/*
 * Copyright (c) 2013, 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 com.oracle.java.testlibrary.gc;

import java.util.List;
import java.util.ArrayList;
import com.oracle.java.testlibrary.*;

/**
 * A helper class for creating a command that starts a {@code jmap} process.
 *
 * The JmapLauncher can in particular be combined with a
 * java.lang.ProcessBuilder to easily start a jmap process. For example, the
 * following code run {@code jmap -heap} against a process with GC logging
 * turned on for the {@code jmap} process:
 *
 * <pre>
 * {@code
 * JmapLauncher jmap = new JmapLauncher("-XX:+PrintGC");
 * jmap.setJmapArguments("-heap", pid);
 * ProcessBuilder pb = new ProcessBuilder(jmap.getCommand());
 * Process p = pb.start();
 * }
 * </pre>
 */
public class JmapLauncher {
    private final String executable;
    private final List<String> vmArgs = new ArrayList<String>();
    private final List<String> jmapArgs = new ArrayList<String>();

    /**
     * Creates a new {@code jmap} launcher and also sets the Java virtual
     * machine (JVM) arguments of the command.
     *
     * The JVM arguments are the arguments that are prefixed {@code -J} and
     * are passed to the underlying JVM that runs the {@code jmap} program.
     *
     * Any platform specific arguments that are needed to run the {@code jmap}
     * command will automatically be added.
     *
     * @param args The arguments to the JVM. Will be automatically prefix with
     *             {@code J}.
     */
    public JmapLauncher(String ... args) {
        executable = JDKToolFinder.getJDKTool("jmap");
        setVMArgs(ProcessTools.getPlatformSpecificVMArgs());
        setVMArgs(args);
    }

    /**
     * Sets the arguments for {@code jmap}. Note that any JVM specific
     * arguments must be passed via the constructor.
     *
     * @param args The arguments to {@code jmap}.
     */
    public void setJmapArguments(String ... args) {
        for (String arg : args) {
            jmapArgs.add(arg);
        }
    }

    /**
     * Returns the command that can be used for starting the {@code jmap}
     * process.
     *
     * @return An array whose elements are the arguments of the command.
     */
    public String[] getCommand() {
        List<String> command = new ArrayList<String>();
        command.add(executable);
        command.addAll(vmArgs);
        command.addAll(jmapArgs);
        return command.toArray(new String[command.size()]);
    }

    private void setVMArgs(String[]  args) {
        for (String arg : args) {
            vmArgs.add("-J" + arg);
        }
    }
}