import java.util.ArrayList;

/**
 * Towers of Hanoi.
 * <p>
 * Fill in the three TODOs, in this order:
 * move     then run TestMove to check it
 * isLegal  then run TestIsLegal to check it
 * hanoi    then run this file and press Solve
 */
public class Hanoi {

  // pegs.get(p) is peg p; bottom disk at index 0, top disk at the end
  static ArrayList<ArrayList<Integer>> pegs = new ArrayList<ArrayList<Integer>>();
  static HanoiView view;
  static int selected = -1;   // peg picked up in manual play, or -1

  /**
   * Put n disks on peg 0, largest at the bottom; pegs 1 and 2 empty.
   */
  static void setup(int n) {
    pegs.clear();
    for (int p = 0; p < 3; p++) {
      pegs.add(new ArrayList<Integer>());
    }
    for (int d = n; d >= 1; d--) {
      pegs.getFirst().add(d);
    }
  }

  /**
   * Can the top disk of 'from' go on top of 'to'?
   */
  static boolean isLegal(int from, int to) {
    ArrayList<Integer> a = pegs.get(from);
    ArrayList<Integer> b = pegs.get(to);
    // TODO
    return false;
  }

  /**
   * Move the top disk of 'from' onto 'to', then show it.
   */
  static void move(int from, int to) {
    // TODO
    view.show(from, to);
  }

  /**
   * Move n disks from peg a to peg b, using peg c.
   */
  static void hanoi(int n, int a, int b, int c) {
    // TODO
  }

  static void main(String[] args) {
    int n = 4;
    setup(n);
    view = new HanoiView(pegs);

    while (view.running()) {
      String event = view.nextEvent();

      if (event.equals("size")) {
        n = view.size();
        setup(n);
        selected = -1;
        view.select(-1);
        view.refresh();
      } else if (event.equals("reset")) {
        setup(n);
        selected = -1;
        view.select(-1);
        view.refresh();
      } else if (event.equals("solve")) {
        setup(n);
        selected = -1;
        view.select(-1);
        view.refresh();
        hanoi(n, 0, 2, 1);
      } else if (event.equals("click")) {
        int peg = view.clickedPeg();
        if (selected == -1) {
          if (!pegs.get(peg).isEmpty()) {
            selected = peg;
            view.select(peg);
          }
        } else {
          // ignore any IntelliJ warning about "this is always false"
          if (peg != selected && isLegal(selected, peg)) {
            move(selected, peg);
          }
          selected = -1;
          view.select(-1);
        }
      }
    }
  }
}