/*
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN
 * OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR
 * FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR
 * PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF
 * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that Software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of
 * any nuclear facility. 
 */


import java.io.Serializable;

/**
 *
 * @author Matthew Bohm
 */
public class SimpleTask implements Runnable, Serializable {
    
    private String taskId;
    private Thread thread;      //thread in which to run task. task is in progress if thread != null
    private boolean paused, cancelled;   //indicates task has been paused or cancelled by client and not yet restarted
    private boolean indeterminate, doomed, failed;  //indicates whether progress is indeterminate or if task is doomed to fail or failed
    private int percentage, interval = 1200, sleepDelay = 800, indeterminatePercentage = 0;
    
    /** Creates a new instance of SimpleTask */
    public SimpleTask(String taskId, int interval, int sleepDelay, boolean indeterminate) {
        if (taskId == null) {
            throw new NullPointerException();
        }
        this.taskId = taskId;
        if (interval >= 0) {
            this.interval = interval;
        }
        if (sleepDelay > 0) {
            this.sleepDelay = sleepDelay;
        }
        this.indeterminate = indeterminate;
    }
    
    public String getTaskId() {
        return taskId;
    }
    
    public int getInterval() {
        return interval;
    }
    
    public int getPercentage() {
        return percentage;
    }
    
    public boolean isFailed() {
        return failed;
    }
    
    public int getStatus() {
        int percentageSnapshot = percentage;
        if (failed) {
            return -1;
        }
        else if (cancelled) {
            return 4;
        }
        else if (paused) {
            return 2;
        }
        else if (percentageSnapshot >= 100) {
            return 5;
        }
        else if (thread == null) {
            return 0;
        }
        else {
            return 1;
        }
    }
    
    public synchronized String getPercentageText() {
        StringBuffer sb = new StringBuffer();
        int percentageSnapshot = percentage;
        if (!indeterminate || percentage == 0) {
            sb.append(percentageSnapshot);
            sb.append("%<br />");
        }
        if (failed) {
            sb.append("(failed)");
        }
        else if (cancelled) {
            sb.append("(cancelled)");
        }
        else if (paused) {
            sb.append("(paused)");
        }
        else if (percentageSnapshot >= 100) {
            sb.append("(complete)");
        }
        else if (percentageSnapshot == -1) {
            sb.append("(time remaining unknown)");
        }
        else if (thread == null) {
            sb.append("(not started)");
        }
        else {
            //sb.append("(in progress)");
        }
        return sb.toString();
    }
    
    public synchronized void start(boolean doomed) {
        if (thread != null && (paused || cancelled)) {
            //task is taking a while to actually pause or cancel
            //give it a few chances
            for (int i = 0; i < 3; i++) {
                try {
                    Thread.sleep(sleepDelay + 300);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (thread == null) {
                    break;
                }
            }
            if (thread != null) {
                System.err.println("Could not restart task " + taskId + ": task is taking too long to pause or cancel");
            }
        }
        if (thread != null) {
            System.err.println("Could not start task " + taskId + ": task already in progress");
            return;
        }
        if (indeterminate && percentage == 0) { //never started before
            percentage = -1;
        }
        //if task is already complete, failed, or has been cancelled, restart task from the beginnning
        if (percentage >= 100 || cancelled || failed) {
            if (indeterminate) {
                percentage = -1;
                indeterminatePercentage = 0;
            }
            else {
                percentage = 0;
            }
        }
        //we're about to (re)start the task, so set pause and cancelled to false
        paused = false;
        cancelled = false;
        failed = false;
        this.doomed = doomed;
        //(re)start the task
        thread = new Thread(this);
        thread.start();
    }
    
    public synchronized void pause() {
        paused = true;
    }
    
    public synchronized void cancel() {
        cancelled = true;
    }
    
    public void run() {
        while(!failed && !paused && !cancelled && percentage < 100) {
            try {
                Thread.sleep(sleepDelay);
            }
            catch (InterruptedException e) {
                e.printStackTrace();
            }
            if (!paused && !cancelled) {    //operation could have been paused or cancelled during sleep
                if (indeterminate) {
                    indeterminatePercentage++;
                    if (doomed) {
                        if (indeterminatePercentage > 24) {
                            failed = true;
                        }
                    }
                    else if (indeterminatePercentage > 44) {
                        percentage = 100;
                    }
                }
                else {
                    percentage++;
                    if (doomed && percentage > 24) {
                        failed = true;
                    }
                }
            }
        }
        //task is complete or has been paused/cancelled, so thread's execution will discontinue
        //release reference to the thread
        thread = null;
    }
}