// ── A website account is being deleted (MODULE_API 1.20.0) ──────────────────
//
// ACCOUNT_DELETION.md §4.4. Core asks before the users row goes (AD10), and the
// row's cascade would drop `shard_account_links` anyway — but that table is only
// a mirror. The shard keeps the site user id on the game account and reports it
// as `webId` on every `mob.login`, so a cascade alone would leave the shard
// attributing the account to a user who no longer exists. The unlink here is the
// staff unlink's path (usersShard.controller.js): the sidecar's
// `DELETE /link/{account}` first, the mirror after. The shard account and its
// characters stay (AD8).
//
// **An unlink that cannot finish never holds up the deletion** (AD11):
//
//   • every account is queued in `shard_pending_unlinks` BEFORE the first call,
//     so a hook core abandons at its ten-second limit still leaves the rest
//     queued (one sidecar call may take twelve);
//   • a shard that is away (503, no sidecar, a timeout) leaves the row
//     `pending`, retried whenever the bridge comes back — the WS reconnecting,
//     which is also how a boot gets here, and a live `server.hello`;
//   • a protected staff account, which the shard refuses by design (403), is
//     `refused`: retrying will not help, so Admin → Shard lists it as still
//     linked on the shard for the shard's staff to clear by hand.
//
// Either kind of row goes once the shard reports a live login on that account
// with no `webId`, or a different one: the tag is gone, whoever cleared it.

const core = require('../core')
const shardLinks = require('../model/shardLinks/shardLinks.model')
const pendingDb = require('../model/shardPendingUnlinks/shardPendingUnlinks.db')
const uoLinkClient = require('./uoLinkClient')

const log = core.logger('account-deletion')

// What the shard's audit records as the one who asked.
const ACTOR = 'web:account-deletion'

/**
 * Ask the shard to unlink one queued account, and record what it said.
 *
 * 200 and 404 both finish it: 404 means the shard has nothing to clear. Never
 * throws for a shard answer; a database error does throw, to the caller's catch.
 *
 * @returns {Promise<'unlinked'|'absent'|'refused'|'pending'>}
 */
async function attempt({ account, webUserId, reason }) {
  const result = await uoLinkClient.unlinkAccount({ actor: ACTOR, account })
  if (result.ok || result.status === 404) {
    await shardLinks.removeByAccount(account)
    await pendingDb.remove(account)
    if (!result.ok) return 'absent'
    // No `userId` on the entry: on a retry the account is already gone, and the
    // activity log's user_id is a key into `users`. The id is in the detail.
    await core.activity.log({
      action: 'shard.account.unlink',
      detail: { account, webUserId, reason: 'account deleted', ...(reason ? { deletedBy: reason } : {}) },
    })
    return 'unlinked'
  }
  const error = result.error || `status ${result.status}`
  if (result.status === 403) {
    await pendingDb.recordAttempt({ account, state: 'refused', error })
    log.warn('the shard refused to unlink a deleted account’s game account (protected); listed for shard staff', { account, webUserId })
    return 'refused'
  }
  await pendingDb.recordAttempt({ account, state: 'pending', error })
  return 'pending'
}

/**
 * Core's `api.onUserDeleting`. Unlinks every game account this website account
 * holds, through the staff unlink's path. Cannot stop the deletion; whatever it
 * does not finish stays queued.
 */
async function onUserDeleting({ userId, deletedBy }) {
  const links = await shardLinks.listForUser(userId)
  if (!links.length) return

  for (const { account } of links) {
    // eslint-disable-next-line no-await-in-loop
    await pendingDb.queue({ account, webUserId: userId })
  }

  const outcomes = []
  for (const { account } of links) {
    try {
      // eslint-disable-next-line no-await-in-loop
      outcomes.push({ account, outcome: await attempt({ account, webUserId: userId, reason: deletedBy }) })
    } catch (err) {
      log.warn('an unlink before an account deletion failed; it stays queued', { account, error: err.message })
      outcomes.push({ account, outcome: 'pending' })
    }
  }
  log.info('game accounts unlinked before an account was deleted', { userId, deletedBy, outcomes })
}

let inFlight = null

/**
 * Try every `pending` row once more. One pass at a time: a reconnect and a
 * `server.hello` arriving together share the pass already running. Every row is
 * tried, so one account the shard keeps failing on does not hold up the rest.
 * Never rejects, so a caller may leave it un-awaited.
 */
function retryPending() {
  if (inFlight) return inFlight
  inFlight = (async () => {
    try {
      const rows = await pendingDb.listPending()
      for (const row of rows) {
        // eslint-disable-next-line no-await-in-loop
        const outcome = await attempt({ account: row.account, webUserId: row.web_user_id })
        if (outcome !== 'pending') log.info('a deleted account’s queued unlink finished', { account: row.account, outcome })
      }
    } catch (err) {
      log.warn('retrying queued unlinks failed (will try on the next reconnect)', { error: err.message })
    } finally {
      inFlight = null
    }
  })()
  return inFlight
}

/**
 * A live `mob.login`: when this account is queued and the shard no longer
 * reports the deleted user's id on it, the row is done. Never on a backfill —
 * a replayed login from before the account was linked carries no `webId` and
 * would clear a row whose tag is still there.
 */
async function seenLogin({ account, webId }) {
  if (!account) return
  const id = webId === undefined || webId === null || webId === '' ? null : Number(webId)
  const dropped = await pendingDb.clearIfNotAttributed(account, Number.isFinite(id) ? id : null)
  if (dropped) log.info('a queued unlink cleared itself: the shard no longer attributes the account', { account })
}

/** Admin → Shard's list: what a deletion left linked on the shard. */
async function listForAdmin() {
  const rows = await pendingDb.listAll()
  return rows.map((r) => ({
    account: r.account,
    webUserId: r.web_user_id,
    state: r.state,
    queuedAt: r.queued_at,
    attempts: Number(r.attempts) || 0,
    lastAttemptAt: r.last_attempt_at || null,
    lastError: r.last_error || null,
  }))
}

function _reset() {
  inFlight = null
}

module.exports = { ACTOR, onUserDeleting, retryPending, seenLogin, listForAdmin, _reset }