Resource Extractor

/**
 *
 * This software is part of the TheEnderBox
 *
 * TheEnderBox 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
 * any later version.
 *
 * TheEnderBox 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 TheEnderBox. If not, see <http://www.gnu.org/licenses/>.
 *
 */
package me.cybermaxke.enderbox.api.resource;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.apache.commons.lang.Validate;

import org.bukkit.plugin.java.JavaPlugin;

public final class ResourceExtractor {
	protected final JavaPlugin plugin;
	protected final File extractfolder;

	protected final String folderpath;
	protected final String regex;

	/**
	 * You can extract complete folders of resources from your plugin jar to a target folder. You
	 * can append a regex to match the file names.
	 * @param plugin The plugin the files will be extracted from.
	 * @param extractfolder The folder where the files will be extracted to.
	 * @param folderpath The path where the files are inside in the jar located.
	 * @param regex A regex to match the file names. This can be 'null' if you don't want to use it.
	 */
	public ResourceExtractor(JavaPlugin plugin, File extractfolder, String folderpath, String regex) {
		Validate.notNull(plugin, "The plugin cannot be null!");
		Validate.notNull(plugin, "The extract folder cannot be null!");
		Validate.notNull(plugin, "The folder path cannot be null!");

		this.extractfolder = extractfolder;
		this.folderpath = folderpath;
		this.plugin = plugin;
		this.regex = regex;
	}

	/**
	 * Starts extracting the files.
	 * @throws IOException
	 */
	public void extract() throws IOException {
		this.extract(false, true);
	}

	/**
	 * Starts extracting the files.
	 * @param override Whether you want to override the old files.
	 * @throws IOException
	 */
	public void extract(boolean override) throws IOException {
		this.extract(override, true);
	}

	/**
	 * Starts extracting the files.
	 * @param override Whether you want to override the old files.
	 * @param subpaths Whether you want to create sub folders if it's also found in the jar file.
	 * @throws IOException
	 */
	public void extract(boolean override, boolean subpaths) throws IOException {
		File jarfile = null;

		/**
		 * Get the jar file from the plugin.
		 */
		try {
			Method method = JavaPlugin.class.getDeclaredMethod("getFile");
			method.setAccessible(true);

			jarfile = (File) method.invoke(this.plugin);
		} catch (Exception e) {
			throw new IOException(e);
		}

		/**
		 * Make the folders if missing.
		 */
		if (!this.extractfolder.exists()) {
			this.extractfolder.mkdirs();
		}

		JarFile jar = new JarFile(jarfile);

		/**
		 * Loop through all the entries.
		 */
		Enumeration<JarEntry> entries = jar.entries();
		while (entries.hasMoreElements()) {
			JarEntry entry = entries.nextElement();
			String path = entry.getName();

			/**
			 * Not in the folder.
			 */
			if (!path.startsWith(this.folderpath)) {
				continue;
			}

			if (entry.isDirectory()) {
				if (subpaths) {
					File file = new File(this.extractfolder, entry.getName().replaceFirst(this.folderpath, ""));

					if (!file.exists()) {
						file.mkdirs();
					}
				}
			} else {
				File file;

				/**
				 * Use the right path.
				 */
				if (subpaths) {
					file = new File(this.extractfolder, path.replaceFirst(this.folderpath, ""));
				} else {
					file = new File(this.extractfolder, path.substring(path.indexOf(File.separatorChar), path.length()));
				}

				String name = file.getName();

				/**
				 * Be sure that the file is valid.
				 */
				if (this.regex == null || name.matches(this.regex)) {
					if (file.exists() && override) {
						file.delete();
					}

					if (!file.exists()) {
						/**
						 * Copy the file to the path.
						 */
						InputStream is = jar.getInputStream(entry);
						FileOutputStream fos = new FileOutputStream(file);

						while (is.available() > 0) {
							fos.write(is.read());
						}

						fos.close();
						is.close();
					}
				}
			}
		}

		jar.close();
	}
}