/**
 *    PackageLoader.java
 *    Copyright (C) 2010 New Zealand Digital Library, http://expeditee.org
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    This program 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 General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.expeditee.reflection;

import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.zip.ZipEntry;


public class PackageLoader {

	// The following is adapted from:
	// http://stackoverflow.com/questions/1456930/how-do-i-read-all-classes-from-a-java-package-in-the-classpath

	public static List<Class<?>> getClassesNew(String packageName) throws ClassNotFoundException
	{
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

		ArrayList<String> names = new ArrayList<String>();

		final ArrayList<Class<?>> classes = new ArrayList<Class<?>>();

		String realPackageName = packageName;
		packageName = packageName.replace(".", "/");
		URL packageURL = classLoader.getResource(packageName);

		if (packageURL.getProtocol().equals("jar")) {

			// build jar file name, then loop through zipped entries

			String jarFileNameUndecoded = packageURL.getFile();

			try {
				JarURLConnection ju_connection = (JarURLConnection) packageURL
						.openConnection();
				JarFile jf = ju_connection.getJarFile();

				Enumeration<JarEntry> jarEntries = jf.entries();
				while (jarEntries.hasMoreElements()) {
					String entryName = jarEntries.nextElement().getName();

					if (entryName.startsWith(packageName)) {

						if (entryName.endsWith(".class")
								&& !entryName.contains("$")) {

							// Deal with situation where the class found might
							// be a further sub-package
							// e.g. for "org.expeditee.action"
							// there is:
							// org/expeditee/action/widgets/Chart.class
							// which would produce a value of 'entryName' as
							// widgets/Chart.class

							entryName = entryName.substring(0,
									entryName.length() - 6); // 6 = '.class'
							entryName = entryName.replace('/', '.');

							names.add(entryName);
							classes.add(Class.forName(entryName));
						}
					}
				}
			} catch (Exception e) {
				System.err.println("Failed to decode jar file: "
						+ jarFileNameUndecoded);
				e.printStackTrace();
			}
		} else if (packageURL.getProtocol().equals("bundleresource")) {
			try {
				final URLConnection urlConnection = packageURL.openConnection();
				final Class<?> c = urlConnection.getClass();
				final java.lang.reflect.Method toInvoke = c.getMethod("getFileURL");
				final URL fileURL = (URL)toInvoke.invoke(urlConnection);
				final File folder = new File(fileURL.getFile());
				final List<String> files = findFiles(folder);
				for (final String s : files) {
					String entryName = realPackageName + s;
					if (entryName.endsWith(".class") && !entryName.contains("$")) {
						entryName = entryName.substring(0, entryName.lastIndexOf('.'));
						entryName = entryName.replace('/', '.');
						names.add(entryName);
						try {
							final Class<?> tmpc = Class.forName(entryName);
							classes.add(tmpc);
						} catch (NoClassDefFoundError e) {
							System.err.println("Unable to instantiate class " + entryName);
							System.err.println(e.getMessage());
						}
					}
				}
			} catch (final Exception e) {
				System.err.println("Failed to process file: " + packageName);
				e.printStackTrace();
			}
		} else {
			// loop through files in classpath

			String packageURLString = packageURL.toString();
			try {
				URI uri = new URI(packageURLString);
				File folder = new File(uri.getPath());

				List<String> files = findFiles(folder);
				for (String s : files) {
					String entryName = realPackageName + s;

					if (entryName.endsWith(".class")
							&& !entryName.contains("$")) {
						entryName = entryName.substring(0,
								entryName.lastIndexOf('.'));
						entryName = entryName.replace('/', '.');

						names.add(entryName);
						classes.add(Class.forName(entryName));
					}
				}
			} catch (Exception e) {
				System.err.println("Failed to process file: "
						+ packageURLString);
				e.printStackTrace();
			}
		}

		return classes;
	}

	/**
	 * Finds all files in a directory and it's subdirectories
	 * 
	 * @param directory
	 *            The folder to start in
	 * 
	 * @return A list of Strings containing file paths relative to the starting
	 *         directory
	 */
	private static List<String> findFiles(File directory) {
		List<String> files = new LinkedList<String>();
		for (File f : directory.listFiles()) {
			if (f.isDirectory()) {
				for (String s : findFiles(f)) {
					files.add(f.getName() + "/" + s);
				}
			} else {
				files.add(f.getName());
			}
		}
		return files;
	}

	public static List<Class<?>> getClasses(final String pckgname)
			throws ClassNotFoundException {

		final ArrayList<Class<?>> classes = new ArrayList<Class<?>>();

