// ── Chat titles, read against the live standings (phase 17) ────────────────
//
// `titles.js` decides; this file fetches what it decides from. One answer per
// server serves three readers — the push to the game, the web leaderboard and
// the app's — so it is remembered briefly: the leaderboard is polled by every
// open page, and each rule is a leaderboard query of its own.

const serversDb = require('../servers/servers.db')
const db = require('./titles.db')
const lists = require('./lists')
const titles = require('./titles')

/** How long one server's answer is reused. The same as the push loop's tick. */
const MEMO_MS = 30 * 1000

const memo = new Map()

/** A server's settings as the admin form reads them. */
async function settingsFor(serverId) {
  const [mode, rules] = await Promise.all([db.getMode(serverId), db.listRules(serverId)])
  return shapeSettings(mode, rules)
}

function shapeSettings(mode, rules) {
  return {
    mode: titles.normaliseMode(mode && mode.mode),
    max: mode && Number(mode.max) ? Number(mode.max) : 2,
    rules: rules.map((r) => ({ stat: r.stat, topN: Number(r.topN), text: r.text, color: r.color })),
  }
}

/** Every server's settings, keyed by id, for the admin server list. */
async function settingsByServer() {
  const [modes, rules] = await Promise.all([db.listModes(), db.listAllRules()])
  const out = new Map(modes.map((m) => [m.serverId, shapeSettings(m, [])]))

  for (const r of rules) {
    const s = out.get(r.serverId)
    if (s) s.rules.push({ stat: r.stat, topN: Number(r.topN), text: r.text, color: r.color })
  }

  return out
}

async function saveSettings(serverId, value) {
  await db.saveSettings(serverId, value)
  forget(serverId)
}

/** Forgets one server's answer, or every server's when a category was renamed. */
function forget(serverId = null) {
  for (const key of memo.keys()) if (serverId === null || key.startsWith(`${serverId} `)) memo.delete(key)
}

/**
 * The categories as the admin screen shows them (D175): each one's label, the
 * shipped default, the admin's own title if any, and what rules show now.
 */
async function categories() {
  const own = new Map((await db.listCategories()).map((r) => [r.stat, r]))
  return titles.CATEGORY_IDS.map((stat) => {
    const row = own.get(stat)
    const def = titles.STATS[stat]
    return {
      stat,
      label: def.label,
      default: def.title,
      text: row ? row.text : null,
      current: row ? row.text : def.title,
      updatedAt: row ? row.updatedAt : null,
    }
  })
}

/**
 * Sets or resets one category's title. An empty text is the Reset. Every
 * server's answer is forgotten, because every server's rules may use it, and
 * the next push carries the new name (§4.6: "from the next push").
 */
async function setCategory(stat, text, userId = null) {
  if (text) await db.setCategory(stat, text, userId)
  else await db.clearCategory(stat)
  forget()
}

/**
 * Who holds which title on one server right now: a Map of Steam id to
 * `[{ text, color }]`, after the server's mode. Empty with no rules, and empty
 * with no current wipe — a title ranks the current wipe (D135), and a server that
 * has never said which wipe it is on has none to rank.
 */
async function heldFor(serverId, { wipeId, now = Date.now() } = {}) {
  if (!wipeId) return new Map()

  const key = `${serverId} ${wipeId}`
  const hit = memo.get(key)
  if (hit && now - hit.at < MEMO_MS) return hit.held

  const [settings, overrides] = await Promise.all([settingsFor(serverId), db.categoryTitles()])
  const rules = titles.resolveRules(settings.rules, overrides)
  const standings = {}

  // One query per STAT, at the deepest top N any rule on it asks for, rather
  // than one per rule: two rules on kills read the same rows.
  const depth = new Map()
  for (const r of rules) if (titles.STATS[r.stat]) depth.set(r.stat, Math.max(depth.get(r.stat) || 0, r.topN))

  await Promise.all(
    [...depth.entries()].map(async ([stat, limit]) => {
      const rows = await db.standings({ serverId, wipeId, source: titles.STATS[stat].source, lists, limit })
      // SUM() and MAX() come back as strings; the rules compare numbers.
      standings[stat] = rows.map((r) => ({ steamId: r.steamId, value: Number(r.value) || 0 }))
    }),
  )

  const held = titles.evaluate(rules, standings, settings)
  memo.set(key, { at: now, held })
  return held
}

/** The same, for a server by id, reading its current wipe from its last report. */
async function currentFor(serverId) {
  const state = await serversDb.getState(serverId)
  return heldFor(serverId, { wipeId: state && state.wipeId ? state.wipeId : null })
}

module.exports = {
  MEMO_MS,
  settingsFor,
  settingsByServer,
  saveSettings,
  heldFor,
  currentFor,
  forget,
  categories,
  setCategory,
}