// ── Who owns which Steam account ──────────────────────────────────────────
//
// R1's identity link, site-side. The flow it sits in the middle of:
//
//   1. In game, a player types `/link`. The plugin mints a one-time code, tells
//      them privately, and holds it in memory for five minutes.
//   2. On the website, the player types that code. This module asks the sidecar,
//      which asks the plugin, which answers with the Steam id the code belongs
//      to and drops it.
//   3. This file records the result.
//
// **The site is the author of record and the game holds nothing.** That is the
// one real difference from the UO bridge, which writes a tag onto the game
// account: there is no equivalent per-account store in Rust that survives a wipe,
// and phase 7 needs the site to be authoritative anyway — it pushes permissions
// INTO the game keyed by Steam id. A copy in the game would be a second thing to
// reconcile every wipe, for no question it could answer better.

const core = require('../../core')
const db = require('./links.db')
const servers = require('../servers/servers.model')
const sidecar = require('../../sidecarClient')

const log = core.logger('links')

/** What a link looks like to any caller. Never carries a raw code. */
function shape(row) {
  if (!row) return null
  return {
    steamId: row.steamId,
    name: row.name || null,
    serverId: row.serverId || null,
    linkedAt: row.linkedAt,
  }
}

/**
 * The Steam accounts one website user holds.
 *
 * The name is the one the GAME last saw, falling back to the one recorded when
 * they linked — the rule the admin panel already used, applied on the page the
 * player themselves reads. A browser walk found the two disagreeing: staff saw
 * `Wanderer` and the player saw `Wanderer-old`, for the same person on the same
 * site.
 */
async function listForUser(userId) {
  return (await db.listForUser(userId)).map((row) => ({
    ...shape(row),
    name: row.playerName || row.name || null,
  }))
}

/** True when this user holds this Steam id. The ownership gate every player read uses. */
async function owns(steamId, userId) {
  const row = await db.getBySteamId(steamId)
  return Boolean(row && Number(row.userId) === Number(userId))
}

/**
 * Redeem a code against one server, and record the link.
 *
 * Answers a discriminated result rather than throwing, because every outcome
 * here is a sentence somebody has to read:
 *
 *   `{ ok: true, link }`               — linked
 *   `{ ok: false, reason: 'rejected' }`— the game says that code is not good
 *   `{ ok: false, reason: 'taken', username }` — someone else holds that Steam id
 *   `{ ok: false, reason: 'offline' }` — the game or its sidecar did not answer
 *
 * **`rejected` deliberately collapses "unknown" and "expired".** The plugin
 * distinguishes them and an operator reading its log can too; a stranger typing
 * codes must not learn which of the two they hit, because that is the difference
 * between "keep guessing" and "guess faster".
 */
async function confirmOne({ server, code, userId }) {
  const result = await sidecar.confirmLink(server, code)

  // The transport failed: the sidecar is unreachable, the game is not connected,
  // or the reply never came. None of those is a verdict on the code, so the
  // player is told to try again rather than that their code is wrong.
  if (!result.ok) {
    log.warn('link confirm did not reach the game', { server: server.id, status: result.status })
    return { ok: false, reason: 'offline' }
  }

  const frame = result.data || {}

  // The plugin's own refusal. `frame.reason` is `unknown`, `expired` or
  // `malformed`; it is logged and not surfaced (see the doc above).
  if (frame.kind !== 'link.ok' || !frame.steamId) {
    log.info('link code refused', { server: server.id, reason: frame.reason || frame.kind || 'unknown' })
    return { ok: false, reason: 'rejected' }
  }

  const steamId = String(frame.steamId)
  const held = await db.getBySteamId(steamId)

  // D23: refuse, and say whose it is. A move would transfer every permission and
  // entitlement phases 7 and 13 hang off this link, on a code anybody in game
  // could have run — and the player's way out is `/unlink` in game, which they
  // can reach from the machine they are sitting at.
  if (held) {
    if (Number(held.userId) === Number(userId)) {
      // Already theirs. Not an error: a player who pressed the button twice, or
      // one whose code was confirmed on a request that then timed out.
      return { ok: true, link: shape(held), already: true }
    }
    return { ok: false, reason: 'taken', username: held.username }
  }

  try {
    await db.insert({
      steamId,
      userId,
      name: frame.name || null,
      serverId: server.id,
    })
  } catch (err) {
    // The race the PRIMARY KEY exists for: two confirmations of the same Steam
    // id, interleaved between the check above and this write. The key refuses the
    // second and it becomes the same refusal, rather than a 500.
    if (err && (err.code === 'ER_DUP_ENTRY' || err.errno === 1062)) {
      const now = await db.getBySteamId(steamId)
      if (now && Number(now.userId) === Number(userId)) {
        return { ok: true, link: shape(now), already: true }
      }
      return { ok: false, reason: 'taken', username: now && now.username }
    }
    throw err
  }

  const link = shape(await db.getBySteamId(steamId))
  log.info('steam account linked', { steamId, userId, server: server.id })
  return { ok: true, link }
}

