// ── 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 eventsDb = require('../events/events.db')
const serversDb = require('../servers/servers.db')
const db = require('./titles.db')
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)
}

function forget(serverId) {
  for (const key of memo.keys()) if (key.startsWith(`${serverId} `)) memo.delete(key)
}

/**
 * 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 = await settingsFor(serverId)
  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 settings.rules) depth.set(r.stat, Math.max(depth.get(r.stat) || 0, r.topN))

  await Promise.all(
    [...depth.entries()].map(async ([stat, limit]) => {
      standings[stat] = await eventsDb.leaderboard({ serverId, wipeId, sort: titles.STATS[stat].sort, limit })
    }),
  )

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

/** The leaderboard's rows carry numbers as strings from SUM(); the rules compare numbers. */
function normalise(standings) {
  const out = {}
  for (const [stat, rows] of Object.entries(standings)) {
    out[stat] = rows.map((r) => ({
      steamId: r.steamId,
      kills: Number(r.kills) || 0,
      npcKills: Number(r.npcKills) || 0,
      playtimeSec: Number(r.playtimeSec) || 0,
    }))
  }
  return out
}

/** 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 }