// ── Report, block and hide, for chat lines ─────────────────────────────────
//
// USER_SAFETY.md §4.2 (MODULE_API 1.21.0). Core owns the Reports queue, a
// member's blocks and their "Hide for me" list; this module owns the chat lines
// those name, and is the only one that can say what a line is, who said it, and
// whether a reader may see it. Four things live here:
//
//   REPORT_TARGETS   `rust.chat`: a chat line, as core's resolver asks for it —
//                    `snapshot` for one reader, and staff's hide for everyone
//   GAME_IDENTITIES  `steam`: which website account a Steam id is linked to,
//                    so a block on a linked speaker lands on their account (S12)
//                    and a Steam-id block becomes one once the id links (S14)
//   feedFilter       what one reader's events feed leaves out of the chat (S11)
//   annotate         `canBlock` on each chat line, for a signed-in reader (S13)
//
// ── The rules, each decided by the org lead ───────────────────────────────
//
//   S6   Reporting, hiding and blocking all need an account. A signed-out reader
//        gets the feed as it is, with no `canBlock`.
//   S8   Staff cannot be blocked. Core refuses the block and drops a block whose
//        target later became staff; here a line whose speaker is linked to staff
//        says `canBlock: false`.
//   S10  A line staff hid for everyone is still staff's to see, marked.
//   S12  A speaker is checked by their linked ACCOUNT first, and by Steam id only
//        when they have none.
//
// A block hides what someone SAYS: chat lines. Their deaths, connects and kills
// stay in the feed, because the feed is what happened on the server and a block
// is not a way to rewrite that.

const core = require('./core')

const eventsDb = require('./model/events/events.db')
const linksDb = require('./model/links/links.db')
const serversDb = require('./model/servers/servers.db')
const visibility = require('./model/visibility/visibility.model')

const log = core.logger('safety')

const CHAT = 'rust.chat'
const STEAM = 'steam'

function parseFrame(raw) {
  try {
    return typeof raw === 'string' ? JSON.parse(raw) : raw || {}
  } catch {
    return {}
  }
}

const ids = (list) => [...new Set((list || []).filter((v) => v != null).map(String))]

/** Steam id → website account id, for the ids that are linked. */
async function ownersOf(steamIds) {
  const wanted = ids(steamIds)
  if (!wanted.length) return {}
  const rows = await linksDb.userIdsForSteamIds(wanted)
  return Object.fromEntries(rows.map((r) => [String(r.steamId), Number(r.userId)]))
}

/**
 * One chat line, for one reader, or null.
 *
 * Null is the answer for a line that is gone AND for one this reader could not
 * have seen — on a server whose presence is hidden from them, or hidden by staff
 * when they are not staff — because core answers 404 to both, and a report or a
 * block must never confirm who said line 4410 to somebody the feed never showed
 * it to (MODULE_API.md §2.4).
 */
async function snapshot({ targetId, viewer }) {
  const row = await eventsDb.chatLineById(targetId)
  if (!row) return null

  const presence = await visibility.canSeePresenceAs(viewer && viewer.userId, row.serverId)
  if (!presence.visible) return null
  if (row.hiddenAt && presence.level !== 'staff') return null

  const frame = parseFrame(row.raw)
  const steamId = row.steamId ? String(row.steamId) : null
  const [owners, server] = await Promise.all([
    steamId ? ownersOf([steamId]) : {},
    serversDb.getServer(row.serverId).catch(() => null),
  ])

  return {
    author: {
      name: frame.name || null,
      userId: steamId && owners[steamId] ? owners[steamId] : null,
      identity: steamId ? { kind: STEAM, id: steamId } : null,
    },
    text: typeof frame.message === 'string' ? frame.message : '',
    at: Number.isFinite(Number(row.t)) ? new Date(Number(row.t)).toISOString() : null,
    where: {
      server: row.serverId,
      serverName: server ? server.name : null,
      channel: frame.channel || 'Global',
      wipe: row.wipeId || null,
    },
  }
}

