package memento;

import java.util.ArrayDeque;
import java.util.Deque;

/**
 * Caretaker — manages the stack of mementos.
 * It does NOT open or inspect the mementos; it just stores and returns them.
 */
public class History {
    private final Deque<EditorMemento> snapshots = new ArrayDeque<>();

    public void save(EditorMemento memento) {
        snapshots.push(memento);
        System.out.println("  [History] Saved: " + memento);
    }

    public EditorMemento undo() {
        if (snapshots.isEmpty()) return null;
        return snapshots.pop();
    }

    public int size() { return snapshots.size(); }
}