/*
 * Copyright (c) 1997, 2018, 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
 * questions.
 */

package jdk.javadoc.internal.tool;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Path;
import java.text.BreakIterator;
import java.text.Collator;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.IllformedLocaleException;
import java.util.List;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.Objects;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.StandardLocation;

import com.sun.tools.javac.api.JavacTrees;
import com.sun.tools.javac.file.BaseFileManager;
import com.sun.tools.javac.file.JavacFileManager;
import com.sun.tools.javac.jvm.Target;
import com.sun.tools.javac.main.Arguments;
import com.sun.tools.javac.main.CommandLine;
import com.sun.tools.javac.main.OptionHelper;
import com.sun.tools.javac.main.OptionHelper.GrumpyHelper;
import com.sun.tools.javac.platform.PlatformDescription;
import com.sun.tools.javac.platform.PlatformUtils;
import com.sun.tools.javac.util.ClientCodeException;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.Log;
import com.sun.tools.javac.util.Log.WriterKind;
import com.sun.tools.javac.util.Options;
import com.sun.tools.javac.util.StringUtils;

import jdk.javadoc.doclet.Doclet;
import jdk.javadoc.doclet.Doclet.Option;
import jdk.javadoc.doclet.DocletEnvironment;
import jdk.javadoc.internal.tool.Main.Result;

import static javax.tools.DocumentationTool.Location.*;

import static com.sun.tools.javac.main.Option.*;
import static jdk.javadoc.internal.tool.Main.Result.*;

Main program of Javadoc.
Previously named "Main".
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
Author:
Robert Field, Neal Gafter (rewrite)/**
 * Main program of Javadoc.
 * Previously named "Main".
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 *
 * @author Robert Field
 * @author Neal Gafter (rewrite)
 */
public class Start extends ToolOption.Helper {

    private static final Class<?> StdDoclet =
            jdk.javadoc.doclet.StandardDoclet.class;
    
Context for this invocation. /** Context for this invocation. */
    private final Context context;

    private static final String ProgramName = "javadoc";

    private Messager messager;

    private final String docletName;

    private final ClassLoader classLoader;

    private Class<?> docletClass;

    private Doclet doclet;

    // used to determine the locale for the messager
    private Locale locale;


    
In API mode, exceptions thrown while calling the doclet are
propagated using ClientCodeException.
/**
     * In API mode, exceptions thrown while calling the doclet are
     * propagated using ClientCodeException.
     */
    private boolean apiMode;

    private JavaFileManager fileManager;

    Start() {
        this(null, null, null, null, null, null);
    }

    Start(PrintWriter outWriter, PrintWriter errWriter) {
        this(null, null, outWriter, errWriter, null, null);
    }

    Start(Context context, String programName,
            PrintWriter outWriter, PrintWriter errWriter,
            String docletName, ClassLoader classLoader) {
        this.context = context == null ? new Context() : context;
        String pname = programName == null ? ProgramName : programName;
        this.messager = (outWriter == null && errWriter == null)
                ? new Messager(this.context, pname)
                : new Messager(this.context, pname, outWriter, errWriter);
        this.docletName = docletName;
        this.classLoader = classLoader;
        this.docletClass = null;
        this.locale = Locale.getDefault();
    }

    public Start(Context context) {
        this.docletClass = null;
        this.context = Objects.requireNonNull(context);
        this.apiMode = true;
        this.docletName = null;
        this.classLoader = null;
        this.locale = Locale.getDefault();
    }

    void initMessager() {
        if (!apiMode)
            return;
        if (messager == null) {
            Log log = context.get(Log.logKey);
            if (log instanceof Messager) {
                messager = (Messager) log;
            } else {
                PrintWriter out = context.get(Log.errKey);
                messager = (out == null)
                        ? new Messager(context, ProgramName)
                        : new Messager(context, ProgramName, out, out);
            }
        }
    }

    
Usage
/**
     * Usage
     */
    @Override
    void usage() {
        usage("main.usage", OptionKind.STANDARD, "main.usage.foot");
    }

    @Override
    void Xusage() {
        usage("main.Xusage", OptionKind.EXTENDED, "main.Xusage.foot");
    }

