import type { RowDataPacket, ResultSetHeader } from 'mysql2'
import { db, DB } from './db'

/**
 * Códigos de promoción: se canjean por PD y/o PV. Cada código tiene usos totales
 * limitados (`max_uses`) y solo puede canjearse una vez por cuenta. Los códigos
 * son sensibles a mayúsculas/minúsculas (columna con collation utf8mb4_bin).
 */

export interface RedeemResult {
  success: boolean
  error?: string
  pd?: number
  pv?: number
}

export async function redeemPromoCode(accountId: number, rawCode: string): Promise<RedeemResult> {
  const code = rawCode.trim()
  if (!accountId) return { success: false, error: 'notAuthenticated' }
  if (!code) return { success: false, error: 'missingCode' }
  if (code.length > 64) return { success: false, error: 'notFound' }

  const conn = await db(DB.default).getConnection()
  try {
    await conn.beginTransaction()

    // Bloquea la fila del código (comparación binaria => sensible a may/min).
    const [rows] = await conn.query<RowDataPacket[]>(
      'SELECT id, pd, pv, max_uses, uses, active, expires_at FROM promocode WHERE code = ? COLLATE utf8mb4_bin LIMIT 1 FOR UPDATE',
      [code],
    )
    const promo = rows[0]
    if (!promo || promo.active !== 1) {
      await conn.rollback()
      return { success: false, error: 'notFound' }
    }
    if (promo.expires_at && new Date(promo.expires_at).getTime() <= Date.now()) {
      await conn.rollback()
      return { success: false, error: 'expired' }
    }
    if (Number(promo.uses) >= Number(promo.max_uses)) {
      await conn.rollback()
      return { success: false, error: 'exhausted' }
    }

    // Registra el canje (la clave única promo+cuenta evita el doble uso).
    try {
      await conn.query('INSERT INTO promoredemption (promo_id, account_id, redeemed_at) VALUES (?, ?, NOW())', [
        promo.id,
        accountId,
      ])
    } catch (e) {
      await conn.rollback()
      if ((e as { code?: string }).code === 'ER_DUP_ENTRY') return { success: false, error: 'alreadyUsed' }
      return { success: false, error: 'genericError' }
    }

    // Consume un uso (condicional, por si hubo carrera con otro canje).
    const [upd] = await conn.query<ResultSetHeader>(
      'UPDATE promocode SET uses = uses + 1 WHERE id = ? AND uses < max_uses',
      [promo.id],
    )
    if (upd.affectedRows !== 1) {
      await conn.rollback()
      return { success: false, error: 'exhausted' }
    }

    // Acredita PD/PV a la cuenta (upsert).
    const pd = Number(promo.pd)
    const pv = Number(promo.pv)
    await conn.query(
      'INSERT INTO api_points (accountID, vp, dp) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE vp = vp + VALUES(vp), dp = dp + VALUES(dp)',
      [accountId, pv, pd],
    )

    await conn.commit()
    return { success: true, pd, pv }
  } catch {
    try {
      await conn.rollback()
    } catch {
      /* ignore */
    }
    return { success: false, error: 'genericError' }
  } finally {
    conn.release()
  }
}