!7

cmodule AnalyzeWifiOut > DynPrintLog {
  transient new Set<S> current;
  transient Set<S> lastSet;
  transient S date = null;
  transient new L<Change> log;
  
  sclass Change {
    S date;
    Set<S> newNetworks, disappearedNetworks;
  }
  
  start-thread {
    temp CloseableItIt<S> it = linesFromFile(userDir("wifi.out"));
    for (S s : it) {
      if (startsWith(s, "BSS"))
        current.add(s);
      else if (nempty(s)) {
        wrapUp();
        date = s;
        current = new Set;
      }
    }
    wrapUp();
    printShortLog();
  }
  
  void wrapUp {
    if (lastSet != null) {
      Set<S> newNetworks = setMinusSet(current, lastSet);
      Set<S> disappearedNetworks = setMinusSet(lastSet, current);
      if (nempty(newNetworks) || nempty(disappearedNetworks)) {
        log.add(nu Change(+date, +newNetworks, +disappearedNetworks));
        print(date);
        for (S network : newNetworks) print("+" + network);
        for (S network : disappearedNetworks) print("-" + network);
      }
    }
    lastSet = current;
  }
  
  void printShortLog {
    print();
    for (Change c : log)
      print(c.date + ":"
        + (empty(c.newNetworks) ? "" : " +" + l(c.newNetworks))
        + (empty(c.disappearedNetworks) ? "" : " -" + l(c.disappearedNetworks)));
  }
}