/*
 * Copyright (c) 2004, 2021, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package sun.jvmstat.monitor;

/**
 * Utility class proving concenience methods for extracting various
 * information from an MonitoredVm object.
 *
 * @author Brian Doherty
 * @since 1.5
 */
public class MonitoredVmUtil {

    /**
     * Private constructor - prevent instantiation.
     */
    private MonitoredVmUtil() { }

    /**
     * Return the Java Virtual Machine Version.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the version of the target JVM or the
     *                  the string "Unknown" if the version cannot be
     *                  determined.
     */
    public static String vmVersion(MonitoredVm vm) throws MonitorException {
        StringMonitor ver =
               (StringMonitor)vm.findByName("java.property.java.vm.version");
        return (ver == null) ? "Unknown" : ver.stringValue();
    }

    /**
     * Return the command line for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the command line of the target Java
     *                  application or the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String commandLine(MonitoredVm vm) throws MonitorException {
        StringMonitor cmd = (StringMonitor)vm.findByName("sun.rt.javaCommand");
        return (cmd == null) ? "Unknown" : cmd.stringValue();
    }

    /**
     * Return the arguments to the main class for the target Java application.
     * Returns the arguments to the main class. If the arguments can't be
     * found, the string "Unknown" is returned.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments to the main class for the
     *                  target Java application or the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String mainArgs(MonitoredVm vm) throws MonitorException {
        String commandLine = commandLine(vm);

        int firstSpace = commandLine.indexOf(' ');
        if (firstSpace > 0) {
            return commandLine.substring(firstSpace + 1);
        } else if (commandLine.equals("Unknown")) {
            return commandLine;
        } else {
            return null;
        }
    }

    /**
     * Return the main class for the target Java application.
     * Returns the main class or the name of the jar file if the application
     * was started with the <em>-jar</em> option.
     *
     * @param vm the target MonitoredVm
     * @param fullPath include the full path to Jar file, where applicable
     * @return String - contains the main class of the target Java
     *                  application or the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String mainClass(MonitoredVm vm, boolean fullPath)
                         throws MonitorException {
        String cmdLine = commandLine(vm);
        int firstSpace = cmdLine.indexOf(' ');
        if (firstSpace > 0) {
            cmdLine = cmdLine.substring(0, firstSpace);
        }
        if (fullPath) {
            return cmdLine;
        }
        /*
         * Can't use File.separator() here because the separator for the target
         * jvm may be different than the separator for the monitoring jvm.
         * And we also strip embedded module e.g. "module/MainClass"
         */
        int lastSlash = cmdLine.lastIndexOf("/");
        int lastBackslash = cmdLine.lastIndexOf("\\");
        int lastSeparator = lastSlash > lastBackslash ? lastSlash : lastBackslash;
        if (lastSeparator > 0) {
            cmdLine = cmdLine.substring(lastSeparator + 1);
        }

        int lastPackageSeparator = cmdLine.lastIndexOf('.');
        if (lastPackageSeparator > 0) {
            String lastPart = cmdLine.substring(lastPackageSeparator + 1);
            /*
             * We could have a relative path "my.module" or
             * a module called "my.module" and a jar file called "my.jar" or
             * class named "jar" in package "my", e.g. "my.jar".
             * We can never be sure here, but we assume *.jar is a jar file
             */
            if (lastPart.equals("jar")) {
                return cmdLine; /* presumably a file name without path */
            }
            return lastPart; /* presumably a class name without package */
        }

        return cmdLine;
    }

    /**
     * Return the JVM arguments for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments passed to the JVM for the
     *                  target Java application or the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmArgs(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmArgs = (StringMonitor)vm.findByName("java.rt.vmArgs");
        return (jvmArgs == null) ? "Unknown" : jvmArgs.stringValue();
    }

    /**
     * Return the JVM flags for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the flags passed to the JVM for the
     *                  target Java application or the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmFlags(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmFlags =
               (StringMonitor)vm.findByName("java.rt.vmFlags");
        return (jvmFlags == null) ? "Unknown" : jvmFlags.stringValue();
    }

    // Index of the sun.rt.jvmCapabilities counter
    private static int IS_ATTACHABLE = 0;
    private static int IS_KERNEL_VM  = 1;

    /**
     * Returns true if the VM supports attach-on-demand.
     *
     * @param vm the target MonitoredVm
     */
    public static boolean isAttachable(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmCapabilities =
               (StringMonitor)vm.findByName("sun.rt.jvmCapabilities");
        if (jvmCapabilities == null) {
             return false;
        } else {
             return jvmCapabilities.stringValue().charAt(IS_ATTACHABLE) == '1';
        }
    }

}
