// ── First-party clans: the board, the events, and who may see a roster ────
//
// Rust's OWN clan system, which this module turns into core's Teams (R5,
// PLAN.md §24). Three jobs, one file, because all three have to agree on what a
// clan's identity is:
//
//   applyBoard    a `clans` snapshot → the store, plus what changed
//   applyEvent    a `clan.*` event → core (publish) and the Team feed
//   canSeeRoster  D48's audience, for core's `projectRoster` and our own page
//
// ── The identity (D52) ────────────────────────────────────────────────────
//
// `<serverId>:<clanId>:<createdMs>`. The game's clan id alone is not one: its
// database file carries a hard-coded version, so a game update that bumps it
// starts a fresh file and ids restart at 1. Keyed on the id, the new clan #1
// would inherit the old clan #1's Team, forum and history.
//
// ── What a board may conclude, and what it may not ───────────────────────
//
// A board is authoritative for the clans it CARRIES. It is authoritative about
// the clans it does NOT carry only when it is complete: a board truncated at the
// game's 100-clan ceiling (D55), or one with a row this build could not read,
// proves nothing about a clan it leaves out, and marking that clan gone would
// hand core an archive on no evidence.

const crypto = require('node:crypto')

const core = require('../../core')

const db = require('./clans.db')
const visibility = require('../visibility/visibility.model')

const log = core.logger('clans')

/**
 * How long a board may go without its `t` advancing and still count as current.
 *
 * The plugin re-sends it every 60 seconds and this module reads it every 30, so
 * three minutes tolerates two missed boards before a server stops vouching for
 * its clans.
 */
const FRESH_MS = 3 * 60 * 1000

/**
 * How far back a clan event's feed item is offered to core again.
 *
 * Core writes an item only for a Team it already holds, and a clan founded a
 * moment ago is not one yet: its Team appears on core's next reconcile, which is
 * debounced by up to 30 seconds. So the "founded" line — the first line of every
 * clan's feed — would always be dropped if it were offered once. It is offered
 * on every board refresh for this long instead, and core's dedupe key makes every
 * offer after the first that lands a no-op.
 */
const REOFFER_MS = 10 * 60 * 1000

/** Team kinds core's `publish` takes, by the clan event that produces them. */
const PUBLISH = Object.freeze({
  'clan.created': 'team.created',
  'clan.disbanded': 'team.disbanded',
  'clan.member.added': 'team.member.added',
  'clan.member.left': 'team.member.removed',
  'clan.member.kicked': 'team.member.removed',
})

/**
 * The feed items D49 allows: membership, and nothing else. Every one is
 * members-only. A disband is not here — it was not one of the four the org lead
 * chose, and the Team it would be written to is about to be archived anyway.
 */
const ACTIVITY = Object.freeze({
  'clan.created': 'rust.clan.founded',
  'clan.member.added': 'rust.clan.joined',
  'clan.member.left': 'rust.clan.left',
  'clan.member.kicked': 'rust.clan.removed',
})

const CLAN_KINDS = Object.freeze(Object.keys(PUBLISH))

const STEAM_ID = /^\d{1,32}$/
const COLOR = /^#[0-9a-f]{6}$/i

/** The Team identity (D52). */
function externalIdOf(serverId, clanId, createdMs) {
  return `${serverId}:${clanId}:${createdMs}`
}

const text = (value, max) => (typeof value === 'string' && value.trim() ? value.trim().slice(0, max) : null)
const int = (value) => (Number.isInteger(Number(value)) && value !== null && value !== '' ? Number(value) : null)

