/* 
 * Copyright (c) 2002-2008 LWJGL Project
 * 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.
 *
 * * Redistributions 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 'LWJGL' nor the names of 
 *   its contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.lwjgl.util.applet;

import java.applet.Applet;
import java.applet.AppletStub;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilePermission;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.net.SocketPermission;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLConnection;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.CodeSource;
import java.security.PermissionCollection;
import java.security.PrivilegedExceptionAction;
import java.security.SecureClassLoader;
import java.security.cert.Certificate;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
import java.util.jar.Pack200;

import sun.security.util.SecurityConstants;

/**
 * <p>
 * The AppletLoader enables deployment of LWJGL to applets in an easy
 * and polished way. The loader will display a configurable logo and progressbar
 * while the relevant jars (generic and native) are downloaded from a specified source.
 * </p>
 * <p>
 * The downloaded jars are extracted to the users temporary directory - and if enabled, cached for 
 * faster loading in future uses.
 * </p>
 * <p>
 * The following applet parameters are required:
 * <ul>
 * <li>al_main - [String] Full package and class the applet to instantiate and display when loaded.</li>
 * <li>al_logo - [String Path of of the logo resource to paint while loading.</li>
 * <li>al_progressbar - [String] Path of the progressbar resource to paint on top of the logo, width clipped by percentage.</li>
 * <li>al_jars - [String] Comma seperated list of jars to download.</li>
 * <li>al_windows - [String] Jar containing native files for windows.</li>
 * <li>al_linux - [String] Jar containing native files for linux.</li>
 * <li>al_mac - [String] Jar containing native files for mac.</li>
 * <li>al_solaris - [String] Jar containing native files for solaris.</li>
 * </ul>
 * </p>
 * <p>
 * Additionally the following parameters can be supplied to tweak the behaviour of the AppletLoader.
 * <ul>
 * <li>al_version - [int or float] Version of deployment. If this is specified, the jars will be cached and 
 * reused if the version matches. If version doesn't match all of the files are reloaded.</li>
 * <li>al_bgcolor - [String] Hex formated color to use as background. <i>Default: ffffff</i>.</li>
 * <li>al_fgcolor - [String] Hex formated color to use as foreground. <i>Default: 000000</i>.</li>
 * <li>al_errorcolor - [String] Hex formated color to use as foreground color on error. <i>Default: ff0000</i>.</li>
 * <li>al_debug - [boolean] Whether to enable debug mode. <i>Default: false</i>.</li>
 * <li>al_prepend_host - [boolean] Whether to limit caching to this domain, disable if your applet is hosted on multple domains and needs to share the cache. <i>Default: true</i>.</li>
 * </ul>
 * </p>
 * @author kappaOne
 * @author Brian Matzon <brian@matzon.dk>
 * @version $Revision$
 * $Id$
 */
public class AppletLoader extends Applet implements Runnable, AppletStub {
	
	/** initializing */
	public static final int STATE_INIT 						= 1;
	
	/** determining which packages that are required */
	public static final int STATE_DETERMINING_PACKAGES 		= 2;
	
	/** checking for already downloaded files */
	public static final int STATE_CHECKING_CACHE 			= 3;
	
	/** downloading packages */
	public static final int STATE_DOWNLOADING 				= 4;
	
	/** extracting packages */
	public static final int STATE_EXTRACTING_PACKAGES 		= 5;
	
	/** updating the classpath */
	public static final int STATE_UPDATING_CLASSPATH 		= 6;
	
	/** switching to real applet */
	public static final int STATE_SWITCHING_APPLET 			= 7;

	/** initializing real applet */
	public static final int STATE_INITIALIZE_REAL_APPLET	= 8;
	
	/** stating real applet */
	public static final int STATE_START_REAL_APPLET 		= 9;
	
	/** done */
	public static final int STATE_DONE 						= 10;
	
	/** used to calculate length of progress bar */
	protected int		percentage;

	/** current size of download in bytes */
	protected int		currentSizeDownload; 

	/** total size of download in bytes */
	protected int		totalSizeDownload; 

	/** current size of extracted in bytes */
	protected int		currentSizeExtract; 

	/** total size of extracted in bytes */
	protected int		totalSizeExtract; 
	
	/** logo to be shown while loading */
	protected Image		logo;

	/** progressbar to render while loading */
	protected Image		progressbar;
	
	/** offscreen image used */
	protected Image 	offscreen;
	
	/** background color of applet */
	protected Color		bgColor 	= Color.white;
	
