const { query } = require('../../core')

const COLS = 'account, user_id, char_name, linked_at'

// Upsert a link. account is the PK, so a re-link moves the account to the new
// user (the sidecar already treats /link/confirm as authoritative).
async function upsert({ account, userId, charName }) {
  await query(
    `INSERT INTO shard_account_links (account, user_id, char_name)
     VALUES (?, ?, ?)
     ON DUPLICATE KEY UPDATE user_id = VALUES(user_id), char_name = VALUES(char_name)`,
    [account, userId, charName || null],
  )
  return getByAccount(account)
}

async function getByAccount(account) {
  const rows = await query(`SELECT ${COLS} FROM shard_account_links WHERE account = ? LIMIT 1`, [account])
  return rows[0] || null
}

const listByUser = (userId) =>
  query(`SELECT ${COLS} FROM shard_account_links WHERE user_id = ? ORDER BY linked_at DESC`, [userId])

async function isOwnedBy(account, userId) {
  const rows = await query(
    'SELECT 1 FROM shard_account_links WHERE account = ? AND user_id = ? LIMIT 1',
    [account, userId],
  )
  return rows.length > 0
}

const remove = (account, userId) =>
  query('DELETE FROM shard_account_links WHERE account = ? AND user_id = ?', [account, userId])

// Drop the mirror for an account regardless of which user held it — used to
// reconcile when the tie is severed at the source (an in-game [unlink →
// account.unlinked event, or a site-side DELETE /link/{account}).
const removeByAccount = (account) =>
  query('DELETE FROM shard_account_links WHERE account = ?', [account])


// A bound on every "resolve a set of people" read below. It mirrors core's own
// `MAX_AUDIENCE` (engagementRecipients.db.js) rather than importing it: a module
// cannot reach into core's models, and the number this file has to respect is
// "no more ids than core will accept" whatever core calls it.
const MAX_AUDIENCE = 5000

// **Website user ids for a set of game accounts.** The bulk form of
// `getByAccount`, and the one the engagement mapper needs: a guild event's
// audience is its members, and turning a roster into a set of people is one join
// rather than one query per member (Phase 11).
//
// DISTINCT because two characters on one guild roster can share an account, and
// the caller wants people rather than characters.
async function userIdsForAccounts(accounts) {
  const wanted = [...new Set((accounts || []).filter((a) => typeof a === 'string' && a))]
  if (!wanted.length) return []
  const capped = wanted.slice(0, MAX_AUDIENCE)
  const marks = capped.map(() => '?').join(', ')
  const rows = await query(
    `SELECT DISTINCT user_id FROM shard_account_links WHERE account IN (${marks})`,
    capped,
  )
  return rows.map((r) => Number(r.user_id)).filter((n) => Number.isInteger(n) && n > 0)
}

// **Every website user with a linked game account** — the `uo.linked.accounts`
// audience (ENGAGEMENT.md §5.1a). The set an operator reaches for first, and the
// one a `not` composes against ("everyone who has NOT linked").
//
// It returns ids and nothing else: §5.1a rule 2 is that a module's resolver
// never sees an address, a channel or a template, and core maps ids to addresses
// on its own side after preferences, suppression and the verification gate.
async function allLinkedUserIds(limit = MAX_AUDIENCE) {
  const rows = await query(
    'SELECT DISTINCT user_id FROM shard_account_links ORDER BY user_id LIMIT ?',
    [limit],
  )
  return rows.map((r) => Number(r.user_id)).filter((n) => Number.isInteger(n) && n > 0)
}

module.exports = {
  upsert,
  getByAccount,
  listByUser,
  isOwnedBy,
  remove,
  removeByAccount,
  userIdsForAccounts,
  allLinkedUserIds,
  MAX_AUDIENCE,
}