// Offline example: prints signed JSON only; never sends an order.
import crypto from 'node:crypto';
export function createSign(secretKey,params){
 const scalar=value=>typeof value==='object'?JSON.stringify(value):String(value);
 const body=Object.keys(params||{}).filter(key=>!['sign','cards'].includes(key)&&params[key]!==undefined&&params[key]!==null&&params[key]!=='')
   .sort().map(key=>`${key}=${scalar(params[key])}`).join('&');
 return crypto.createHash('md5').update(`${secretKey}${body}${secretKey}`.toLowerCase(),'utf8').digest('hex');
}
const vectors=[
 {secret:'FakeSecret#A',params:{dealer_no:'DEMO001',timestamp:1800000000,pageNum:1,pageSize:100}},
 {secret:'FakeSecret#A',params:{z:0,a:false,empty:'',nil:null,account:'CaseSensitive',payment_amount:'1.0000',cards:['ignored'],sign:'ignored'}}
];
for(const v of vectors)console.log(JSON.stringify({...v,expected:createSign(v.secret,v.params)}));