	/** Color to write errors in */
	protected Color		errorColor 	= Color.red;

	/** color to write foreground in */
	protected Color		fgColor 	= Color.black;	

	/** urls of the jars to download */
	protected URL[]		urlList;
	
	/** classLoader used to add downloaded jars to the classpath */
	protected ClassLoader classLoader;
	
	/** actual thread that does the loading */
	protected Thread	loaderThread;
	
	/** animation thread that renders our load screen while loading */
	protected Thread 	animationThread;

	/** applet to load after all downloads are complete */
	protected Applet	lwjglApplet;
	
	/** whether a fatal error occured */
	protected boolean	fatalError;
	
	/** fatal error that occured */
	protected String	fatalErrorDescription;
	
	/** whether we're running in debug mode */
	protected boolean 	debugMode;
	
	/** whether to prepend host to cache path */
	protected boolean 	prependHost;
	
	/** String to display as a subtask */
	protected String	subtaskMessage = "";

	/** state of applet loader */
	protected int		state = STATE_INIT;
	
	/** whether lzma is supported */
	protected boolean 	lzmaSupported = false;
	
	/** whether pack200 is supported */
	protected boolean 	pack200Supported = false;
	
	/** generic error message to display on error */
	protected String[] 	genericErrorMessage = {	"An error occured while loading the applet.",
												"Please contact support to resolve this issue.",
												"<placeholder for error message>"};
	
	/** whether a certificate refused error occured */
	protected boolean	certificateRefused;
	
	/** error message to display if user refuses to accept certicate*/
	protected String[] 	certificateRefusedMessage = { "Permissions for Applet Refused.",
												      "Please accept the permissions dialog to allow",
												      "the applet to continue the loading process."};
	
	/*
	 * @see java.applet.Applet#init()
	 */
	public void init() {
		state = STATE_INIT;
		
		// sanity check
		String[] requiredArgs = {"al_main", "al_logo", "al_progressbar", "al_jars"};
		for(int i=0; i<requiredArgs.length; i++) {
			if(getParameter(requiredArgs[i]) == null) {
				fatalErrorOccured("missing required applet parameter: " + requiredArgs[i], null);
				return;				
			}
		}

		// whether to run in debug mode
		debugMode 		= getBooleanParameter("al_debug", false);
		
		// whether to prepend host to cache path
		prependHost 	= getBooleanParameter("al_prepend_host", true);
		
		// get colors of applet
		bgColor 		= getColor("al_bgcolor", Color.white);
		setBackground(bgColor);

		fgColor 		= getColor("al_fgcolor", Color.black);
		errorColor 		= getColor("al_errorcolor", Color.red);		

		// load logos
		logo 			= getImage(getParameter("al_logo"));
		progressbar 	= getImage(getParameter("al_progressbar"));
		
		//sanity check
		if(logo == null || progressbar == null) {
			fatalErrorOccured("Unable to load logo and progressbar images", null);
		}
		
		// check for lzma support
		try {
			Class.forName("LZMA.LzmaInputStream");
			lzmaSupported = true;
		} catch (Throwable e) {
			/* no lzma support */
		}
		
		// check pack200 support
		try {
			java.util.jar.Pack200.class.getSimpleName();
			pack200Supported = true;
		} catch (Throwable e) {
			/* no pack200 support */
		}		
	}

	/**
	 * Generates a stacktrace in the form of a string
	 * @param exception Exception to make stacktrace of
	 * @return Stacktrace of exception in the form of a string
	 */
	private String generateStacktrace(Exception exception) {
		Writer result = new StringWriter();
		PrintWriter printWriter = new PrintWriter(result);
		exception.printStackTrace(printWriter);
		return result.toString();
	}

	/*
	 * @see java.applet.Applet#start()
	 */
	public void start() {
		if (lwjglApplet != null) {
			lwjglApplet.start();
		}
		else {
			if(loaderThread == null && !fatalError) {
				loaderThread = new Thread(this);
				loaderThread.setName("AppletLoader.loaderThread");
				loaderThread.start();
				
				animationThread = new Thread() {
					public void run() {
						while(loaderThread != null) {
							repaint();
							AppletLoader.this.sleep(100);
						}
						animationThread = null;
					}
				};
				animationThread.setName("AppletLoader.animationthread");
				animationThread.start();
			}
		}
	}
	
	/*
	 * @see java.applet.Applet#stop()
	 */
	public void stop() {
		if (lwjglApplet != null) {
			lwjglApplet.stop();
		}
		super.stop();
	}
	
