/*

 * Copyright (c) 2016, 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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 */

package jdk.jshell.execution;

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import com.sun.jdi.Bootstrap;

import com.sun.jdi.VirtualMachine;

import com.sun.jdi.connect.Connector;

import com.sun.jdi.connect.LaunchingConnector;

import com.sun.jdi.connect.ListeningConnector;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.TimeoutException;

import com.sun.jdi.connect.IllegalConnectorArgumentsException;

/**

 * Sets up a JDI connection, providing the resulting JDI {@link VirtualMachine}

 * and the {@link Process} the remote agent is running in.

 */

public class JdiInitiator {

    // factor for the timeout on all of connect

    private static final double CONNECT_TIMEOUT_FACTOR = 1.5;

    // Over-all connect time-out

    private final int connectTimeout;

    private VirtualMachine vm;

    private Process process = null;

    private final Connector connector;

    private final String remoteAgent;

    private final Map<String, com.sun.jdi.connect.Connector.Argument> connectorArgs;

    /**

     * Start the remote agent and establish a JDI connection to it.

     *

     * @param port the socket port for (non-JDI) commands

     * @param remoteVMOptions any user requested VM options

     * @param remoteAgent full class name of remote agent to launch

     * @param isLaunch does JDI do the launch? That is, LaunchingConnector,

     * otherwise we start explicitly and use ListeningConnector

     * @param host explicit hostname to use, if null use discovered

     * hostname, applies to listening only (!isLaunch)

     * @param timeout the start-up time-out in milliseconds

     */

    public JdiInitiator(int port, List<String> remoteVMOptions, String remoteAgent,

            boolean isLaunch, String host, int timeout) {

        this.remoteAgent = remoteAgent;

        this.connectTimeout = (int) (timeout * CONNECT_TIMEOUT_FACTOR);

        String connectorName

                = isLaunch

                        ? "com.sun.jdi.CommandLineLaunch"

                        : "com.sun.jdi.SocketListen";

        this.connector = findConnector(connectorName);

        if (connector == null) {

            throw new IllegalArgumentException("No connector named: " + connectorName);

        }

        Map<String, String> argumentName2Value

                = isLaunch

                        ? launchArgs(port, String.join(" ", remoteVMOptions))

                        : new HashMap<>();

        if (!isLaunch) {

            argumentName2Value.put("timeout", ""+timeout);

            if (host != null && !isLaunch) {

                argumentName2Value.put("localAddress", host);

            }

        }

        this.connectorArgs = mergeConnectorArgs(connector, argumentName2Value);

        this.vm = isLaunch

                ? launchTarget()

                : listenTarget(port, remoteVMOptions);

    }

    /**

     * Returns the resulting {@code VirtualMachine} instance.

     *

     * @return the virtual machine

     */

    public VirtualMachine vm() {

        return vm;

    }

    /**

     * Returns the launched process.

     *

     * @return the remote agent process

     */

    public Process process() {

        return process;

    }

    /* launch child target vm */

    private VirtualMachine launchTarget() {

        LaunchingConnector launcher = (LaunchingConnector) connector;

        try {

            VirtualMachine new_vm = timedVirtualMachineCreation(() -> launcher.launch(connectorArgs), null);

            process = new_vm.process();

            return new_vm;

        } catch (Throwable ex) {

            throw reportLaunchFail(ex, "launch");

        }

    }

    /**

     * Directly launch the remote agent and connect JDI to it with a

     * ListeningConnector.

     */

    private VirtualMachine listenTarget(int port, List<String> remoteVMOptions) {

        ListeningConnector listener = (ListeningConnector) connector;

        try {

            // Start listening, get the JDI connection address

            String addr = listener.startListening(connectorArgs);

            debug("Listening at address: " + addr);

            // Launch the RemoteAgent requesting a connection on that address

            String javaHome = System.getProperty("java.home");

            List<String> args = new ArrayList<>();

            args.add(javaHome == null

                    ? "java"

                    : javaHome + File.separator + "bin" + File.separator + "java");

            args.add("-agentlib:jdwp=transport=" + connector.transport().name() +

                    ",address=" + addr);

            args.addAll(remoteVMOptions);

            args.add(remoteAgent);

            args.add("" + port);

            ProcessBuilder pb = new ProcessBuilder(args);

            process = pb.start();

            // Accept the connection from the remote agent

            vm = timedVirtualMachineCreation(() -> listener.accept(connectorArgs),

                    () -> process.waitFor());

            return vm;

        } catch (Throwable ex) {

            if (process != null) {

                process.destroyForcibly();

            }

            throw reportLaunchFail(ex, "listen");

        } finally {

            try {

                listener.stopListening(connectorArgs);

            } catch (IOException | IllegalConnectorArgumentsException ex) {

                // ignore

            }

        }

    }

    VirtualMachine timedVirtualMachineCreation(Callable<VirtualMachine> creator,

            Callable<Integer> processComplete) throws Exception {

        VirtualMachine result;

        ExecutorService executor = Executors.newCachedThreadPool(runnable -> {

            Thread thread = Executors.defaultThreadFactory().newThread(runnable);

            thread.setDaemon(true);

            return thread;

        });

        try {

            Future<VirtualMachine> future = executor.submit(creator);

            if (processComplete != null) {

                executor.submit(() -> {

                    Integer i = processComplete.call();

                    future.cancel(true);

                    return i;

                });

            }

            try {

                result = future.get(connectTimeout, TimeUnit.MILLISECONDS);

            } catch (TimeoutException ex) {

                future.cancel(true);

                throw ex;

            }

        } finally {

            executor.shutdownNow();

        }

        return result;

    }

    private Connector findConnector(String name) {

        for (Connector cntor

                : Bootstrap.virtualMachineManager().allConnectors()) {

            if (cntor.name().equals(name)) {

                return cntor;

            }

        }

        return null;

    }

    private Map<String, Connector.Argument> mergeConnectorArgs(Connector connector, Map<String, String> argumentName2Value) {

        Map<String, Connector.Argument> arguments = connector.defaultArguments();

        for (Entry<String, String> argumentEntry : argumentName2Value.entrySet()) {

            String name = argumentEntry.getKey();

            String value = argumentEntry.getValue();

            Connector.Argument argument = arguments.get(name);

            if (argument == null) {

                throw new IllegalArgumentException("Argument is not defined for connector:" +

                        name + " -- " + connector.name());

            }

            argument.setValue(value);

        }

        return arguments;

    }

    /**

     * The JShell specific Connector args for the LaunchingConnector.

     *

     * @param portthe socket port for (non-JDI) commands

     * @param remoteVMOptions any user requested VM options

     * @return the argument map

     */

    private Map<String, String> launchArgs(int port, String remoteVMOptions) {

        Map<String, String> argumentName2Value = new HashMap<>();

        argumentName2Value.put("main", remoteAgent + " " + port);

        argumentName2Value.put("options", remoteVMOptions);

        return argumentName2Value;

    }

    private InternalError reportLaunchFail(Throwable ex, String context) {

        return new InternalError("Failed remote " + context + ": "

                + ex.toString()

                + " @ " + connector +

                " -- " + connectorArgs, ex);

    }

    /**

     * Log debugging information. Arguments as for {@code printf}.

     *

     * @param format a format string as described in Format string syntax

     * @param args arguments referenced by the format specifiers in the format

     * string.

     */

    private void debug(String format, Object... args) {

        // Reserved for future logging

    }

    /**

     * Log a serious unexpected internal exception.

     *

     * @param ex the exception

     * @param where a description of the context of the exception

     */

    private void debug(Throwable ex, String where) {

        // Reserved for future logging

    }

}