// ── 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 stats a rule may rank, and the leaderboard sort and column each means. */
const STATS = {
  kills: { sort: 'kills', value: (row) => row.kills, label: 'kills' },
  npckills: { sort: 'npcKills', value: (row) => row.npcKills, label: 'NPC kills' },
  playtime: { sort: 'playtime', value: (row) => row.playtimeSec, label: 'playtime' },
}

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}`)

    const text = cleanText(r.text)
    if (!text) 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 } }
}

/**
 * Who holds which title.
 *
 * @param {Array} rules              in precedence order: `{ stat, topN, text, color }`
 * @param {object} standings         stat → leaderboard 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 || []) {
    const stat = STATS[rule.stat]
    if (!stat) continue

    const rows = (standings[rule.stat] || []).filter((row) => Number(stat.value(row)) > 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,
  MODES,
  MAX_RULES,
  MAX_TOP_N,
  MAX_UPTO,
  TEXT_MAX,
  cleanText,
  normaliseMode,
  validateSettings,
  evaluate,
  markup,
  wireSet,
  digest,
}