	/*
	 * @see java.applet.Applet#destroy()
	 */
	public void destroy() {
		if (lwjglApplet != null) {
			lwjglApplet.destroy();
		}
		
		progressbar = null;
		logo 		= null;
		
		super.destroy();
	}
	
	/**
	 * Retrieves the applet that has been loaded. Useful for liveconnect.
	 */
	public Applet getApplet() {
		return lwjglApplet;
	}
	
	/**
	 * Transfers the call of AppletResize from the stub to the lwjglApplet.	 
	 */
	public void appletResize(int width, int height) {
		resize(width, height);
	}	

	/*
	 * @see java.awt.Container#update(java.awt.Graphics)
	 */
	public final void update(Graphics g) {
		paint(g);
	}
	
	/*
	 * @see java.awt.Container#paint(java.awt.Graphics)
	 */
	public void paint(Graphics g) {
		
		// don't paint loader if applet loaded
		if(state == STATE_DONE) {
			return;
		}
		
		// create offscreen if missing
		if (offscreen == null) {
			offscreen = createImage(getWidth(), getHeight());
		}

		// draw everything onto an image before drawing to avoid flicker
		Graphics og = offscreen.getGraphics();
		FontMetrics fm = og.getFontMetrics();

		// set background color
		og.setColor(bgColor);
		og.fillRect(0, 0, getWidth(), getHeight());

		// get logo position so its in the middle of applet
		int x = 0, y = 0;
		
		if(logo != null && !fatalError) {
			x = (getWidth() - logo.getWidth(this)) / 2;
			y = (getHeight() - logo.getHeight(this)) / 2;
		}

		og.setColor(fgColor);
		String message = getDescriptionForState();

		// if we had a failure of some sort, notify the user
		if (fatalError) {
			String[] errorMessage = (certificateRefused) ? certificateRefusedMessage : genericErrorMessage;
			
			if (!certificateRefused) {
				errorMessage[errorMessage.length-1] = fatalErrorDescription;
			}			
			
			for(int i=0; i<errorMessage.length; i++) {
				if(errorMessage[i] != null) {
					int messageX = (getWidth() - fm.stringWidth(errorMessage[i])) / 2;
					int messageY = (getHeight() - (fm.getHeight() * errorMessage.length)) / 2;
					
					og.setColor(errorColor);
					og.drawString(errorMessage[i], messageX, messageY + i*fm.getHeight());
				}
			}
		} else {
			og.setColor(fgColor);

			// draw logo
			og.drawImage(logo, x, y, null);
			
			// draw message
			int messageX = (getWidth() - fm.stringWidth(message)) / 2;
			int messageY = y + logo.getHeight(null) + 20;
			og.drawString(message, messageX, messageY);
			
			// draw subtaskmessage, if any
			if(subtaskMessage.length() > 0) {
				messageX = (getWidth() - fm.stringWidth(subtaskMessage)) / 2;
				og.drawString(subtaskMessage, messageX, messageY+20);
			}

			// draw loading bar, clipping it depending on percentage done
			int barSize = (progressbar.getWidth(this) * percentage) / 100;
			og.clipRect(0, 0, x + barSize, getHeight());
			og.drawImage(progressbar, x, y, null);
		}
		
		og.dispose();

		// finally draw it all
		g.drawImage(offscreen, 0, 0, null);
	}	

	/**
	 * @return string describing the state of the loader
	 */
	protected String getDescriptionForState() {
		switch (state) {
			case STATE_INIT:
				return "Initializing loader";
			case STATE_DETERMINING_PACKAGES:
				return "Determining packages to load";
			case STATE_CHECKING_CACHE:
				return "Checking cache for existing files";
			case STATE_DOWNLOADING:
				return "Downloading packages";
			case STATE_EXTRACTING_PACKAGES:
				return "Extracting downloaded packages";
			case STATE_UPDATING_CLASSPATH:
				return "Updating classpath";
			case STATE_SWITCHING_APPLET:
				return "Switching applet";
			case STATE_INITIALIZE_REAL_APPLET:
				return "Initializing real applet";
			case STATE_START_REAL_APPLET:
				return "Starting real applet";
			case STATE_DONE:
				return "Done loading";
			default:
				return "unknown state";
		}
	}
	
	/**
	 * Trims the passed file string based on the available capabilities
	 * @param file string of files to be trimmed
	 * @return trimmed string based on capabilities of client
	 */
	protected String trimExtensionByCapabilities(String file) {
		if (!pack200Supported) {
			file = file.replaceAll(".pack", "");
		}
		
		if (!lzmaSupported) {
			file = file.replaceAll(".lzma", "");
		}	
		return file;
	}

