/*
 *
 * Copyright 2014 McEvoy Software Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.milton.config;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 *
 * @author brad
 */
public class ReflectionUtils {

	private static final Logger log = LoggerFactory.getLogger(ReflectionUtils.class);

	public static List<Class> getClassNamesFromPackage(String packageName) throws IOException, ClassNotFoundException {
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		ArrayList<Class> classes = new ArrayList<Class>();

		String packagePath = packageName.replace(".", "/");
		Enumeration<URL> packageResources = classLoader.getResources(packagePath);
		while (packageResources.hasMoreElements()) {
			URL packageURL = packageResources.nextElement();

			if (log.isTraceEnabled()) {
				log.trace("Finding classes for package: '" + packageName + "'. packageUrl: " + packageURL);
			}
			if (packageURL == null) {
				log.warn("getClassNamesFromPackage: No package could be found: " + packagePath + " from classloader: " + classLoader);
				return classes;
			}

			ClassLoader cld = Thread.currentThread().getContextClassLoader();

			String packageProtocol = packageURL.getProtocol();
			if (packageProtocol.equalsIgnoreCase("jar") || packageProtocol.equalsIgnoreCase("zip")) {
				String jarFileName;
				JarFile jf;
				Enumeration<JarEntry> jarEntries;
				String entryName;

				// build jar file name, then loop through zipped entries
				jarFileName = URLDecoder.decode(packageURL.getFile(), "UTF-8");
				jarFileName = jarFileName.substring(5, jarFileName.indexOf("!")); // put this back, causes problem scanning jars
				jf = new JarFile(jarFileName);
				jarEntries = jf.entries();
				if (log.isTraceEnabled()) {
					log.trace("Loading classes from JAR: url: " + packageURL + ", jarFileName: " + jarFileName);
				}
				int filesCountInJar = 0;
				while (jarEntries.hasMoreElements()) {
					entryName = jarEntries.nextElement().getName();
					if (entryName.startsWith(packagePath) && entryName.length() > packagePath.length() + 5) {
						if (entryName.endsWith(".class")) {
							//entryName = entryName.substring(packageName.length()+1, entryName.lastIndexOf('.'));
							String className = entryName.replace("/", ".");
							className = className.substring(0, className.length() - 6);
							Class c = cld.loadClass(className);
							classes.add(c);
						}
					}
					++filesCountInJar;
				}
				jf.close();
				if (log.isTraceEnabled()) {
					log.trace("Files count in " + packageURL + ": " + filesCountInJar + ", count of class files in package " + packagePath + ":" + classes.size());
				}

				// loop through files in classpath
			} else {
				String f = URLDecoder.decode(packageURL.getFile(), "UTF-8");
				File directory = new File(f);
				String[] files = directory.list();
				if (files != null && files.length > 0) {
					if (log.isTraceEnabled()) {
						log.trace("Loading classes from directory: " + directory.getAbsolutePath() + " files=" + files.length);
					}
					for (String file : files) {
						if (file.endsWith(".class")) {
							String className = packageName + '.' + file.substring(0, file.length() - 6);
							Class c = cld.loadClass(className);
							classes.add(c);
						}
					}
				} else {
					log.info("No files found in package: " + packageName + " with physical path=" + directory.getAbsolutePath());
				}
			}

		}
		return classes;
	}

	public static Class loadClass(String className) throws ClassNotFoundException {
		ClassLoader cld = Thread.currentThread().getContextClassLoader();
		return cld.loadClass(className);
	}
}