// ── 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 worldEvents = require('../../worldEvents')
const dynamicPvp = require('../../dynamicPvp')
const dangerousTreasures = require('../../dangerousTreasures')
const guardedCrate = require('../../guardedCrate')
const db = require('./events.db')
const mapDb = require('../map/map.db')
const serversDb = require('../servers/servers.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, staff = false, presence = false, kind = null, wipeId = null, limit }) {
  const kinds = catalogue.kindsFor({ admin, presence, 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),
  })

  const shaped = rows.map(shape)
  if (!shaped.some((r) => r.kind === 'world.event' || dynamicPvp.KINDS.includes(r.kind) || dangerousTreasures.isKind(r.kind) || guardedCrate.isKind(r.kind))) return shaped

  // Protocol 14 (§14.3.1): each world event is read for THIS viewer — its type
  // allowed, its names to the presence audience, its Steam ids to staff, its
  // credit by the server's rule — and given a grid from the map's geometry.
  // Dynamic PVP's zone lines (§14.3.3) are read the same way for their grid and
  // position, and Dangerous Treasures' (§14.3.4) for their grid, the winner's
  // name and the Steam ids, and Guarded Crate's (§14.3.5) alike. Both reads only
  // when the page holds one of them at all.
  const view = await worldView(serverId, { staff: staff || admin, presence })
  return shaped
    .map((row) => {
      if (row.kind === 'world.event') return worldRow(row, view)
      if (dynamicPvp.KINDS.includes(row.kind)) return pvpRow(row, view)
      if (dangerousTreasures.isKind(row.kind)) return dtRow(row, view)
      if (guardedCrate.isKind(row.kind)) return gcRow(row, view)
      return row
    })
    .filter(Boolean)
}

/** What reading a world event for one viewer needs: the server's credit rule and map geometry. */
async function worldView(serverId, { staff, presence }) {
  const [server, meta] = await Promise.all([
    serversDb.getServer(serverId).catch(() => null),
    mapDb.getMeta(serverId).catch(() => null),
  ])
  return {
    staff,
    presence,
    rule: worldEvents.creditRuleOf(server && server.creditRule),
    geometry: meta
      ? { worldSize: Number(meta.worldSize), gridCells: Number(meta.gridCells), gridCellSize: Number(meta.gridCellSize) }
      : null,
  }
}

/** One Dynamic PVP row for a viewer (§14.3.3): its grid for everyone, its position for staff. */
function pvpRow(row, view) {
  return { ...row, frame: dynamicPvp.shapeFor(row.frame, view) }
}

/** One Dangerous Treasures row for a viewer (§14.3.4). The row's own Steam id, the winner's, is staff's. */
function dtRow(row, view) {
  return { ...row, steamId: view.staff ? row.steamId : null, frame: dangerousTreasures.shapeFor(row.frame, view) }
}

/** One Guarded Crate row for a viewer (§14.3.5). The row's own Steam id, the clearer's, is staff's. */
function gcRow(row, view) {
  return { ...row, steamId: view.staff ? row.steamId : null, frame: guardedCrate.shapeFor(row.frame, view) }
}

/** One world-event row for a viewer, or null when they may not see it. The row's own Steam id is staff's too. */
function worldRow(row, view) {
  const frame = worldEvents.shapeFor(row.frame, view)
  if (!frame) return null
  return { ...row, steamId: view.staff ? row.steamId : null, frame }
}

/**
 * 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, presence = false, economics = null }) {
  // The richest column (§11.2.2): only for one wipe — a balance is a value, and
  // there is no all-time one — and only where the server reports Economics.
  const withBalance = Boolean(economics && wipeId)
  const rows = await db.leaderboard({
    serverId,
    wipeId,
    sort: sort === 'balance' && !withBalance ? 'kills' : sort,
    limit: boundedLimit(limit, 25),
    balanceFloor: withBalance && sort === 'balance' ? economics.startingBalance : null,
  })

  return rows.map((r) => ({
    ...(withBalance ? { balance: r.balance === null || r.balance === undefined ? null : Number(r.balance) } : {}),
    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,
    // Protocol 14 (D356): Safecracker's and Scavenger's counts.
    cratesHacked: Number(r.cratesHacked) || 0,
    dropsLooted: Number(r.dropsLooted) || 0,
    // Protocol 14 (D375): Treasure Hunter's count.
    treasuresWon: Number(r.treasuresWon) || 0,
    // Protocol 14 (D375): Warden's count.
    guardedWon: Number(r.guardedWon) || 0,
    // Withheld below the presence audience. A tally refreshes it every minute a
    // player is on, so a `lastSeen` of forty seconds ago is the Online tab by
    // another name. The ORDER still uses it as a tie-break — that says who was
    // on more recently, never whether anybody is on now.
    ...(presence ? { 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 }