	/**
	 * Reads list of jars to download and adds the urls to urlList
	 * also finds out which OS you are on and adds appropriate native
	 * jar to the urlList
	 */
	protected void loadJarURLs() throws Exception {
		state = STATE_DETERMINING_PACKAGES;
		
		// jars to load
		String jarList = getParameter("al_jars");
		
		jarList = trimExtensionByCapabilities(jarList);
		
		StringTokenizer jar = new StringTokenizer(jarList, ", ");

		int jarCount = jar.countTokens() + 1;
		
		urlList = new URL[jarCount];

		URL path = getCodeBase();

		// set jars urls
		for (int i = 0; i < jarCount - 1; i++) {
			urlList[i] = new URL(path, jar.nextToken());
		}

		// native jar url
		String osName 		= System.getProperty("os.name");
		String nativeJar 	= null;
		
		if (osName.startsWith("Win")) {
			nativeJar = getParameter("al_windows");
		} else if (osName.startsWith("Linux") || osName.startsWith("FreeBSD")) {
			nativeJar = getParameter("al_linux");
		} else if (osName.startsWith("Mac")) {
			nativeJar = getParameter("al_mac");
		} else if (osName.startsWith("Solaris") || osName.startsWith("SunOS")) {
			nativeJar = getParameter("al_solaris");
		} else {
			fatalErrorOccured("OS (" + osName + ") not supported", null);
		}

		if (nativeJar == null) {
			fatalErrorOccured("no lwjgl natives files found", null);
		} else {
			nativeJar = trimExtensionByCapabilities(nativeJar);
			urlList[jarCount - 1] = new URL(path, nativeJar);
		}
	}

	/**
	 * 4 steps
	 * 
	 * 1) check version of applet and decide whether to download jars
	 * 2) download the jars
	 * 3) extract natives
	 * 4) add to jars to class path
	 * 5) switch applets
	 */
	public void run() {
		state = STATE_CHECKING_CACHE;
		
 		percentage = 5;

 		try {
			debug_sleep(2000);

			// parse the urls for the jars into the url list
			loadJarURLs();
			
			// get path where applet will be stored
			String path = (String) AccessController.doPrivileged(new PrivilegedExceptionAction() {
				public Object run() throws Exception {
					
					// we append the code base to avoid naming collisions with al_title
					String codebase = "";
					if(prependHost) {
						codebase = getCodeBase().getHost();
						if(codebase == null || codebase.length() == 0) {
							codebase = "localhost";
						}
						codebase += File.separator;
					}
					return System.getProperty("java.io.tmpdir") + File.separator + codebase + getParameter("al_title") + File.separator;
				}
			});
			
			File dir = new File(path);

			// create directory
			if (!dir.exists()) {
				dir.mkdirs();
			}
			dir = new File(dir, "version");

			// if applet already available don't download anything
			boolean cacheAvailable = false;

			// version of applet
			String version = getParameter("al_version");
			float latestVersion = 0;
			
			// if applet version specifed, check if you have latest version of applet
			if (version != null) {

				latestVersion = Float.parseFloat(version);

				// if version file exists
				if (dir.exists()) {
					// compare to new version
					if (latestVersion <= readVersionFile(dir)) {
						cacheAvailable = true;
						percentage = 90;
						
						if(debugMode) {
							System.out.println("Loading Cached Applet Version " + latestVersion);
						}
						debug_sleep(2000);
					}
				}
			}

			// if jars not available or need updating download them
			if (!cacheAvailable) {
				// downloads jars from the server
				downloadJars(path);		// 10-55%
				
				// Extract Pack and LZMA files
				extractJars(path);		// 55-65%

				// Extracts Native Files
				extractNatives(path);	// 65-85%

				// add version information once jars downloaded successfully
				if (version != null) {
					percentage = 90;
					writeVersionFile(dir, latestVersion);
				}
			}

			// add the downloaded jars and natives to classpath
			updateClassPath(path);

			// switch to LWJGL Applet
			switchApplet();

			state = STATE_DONE;		
		} catch (AccessControlException ace) {
			fatalErrorOccured(ace.getMessage(), ace);
			certificateRefused = true;
		} catch (Exception e) {
			fatalErrorOccured(e.getMessage(), e);
		} finally {
			loaderThread = null;
		}
	}

