export type FriendlyApiError = {
  summary: string
  detail?: string
}

type MaybeAxiosError = {
  isAxiosError?: boolean
  response?: { status?: number; data?: unknown }
  code?: string
  message?: string
}

function stringifyMaybe(value: unknown): string {
  if (value == null) return ''
  if (typeof value === 'string') return value
  try {
    return JSON.stringify(value)
  } catch {
    return String(value)
  }
}

export function toFriendlyApiError(err: unknown): FriendlyApiError {
  const maybeAxios = err as MaybeAxiosError | null
  const isAxiosError = Boolean(maybeAxios && typeof maybeAxios === 'object' && maybeAxios.isAxiosError)
  if (!isAxiosError) {
    const detail = err instanceof Error ? err.message : stringifyMaybe(err)
    return { summary: '请求失败', detail: detail || undefined }
  }

  const status = maybeAxios?.response?.status
  const data: any = maybeAxios?.response?.data
  const serverMessage = stringifyMaybe(data?.message || data?.error || data)

  if (!status) {
    if (maybeAxios?.code === 'ECONNABORTED') return { summary: '请求超时', detail: '服务器响应超时，请稍后重试。' }
    if (maybeAxios?.code === 'ERR_NETWORK' || maybeAxios?.message === 'Network Error') {
      return { summary: '无法连接到服务器', detail: '请确认后端服务已启动，或检查网络/CORS 配置。' }
    }
    if (maybeAxios?.code === 'ERR_CANCELED') return { summary: '请求已取消' }
    return { summary: '网络异常', detail: '请检查网络连接或稍后重试。' }
  }

  if (status === 401) return { summary: '登录已失效', detail: serverMessage || '请重新登录后继续操作。' }
  if (status === 403) return { summary: '没有权限', detail: serverMessage || '当前账号无权限访问该资源。' }
  if (status === 404) return { summary: '资源不存在', detail: serverMessage || '接口不存在或已下线。' }
  if (status >= 500) return { summary: '服务器异常', detail: serverMessage || '服务端发生错误，请稍后重试。' }
  if (status === 400) return { summary: '请求参数错误', detail: serverMessage || '请检查输入内容后重试。' }

  return { summary: `请求失败 (${status})`, detail: serverMessage || undefined }
}