/**
 * One board row as this module stores it, or null when it cannot be read.
 *
 * A member whose Steam id is not a Steam id is dropped rather than failing the
 * clan: the roster is still true about everybody else. A clan with no id, no
 * creation time or no name fails as a whole, because it has no identity to
 * store it under.
 */
function normaliseClan(serverId, raw) {
  if (!raw || typeof raw !== 'object') return null

  const clanId = int(raw.clanId)
  const createdMs = int(raw.createdMs)
  const name = text(raw.name, 191)
  if (clanId == null || createdMs == null || createdMs <= 0 || !name) return null

  const members = []
  for (const m of Array.isArray(raw.members) ? raw.members : []) {
    const steamId = m && typeof m.steamId === 'string' && STEAM_ID.test(m.steamId) ? m.steamId : null
    if (!steamId) continue
    members.push({
      steamId,
      name: text(m.name, 191),
      rank: int(m.rank),
      role: text(m.role, 64),
      joinedMs: int(m.joinedMs),
    })
  }

  return {
    externalId: externalIdOf(serverId, clanId, createdMs),
    serverId,
    clanId,
    createdMs,
    name,
    color: typeof raw.color === 'string' && COLOR.test(raw.color) ? raw.color.toLowerCase() : null,
    score: int(raw.score) || 0,
    maxMembers: int(raw.maxMembers),
    memberCount: members.length,
    members,
  }
}

/** A member signature, so an unchanged roster is not rewritten every minute. */
const signature = (members) =>
  members
    .map((m) => `${m.steamId}|${m.rank == null ? '' : m.rank}|${m.role || ''}|${m.name || ''}`)
    .sort()
    .join('\n')

const leadersOf = (members) => new Set(members.filter((m) => Number(m.rank) === 1).map((m) => m.steamId))

/**
 * Tells core something, and never lets core's answer become this module's
 * problem. Both calls are fire-and-forget by contract; the catch is for a core
 * that throws synchronously all the same.
 */
function publish(event) {
  try {
    Promise.resolve(core.teams.publish(event)).catch((err) => {
      log.warn('teams publish failed', { kind: event.kind, externalId: event.externalId, error: err.message })
    })
  } catch (err) {
    log.warn('teams publish threw', { kind: event.kind, externalId: event.externalId, error: err.message })
  }
}

function requestReconcile(reason) {
  try {
    core.teams.reconcile({ reason })
  } catch (err) {
    log.warn('teams reconcile request threw', { reason, error: err.message })
  }
}

function pushActivity(items) {
  if (!items.length) return
  try {
    Promise.resolve(core.teams.pushActivity(items)).catch((err) => {
      log.warn('teams activity push failed', { items: items.length, error: err.message })
    })
  } catch (err) {
    log.warn('teams activity push threw', { items: items.length, error: err.message })
  }
}

// ── The board ──────────────────────────────────────────────────────────────

/**
 * Applies one server's `clans` board.
 *
 * `board` is undefined when the sidecar holds none — a plugin older than
 * protocol 6, or one that has not connected since it was upgraded. That is
 * recorded as unsupported, and the clans already stored are left exactly as they
 * are: a missing board is the absence of an answer, not an answer of absence.
 *
 * Returns what happened, for the log and the tests.
 */
async function applyBoard(serverId, board) {
  if (!board || typeof board !== 'object') {
    await db.putBoard({
      serverId,
      boardT: null,
      advanced: false,
      enabled: true,
      supported: false,
      truncated: false,
      backend: null,
      reason: "this server has not sent a clan board; its plugin may predate protocol 6",
      umodClans: false,
      clanCount: 0,
    })
    return { applied: false, reason: 'no board' }
  }

  const previous = await db.getBoard(serverId)
  const boardT = Number(board.t)
  const known = previous && previous.boardT != null ? Number(previous.boardT) : null
  const advanced = Number.isFinite(boardT) && (known == null || boardT > known)

  const supported = board.supported === true
  const raw = supported && Array.isArray(board.clans) ? board.clans : null

  const clans = []
  let unreadable = 0
  for (const row of raw || []) {
    const clan = normaliseClan(serverId, row)
    if (clan) clans.push(clan)
    else unreadable += 1
  }

  // A row this build could not read is treated like the ceiling: the board no
  // longer vouches for what it leaves out.
  const truncated = board.truncated === true || unreadable > 0

  await db.putBoard({
    serverId,
    boardT: Number.isFinite(boardT) ? boardT : null,
    advanced,
    enabled: board.enabled !== false,
    supported,
    truncated,
    backend: text(board.backend, 64),
    reason: supported ? null : text(board.reason, 255) || 'the plugin could not read this server\'s clans',
    umodClans: board.umodClans === true,
    clanCount: clans.length,
  })

  if (unreadable) log.warn('clan board carried rows this build could not read', { server: serverId, unreadable })

