source: osm/applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/commands/MapillaryRecord.java@ 31245

package org.openstreetmap.josm.plugins.mapillary.commands;

import java.util.ArrayList;

/**
 * History record system in order to let you undo commands
 * @author nokutu
 *
 */
public class MapillaryRecord {
        public static MapillaryRecord INSTANCE;

        public ArrayList<MapillaryCommand> commandList;
        /** Last written command */
        public int position;

        public MapillaryRecord() {
                commandList = new ArrayList<>();
                position = -1;
        }

        public static synchronized MapillaryRecord getInstance() {
                if (MapillaryRecord.INSTANCE == null)
                        MapillaryRecord.INSTANCE = new MapillaryRecord();
                return MapillaryRecord.INSTANCE;
        }

        /**
         * Adds a new command to the list.
         * 
         * @param command
         */
        public void addCommand(MapillaryCommand command) {
                commandList.add(position + 1, command);
                position++;
                while (commandList.size() > position + 1) {
                        commandList.remove(position + 1);
                }
        }

        /**
         * Undo latest command.
         */
        public void undo() {
                if (position == -1)
                        return;
                commandList.get(position).undo();
                position--;
        }

        /**
         * Redo latest undoed action.
         */
        public void redo() {
                if (position >= commandList.size())
                        return;
                commandList.get(position).redo();
                position++;
        }
}