/*

 * Copyright (c) 2015, 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.dcmd;

import com.oracle.java.testlibrary.OutputAnalyzer;

import javax.management.*;

import javax.management.remote.JMXConnector;

import javax.management.remote.JMXConnectorFactory;

import javax.management.remote.JMXServiceURL;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.lang.management.ManagementFactory;

import java.util.HashMap;

/**

 * Executes Diagnostic Commands on the target VM (specified by a host/port combination or a full JMX Service URL) using

 * the JMX interface. If the target is not the current VM, the JMX Remote interface must be enabled beforehand.

 */

public class JMXExecutor extends CommandExecutor {

    private final MBeanServerConnection mbs;

    /**

     * Instantiates a new JMXExecutor targeting the current VM

     */

    public JMXExecutor() {

        super();

        mbs = ManagementFactory.getPlatformMBeanServer();

    }

    /**

     * Instantiates a new JMXExecutor targeting the VM indicated by the given host/port combination or a full JMX

     * Service URL

     *

     * @param target a host/port combination on the format "host:port" or a full JMX Service URL of the target VM

     */

    public JMXExecutor(String target) {

        String urlStr;

        if (target.matches("^\\w[\\w\\-]*(\\.[\\w\\-]+)*:\\d+$")) {

            /* Matches "hostname:port" */

            urlStr = String.format("service:jmx:rmi:///jndi/rmi://%s/jmxrmi", target);

        } else if (target.startsWith("service:")) {

            urlStr = target;

        } else {

            throw new IllegalArgumentException("Could not recognize target string: " + target);

        }

        try {

            JMXServiceURL url = new JMXServiceURL(urlStr);

            JMXConnector c = JMXConnectorFactory.connect(url, new HashMap<>());

            mbs = c.getMBeanServerConnection();

        } catch (IOException e) {

            throw new CommandExecutorException("Could not initiate connection to target: " + target, e);

        }

    }

    protected OutputAnalyzer executeImpl(String cmd) throws CommandExecutorException {

        String stdout = "";

        String stderr = "";

        String[] cmdParts = cmd.split(" ", 2);

        String operation = commandToMethodName(cmdParts[0]);

        Object[] dcmdArgs = produceArguments(cmdParts);

        String[] signature = {String[].class.getName()};

        ObjectName beanName = getMBeanName();

        try {

            stdout = (String) mbs.invoke(beanName, operation, dcmdArgs, signature);

        }

        /* Failures on the "local" side, the one invoking the command. */

        catch (ReflectionException e) {

            Throwable cause = e.getCause();

            if (cause instanceof NoSuchMethodException) {

                /* We want JMXExecutor to match the behavior of the other CommandExecutors */

                String message = "Unknown diagnostic command: " + operation;

                stderr = exceptionTraceAsString(new IllegalArgumentException(message, e));

            } else {

                rethrowExecutorException(operation, dcmdArgs, e);

            }

        }

        /* Failures on the "local" side, the one invoking the command. */

        catch (InstanceNotFoundException | IOException e) {

            rethrowExecutorException(operation, dcmdArgs, e);

        }

        /* Failures on the remote side, the one executing the invoked command. */

        catch (MBeanException e) {

            stdout = exceptionTraceAsString(e);

        }

        return new OutputAnalyzer(stdout, stderr);

    }

    private void rethrowExecutorException(String operation, Object[] dcmdArgs,

                                          Exception e) throws CommandExecutorException {

        String message = String.format("Could not invoke: %s %s", operation,

                String.join(" ", (String[]) dcmdArgs[0]));

        throw new CommandExecutorException(message, e);

    }

    private ObjectName getMBeanName() throws CommandExecutorException {

        String MBeanName = "com.sun.management:type=DiagnosticCommand";

        try {

            return new ObjectName(MBeanName);

        } catch (MalformedObjectNameException e) {

            String message = "MBean not found: " + MBeanName;

            throw new CommandExecutorException(message, e);

        }

    }

    private Object[] produceArguments(String[] cmdParts) {

        Object[] dcmdArgs = {new String[0]}; /* Default: No arguments */

        if (cmdParts.length == 2) {

            dcmdArgs[0] = cmdParts[1].split(" ");

        }

        return dcmdArgs;

    }

    /**

     * Convert from diagnostic command to MBean method name

     *

     * Examples:

     * help            --> help

     * VM.version      --> vmVersion

     * VM.command_line --> vmCommandLine

     */

    private static String commandToMethodName(String cmd) {

        String operation = "";

        boolean up = false; /* First letter is to be lower case */

        /*

         * If a '.' or '_' is encountered it is not copied,

         * instead the next character will be converted to upper case

         */

        for (char c : cmd.toCharArray()) {

            if (('.' == c) || ('_' == c)) {

                up = true;

            } else if (up) {

                operation = operation.concat(Character.toString(c).toUpperCase());

                up = false;

            } else {

                operation = operation.concat(Character.toString(c).toLowerCase());

            }

        }

        return operation;

    }

    private static String exceptionTraceAsString(Throwable cause) {

        StringWriter sw = new StringWriter();

        cause.printStackTrace(new PrintWriter(sw));

        return sw.toString();

    }

}