  // A board whose `t` has not moved is the one already applied. Re-applying it
  // would rewrite every roster every 30 seconds to say what it already says.
  if (!advanced || !raw) return { applied: false, reason: advanced ? 'unsupported' : 'unchanged' }

  const [before, beforeMembers] = await Promise.all([
    db.listClansForServer(serverId),
    db.listMembersForServer(serverId),
  ])

  const wasActive = new Map(before.filter((c) => !c.goneAt).map((c) => [c.externalId, c]))
  const rosterBefore = new Map()
  for (const m of beforeMembers) {
    if (!rosterBefore.has(m.externalId)) rosterBefore.set(m.externalId, [])
    rosterBefore.get(m.externalId).push(m)
  }

  let created = 0
  let rosterChanged = 0
  const leaderEvents = []

  for (const clan of clans) {
    // eslint-disable-next-line no-await-in-loop
    await db.upsertClan(clan)

    const old = rosterBefore.get(clan.externalId) || []
    if (!wasActive.has(clan.externalId)) created += 1

    if (signature(old) !== signature(clan.members)) {
      // eslint-disable-next-line no-await-in-loop
      await db.replaceMembers(clan.externalId, clan.members)
      rosterChanged += 1
    }

    // Leadership is only ever learned here (D54): the game raises no hook when
    // somebody is promoted. Published only for a clan that was already on the
    // previous board — a brand-new clan's leaders reach core with the Team.
    if (wasActive.has(clan.externalId)) {
      const was = leadersOf(old)
      const now = leadersOf(clan.members)
      for (const key of now) if (!was.has(key)) leaderEvents.push({ kind: 'team.leader.added', externalId: clan.externalId, memberKey: key })
      for (const key of was) if (!now.has(key)) leaderEvents.push({ kind: 'team.leader.removed', externalId: clan.externalId, memberKey: key })
    }
  }

  // Only a complete board may say a clan is gone.
  const onBoard = new Set(clans.map((c) => c.externalId))
  const gone = truncated ? [] : [...wasActive.keys()].filter((id) => !onBoard.has(id))
  await db.markGone(gone)

  for (const event of leaderEvents) publish(event)

  if (created || gone.length || rosterChanged) {
    requestReconcile('rust clans board changed')
  }

  if (created || gone.length || rosterChanged || leaderEvents.length) {
    log.info('clan board applied', {
      server: serverId, clans: clans.length, created, gone: gone.length, rosterChanged,
      leaderChanges: leaderEvents.length, truncated,
    })
  }

  return { applied: true, clans: clans.length, created, gone: gone.length, rosterChanged, leaderChanges: leaderEvents.length }
}

// ── The events ─────────────────────────────────────────────────────────────

const nameOr = (name) => name || 'A player'

/** The feed line for one clan event, as core stores it verbatim. */
function summaryOf(kind, frame) {
  switch (kind) {
    case 'clan.created':
      return `${nameOr(frame.name)} founded the clan.`
    case 'clan.member.added':
      return `${nameOr(frame.name)} joined the clan.`
    case 'clan.member.left':
      return `${nameOr(frame.name)} left the clan.`
    case 'clan.member.kicked':
      return frame.byName
        ? `${nameOr(frame.name)} was removed from the clan by ${frame.byName}.`
        : `${nameOr(frame.name)} was removed from the clan.`
    default:
      return null
  }
}

/**
 * A key core can dedupe on, from the frame's own content.
 *
 * Content rather than this module's event row id, so that the same frame read
 * twice — a cursor replayed after a crash, or the re-offer below — is the same
 * item. **Hashed, because core clamps a dedupe key to 40 characters**, and a
 * readable key long enough to be unique (server, clan, creation time, kind,
 * player, instant) would be cut short into collisions without a word.
 */
function dedupeKeyOf(serverId, kind, frame) {
  const parts = [serverId, frame.clanId, frame.createdMs, kind, frame.steamId || '', frame.t]
  return crypto.createHash('sha1').update(parts.join('|')).digest('hex')
}

