package com.roboclub.robobuggy.nodes.baseNodes;

import com.roboclub.robobuggy.messages.StateMessage;
import com.roboclub.robobuggy.ros.NodeChannel;
import com.roboclub.robobuggy.ros.Publisher;

import java.util.Timer;
import java.util.TimerTask;

/**
 * Base implementation of a Buggy {@link BuggyNode} to be decorated
 * with {@link BuggyDecoratorNode}s according to the decorator pattern.
 * The {@link BuggyBaseNode} implements the functionality for health/status
 * monitoring.
 *
 * @author Zachary Dawson
 */
public class BuggyBaseNode implements BuggyNode {
    private String name;
    private static final long WATCHDOG_PERIOD = 2000;

    private Publisher statePub;
    private NodeState state;
    private Long lastUpdate;
    private Timer timer;

    /**
     * Construct a new {@link BuggyBaseNode}
     *
     * @param nodeChannel {@link NodeChannel} for the node being created
     */
    public BuggyBaseNode(NodeChannel nodeChannel) {
        statePub = new Publisher(nodeChannel.getStatePath());
        state = NodeState.NOT_IN_USE;
        lastUpdate = 0L;
        TimerTask timerTask = new UpdateTask();
        timer = new Timer(true);
        timer.scheduleAtFixedRate(timerTask, 0, WATCHDOG_PERIOD);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean startNode() {
        //Set the state to be on and record the time
        state = NodeState.ON;
        lastUpdate = System.currentTimeMillis();
        //Return true as the base node can always be started
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean shutdown() {
        //Set the state to not in use
        state = NodeState.NOT_IN_USE;
        timer.cancel(); //needs to stop the thread from continuing to operate
        //Return true as the base node can always be shut down
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setNodeState(NodeState state) {
        this.state = state;
        lastUpdate = System.currentTimeMillis();
    }

    /**
     * Task used to call the update method
     */
    private class UpdateTask extends TimerTask {

        @Override
        public void run() {
            if (System.currentTimeMillis() - lastUpdate > WATCHDOG_PERIOD &&
                    state == NodeState.ON) {
                state = NodeState.WATCHDOG_DEAD;
            }
            statePub.publish(new StateMessage(state));
        }
    }

    /**
     * used for updating the name by which this node is known
     *
     * @param newName the new name for this node
     */
    public void setName(String newName) {
        name = newName;
    }

    /**
     * gives access to the current value of this nodes name
     *
     * @return the name of the node
     */
    public String getName() {
        return name;
    }

}