.push(`rule ${n}: a title is at most ${TEXT_MAX} characters`)

    const color = String(r.color || '').trim().toLowerCase()
    if (!/^#[0-9a-f]{6}$/.test(color)) errors.push(`rule ${n}: colour must look like #ffaa55`)

    clean.push({ stat: r.stat, topN, text, color })
  }

  return errors.length ? { ok: false, errors } : { ok: true, value: { mode, max, rules: clean } }
}

/**
 * The title a category shows (D175): the admin's, if they wrote one, else the
 * shipped default. `overrides` is stat → the admin's text.
 */
function categoryTitle(stat, overrides = {}) {
  const own = overrides[stat]
  if (own) return own
  return STATS[stat] ? STATS[stat].title : null
}

/**
 * Checks an admin's title for a category. Resolves `{ ok, text }` or
 * `{ ok: false, error }`. An empty text is not an error here — it is the Reset,
 * and the caller deletes the row.
 */
function validateCategory(stat, raw) {
  if (!CATEGORY_IDS.includes(stat)) return { ok: false, error: `no category ${stat}` }
  const typed = String(raw === undefined || raw === null ? '' : raw).trim()
  const text = cleanText(raw)
  if (typed && !text) return { ok: false, error: 'the title needs some text' }
  if (text.length > TEXT_MAX) return { ok: false, error: `a title is at most ${TEXT_MAX} characters` }
  return { ok: true, text }
}

/**
 * Rules with their text settled, first that is set winning (§4.6): the rule's
 * own, the admin's for the category, the module's default. A rule that ends up
 * with none — only possible for a rule saved before its category lost a title —
 * is dropped rather than shown as an empty chip.
 */
function resolveRules(rules, overrides = {}) {
  return (rules || [])
    .map((r) => ({ ...r, text: r.text || categoryTitle(r.stat, overrides) || '' }))
    .filter((r) => r.text)
}

/**
 * Who holds which title.
 *
 * @param {Array} rules              in precedence order: `{ stat, topN, text, color }`,
 *                                   with the text already settled (`resolveRules`)
 * @param {object} standings         stat → `{ steamId, value }` rows for the current
 *                                   wipe, in the leaderboard's order, at least `topN` long
 * @param {object} options
 * @param {string} options.mode      `first` · `all` · `upto`
 * @param {number} options.max       how many `upto` shows
 * @returns {Map<string, Array<{text, color}>>}  Steam id → titles, in rule order
 */
function evaluate(rules, standings, { mode = 'first', max = 2 } = {}) {
  const held = new Map()

  for (const rule of rules || []) {
    if (!STATS[rule.stat]) continue

    const rows = (standings[rule.stat] || []).filter((row) => Number(row.value) > 0).slice(0, rule.topN)

    for (const row of rows) {
      if (!held.has(row.steamId)) held.set(row.steamId, [])
      held.get(row.steamId).push({ text: rule.text, color: rule.color })
    }
  }

  const keep = { first: 1, upto: max, all: Infinity }[normaliseMode(mode)]

  for (const [steamId, list] of held) held.set(steamId, list.slice(0, keep))

  return held
}

/** One player's titles as BetterChat markup: `[#hex]text[/#]`, space-separated. */
function markup(list) {
  return list.map((t) => `[#${t.color.replace(/^#/, '')}]${t.text}[/#]`).join(' ')
}

/** The wire set, sorted so an unchanged set digests the same on every tick. */
function wireSet(held) {
  return [...held.entries()]
    .map(([steamId, list]) => ({ steamId, text: markup(list) }))
    .sort((a, b) => a.steamId.localeCompare(b.steamId))
}

function digest(set) {
  return crypto
    .createHash('sha256')
    .update(set.map((t) => `${t.steamId} ${t.text}`).join('\n'))
    .digest('hex')
}

module.exports = {
  STATS,
  CATEGORY_IDS,
  categoryTitle,
  validateCategory,
  resolveRules,
  MODES,
  MAX_RULES,
  MAX_TOP_N,
  MAX_UPTO,
  TEXT_MAX,
  cleanText,
  normaliseMode,
  validateSettings,
  evaluate,
  markup,
  wireSet,
  digest,
}