struct _gsmFS {
  String lastPath;
  String items[16];
  String trail[8];
  char drive;
  long drvSize;
  int len;
  int depth;
}
gsmFS;

String strings[] = {
  "ONE", "TWO", "THREE", "FOUR", "FIVE", "SIX", "SEVEN", "EIGHT", "NINE", "TEN"
};

void makeList() {
  for (int i = 0; i<10; i++) {
    //Serial1.println(strings[i]);
    gsmFS.items[i] = strings[i];
  }
  gsmFS.len = 10;
}

void lister() {
  /*
  int index = 0;
  int pgSize = 6;
  int page = (index / pgSize);
  int offs = (page * pgSize);
  int lim = (offs+pgSize < gsmFS.len) ? offs+pgSize : gsmFS.len;
  int choice = 0;
  */
  String input;
  int page, offs, index, pgSize = 6;
  int choice, lim = (pgSize < gsmFS.len-1) ? pgSize : gsmFS.len;
  offs = index = 0;

  while (1) {
    Serial1.print("\n\n");
    for (int i = offs; i < lim; i++) {
      Serial1.print((i == index) ? "* " : "> "); 
      Serial1.println(gsmFS.items[i]);
    }
    while (!Serial1.available()) delay(1);
    input = Serial1.readStringUntil('\n'); input.trim();
    choice = input.toInt();
    if (choice == 2 || choice == 8) {
      if (choice == 2) 
        index = (index > 0) ? index-1 : index;
      else if (choice == 8)
        index = (index < gsmFS.len-1) ? index+1 : index;
      page = (index / pgSize);
      offs = (page * pgSize);
      lim = (offs+pgSize < gsmFS.len-1) ? offs+pgSize : gsmFS.len;
    }
    //Serial1.print("choice: "); Serial1.println(choice);
    delay(1);
  }
}

void setup() {
  Serial1.begin(115200);
  Serial1.println("Ready");

  makeList();
  lister();
}

void loop() {
  delay(1);
}