// ── The read path's logic ─────────────────────────────────────────────────
//
// Everything that decides WHAT a caller gets, separated from the SQL that
// fetches it, so this file can be tested with no database and `events.db.js` has
// no branching to test.
//
// The decision that matters here is not a business rule, it is a boundary: what
// a signed-out visitor may see. Protocol 2 carries IP addresses and player
// reports, and the only thing standing between them and a public page is
// `catalogue.js`'s allowlist and the fact that **every read on this file takes an
// explicit viewer**. There is no default, because a default is what a caller
// gets when they forget — and the safe value is never the one that is easier to
// type.

const catalogue = require('../../catalogue')
const db = require('./events.db')

/** Hard ceiling on a page, whatever a caller asks for. */
const MAX_LIMIT = 200

function boundedLimit(requested, fallback = 50) {
  const n = Number(requested)
  if (!Number.isFinite(n) || n <= 0) return fallback
  return Math.min(Math.trunc(n), MAX_LIMIT)
}

/**
 * Parses a `kind` query parameter into a list.
 *
 * Accepts `?kind=player.death` and `?kind=player.death,player.chat`, and answers
 * `null` for anything empty — which means "whatever this viewer may see" rather
 * than "nothing", and is then narrowed by the catalogue.
 */
function parseKinds(raw) {
  if (!raw) return null

  const list = String(raw)
    .split(',')
    .map((k) => k.trim())
    .filter(Boolean)

  return list.length > 0 ? list : null
}

/**
 * Recent events for one server, already narrowed to what this viewer may see.
 *
 * **`admin` is a parameter, not a default.** A route that forgets it gets the
 * public list, which is the direction it is safe to be wrong in. And a kind the
 * caller asked for that they may not see is dropped silently rather than
 * refused: naming it in an error would confirm the kind exists, which is a small
 * thing to leak and a free one to avoid.
 */
async function recent({ serverId, admin = false, kind = null, wipeId = null, limit }) {
  const kinds = catalogue.kindsFor({ admin, requested: parseKinds(kind) })

  // Every requested kind was refused. Answering with an empty list is right —
  // the events they asked for are, as far as they are concerned, not there.
  if (kinds.length === 0) return []

  const rows = await db.recentEvents({
    serverId,
    kinds,
    wipeId,
    limit: boundedLimit(limit),
  })

  return rows.map(shape)
}

/**
 * One stored row as an API object.
 *
 * `raw` comes back from the database as text and is parsed here rather than in
 * the db layer, because a row whose JSON will not parse is a reporting problem
 * and not a query problem: it answers with the envelope it does know and an
 * empty body, instead of failing a whole page over one bad row.
 */
function shape(row) {
  let frame = {}

  try {
    frame = typeof row.raw === 'string' ? JSON.parse(row.raw) : row.raw || {}
  } catch {
    frame = {}
  }

  return {
    id: Number(row.id),
    kind: row.kind,
    t: Number(row.t),
    wipeId: row.wipeId || null,
    steamId: row.steamId || null,
    frame,
  }
}

/**
 * The leaderboard for a server, per wipe or all-time.
 *
 * All-time is the same rows summed differently rather than a second set of
 * counters, so the two can never disagree — which is the whole reason R12's
 * "per-wipe detail plus all-time rollups" is one table and not two.
 */
async function leaderboard({ serverId, wipeId = null, sort = 'kills', limit }) {
  const rows = await db.leaderboard({
    serverId,
    wipeId,
    sort,
    limit: boundedLimit(limit, 25),
  })

  return rows.map((r) => ({
    steamId: r.steamId,
    name: r.name || null,
    kills: Number(r.kills) || 0,
    deaths: Number(r.deaths) || 0,
    npcKills: Number(r.npcKills) || 0,
    structures: Number(r.structures) || 0,
    playtimeSec: Number(r.playtimeSec) || 0,
    lastSeen: r.lastSeen || null,
  }))
}

/**
 * Every wipe this server has had, newest first.
 *
 * The list is what makes the per-wipe view navigable, and it is also the proof
 * R12 asks for: a wipe that ended is still here, with its stats still attached.
 */
async function wipes(serverId) {
  const rows = await db.listWipes(serverId)

  return rows.map((r) => ({
    wipeId: r.wipeId,
    saveCreatedAt: r.saveCreatedAt || null,
    firstSeen: r.firstSeen,
    lastSeen: r.lastSeen,
  }))
}

/**
 * Who is on the server right now.
 *
 * Read from the presence board rather than counted from connect and disconnect
 * events: the board is re-sent on every bridge connect and every minute, so it
 * is right even after this module has missed something. Counting transitions
 * instead would drift, and drift in exactly the direction people notice —
 * players who never left.
 */
async function online(serverId) {
  const rows = await db.presenceFor(serverId)

  return rows.map((r) => ({
    steamId: r.steamId,
    name: r.name || null,
    sleeping: Boolean(r.sleeping),
    connectedAt: r.connectedAt || null,
  }))
}

module.exports = { recent, leaderboard, wipes, online, parseKinds, boundedLimit, MAX_LIMIT }