// 通用排序工具：在分页列表内与相邻行交换 sortOrder
// 用法：
//   const { swapAdjacent } = useAdminSort('/api/admin/faqs')
//   await swapAdjacent(currentRow, neighborRow)  // 把两条的 sortOrder 字段互换并落库
export function useAdminSort(apiBase) {
  const { adminFetch } = useAdmin()

  async function swapAdjacent(a, b) {
    if (!a || !b) return
    const orderA = a.sortOrder ?? 0
    const orderB = b.sortOrder ?? 0
    // 同时发两次 PUT（并行）
    await Promise.all([
      adminFetch(`${apiBase}/${a.id}`, { method: 'PUT', body: { sortOrder: orderB } }),
      adminFetch(`${apiBase}/${b.id}`, { method: 'PUT', body: { sortOrder: orderA } }),
    ])
    a.sortOrder = orderB
    b.sortOrder = orderA
  }

  // 在列表内按 UI 位置上移/下移（仅与相邻行交换）
  async function moveUp(list, index) {
    if (index <= 0) return
    const a = list[index]
    const b = list[index - 1]
    await swapAdjacent(a, b)
    // UI 顺序也要立即交换，让人看见结果
    ;[list[index - 1], list[index]] = [list[index], list[index - 1]]
  }

  async function moveDown(list, index) {
    if (index >= list.length - 1) return
    const a = list[index]
    const b = list[index + 1]
    await swapAdjacent(a, b)
    ;[list[index], list[index + 1]] = [list[index + 1], list[index]]
  }

  return { swapAdjacent, moveUp, moveDown }
}