/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package jdk.vm.ci.services;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

import sun.misc.VM;

/**
 * Utility called from the VM to create and register a separate class loader for loading JVMCI
 * classes (i.e., those in found in lib/jvmci/*.jar) as well as those available on the class path in
 * the {@code "jvmci.class.path.append"} system property.
 */
class JVMCIClassLoaderFactory {

    /**
     * Copy of the {@code UseJVMCIClassLoader} VM option. Set by the VM before the static
     * initializer is called.
     */
    private static boolean useJVMCIClassLoader;

    /**
     * Registers the JVMCI class loader in the VM.
     */
    private static native void init(ClassLoader loader);

    static {
        init(useJVMCIClassLoader ? newClassLoader() : null);
    }

    /**
     * Creates a new class loader for loading JVMCI classes.
     */
    private static ClassLoader newClassLoader() {
        URL[] urls = getJVMCIJarsUrls();
        ClassLoader parent = null;
        return URLClassLoader.newInstance(urls, parent);
    }

    /**
     * Gets the URLs for lib/jvmci/*.jar.
     */
    private static URL[] getJVMCIJarsUrls() {
        File javaHome = new File(VM.getSavedProperty("java.home"));
        File lib = new File(javaHome, "lib");
        File jvmci = new File(lib, "jvmci");
        if (!jvmci.isDirectory()) {
            throw new InternalError(jvmci + " does not exist or is not a directory");
        }

        List<URL> urls = new ArrayList<>();
        for (String fileName : jvmci.list()) {
            if (fileName.endsWith(".jar")) {
                File file = new File(jvmci, fileName);
                if (file.isDirectory()) {
                    continue;
                }
                try {
                    urls.add(file.toURI().toURL());
                } catch (MalformedURLException e) {
                    throw new InternalError(e);
                }
            }
        }

        String append = VM.getSavedProperty("jvmci.class.path.append");
        if (append != null) {
            for (String entry : append.split(File.pathSeparator)) {
                File file = new File(entry);
                try {
                    urls.add(file.toURI().toURL());
                } catch (MalformedURLException e) {
                    throw new InternalError(e);
                }
            }
        }

        return urls.toArray(new URL[urls.size()]);
    }
}