    @Override
    void version() {
        messager.notice("javadoc.version", messager.programName, version("release"));
    }

    @Override
    void fullVersion() {
        messager.notice("javadoc.fullversion", messager.programName, version("full"));
    }

    private void usage(String headerKey, OptionKind kind, String footerKey) {
        messager.notice(headerKey);
        showToolOptions(kind);

        // let doclet print usage information
        if (docletClass != null) {
            String name = doclet.getName();
            messager.notice("main.doclet.usage.header", name);
            showDocletOptions(kind == OptionKind.EXTENDED
                    ? Option.Kind.EXTENDED
                    : Option.Kind.STANDARD);
        }
        if (footerKey != null)
            messager.notice(footerKey);
    }

    private static final String versionRBName = "jdk.javadoc.internal.tool.resources.version";
    private static ResourceBundle versionRB;

    private static String version(String key) {
        if (versionRB == null) {
            try {
                versionRB = ResourceBundle.getBundle(versionRBName);
            } catch (MissingResourceException e) {
                return Log.getLocalizedString("version.not.available");
            }
        }
        try {
            return versionRB.getString(key);
        } catch (MissingResourceException e) {
            return Log.getLocalizedString("version.not.available");
        }
    }

    void showToolOptions(OptionKind kind) {
        Comparator<ToolOption> comp = new Comparator<ToolOption>() {
            final Collator collator = Collator.getInstance(Locale.US);
            { collator.setStrength(Collator.PRIMARY); }

            @Override
            public int compare(ToolOption o1, ToolOption o2) {
                return collator.compare(o1.primaryName, o2.primaryName);
            }
        };

        Stream.of(ToolOption.values())
                    .filter(opt -> opt.kind == kind)
                    .sorted(comp)
                    .forEach(this::showToolOption);
    }

    void showToolOption(ToolOption option) {
        List<String> names = option.getNames();
        String parameters;
        if (option.hasArg || option.primaryName.endsWith(":")) {
            String sep = (option == ToolOption.J) || option.primaryName.endsWith(":") ? "" : " ";
            parameters = sep + option.getParameters(messager);
        } else {
            parameters = "";
        }
        String description = option.getDescription(messager);
        showUsage(names, parameters, description);
    }

    void showDocletOptions(Option.Kind kind) {
        Comparator<Doclet.Option> comp = new Comparator<Doclet.Option>() {
            final Collator collator = Collator.getInstance(Locale.US);
            { collator.setStrength(Collator.PRIMARY); }

            @Override
            public int compare(Doclet.Option o1, Doclet.Option o2) {
                return collator.compare(o1.getNames().get(0), o2.getNames().get(0));
            }
        };

        doclet.getSupportedOptions().stream()
                .filter(opt -> opt.getKind() == kind)
                .sorted(comp)
                .forEach(this::showDocletOption);
    }

    void showDocletOption(Doclet.Option option) {
        List<String> names = option.getNames();
        String parameters;
        String optname = names.get(0);
        if (option.getArgumentCount() > 0 || optname.endsWith(":")) {
            String sep = optname.endsWith(":") ? "" : " ";
            parameters = sep + option.getParameters();
        } else {
            parameters = "";
        }
        String description = option.getDescription();
        showUsage(names, parameters, description);
    }

    // The following constants are intended to format the output to
    // be similar to that of the java launcher: i.e. "java -help".

    
The indent for the option synopsis. /** The indent for the option synopsis. */
    private static final String SMALL_INDENT = "    ";
    
The automatic indent for the description. /** The automatic indent for the description. */
    private static final String LARGE_INDENT = "                  ";
    
The space allowed for the synopsis, if the description is to be shown on the same line. /** The space allowed for the synopsis, if the description is to be shown on the same line. */
    private static final int DEFAULT_SYNOPSIS_WIDTH = 13;
    
The nominal maximum line length, when seeing if text will fit on a line. /** The nominal maximum line length, when seeing if text will fit on a line. */
    private static final int DEFAULT_MAX_LINE_LENGTH = 80;
    