/** One clan event as a Team feed item, or null when D49 does not allow it. */
function activityItem(serverId, externalId, kind, frame) {
  const itemKind = ACTIVITY[kind]
  const summary = itemKind && summaryOf(kind, frame)
  if (!summary) return null

  const t = Number(frame.t)
  return {
    externalId,
    kind: itemKind,
    summary,
    occurredAt: Number.isFinite(t) ? t : Date.now(),
    visibility: 'members',
    actorMemberKey: kind === 'clan.member.kicked' ? frame.bySteamId || null : frame.steamId || null,
    payload: { serverId, steamId: frame.steamId || null },
    dedupeKey: dedupeKeyOf(serverId, kind, frame),
  }
}

/** The Team identity a clan event names, or null when it cannot be worked out. */
async function resolveExternalId(serverId, frame) {
  const clanId = int(frame.clanId)
  const createdMs = int(frame.createdMs)
  if (clanId == null) return null
  if (createdMs != null && createdMs > 0) return externalIdOf(serverId, clanId, createdMs)

  // `clan.member.added` can arrive without a creation time when the plugin could
  // not read the clan back. Matched on the game id, newest first.
  const known = await db.findByGameId(serverId, clanId)
  return known ? known.externalId : null
}

/**
 * Applies one `clan.*` event: tells core, and writes the Team feed.
 *
 * Called from ingest, after the raw frame is stored. The board that follows
 * every one of these (the plugin re-sends it a few seconds later) is what the
 * store is rebuilt from; this only makes the change visible sooner and records
 * the line for the feed.
 */
async function applyEvent(serverId, frame) {
  const kind = frame && frame.kind
  if (!PUBLISH[kind]) return { applied: false }

  if (frame.steamId) await db.rememberName(frame.steamId, text(frame.name, 191))
  if (frame.bySteamId) await db.rememberName(frame.bySteamId, text(frame.byName, 191))

  const externalId = await resolveExternalId(serverId, frame)
  if (!externalId) {
    log.info('clan event names a clan this module has never seen', { server: serverId, kind, clanId: frame.clanId })
    return { applied: false }
  }

  // The game said it: this clan is gone. Recorded here as well as by the next
  // board, because a board truncated at the ceiling would never say so.
  if (kind === 'clan.disbanded') await db.markGone([externalId])

  const event = { kind: PUBLISH[kind], externalId }
  if (event.kind.startsWith('team.member.')) {
    if (!frame.steamId) return { applied: false }
    event.memberKey = String(frame.steamId)
  }
  publish(event)

  const item = activityItem(serverId, externalId, kind, frame)
  if (item) pushActivity([item])

  return { applied: true, externalId }
}

/**
 * Offers the last few minutes of one server's clan feed items to core again.
 *
 * See `REOFFER_MS`. Called after each board refresh; idempotent by construction.
 */
async function reofferActivity(serverId, now = Date.now()) {
  const rows = await db.recentClanEvents(serverId, now - REOFFER_MS)
  const items = []

  for (const row of rows) {
    let frame
    try {
      frame = typeof row.raw === 'string' ? JSON.parse(row.raw) : row.raw
    } catch (err) {
      continue
    }
    if (!frame || !ACTIVITY[frame.kind]) continue

    // eslint-disable-next-line no-await-in-loop
    const externalId = await resolveExternalId(serverId, frame)
    const item = externalId && activityItem(serverId, externalId, frame.kind, frame)
    if (item) items.push(item)
  }

  pushActivity(items)
  return items.length
}

// ── Who may see a roster (D48) ─────────────────────────────────────────────

/**
 * May this viewer see this clan's roster?
 *
 * `viewer` is `{ userId, role }` or null — the shape core hands `projectRoster`,
 * so core's roster and this module's page decide it with one function.
 *
 * The viewer's standing is re-read from the `users` row, never taken from what
 * the caller says, for the same reason the presence gate does it: a moderator
 * demoted this morning, or an account banned, must lose the roster on the next
 * request. Everything that cannot be answered answers no.
 */
async function canSeeRoster(viewer, externalId) {
  const audience = await visibility.clanRosterAudience()
  if (audience === 'public') return true
  if (!viewer || viewer.userId == null) return false

  const user = await core.users.getById(viewer.userId)
  if (!user || (user.status && user.status !== 'active')) return false

  if (audience === 'signed_in') return true
  if (user.role === 'admin' || user.role === 'moderator') return true
  return db.userIsMember(externalId, user.id)
}