	/**
	 * read the current version file
	 * 
	 * @param file the file to read
	 * @return the version value of saved file
	 * @throws Exception if it fails to read value
	 */
	protected float readVersionFile(File file) throws Exception {
		DataInputStream dis = new DataInputStream(new FileInputStream(file));
		float version = dis.readFloat();
		dis.close();
		return version;
	}

	/**
	 * write out version file of applet
	 * 
	 * @param file the file to write out to
	 * @param version the version of the applet as a float
	 * @throws Exception if it fails to write file
	 */
	protected void writeVersionFile(File file, float version) throws Exception {
		DataOutputStream dos = new DataOutputStream(new FileOutputStream(file));
		dos.writeFloat(version);
		dos.close();
	}

	/**
	 * Edits the ClassPath at runtime to include the jars
	 * that have just been downloaded and then adds the
	 * lwjgl natives folder property.
	 * 
	 * @param path location where applet is stored
	 * @throws Exception if it fails to add classpath
	 */
	protected void updateClassPath(String path) throws Exception {
		
		state = STATE_UPDATING_CLASSPATH;
		
		percentage = 95;
		
		URL[] urls = new URL[urlList.length];
		
		for (int i = 0; i < urlList.length; i++) {
			urls[i] = new URL("file:" + path + getJarName(urlList[i]));
		}
		
		// add downloaded jars to the classpath with required permissions
		classLoader = new URLClassLoader(urls) {
			protected PermissionCollection getPermissions (CodeSource codesource) {
				PermissionCollection perms = null;
				
				try {
					// getPermissions from original classloader is important as it checks for signed jars and shows any security dialogs needed
					Method method = SecureClassLoader.class.getDeclaredMethod("getPermissions", new Class[] { CodeSource.class });
					method.setAccessible(true);
					perms = (PermissionCollection)method.invoke(getClass().getClassLoader(), new Object[] {codesource});
					
					String host = getCodeBase().getHost();
			        
			        if (host != null && (host.length() > 0)) {
			        	// add permission for downloaded jars to access host they were from
			        	perms.add(new SocketPermission(host, SecurityConstants.SOCKET_CONNECT_ACCEPT_ACTION));
			        }
			        else if (codesource.getLocation().getProtocol().equals("file")) {
			        	// if running locally add file permission
			        	String path = codesource.getLocation().getFile().replace('/', File.separatorChar);
			            perms.add(new FilePermission(path, SecurityConstants.FILE_READ_ACTION));
			        }
		        
		        } catch (Exception e) {
					e.printStackTrace();
				}
		        
		        return perms;
		    }
		};
		
		debug_sleep(2000);

		// add natives files path to native class path
		System.setProperty("org.lwjgl.librarypath", path + "natives");

		// Make sure jinput knows about the new path too
		System.setProperty("net.java.games.input.librarypath", path + "natives");
	}

	/**
	 * replace the current applet with the lwjgl applet
	 * using AppletStub and initialise and start it
	 */
	protected void switchApplet() throws Exception {
		
		state = STATE_SWITCHING_APPLET;
		percentage = 100;
		
		debug_sleep(2000);

		Class appletClass = classLoader.loadClass(getParameter("al_main"));
		lwjglApplet = (Applet) appletClass.newInstance();

		lwjglApplet.setStub(this);
		lwjglApplet.setSize(getWidth(), getHeight());

		setLayout(new BorderLayout());
		add(lwjglApplet);
		validate();

		state = STATE_INITIALIZE_REAL_APPLET;
		lwjglApplet.init();

		state = STATE_START_REAL_APPLET;
		lwjglApplet.start();
	}

	/**
	 * Will download the jars from the server using the list of urls
	 * in urlList, while at the same time updating progress bar
	 * 
	 * @param path location of the directory to save to
	 * @throws Exception if download fails
	 */
	protected void downloadJars(String path) throws Exception {
		
		state = STATE_DOWNLOADING;

		URLConnection urlconnection;

		// calculate total size of jars to download
		for (int i = 0; i < urlList.length; i++) {
			urlconnection = urlList[i].openConnection();
			urlconnection.setDefaultUseCaches(false);
			totalSizeDownload += urlconnection.getContentLength();
		}
		
		int initialPercentage = percentage = 10;

		// download each jar
		byte buffer[] = new byte[65536];
		for (int i = 0; i < urlList.length; i++) {
			debug_sleep(2000);

			urlconnection = urlList[i].openConnection();
			
