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package org.unlaxer.compiler;

import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.function.Function;
import java.util.jar.JarEntry;

import javax.tools.JavaFileObject;

/*
 * modified and repackage below sources for java9 and j2ee container
 * https://atamur.blogspot.com/2009/10/using-built-in-javacompiler-with-custom.html
 * 
 * @author atamur
 * @author opa
 * @since 15-Oct-2009
 */
class PackageInternalsFinder {
	private ClassLoader classLoader;
	private final Function jarURLStringFromURL;
	private static final String CLASS_FILE_EXTENSION = ".class";

	public PackageInternalsFinder(ClassLoader classLoader, Function jarURLStringFromURL) {
		this.classLoader = classLoader;
		this.jarURLStringFromURL = jarURLStringFromURL;
	}

	public List find(String packageName) throws IOException {
		String javaPackageName = packageName.replaceAll("\\.", "/");

		List result = new ArrayList();

		Enumeration urlEnumeration = classLoader.getResources(javaPackageName);
		while (urlEnumeration.hasMoreElements()) { // one URL for each jar on the classpath that has the given package
			URL packageFolderURL = urlEnumeration.nextElement();
			result.addAll(listUnder(packageName, packageFolderURL));
		}

		return result;
	}

	private Collection listUnder(String packageName, URL packageFolderURL) {
		File directory = new File(packageFolderURL.getFile());
		if (directory.isDirectory()) { // browse local .class files - useful for local execution
			return processDir(packageName, directory);
		} else { // browse a jar file
			return processJar(packageFolderURL);
		} // maybe there can be something else for more involved class loaders
	}

	private List processJar(URL packageFolderURL) {
		List result = new ArrayList();
		try {

			String jarUri = jarURLStringFromURL.apply(packageFolderURL);

			packageFolderURL = new URL(jarUri + "!/");

			JarURLConnection jarConn = (JarURLConnection) packageFolderURL.openConnection();
			String rootEntryName = jarConn.getEntryName();
			rootEntryName = rootEntryName == null ? "" : rootEntryName;
//			int rootEnd = rootEntryName.length() + 1;

			Enumeration entryEnum = jarConn.getJarFile().entries();
			while (entryEnum.hasMoreElements()) {
				JarEntry jarEntry = entryEnum.nextElement();
				String name = jarEntry.getName();

				if (/* name.startsWith(rootEntryName) && */ /*
															 * name.indexOf('/', rootEnd) == -1 &&
															 */ name.endsWith(CLASS_FILE_EXTENSION)) {
					URI uri = URI.create(jarUri + "!/" + name);
					String binaryName = name.replaceAll("/", ".");
					binaryName = binaryName.replaceAll(CLASS_FILE_EXTENSION + "$", "");

					result.add(new CustomJavaFileObject(binaryName, uri));
				}
			}
		} catch (Exception e) {
			throw new RuntimeException("Wasn't able to open " + packageFolderURL + " as a jar file", e);
		}
		return result;
	}

	private List processDir(String packageName, File directory) {
		List result = new ArrayList();

		File[] childFiles = directory.listFiles();
		for (File childFile : childFiles) {
			if (childFile.isFile()) {
				// We only want the .class files.
				if (childFile.getName().endsWith(CLASS_FILE_EXTENSION)) {
					String binaryName = packageName + "." + childFile.getName();
					binaryName = binaryName.replaceAll(CLASS_FILE_EXTENSION + "$", "");

					result.add(new CustomJavaFileObject(binaryName, childFile.toURI()));
				}
			}
		}

		return result;
	}
}