The format for a single-line help entry. /** The format for a single-line help entry. */
    private static final String COMPACT_FORMAT = SMALL_INDENT + "%-" + DEFAULT_SYNOPSIS_WIDTH + "s %s";

    void showUsage(List<String> names, String parameters, String description) {
        String synopses = names.stream()
                .map(s -> s + parameters)
                .collect(Collectors.joining(", "));
        // If option synopses and description fit on a single line of reasonable length,
        // display using COMPACT_FORMAT
        if (synopses.length() < DEFAULT_SYNOPSIS_WIDTH
                && !description.contains("\n")
                && (SMALL_INDENT.length() + DEFAULT_SYNOPSIS_WIDTH + 1 + description.length() <= DEFAULT_MAX_LINE_LENGTH)) {
            messager.printNotice(String.format(COMPACT_FORMAT, synopses, description));
            return;
        }

        // If option synopses fit on a single line of reasonable length, show that;
        // otherwise, show 1 per line
        if (synopses.length() <= DEFAULT_MAX_LINE_LENGTH) {
            messager.printNotice(SMALL_INDENT + synopses);
        } else {
            for (String name: names) {
                messager.printNotice(SMALL_INDENT + name + parameters);
            }
        }

        // Finally, show the description
        messager.printNotice(LARGE_INDENT + description.replace("\n", "\n" + LARGE_INDENT));
    }


    
Main program - external wrapper. In order to maintain backward
CLI compatibility, the execution is dispatched to the appropriate
Start mechanism, depending on the doclet variant.
The doclet tests are performed in the begin method, further on,
this is to minimize argument processing and most importantly the impact
of class loader creation, needed to detect the doclet class variants.
/**
     * Main program - external wrapper. In order to maintain backward
     * CLI compatibility, the execution is dispatched to the appropriate
     * Start mechanism, depending on the doclet variant.
     *
     * The doclet tests are performed in the begin method, further on,
     * this is to minimize argument processing and most importantly the impact
     * of class loader creation, needed to detect the doclet class variants.
     */
    @SuppressWarnings("deprecation")
    Result begin(String... argv) {
        // Preprocess @file arguments
        try {
            argv = CommandLine.parse(argv);
            return begin(Arrays.asList(argv), Collections.emptySet());
        } catch (IOException e) {
            error("main.cant.read", e.getMessage());
            return ERROR;
        }
    }

    // Called by 199 API.
    public boolean begin(Class<?> docletClass,
            Iterable<String> options,
            Iterable<? extends JavaFileObject> fileObjects) {
        this.docletClass = docletClass;
        List<String> opts = new ArrayList<>();
        for (String opt: options)
            opts.add(opt);

        return begin(opts, fileObjects).isOK();
    }

    @SuppressWarnings("removal")
    private Result begin(List<String> options, Iterable<? extends JavaFileObject> fileObjects) {
        fileManager = context.get(JavaFileManager.class);
        if (fileManager == null) {
            JavacFileManager.preRegister(context);
            fileManager = context.get(JavaFileManager.class);
            if (fileManager instanceof BaseFileManager) {
                ((BaseFileManager) fileManager).autoClose = true;
            }
        }

        // locale, doclet and maybe taglet, needs to be determined first
        try {
            docletClass = preprocess(fileManager, options);
        } catch (ToolException te) {
            if (!te.result.isOK()) {
                if (te.message != null) {
                    messager.printError(te.message);
                }
                Throwable t = te.getCause();
                dumpStack(t == null ? te : t);
            }
            return te.result;
        } catch (OptionException oe) {
            if (oe.message != null) {
                messager.printError(oe.message);
            }
            oe.m.run();
            Throwable t = oe.getCause();
            dumpStack(t == null ? oe : t);
            return oe.result;
        }
        if (jdk.javadoc.doclet.Doclet.class.isAssignableFrom(docletClass)) {
            // no need to dispatch to old, safe to init now
            initMessager();
            messager.setLocale(locale);
            try {
                Object o = docletClass.getConstructor().newInstance();
                doclet = (Doclet) o;
            } catch (ReflectiveOperationException exc) {
                if (apiMode) {
                    throw new ClientCodeException(exc);
                }
                error("main.could_not_instantiate_class", docletClass);
                return ERROR;
            }
        } else {
            if (apiMode) {
                com.sun.tools.javadoc.main.Start ostart
                        = new com.sun.tools.javadoc.main.Start(context);
                return ostart.begin(docletClass, options, fileObjects)
                        ? OK
                        : ERROR;
            }
            warn("main.legacy_api");
            String[] array = options.toArray(new String[options.size()]);
            int rc = com.sun.tools.javadoc.Main.execute(
                    messager.programName,
                    messager.getWriter(WriterKind.ERROR),
                    messager.getWriter(WriterKind.WARNING),
                    messager.getWriter(WriterKind.NOTICE),
                    docletClass.getName(),
                    array);
            return (rc == 0) ? OK : ERROR;
        }