			String currentFile = getFileName(urlList[i]);
			InputStream inputstream = getJarInputStream(currentFile, urlconnection);
			FileOutputStream fos = new FileOutputStream(path + currentFile);
			

			int bufferSize;
			long downloadStartTime = System.currentTimeMillis();
			int downloadedAmount = 0;
			String downloadSpeedMessage = "";
			
			while ((bufferSize = inputstream.read(buffer, 0, buffer.length)) != -1) {
				debug_sleep(10);
				fos.write(buffer, 0, bufferSize);
				currentSizeDownload += bufferSize;
				percentage = initialPercentage + ((currentSizeDownload * 45) / totalSizeDownload);
				subtaskMessage = "Retrieving: " + currentFile + " " + ((currentSizeDownload * 100) / totalSizeDownload) + "%";
				
				downloadedAmount += bufferSize;
				long timeLapse = System.currentTimeMillis() - downloadStartTime;
				// update only if a second or more has passed
				if (timeLapse >= 1000) {
					// get kb/s, nice that bytes/millis is same as kilobytes/seconds
					float downloadSpeed = (float) downloadedAmount / timeLapse;
					// round to two decimal places
					downloadSpeed = ((int)(downloadSpeed*100))/100f;
					// set current speed message
					downloadSpeedMessage = " @ " + downloadSpeed + " KB/sec";
					// reset downloaded amount
					downloadedAmount = 0;
					// reset start time
					downloadStartTime = System.currentTimeMillis();
				}
				
				subtaskMessage += downloadSpeedMessage;
			}
			
			inputstream.close();
			fos.close();
		}
		subtaskMessage = "";
	}

	/**
	 * Retrieves a jar files input stream. This method exists primarily to fix an Opera hang in getInputStream
	 * @param urlconnection connection to get input stream from
	 * @return InputStream or null if not possible
	 */
	protected InputStream getJarInputStream(final String currentFile, final URLConnection urlconnection) throws Exception {
		final InputStream[] is = new InputStream[1];
		
		// try to get the input stream 3 times. 
		// Wait at most 5 seconds before interrupting the thread
		for (int j = 0; j < 3 && is[0] == null; j++) {
			Thread t = new Thread() {
				public void run() {
					try {
						is[0] = urlconnection.getInputStream();
					} catch (IOException e) {
						/* ignored */
					}
				}
			};
			t.setName("JarInputStreamThread");
			t.start();
			
			int iterationCount = 0;
			while(is[0] == null && iterationCount++ < 5) {
				try {
					t.join(1000);
				} catch (InterruptedException inte) {
					/* ignored */
				}
			}
			
			if(is[0] == null) {
				try {
					t.interrupt();
					t.join();
				} catch (InterruptedException inte) {
					/* ignored */
				}
			}
		}
		
		if(is[0] == null) {
			throw new Exception("Unable to get input stream for " + currentFile);
		}

		
		return is[0];
	}
	
	/**
	 *  Extract LZMA File
	 *  @param in Input path to pack file
	 *  @param out output path to resulting file
	 *  @throws exception if any errors occur
	 */
	protected void extractLZMA(String in, String out) throws Exception {
		
		File f = new File(in);
		FileInputStream fileInputHandle = new FileInputStream(f);

		// use reflection to avoid hard dependency
		Class clazz = Class.forName( "LZMA.LzmaInputStream" );
		Constructor constructor = clazz.getDeclaredConstructor( new Class[] {InputStream.class} );
		InputStream inputHandle = (InputStream) constructor.newInstance( new Object[] {fileInputHandle} );

		OutputStream outputHandle;
		outputHandle = new FileOutputStream(out);
		
		byte [] buffer = new byte [1<<14];
		
		int ret = inputHandle.read(buffer);
		while (ret >= 1) {
			outputHandle.write(buffer,0,ret);
			ret = inputHandle.read(buffer);
		}

		inputHandle.close();
		outputHandle.close();

		outputHandle = null;
		inputHandle = null;
		
		// delete LZMA file, as it is no longer needed
		f.delete();
	}
	
	/**
	 *  Extract Pack File
	 *  @param in Input path to pack file
	 *  @param out output path to resulting file
	 *  @throws exception if any errors occur
	 */
	protected void extractPack(String in, String out) throws Exception {		
		File f = new File(in);
	    FileOutputStream fostream = new FileOutputStream(out);
	    JarOutputStream jostream = new JarOutputStream(fostream);
	    
	    Pack200.Unpacker unpacker = Pack200.newUnpacker();
	    unpacker.unpack(f, jostream);
	    jostream.close();
	    