/**
 * Staff's hide for everyone, from core's Reports queue (S3, S10). A line the
 * sweep has already pruned has nothing left to hide, and that is not an error:
 * the report is still actioned.
 */
async function hide({ targetId, actor }) {
  if (!(await eventsDb.chatLineById(targetId))) return
  await eventsDb.setChatHidden(targetId, true, actor && actor.id != null ? actor.id : null)
}

async function unhide({ targetId }) {
  await eventsDb.setChatHidden(targetId, false)
}

const REPORT_TARGETS = Object.freeze([
  Object.freeze({ id: CHAT, label: 'Chat line', snapshot, hide, unhide }),
])

const GAME_IDENTITIES = Object.freeze([
  Object.freeze({ kind: STEAM, label: 'Steam account', ownersOf }),
])

/**
 * What one reader's feed leaves out of the chat, as `events.recent` takes it:
 * the Steam ids whose lines they do not get, the lines they hid, and whether
 * staff's hidden lines are theirs to see.
 *
 * The Steam ids are S12 in one set: every id linked to an account they block,
 * plus their Steam-id blocks — which core answers only for ids still unlinked,
 * having already turned a linked one into an account block (S14) or dropped it
 * when that account is staff (S8). So a line is left out by its speaker's
 * account when there is one, and by its Steam id only when there is not.
 *
 * **A failure here shows the feed unfiltered rather than failing it.** The feed
 * is the page the site promises to render while everything behind it is down;
 * a member who sees a blocked line once, with a warning in the log, is the
 * smaller harm than a blank killfeed for everyone signed in.
 */
async function feedFilter({ userId, staff }) {
  const base = { showHidden: Boolean(staff), steamIds: [], ids: [] }
  if (userId == null) return base
  try {
    const mine = await core.safety.forViewer(userId)
    const blockedUsers = (mine.blockedUserIds || []).map(Number).filter((n) => Number.isInteger(n) && n > 0)
    const linked = blockedUsers.length ? await linksDb.steamIdsForUsers(blockedUsers) : []
    const unlinked = (mine.blockedIdentities && mine.blockedIdentities[STEAM]) || []
    const hidden = (mine.hidden && mine.hidden[CHAT]) || []
    return {
      ...base,
      steamIds: ids([...linked, ...unlinked]),
      ids: [...new Set(hidden.map(Number).filter((n) => Number.isInteger(n) && n > 0))],
    }
  } catch (err) {
    log.warn('could not read the reader’s blocks; the feed is unfiltered for them', { error: err.message })
    return base
  }
}

/**
 * `canBlock` on each chat line, for a signed-in reader (S13). False when the
 * line has no Steam id, when the speaker's linked account is the reader's own,
 * or when it is staff (S8). Signed-out readers get the rows untouched.
 *
 * A failure answers `canBlock: false` on every line: the menu then offers no
 * Block, and core would refuse a block on staff anyway.
 */
async function annotate(events, { userId }) {
  if (userId == null) return events
  const chat = events.filter((e) => e.kind === 'player.chat')
  if (!chat.length) return events

  let owners = {}
  let staff = new Set()
  let ok = true
  try {
    owners = await ownersOf(chat.map((e) => e.steamId))
    const linked = [...new Set(Object.values(owners))]
    staff = new Set((linked.length ? await core.safety.staffAmong(linked) : []).map(Number))
  } catch (err) {
    log.warn('could not work out who can be blocked; offering no block', { error: err.message })
    ok = false
  }

  return events.map((e) => {
    if (e.kind !== 'player.chat') return e
    const owner = e.steamId ? owners[String(e.steamId)] : undefined
    const canBlock = ok && Boolean(e.steamId) && owner !== Number(userId) && !(owner != null && staff.has(owner))
    return { ...e, canBlock }
  })
}

module.exports = { CHAT, STEAM, REPORT_TARGETS, GAME_IDENTITIES, snapshot, hide, unhide, ownersOf, feedFilter, annotate }