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Java Marine API is an NMEA 0183 library for Java (http://ktuukkan.github.io/marine-api/).

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/*
 * ActivityMonitor.java
 * Copyright (C) 2012 Kimmo Tuukkanen
 * 
 * This file is part of Java Marine API.
 * 
 * 
 * Java Marine API is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * Java Marine API is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with Java Marine API. If not, see .
 */
package net.sf.marineapi.nmea.io;

/**
 * Monitor for firing state change events events, i.e. reader started, paused or
 * stopped.
 * 
 * @author Kimmo Tuukkanen
 */
class ActivityMonitor {

	private long lastUpdated = -1;
	private SentenceReader parent;

	public ActivityMonitor(SentenceReader parent) {
		this.parent = parent;
	}

	/**
	 * Resets the monitor in initial state.
	 */
	public void reset() {
		lastUpdated = -1;
	}

	/**
	 * Refreshes the monitor timestamp and fires reading started event if
	 * currently paused.
	 */
	public void refresh() {
		if (lastUpdated < 0) {
			parent.fireReadingStarted();
		}
		this.lastUpdated = System.currentTimeMillis();
	}

	/**
	 * Heartbeat method, checks the time out if not paused.
	 */
	public void tick() {
		if (lastUpdated > 0) {
			long elapsed = System.currentTimeMillis() - lastUpdated;
			int timeout = parent.getPauseTimeout();
			if (elapsed >= timeout) {
				parent.fireReadingPaused();
				reset();
			}
		}
	}
}