// ── The public reads ───────────────────────────────────────────────────────

const shapeBoard = (board, now = Date.now()) => {
  if (!board || board.supported == null) {
    return { supported: false, fresh: false, truncated: false, enabled: true, reason: 'this server has not sent a clan board yet' }
  }
  const seenAt = board.seenAt ? new Date(board.seenAt).getTime() : null
  return {
    supported: Boolean(board.supported),
    enabled: Boolean(board.enabled),
    truncated: Boolean(board.truncated),
    fresh: Boolean(board.supported) && seenAt != null && now - seenAt < FRESH_MS,
    reason: board.reason || null,
  }
}

/** The Clans tab (D58): every clan on one server's board, best first. Public. */
async function listForServer(serverId, now = Date.now()) {
  const [clans, board] = await Promise.all([db.listPublicForServer(serverId), db.getBoard(serverId)])
  return {
    clans: clans.map((c) => ({
      externalId: c.externalId,
      name: c.name,
      color: c.color || null,
      score: Number(c.score) || 0,
      memberCount: Number(c.memberCount) || 0,
      maxMembers: c.maxMembers == null ? null : Number(c.maxMembers),
    })),
    board: shapeBoard(board, now),
  }
}

/**
 * One clan, and its roster if the viewer may see it.
 *
 * The roster carries no Steam id and no website account id — the same two fields
 * core withholds from every public roster. `online` is inside the audience by
 * construction (D48): a viewer who may not see the roster sees no names at all.
 */
async function getForViewer(externalId, viewer) {
  const clan = await db.findClan(externalId)
  if (!clan) return null

  const allowed = await canSeeRoster(viewer, externalId)
  const audience = await visibility.clanRosterAudience()

  const members = allowed && !clan.goneAt ? await db.listMembers(externalId) : []

  return {
    clan: {
      externalId: clan.externalId,
      name: clan.name,
      color: clan.color || null,
      score: Number(clan.score) || 0,
      memberCount: Number(clan.memberCount) || 0,
      maxMembers: clan.maxMembers == null ? null : Number(clan.maxMembers),
      serverId: clan.serverId,
      serverName: clan.serverName,
      founded: Number(clan.createdMs) || null,
      gone: Boolean(clan.goneAt),
    },
    roster: {
      visible: allowed,
      audience,
      members: members.map((m) => ({
        name: m.name || null,
        role: m.role || null,
        leader: Number(m.rank) === 1,
        online: Boolean(Number(m.online)),
        joined: m.joinedMs == null ? null : Number(m.joinedMs),
      })),
    },
  }
}

/**
 * Every configured server's clan board as the admin page shows it: whether it is
 * current, whether it is at the ceiling (D55), why it cannot be read, and
 * whether the uMod Clans plugin is loaded there (D47) — whose clans are a
 * separate system and never Teams.
 */
async function boardsForAdmin(now = Date.now()) {
  const rows = await db.listBoards()
  return rows.map((row) => ({
    id: row.serverId,
    name: row.serverName,
    ...shapeBoard(row.supported == null ? null : row, now),
    clans: Number(row.clanCount) || 0,
    umodClans: Boolean(row.umodClans),
  }))
}

module.exports = {
  FRESH_MS,
  boardsForAdmin,
  REOFFER_MS,
  CLAN_KINDS,
  externalIdOf,
  normaliseClan,
  applyBoard,
  applyEvent,
  resolveExternalId,
  reofferActivity,
  activityItem,
  dedupeKeyOf,
  canSeeRoster,
  shapeBoard,
  listForServer,
  getForViewer,
}