import { Request, Response } from 'express'
import pool from '../utils/db'
import { RowDataPacket } from 'mysql2'

/**
 * Filter products where stock < 20, sorted by stock ascending.
 * Pure logic extracted for testability.
 */
export function filterStockAlerts(
  products: { id: number; name: string; style_no: string; stock: number }[]
): typeof products {
  return products
    .filter((p) => p.stock < 20)
    .sort((a, b) => a.stock - b.stock)
}

// GET /api/admin/stock-alerts
export async function getStockAlerts(_req: Request, res: Response): Promise<void> {
  try {
    const [rows] = await pool.execute<RowDataPacket[]>(
      `SELECT id, name, style_no, stock
       FROM products
       WHERE stock < 20
       ORDER BY stock ASC`
    )
    res.json({ code: 0, data: rows })
  } catch (err) {
    console.error('getStockAlerts error:', err)
    res.status(500).json({ code: 500, message: '获取库存预警失败' })
  }
}