/*

 * Copyright 2007-2008 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.launcher;

/*

 *

 *  <p><b>This is NOT part of any API supported by Sun Microsystems.

 *  If you write code that depends on this, you do so at your own

 *  risk.  This code and its internal interfaces are subject to change

 *  or deletion without notice.</b>

 *

 */

/**

 * A utility package for the java(1), javaw(1) launchers.

 * The following are helper methods that the native launcher uses

 * to perform checks etc. using JNI, see src/share/bin/java.c

 */

import java.io.File;

import java.io.IOException;

import java.io.PrintStream;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.util.ResourceBundle;

import java.text.MessageFormat;

import java.util.jar.Attributes;

import java.util.jar.JarFile;

import java.util.jar.Manifest;

public enum LauncherHelper {

    INSTANCE;

    private static final String defaultBundleName =

            "sun.launcher.resources.launcher";

    private static ResourceBundle javarb =

            ResourceBundle.getBundle(defaultBundleName);

    private static final String MAIN_CLASS = "Main-Class";

    private static StringBuilder outBuf = new StringBuilder();

    /**

     * A private helper method to get a localized message and also

     * apply any arguments that we might pass.

     */

    private static String getLocalizedMessage(String key, Object... args) {

        String msg = javarb.getString(key);

        return (args != null) ? MessageFormat.format(msg, args) : msg;

    }

    /**

     * The java -help message is split into 3 parts, an invariant, followed

     * by a set of platform dependent variant messages, finally an invariant

     * set of lines.

     * This method initializes the help message for the first time, and also

     * assembles the invariant header part of the message.

     */

    static void initHelpMessage(String progname) {

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.header",

                (progname == null) ? "java" : progname ));

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.datamodel",

                32));

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.datamodel",

                64));

    }

    /**

     * Appends the vm selection messages to the header, already created.

     * initHelpSystem must already be called.

     */

    static void appendVmSelectMessage(String vm1, String vm2) {

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.vmselect",

                vm1, vm2));

    }

    /**

     * Appends the vm synoym message to the header, already created.

     * initHelpSystem must be called before using this method.

     */

    static void appendVmSynonymMessage(String vm1, String vm2) {

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.hotspot",

                vm1, vm2));

    }

    /**

     * Appends the vm Ergo message to the header, already created.

     * initHelpSystem must be called before using this method.

     */

    static void appendVmErgoMessage(boolean isServerClass, String vm) {

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.ergo.message1",

                vm));

        outBuf = (isServerClass)

             ? outBuf.append(",\n" +

                getLocalizedMessage("java.launcher.ergo.message2") + "\n\n")

             : outBuf.append(".\n\n");

    }

    /**

     * Appends the last invariant part to the previously created messages,

     * and finishes up the printing to the desired output stream.

     * initHelpSystem must be called before using this method.

     */

    static void printHelpMessage(boolean printToStderr) {

        PrintStream ostream = (printToStderr) ? System.err : System.out;

        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.footer",

                File.pathSeparator));

        ostream.println(outBuf.toString());

    }

    /**

     * Prints the Xusage text to the desired output stream.

     */

    static void printXUsageMessage(boolean printToStderr) {

        PrintStream ostream =  (printToStderr) ? System.err : System.out;

        ostream.println(getLocalizedMessage("java.launcher.X.usage",

                File.pathSeparator));

    }

    static String getMainClassFromJar(String jarname) throws IOException {

        JarFile jarFile = null;

        try {

            jarFile = new JarFile(jarname);

            Manifest manifest = jarFile.getManifest();

            if (manifest == null) {

                throw new IOException("manifest not found in " + jarname);

            }

            Attributes mainAttrs = manifest.getMainAttributes();

            if (mainAttrs == null) {

                throw new IOException("no main mainifest attributes, in " +

                        jarname);

            }

            return mainAttrs.getValue(MAIN_CLASS).trim();

        } finally {

            if (jarFile != null) {

                jarFile.close();

            }

        }

    }

    /**

     * This method does the following:

     * 1. gets the classname from a Jar's manifest, if necessary

     * 2. loads the class using the System ClassLoader

     * 3. ensures the availability and accessibility of the main method,

     *    using signatureDiagnostic method.

     *    a. does the class exist

     *    b. is there a main

     *    c. is the main public

     *    d. is the main static

     *    c. does the main take a String array for args

     * 4. and off we go......

     *

     * @param printToStderr

     * @param isJar

     * @param name

     * @return

     */

    public static Object checkAndLoadMain(boolean printToStderr,

        // get the class name

        String classname = (isJar) ? getMainClassFromJar(name) : name;

        classname = classname.replace('/', '.');

        ClassLoader loader = ClassLoader.getSystemClassLoader();

        Class<?> clazz = null;

        PrintStream ostream = (printToStderr) ? System.err : System.out;

        try {

            clazz = loader.loadClass(classname);

        } catch (ClassNotFoundException cnfe) {

            ostream.println(getLocalizedMessage("java.launcher.cls.error1", classname));

        }

        signatureDiagnostic(ostream, clazz);

        return clazz;

    }

    static void signatureDiagnostic(PrintStream ostream, Class<?> clazz) {

        String classname = clazz.getName();

        Method method = null;

        try {

            method = clazz.getMethod("main", String[].class);

        } catch (Exception e) {

            ostream.println(getLocalizedMessage("java.launcher.cls.error4",

                    classname));

            throw new RuntimeException("Main method not found in " + classname);

        }

        /*

         * getMethod (above) will choose the correct method, based

         * on its name and parameter type, however, we still have to

         * ensure that the method is static and returns a void.

         */

        int mod = method.getModifiers();

        if (!Modifier.isStatic(mod)) {

            ostream.println(getLocalizedMessage("java.launcher.cls.error2",

                    "static", classname));

            throw new RuntimeException("Main method is not static in class " +

                    classname);

        }

        Class<?> rType = method.getReturnType();

        if (!rType.isPrimitive() || !rType.getName().equals("void")) {

            ostream.println(getLocalizedMessage("java.launcher.cls.error3",

                    classname));

            throw new RuntimeException("Main method must return a value" +

                    " of type void in class " +

                    classname);

        }

        return;

    }

}