index.html

<h2>convert GGC codes</h2>
input and hit enter
<br>
<p>Code IATA <input id="iata" type="text" size=5></p>
<p>Code GGC <input id="ggc" type="text" size=5></p>

main.dart

// https://lafibre.info/peering-google/ggc-google-global-cache-chez-sfr/msg239012/#msg239012
 
import 'dart:html';
import 'dart:convert';
 
const String table = '1023456789abcdefghijklmnopqrstuvwxyz';
 
String iata2sn (String iata)
{
  AsciiCodec c = new AsciiCodec();
  int aCode = c.encode('a').first;
  List<int> iatan= c.encode(iata);
  print(iatan);
  print(iata.runes);
 
  return iatan.map((int i) => table[((i-aCode)*7+5)%36]).join();
}
 
String sn2iata (String sn)
{
  return sn.runes.map((int i) { 
  	i=table.indexOf(new String.fromCharCode(i));
  	i = (5-i%7)*5+i~/7+10;
    return table[i];
  }).join();
}
 
void main() {
  
  InputElement sIata = querySelector('#iata');
  InputElement sGgc = querySelector('#ggc');
 
  sIata.onChange.listen((_) {
    sGgc.value = iata2sn(sIata.value);
  });
 
   sGgc.onChange.listen((_) {
    sIata.value = sn2iata(sGgc.value);
  });
}