/* Copyright (c) 2011 Danish Maritime Authority.
 
*
 
* Licensed under the Apache License, Version 2.0 (the "License");
 
* you may not use this file except in compliance with the License.
 
* You may obtain a copy of the License at
 
*
 
*
     
http://www.apache.org/licenses/LICENSE-2.0
 
*
 
* Unless required by applicable law or agreed to in writing, software
 
* distributed under the License is distributed on an "AS IS" BASIS,
 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 
* See the License for the specific language governing permissions and
 
* limitations under the License.
 
*/
package dk.dma.ais.virtualnet.transponder;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

import org.apache.commons.lang.StringUtils;

import dk.dma.ais.sentence.Sentence;
import dk.dma.ais.sentence.SentenceException;
import net.jcip.annotations.NotThreadSafe;

@NotThreadSafe
public class StreamTime {
        

    
private static final int INTERVAL = 10000;
    

    
private static final SimpleDateFormat DATEFORMAT;
    

    
static {
        
DATEFORMAT = new SimpleDateFormat("yyyyMMdd HHmmss");
        
DATEFORMAT.setTimeZone(TimeZone.getTimeZone("GMT+0000"));
    
}
    

   

    
private long lastSent;
    
private long offset;
    

        

    
public void setStreamTime(long timestamp) {
        
offset = System.currentTimeMillis() - timestamp;
    
}
    

    
public long getTime() {
        
return System.currentTimeMillis() - offset;
    
}
    

    
public boolean isDue() {
        
return System.currentTimeMillis() - lastSent > INTERVAL;
        

    
}
    

    
public String createPstt() {
        
lastSent = System.currentTimeMillis();
        
String dateStr = DATEFORMAT.format(new Date(getTime()));
        
String[] dateParts = StringUtils.split(dateStr);
        
String sentence = String.format("$PSTT,10A,%s,%s", dateParts[0], dateParts[1]);
        
String checksum = "00";
        
try {
            
checksum = Sentence.getStringChecksum(Sentence.getChecksum(sentence));
        
} catch (SentenceException e) {
            
e.printStackTrace();
        
}
        
return sentence + "*" + checksum;
    
}

}