// ── SQL for chat titles (phase 17) ────────────────────────────────────────
//
// The rules an operator writes, per server, and the two columns on
// `rust_servers` that say how many titles a player shows. The titles themselves
// are never stored — see `schema.sql` and `titles.js`.

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

const RULES = 'rust_title_rules'
const SERVERS = 'rust_servers'

/** One server's rules, in precedence order. */
async function listRules(serverId) {
  return core.query(
    `SELECT id, stat, top_n AS topN, text, color
       FROM ${RULES}
      WHERE server_id = ?
      ORDER BY position ASC, id ASC`,
    [serverId],
  )
}

/** Every server's rules, for the admin list — one read rather than one per server. */
async function listAllRules() {
  return core.query(
    `SELECT server_id AS serverId, stat, top_n AS topN, text, color
       FROM ${RULES}
      ORDER BY server_id ASC, position ASC, id ASC`,
  )
}

async function getMode(serverId) {
  const rows = await core.query(
    `SELECT title_mode AS mode, title_max AS max FROM ${SERVERS} WHERE id = ?`,
    [serverId],
  )
  return rows[0] || null
}

async function listModes() {
  return core.query(`SELECT id AS serverId, title_mode AS mode, title_max AS max FROM ${SERVERS}`)
}

/**
 * Replace one server's rules and mode whole. The form edits a list, so the
 * write is a list — and a rule's position is its place in that list.
 */
async function saveSettings(serverId, { mode, max, rules }) {
  await core.query(`UPDATE ${SERVERS} SET title_mode = ?, title_max = ? WHERE id = ?`, [mode, max, serverId])
  await core.query(`DELETE FROM ${RULES} WHERE server_id = ?`, [serverId])

  if (!rules.length) return

  await core.query(
    `INSERT INTO ${RULES} (server_id, position, stat, top_n, text, color)
          VALUES ${rules.map(() => '(?, ?, ?, ?, ?, ?)').join(',')}`,
    rules.flatMap((r, i) => [serverId, i, r.stat, r.topN, r.text, r.color]),
  )
}

// ── The standings a category ranks (PLAN_REDESIGNS §5) ────────────────────

const STATS = 'rust_player_wipe_stats'
const WEAPONS = 'rust_weapon_kills'
const GATHER = 'rust_gather_totals'
const CATEGORIES = 'rust_title_categories'

/** Only these ever reach a column position in SQL: the names `titles.js` declares. */
const COLUMN = /^[a-z_]+$/

/**
 * One category's standings for one wipe: `{ steamId, value }` rows, highest
 * first, ties broken by who was seen last — the leaderboard's own order, so a
 * rule's top N is what the web would show (§33.4 reading 2).
 *
 * @param {object} source  a category's `source` from `titles.js`
 * @param {object} lists   list name → the short names it holds (`lists.js`)
 */
async function standings({ serverId, wipeId, source, lists = {}, limit }) {
  const params = [serverId, wipeId]

  if (source.sum || source.diff || source.best) {
    let value
    if (source.sum) value = `SUM(s.${source.sum})`
    else if (source.best) value = `MAX(s.${source.best})`
    // Signed: `npc_kills` is unsigned, and a row counted before `animal_kills`
    // existed must not wrap round to four billion.
    else value = `SUM(CAST(s.${source.diff[0]} AS SIGNED) - CAST(s.${source.diff[1]} AS SIGNED))`

    const cols = [source.sum, source.best, ...(source.diff || [])].filter(Boolean)
    if (!cols.every((c) => COLUMN.test(c))) throw new Error('not a stats column')

    return core.query(
      `SELECT s.steam_id AS steamId, ${value} AS value
         FROM ${STATS} s
        WHERE s.server_id = ? AND s.wipe_id = ?
        GROUP BY s.steam_id
        ORDER BY value DESC, MAX(s.last_seen) DESC
        LIMIT ?`,
      [...params, limit],
    )
  }

  const table = source.weapons ? WEAPONS : GATHER
  const key = source.weapons ? 'weapon' : 'resource'
  const amount = source.weapons ? 'kills' : 'amount'
  const names = lists[source.weapons || source.gathered] || []

  if (!names.length) return []

  // The stats row is joined only for the tie-break; its key is the table's,
  // so one row joins at most one and the sum is not multiplied.
  return core.query(
    `SELECT t.steam_id AS steamId, SUM(t.${amount}) AS value
       FROM ${table} t
       LEFT JOIN ${STATS} s
         ON s.server_id = t.server_id AND s.wipe_id = t.wipe_id AND s.steam_id = t.steam_id
      WHERE t.server_id = ? AND t.wipe_id = ? AND t.${key} IN (${names.map(() => '?').join(', ')})
      GROUP BY t.steam_id
      ORDER BY value DESC, MAX(s.last_seen) DESC
      LIMIT ?`,
    [...params, ...names, limit],
  )
}

/** The admin's category titles (D175), as stat → text. */
async function categoryTitles() {
  const rows = await core.query(`SELECT stat, text FROM ${CATEGORIES}`)
  return Object.fromEntries(rows.map((r) => [r.stat, r.text]))
}

/** The same, with who changed each and when, for the admin screen. */
async function listCategories() {
  return core.query(`SELECT stat, text, updated_by AS updatedBy, updated_at AS updatedAt FROM ${CATEGORIES}`)
}

async function setCategory(stat, text, userId = null) {
  await core.query(
    `INSERT INTO ${CATEGORIES} (stat, text, updated_by, updated_at) VALUES (?, ?, ?, CURRENT_TIMESTAMP)
     ON DUPLICATE KEY UPDATE text = VALUES(text), updated_by = VALUES(updated_by), updated_at = CURRENT_TIMESTAMP`,
    [stat, text, userId],
  )
}

/** Reset: the row goes, and the module's default is back. */
async function clearCategory(stat) {
  await core.query(`DELETE FROM ${CATEGORIES} WHERE stat = ?`, [stat])
}

module.exports = {
  RULES,
  listRules,
  listAllRules,
  getMode,
  listModes,
  saveSettings,
  standings,
  categoryTitles,
  listCategories,
  setCategory,
  clearCategory,
}