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package edu.nps.moves.logger;

import edu.nps.moves.disutil.PduContainer;
import java.io.*;
import java.util.*;
import java.util.concurrent.*;

import edu.nps.moves.dis.*;

/**
 * Writes the contents of the PDU buffer to the file in a separate thread.
 * 
 * This accepts Lists of PDUs from the reader thread and writes them out in
 * XML format. Since the reader thread may be faster at times than the writer,
 * we can queue up PDU lists and write them out as we get the chance.
 *
 * @author mcgredo
 * @version $Id:$
 */
public class LogWriter implements Runnable {

    String exerciseName;
    boolean writing = false;
    boolean unqueuedPdus = false;
    BlockingQueue> listQueue = new LinkedBlockingQueue>();

    /** Creates a new instance of LogWriter. Exercise name is used to
     * create a directory we write log files to
     * @param pExerciseName
     */
    public LogWriter(String pExerciseName) {
        exerciseName = pExerciseName;
    }

    /** 
     * Irritating interaction with the reder thread. They may have read a
     * few PDUs, but don't have enough for a "full" list to send to us.
     * this keeps the writer thread alive until it sends the data to us.
     * @param state
     */
    public void setUnqueuedPdus(boolean state) {
        unqueuedPdus = state;
    }

    /**
     *  Add a list of PDUs to our write queue
     * @param pduList
     */
    public void addListToWriteQueue(List pduList) {
        try {
            listQueue.put(pduList);
        //System.out.println("enqued pdu list of size " + pduList.size());
        } catch (Exception e) {
            System.out.println("unable to add list to write queue" + e);
        }
    }

    /**
     * Create a directory to hold the log files
     */
    private void createLogDirectory() {
        try {
            // Create the directory the log files will be in; this is the exercise name.
            // It may be that this directory has already been created.
            File logDirectory = new File(exerciseName);
            boolean createdDirectory = logDirectory.mkdir();
            if (createdDirectory) {
                System.out.println("created log directory " + exerciseName);
            } else {
                //System.out.println("could not create log directory; assuming is is already there " + exerciseName);
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }

    /**
     * Start writing PDUs. This blocks if it has no PDU lists to write.
     */
    public void run() {
        this.createLogDirectory();

        long startTime = System.currentTimeMillis();
        int count = 0;

        while (true) {
            try {
                // Blocks until there's something in the queue to take
                List pdusToLog = listQueue.take();

                // Flip on a boolean so we don't quit out of the thread while
                // still writing PDUs to disk
                writing = true;

                // Create a log file name, or the format "exerciseName_nnnnn"
                long time = System.currentTimeMillis();
                String fileName = exerciseName + "/" + exerciseName + "_" + time + ".xml";

                PduContainer container = new PduContainer();
                container.setPdus(pdusToLog);

                // Marshall the list out to a file. The long list of class names is
                // essentially all the classes in the dis package; this is the safest
                // option for jaxb. You can copy & paste the list from PduContainer.java
                // in the dis package.

                // TODO write PDU to file.

                writing = false;

            } // End try
            catch (Exception e) {
                System.out.println(e);
            }
        }
    }

    /**
     *  Test to see whether we're done writing and it's OK to quit the thread
     */
    public boolean finishedWriting() {
        return ((listQueue.isEmpty()) && (!writing) && (!unqueuedPdus));
    }
}