export function getErrorMessage(error: unknown): string {
  if (typeof error === 'string') return error;
  
  const message = error instanceof Error ? error.message : '未知错误';

  // Postgres/Supabase errors
  if (message.includes('invalid input syntax for type uuid')) {
    return 'ID 格式错误 (UUID)';
  }
  if (message.includes('duplicate key value violates unique constraint')) {
    return '数据已存在，请勿重复添加';
  }
  if (message.includes('violates foreign key constraint')) {
    return '关联数据不存在或已被删除';
  }
  if (message.includes('violates not-null constraint')) {
    return '必填项不能为空';
  }
  if (message.includes('JSON object requested, multiple (or no) rows returned')) {
    return '数据查询错误：未找到记录或返回多条记录';
  }
  if (message.includes('Failed to fetch')) {
    return '网络请求失败，请检查网络连接';
  }

  return message;
}