		// Must be a forward slash for loading resources
		final String packagePath = pckgname.replace('.', '/');

		if (System.getProperty("eclipse.expeditee.home") == null) {
			final ClassLoader cld = Thread.currentThread()
					.getContextClassLoader();
			if (cld == null) {
				throw new ClassNotFoundException("Can't get class loader.");
			}
			URL resource = null;
			try {
				final Enumeration<URL> resources = cld
						.getResources(packagePath);
				while (resources.hasMoreElements()) {
					URL url = resources.nextElement();
					resource = url;
				}
			} catch (IOException e) {
				System.err
				.println("A IO Error has occured when trying to use the ContextClassLoader"
						+ System.getProperty("line.separator")
						+ "Are you running from within Eclipse? (or just not with Jar)  Then make sure your"
						+ " 'eclipse.expeditee.home' property is set correctly.  It is currently: '"
						+ System.getProperty("eclipse.expeditee.home")
						+ "'"
						+ System.getProperty("line.separator")
						+ "You can set it by adding a VM argument.  "
						+ "Example: -Declipse.expeditee.home=D:\\Desktop\\Research\\expeditee-svn");
				e.printStackTrace();
			}
			if (resource == null) {
				throw new ClassNotFoundException("No resource for "
						+ packagePath);
			}
			final File directory = new File(resource.getFile());

			final int splitPoint = directory.getPath().indexOf('!');
			if (splitPoint > 0) {
				String jarName = directory.getPath().substring(
						"file:".length(), splitPoint);
				// Windows HACK
				if (jarName.indexOf(":") >= 0)
					jarName = jarName.substring(1);

				if (jarName.indexOf("%20") > 0) {
					jarName = jarName.replace("%20", " ");
				}
				// System.out.println("JarName:" + jarName);
				try {
					final JarFile jarFile = new JarFile(jarName);
					final Enumeration<?> entries = jarFile.entries();
					while (entries.hasMoreElements()) {
						final ZipEntry entry = (ZipEntry) entries.nextElement();
						final String className = entry.getName();
						if (className.startsWith(packagePath)) {
							if (className.endsWith(".class")
									&& !className.contains("$")) {
								// The forward slash below is a forwards slash
								// for
								// both windows and linux

								String class_forname = className.substring(0,
										className.length() - 6);
								class_forname = class_forname.replace('/', '.');

								classes.add(Class.forName(class_forname));
							}
						}
					}
					try {
						jarFile.close();
					} catch (IOException e) {
						System.err
						.println("Error attempting to close Jar file");
						e.printStackTrace();
					}
				} catch (IOException e) {
					System.err.println("Error Instantiating Jar File Object");
					e.printStackTrace();
				}
			} else {

				System.err
				.println("A Error has occured when trying to use a Jar file to find actions or agents."
						+ System.getProperty("line.separator")
						+ "Are you running from within Eclipse? (or just not with Jar)  Then make sure your"
						+ " 'eclipse.expeditee.home' property is set correctly.  It is currently: '"
						+ System.getProperty("eclipse.expeditee.home")
						+ "'"
						+ System.getProperty("line.separator")
						+ "You can set it by adding a VM argument.  "
						+ "Example: -Declipse.expeditee.home=D:\\Desktop\\Research\\expeditee-svn");
			}
		} else {
			String eclipse_expeditee_home = System.getProperty(
					"eclipse.expeditee.home", "");
			String full_package_path = eclipse_expeditee_home + File.separator
					+ "bin" + File.separator + packagePath;

			final File directory = new File(full_package_path);

			if (directory.exists()) {
				// Get the list of the files contained in the package
				String[] files = directory.list();
				for (int i = 0; i < files.length; i++) {
					// we are only interested in .class files
					if (files[i].endsWith(".class") && !files[i].contains("$")
							&& !files[i].equals("Actions.class")) {
						// removes the .class extension
						classes.add(Class.forName(pckgname
								+ files[i].substring(0, files[i].length() - 6)));
					}
				}
			} else {
				throw new ClassNotFoundException("The package '" + pckgname
						+ "' in the directory '" + directory
						+ "' does not appear to be a valid package");
			}
		}
		return classes;
	}

}