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package com.seeq.link.agent;

import java.io.File;
import java.io.FilenameFilter;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;
import java.util.function.BiFunction;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.commons.io.filefilter.SuffixFileFilter;
import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import lombok.experimental.UtilityClass;

@UtilityClass
public class ClassPathUtilities {
    /**
     * Adds a URL to an existing classloader.
     *
     * Taken from http://stackoverflow.com/questions/7884393/can-a-directory-be-added-to-the-class-path-at-runtime
     *
     * @param urlClassLoader
     *         classloader to affect
     * @param url
     *         url of classpath to be added
     * @throws Exception
     *         various exceptions can occur
     */
    public static void addToClassPath(URLClassLoader urlClassLoader, URL url) throws Exception {
        Class urlClass = URLClassLoader.class;
        Method method = urlClass.getDeclaredMethod("addURL", URL.class);
        method.setAccessible(true);
        method.invoke(urlClassLoader, url);
    }

    public static List getJarsInFolder(File folder) throws Exception {
        File[] jars = folder.listFiles((FilenameFilter) new SuffixFileFilter(".jar"));
        List urls = new ArrayList<>();
        for (File jar : jars) {
            urls.add(jar.toURI().toURL());
        }

        return urls;
    }

    public static List getEntriesFromClasspathFile(File classPathFile,
            BiFunction entryResolver)
            throws Exception {
        List urls = new ArrayList<>();

        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
        Document doc = dBuilder.parse(classPathFile);

        doc.getDocumentElement().normalize();
        NodeList classpathNodes = doc.getElementsByTagName("classpathentry");
        for (int i = 0; i < classpathNodes.getLength(); i++) {
            Node classpathNode = classpathNodes.item(i);
            NamedNodeMap classpathAttributes = classpathNode.getAttributes();
            String kind = classpathAttributes.getNamedItem("kind").getNodeValue();
            String path = classpathAttributes.getNamedItem("path").getNodeValue();

            String classPathEntry = entryResolver.apply(kind, path);

            if (classPathEntry != null) {
                urls.add(new File(classPathEntry).toURI().toURL());
            }
        }

        return urls;
    }
}