/**
 * Redeem a code against the fleet (D24).
 *
 * **A code is minted by ONE server and the player types six characters into a
 * browser**, so the site cannot know which server it came from — nothing in the
 * code says, and asking the player to pick would make a wrong guess
 * indistinguishable from a wrong code, which is the one refusal that must not be
 * ambiguous. So every enabled server is asked in turn and the first `link.ok`
 * wins. The others answer `unknown` and nothing happens there: a code is only
 * spent at the server that actually holds it.
 *
 * The loop stops early on `taken`, because that is a verdict about the Steam id
 * rather than about this server — asking the rest of the fleet would produce the
 * same answer more slowly.
 *
 * **"Every reachable server refused" is not the same answer as "a server was
 * unreachable"**, and collapsing them is how a player who linked on the one
 * server that is down gets told their code is wrong. `unsure` is that case, and
 * the sentence it earns says to try again rather than to run `/link` again.
 */
async function redeem({ code, userId }) {
  const fleet = await servers.listForPolling()

  if (fleet.length === 0) return { ok: false, reason: 'no-servers' }

  let refused = 0
  let unreachable = 0

  for (const server of fleet) {
    // Sequential, deliberately. In parallel every server would be asked even
    // after one had already answered, and a code spent on the right server would
    // still be travelling to five others — for a fleet of six and a five-minute
    // TTL, there is nothing to win by racing them.
    // eslint-disable-next-line no-await-in-loop
    const result = await confirmOne({ server, code, userId })

    if (result.ok || result.reason === 'taken') return result

    if (result.reason === 'offline') unreachable += 1
    else refused += 1
  }

  if (refused === 0) return { ok: false, reason: 'offline' }
  if (unreachable > 0) return { ok: false, reason: 'unsure' }

  return { ok: false, reason: 'rejected' }
}

/** Remove a link the caller owns. False when they did not hold it. */
async function unlinkOwned(steamId, userId) {
  return (await db.removeOwned(steamId, userId)) > 0
}

/**
 * Remove a link whoever holds it.
 *
 * Two callers, both of which have already established their authority and
 * neither of which is the link's owner: ingest applying an in-game `/unlink`
 * (the authority is the Steam account — whoever is connected as it is who it
 * is), and a staff unlink from the `admin.users.detail` panel (D25).
 *
 * It logs nothing about who asked, because the two callers record that
 * differently: the admin one writes an `activity.log` entry naming the operator,
 * and the game one has no operator to name.
 */
async function unlinkAnyOwner(steamId) {
  return (await db.removeBySteamId(steamId)) > 0
}

/**
 * Remove a link because the player asked in game.
 *
 * Called from ingest, off an `account.unlinked` event.
 */
async function unlinkFromGame(steamId) {
  const removed = await unlinkAnyOwner(steamId)
  if (removed) log.info('steam account unlinked in game', { steamId })
  return removed
}

/** The admin panel's read: every link this user holds, with per-server totals. */
async function forAdmin(userId) {
  const links = await db.listForUserWithPlayer(userId)

  return Promise.all(
    links.map(async (row) => ({
      steamId: row.steamId,
      // The name on the LINK is what they were called when they linked; the one
      // on `rust_players` is what the game last saw. They differ the moment
      // somebody renames, and the newer one is the useful one to show.
      name: row.playerName || row.name || null,
      linkedName: row.name || null,
      serverId: row.serverId || null,
      linkedAt: row.linkedAt,
      firstSeen: row.firstSeen || null,
      lastSeen: row.lastSeen || null,
      servers: (await db.statsForSteamId(row.steamId)).map((s) => ({
        serverId: s.serverId,
        serverName: s.serverName || s.serverId,
        kills: Number(s.kills) || 0,
        deaths: Number(s.deaths) || 0,
        npcKills: Number(s.npcKills) || 0,
        structures: Number(s.structures) || 0,
        playtimeSec: Number(s.playtimeSec) || 0,
        wipes: Number(s.wipes) || 0,
        lastSeen: s.lastSeen || null,
      })),
    })),
  )
}

module.exports = {
  shape,
  listForUser,
  owns,
  confirmOne,
  redeem,
  unlinkOwned,
  unlinkAnyOwner,
  unlinkFromGame,
  forAdmin,
}