	    // delete pack file as its no longer needed
	    f.delete();
	}
	
	/**
	 *  Extract all jars from any lzma/pack files
	 * 
	 *  @param path output path
	 *  @throws exception if any errors occur
	 */
	protected void extractJars(String path) throws Exception {
		state = STATE_EXTRACTING_PACKAGES;
		
		float increment = (float) 10.0 / urlList.length;
		// extract all lzma and pack.lzma files
		for (int i = 0; i < urlList.length; i++) {
			percentage = 55 + (int) (increment * (i+1));
			String filename = getFileName(urlList[i]);
			
			if (filename.endsWith(".pack.lzma")) {
				subtaskMessage = "Extracting: " + filename + " to " + filename.replaceAll(".lzma", "");
				debug_sleep(1000);
				extractLZMA(path + filename, path + filename.replaceAll(".lzma", ""));
				
				subtaskMessage = "Extracting: " + filename.replaceAll(".lzma", "") + " to " + filename.replaceAll(".pack.lzma", "");
				debug_sleep(1000);
				extractPack(path + filename.replaceAll(".lzma", ""), path + filename.replaceAll(".pack.lzma", ""));
			} 
			else if (filename.endsWith(".pack")) {
				subtaskMessage = "Extracting: " + filename + " to " + filename.replace(".pack", "");
				debug_sleep(1000);
				extractPack(path + filename, path + filename.replace(".pack", ""));
			}
			else if (filename.endsWith(".lzma")) {
				subtaskMessage = "Extracting: " + filename + " to " + filename.replace(".lzma", "");
				debug_sleep(1000);
				extractLZMA(path + filename, path + filename.replace(".lzma", ""));
			}
		}
	}	

	/**
	 * This method will extract all file from the native jar and extract them
	 * to the subdirectory called "natives" in the local path, will also check
	 * to see if the native jar files is signed properly 
	 * 
	 * @param path base folder containing all downloaded jars
	 * @throws Exception if it fails to extract files
	 */
	protected void extractNatives(String path) throws Exception {

		state = STATE_EXTRACTING_PACKAGES;
		
		int initialPercentage = percentage;

		// get name of jar file with natives from urlList, it will be the last url
		String nativeJar = getJarName(urlList[urlList.length - 1]);

		// get the current certificate to compare against native files 
		Certificate[] certificate = AppletLoader.class.getProtectionDomain().getCodeSource().getCertificates();

		// create native folder
		File nativeFolder = new File(path + "natives");
		if (!nativeFolder.exists()) {
			nativeFolder.mkdir();
		}

		// open jar file
		JarFile jarFile = new JarFile(path + nativeJar, true);

		// get list of files in jar
		Enumeration entities = jarFile.entries();
		
		totalSizeExtract = 0;

		// calculate the size of the files to extract for progress bar
		while (entities.hasMoreElements()) {
			JarEntry entry = (JarEntry) entities.nextElement();

			// skip directories and anything in directories
			// conveniently ignores the manifest
			if (entry.isDirectory() || entry.getName().indexOf('/') != -1) {
				continue;
			}
			totalSizeExtract += entry.getSize();
		}

		currentSizeExtract = 0;

		// reset point to begining by getting list of file again
		entities = jarFile.entries();

		// extract all files from the jar
		while (entities.hasMoreElements()) {
			JarEntry entry = (JarEntry) entities.nextElement();
			
			// skip directories and anything in directories
			// conveniently ignores the manifest
			if (entry.isDirectory() || entry.getName().indexOf('/') != -1) {
				continue;
			}

			// check if native file already exists if so delete it to make room for new one
			// useful when using the reload button on the browser
			File f = new File(path + "natives" + File.separator + entry.getName());
			if (f.exists()) {
				if (!f.delete()) {
					continue; // unable to delete file, it is in use, skip extracting it
				}
			}
			
			debug_sleep(1000);

			InputStream in = jarFile.getInputStream(jarFile.getEntry(entry.getName()));
			OutputStream out = new FileOutputStream(path + "natives" + File.separator + entry.getName());

			int bufferSize;
			byte buffer[] = new byte[65536];

			while ((bufferSize = in.read(buffer, 0, buffer.length)) != -1) {
				debug_sleep(10);
				out.write(buffer, 0, bufferSize);
				currentSizeExtract += bufferSize;

				// update progress bar
				percentage = initialPercentage + ((currentSizeExtract * 20) / totalSizeExtract);
				subtaskMessage = "Extracting: " + entry.getName() + " " + ((currentSizeExtract * 100) / totalSizeExtract) + "%";
			}

