/*
 * Copyright (c) 1998, 2006, 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.
 */

/**
 *
 */

import java.io.*;
import java.util.Arrays;
import java.util.Properties;
import java.util.StringTokenizer;

/**
 * RMI regression test utility class that uses Runtime.exec to spawn a
 * java process that will run a named java class.
 */
public class JavaVM {

    protected Process vm = null;

    private String classname = "";
    private String args = "";
    private String options = "";
    private OutputStream outputStream = System.out;
    private OutputStream errorStream = System.err;
    private String policyFileName = null;

    // This is used to shorten waiting time at startup.
    private volatile boolean started = false;
    private boolean forcesOutput = true; // default behavior

    private static void mesg(Object mesg) {
        System.err.println("JAVAVM: " + mesg.toString());
    }

    /** string name of the program execd by JavaVM */
    private static String javaProgram = "java";

    static {
        try {
            javaProgram = TestLibrary.getProperty("java.home", "") +
                File.separator + "bin" + File.separator + javaProgram;
        } catch (SecurityException se) {
        }
    }

    public JavaVM(String classname) {
        this.classname = classname;
    }
    public JavaVM(String classname,
                  String options, String args) {
        this.classname = classname;
        this.options = options;
        this.args = args;
    }

    public JavaVM(String classname,
                  String options, String args,
                  OutputStream out, OutputStream err) {
        this(classname, options, args);
        this.outputStream = out;
        this.errorStream = err;
    }

    /* This constructor will instantiate a JavaVM object for which caller
     * can ask for forcing initial version output on child vm process
     * (if forcesVersionOutput is true), or letting the started vm behave freely
     * (when forcesVersionOutput is false).
     */
    public JavaVM(String classname,
                  String options, String args,
                  OutputStream out, OutputStream err,
                  boolean forcesVersionOutput) {
        this(classname, options, args, out, err);
        this.forcesOutput = forcesVersionOutput;
    }


    public void setStarted() {
        started = true;
    }

    // Prepends passed opts array to current options
    public void addOptions(String[] opts) {
        String newOpts = "";
        for (int i = 0 ; i < opts.length ; i ++) {
            newOpts += " " + opts[i];
        }
        newOpts += " ";
        options = newOpts + options;
    }

    // Prepends passed arguments array to current args
    public void addArguments(String[] arguments) {
        String newArgs = "";
        for (int i = 0 ; i < arguments.length ; i ++) {
            newArgs += " " + arguments[i];
        }
        newArgs += " ";
        args = newArgs + args;
    }

    public void setPolicyFile(String policyFileName) {
        this.policyFileName = policyFileName;
    }

    /**
     * This method is used for setting VM options on spawned VMs.
     * It returns the extra command line options required
     * to turn on jcov code coverage analysis.
     */
    protected static String getCodeCoverageOptions() {
        return TestLibrary.getExtraProperty("jcov.options","");
    }

    public void start(Runnable runnable) throws IOException {
        if (runnable == null) {
            throw new NullPointerException("Runnable cannot be null.");
        }

        start();
        new JavaVMCallbackHandler(runnable).start();
    }

    /**
     * Exec the VM as specified in this object's constructor.
     */
    public void start() throws IOException {

        if (vm != null) return;

        /*
         * If specified, add option for policy file
         */
        if (policyFileName != null) {
            String option = "-Djava.security.policy=" + policyFileName;
            addOptions(new String[] { option });
        }

        addOptions(new String[] { getCodeCoverageOptions() });

        /*
         * If forcesOutput is true :
         *  We force the new starting vm to output something so that we can know
         *  when it is effectively started by redirecting standard output through
         *  the next StreamPipe call (the vm is considered started when a first
         *  output has been streamed out).
         *  We do this by prepnding a "-showversion" option in the command line.
         */
        if (forcesOutput) {
            addOptions(new String[] {"-showversion"});
        }

        StringTokenizer optionsTokenizer = new StringTokenizer(options);
        StringTokenizer argsTokenizer = new StringTokenizer(args);
        int optionsCount = optionsTokenizer.countTokens();
        int argsCount = argsTokenizer.countTokens();

        String javaCommand[] = new String[optionsCount + argsCount + 2];
        int count = 0;

        javaCommand[count++] = JavaVM.javaProgram;
        while (optionsTokenizer.hasMoreTokens()) {
            javaCommand[count++] = optionsTokenizer.nextToken();
        }
        javaCommand[count++] = classname;
        while (argsTokenizer.hasMoreTokens()) {
            javaCommand[count++] = argsTokenizer.nextToken();
        }

        mesg("command = " + Arrays.asList(javaCommand).toString());
        System.err.println("");

        vm = Runtime.getRuntime().exec(javaCommand);

        /* output from the execed process may optionally be captured. */
        StreamPipe.plugTogether(this, vm.getInputStream(), this.outputStream);
        StreamPipe.plugTogether(this, vm.getErrorStream(), this.errorStream);

        try {
            if (forcesOutput) {
                // Wait distant vm to start, by using waiting time slices of 100 ms.
                // Wait at most for 2secs, after it considers the vm to be started.
                final long vmStartSleepTime = 100;
                final int maxTrials = 20;
                int numTrials = 0;
                while (!started && numTrials < maxTrials) {
                    numTrials++;
                    Thread.sleep(vmStartSleepTime);
                }

                // Outputs running status of distant vm
                String message =
                    "after " + (numTrials * vmStartSleepTime) + " milliseconds";
                if (started) {
                    mesg("distant vm process running, " + message);
                }
                else {
                    mesg("unknown running status of distant vm process, " + message);
                }
            }
            else {
                // Since we have no way to know if the distant vm is started,
                // we just consider the vm to be started after a 2secs waiting time.
                Thread.sleep(2000);
                mesg("distant vm considered to be started after a waiting time of 2 secs");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            mesg("Thread interrupted while checking if distant vm is started. Giving up check.");
            mesg("Distant vm state unknown");
            return;
        }
    }

    public void destroy() {
        if (vm != null) {
            vm.destroy();
        }
        vm = null;
    }

    protected Process getVM() {
        return vm;
    }

    /**
     * Handles calling the callback.
     */
    private class JavaVMCallbackHandler extends Thread {
        Runnable runnable;

        JavaVMCallbackHandler(Runnable runnable) {
            this.runnable = runnable;
        }


        /**
         * Wait for the Process to terminate and notify the callback.
         */
        @Override
        public void run() {
            if (vm != null) {
                try {
                    vm.waitFor();
                } catch(InterruptedException ie) {
                    // Restore the interrupted status
                    Thread.currentThread().interrupt();
                }
            }

            if (runnable != null) {
                runnable.run();
            }
        }
    }
}