praktikum-holons/src/holeg/ui/model/UndoHistory.java

package holeg.ui.model;

import java.util.Optional;

public class UndoHistory {
    public static final int NumberOfSaves = 35;
    private static final LimitedSizeQueue<String> jsonSaves = new LimitedSizeQueue<>(NumberOfSaves);
    private static int actualIndex = -1;


    public static boolean canUndo(){
        return actualIndex > 0;
    }
    public static Optional<String> undo(){
        if(canUndo()){
            actualIndex -= 1;
            return Optional.of(jsonSaves.get(actualIndex));
        }
        return Optional.empty();
    }
    public static boolean canRedo(){
        return actualIndex < jsonSaves.size() -1;
    }
    public static Optional<String> redo(){
        if(canRedo()){
            actualIndex += 1;
            return Optional.of(jsonSaves.get(actualIndex));
        }
        return Optional.empty();
    }

    public static  void addSave(String save){
        if(canRedo()){
            jsonSaves.removeRange(actualIndex + 1, jsonSaves.size());
        }
        if(actualIndex < NumberOfSaves){
            actualIndex += 1;
        }
        jsonSaves.add(save);
    }

}