			// validate if the certificate for native file is correct
			validateCertificateChain(certificate, entry.getCertificates());

			in.close();
			out.close();
		}
		subtaskMessage = "";

		jarFile.close();
		
		// delete native jar as it is no longer needed
		File f = new File(path + nativeJar);
		f.delete();
	}

	/**
	 * Validates the certificate chain for a single file
	 * 
	 * @param ownCerts Chain of certificates to check against
	 * @param native_certs Chain of certificates to check
	 */
	protected static void validateCertificateChain(Certificate[] ownCerts, Certificate[] native_certs) throws Exception {
		if (native_certs == null)
			throw new Exception("Unable to validate certificate chain. Native entry did not have a certificate chain at all");

		if (ownCerts.length != native_certs.length)
			throw new Exception("Unable to validate certificate chain. Chain differs in length [" + ownCerts.length + " vs " + native_certs.length + "]");

		for (int i = 0; i < ownCerts.length; i++) {
			if (!ownCerts[i].equals(native_certs[i])) {
				throw new Exception("Certificate mismatch: " + ownCerts[i] + " != " + native_certs[i]);
			}
		}
	}
	
	/**
	 * Get Image from path provided
	 * 
	 * @param s location of the image
	 * @return the Image file
	 */
	protected Image getImage(String s) {
		try {
			URL url = AppletLoader.class.getResource("/"+s);
			
			// if image not found in jar, look outside it
			if (url == null) {
				url = new URL(getCodeBase(), s);
			}
			
			Image image = super.getImage(url);
			
			// wait for image to load
			MediaTracker tracker = new MediaTracker(this);
	        tracker.addImage(image, 0);
	        tracker.waitForAll();
	        
	        return image;
		} catch (Exception e) {
			/* */
		}
		return null;
	}

	
	/**
	 * Get jar name from URL.
	 * 
	 * @param url Get jar file name from this url
	 * @return file name as string
	 */
	protected String getJarName(URL url) {
		String fileName = url.getFile();

		if (fileName.endsWith(".pack.lzma")) {
			fileName = fileName.replaceAll(".pack.lzma", "");
		} else if (fileName.endsWith(".pack")) {
			fileName = fileName.replaceAll(".pack", "");
		} else if (fileName.endsWith(".lzma")) {
			fileName = fileName.replaceAll(".lzma", "");
		}

		return fileName.substring(fileName.lastIndexOf('/') + 1);
	}	
	
	/**
	 * Get file name portion of URL.
	 * 
	 * @param url Get file name from this url
	 * @return file name as string
	 */
	protected String getFileName(URL url) {
		String fileName = url.getFile();
		return fileName.substring(fileName.lastIndexOf('/') + 1);
	}
	
	/**
	 * Retrieves the color
	 * 
	 * @param color Color to load
	 * @param defaultColor Default color to use if no color to load
	 * @return Color to use
	 */
	protected Color getColor(String color, Color defaultColor) {
		String param_color = getParameter(color);
		if (param_color != null) {
			return new Color(Integer.parseInt(param_color, 16));
		}
		return defaultColor;
	}
	
	/**
	 * Retrieves the boolean value for the applet
	 * @param name Name of parameter
	 * @param defaultValue default value to return if no such parameter
	 * @return value of parameter or defaultValue
	 */
	protected boolean getBooleanParameter(String name, boolean defaultValue) {
		String parameter = getParameter(name);
		if(parameter != null) {
			return Boolean.parseBoolean(parameter);
		}
		return defaultValue;
	}
	
	/**
	 * Sets the state of the loaded and prints some debug information
	 * 
	 * @param error Error message to print
	 */
	protected void fatalErrorOccured(String error, Exception e) {
		fatalError = true;
		fatalErrorDescription = "Fatal error occured (" + state + "): " + error;
		System.out.println(fatalErrorDescription);
		if(e != null) {
			System.out.println(generateStacktrace(e));
		}
		repaint();
	}
	
	/**
	 * Utility method for sleeping
	 * Will only really sleep if debug has been enabled
	 * @param ms milliseconds to sleep
	 */
	protected void debug_sleep(long ms) {
		if(debugMode) {
			sleep(ms);
		}
	}
	
	/**
	 * Utility method for sleeping
	 * @param ms milliseconds to sleep
	 */
	protected void sleep(long ms) {
		try {
			Thread.sleep(ms);
		} catch (Exception e) {
			/* ignored */
		}
	}	
	

}