#!/usr/bin/gawk -f

BEGIN{
  FS=OFS=",";
  INGNORECASE=1;
  data=0;
  datas=0;
}

data==0{print;}
data==1{datum[datas++]=$0;}
/@data/{data=1; next; }

END{
  srand(seed);
  for ( i = 0; i < datas; i++ )
  {
    item = int( rand() * datas );
    while ( item in printed ) item = int( rand() * datas );
    printed[item] = 1;
    print datum[item];
  }
}