        Result result = OK;
        try {
            result = parseAndExecute(options, fileObjects);
        } catch (com.sun.tools.javac.main.Option.InvalidValueException e) {
            messager.printError(e.getMessage());
            Throwable t = e.getCause();
            dumpStack(t == null ? e : t);
            return ERROR;
        } catch (OptionException toe) {
            if (toe.message != null)
                messager.printError(toe.message);

            toe.m.run();
            Throwable t = toe.getCause();
            dumpStack(t == null ? toe : t);
            return toe.result;
        } catch (ToolException exc) {
            if (exc.message != null) {
                messager.printError(exc.message);
            }
            Throwable t = exc.getCause();
            if (result == ABNORMAL) {
                reportInternalError(t == null ? exc : t);
            } else {
                dumpStack(t == null ? exc : t);
            }
            return exc.result;
        } catch (OutOfMemoryError ee) {
            error("main.out.of.memory");
            result = SYSERR;
            dumpStack(ee);
        } catch (ClientCodeException e) {
            // simply rethrow these exceptions, to be caught and handled by JavadocTaskImpl
            throw e;
        } catch (Error | Exception ee) {
            error("main.fatal.error", ee);
            reportInternalError(ee);
            result = ABNORMAL;
        } finally {
            if (fileManager != null
                    && fileManager instanceof BaseFileManager
                    && ((BaseFileManager) fileManager).autoClose) {
                try {
                    fileManager.close();
                } catch (IOException ignore) {}
            }
            boolean haveErrorWarnings = messager.hasErrors()
                    || (rejectWarnings && messager.hasWarnings());
            if (!result.isOK() && !haveErrorWarnings) {
                // the doclet failed, but nothing reported, flag it!.
                error("main.unknown.error");
            }
            if (haveErrorWarnings && result.isOK()) {
                result = ERROR;
            }
            messager.printErrorWarningCounts();
            messager.flush();
        }
        return result;
    }

    private void reportInternalError(Throwable t) {
        messager.printErrorUsingKey("doclet.internal.report.bug");
        dumpStack(true, t);
    }

    private void dumpStack(Throwable t) {
        dumpStack(false, t);
    }

    private void dumpStack(boolean enabled, Throwable t) {
        if (t != null && (enabled || dumpOnError)) {
            t.printStackTrace(System.err);
        }
    }

    
Main program - internal
/**
     * Main program - internal
     */
    @SuppressWarnings("unchecked")
    private Result parseAndExecute(List<String> argList, Iterable<? extends JavaFileObject> fileObjects)
            throws ToolException, OptionException, com.sun.tools.javac.main.Option.InvalidValueException {
        long tm = System.currentTimeMillis();

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

        compOpts = Options.instance(context);

        // Make sure no obsolete source/target messages are reported
        try {
            com.sun.tools.javac.main.Option.XLINT_CUSTOM.process(getOptionHelper(), "-Xlint:-options");
        } catch (com.sun.tools.javac.main.Option.InvalidValueException ignore) {
        }

        Arguments arguments = Arguments.instance(context);
        arguments.init(ProgramName);
        arguments.allowEmpty();

        doclet.init(locale, messager);
        parseArgs(argList, javaNames);

        if (!arguments.handleReleaseOptions(extra -> true)) {
            // Arguments does not always increase the error count in the
            // case of errors, so increment the error count only if it has
            // not been updated previously, preventing complaints by callers
            if (!messager.hasErrors() && !messager.hasWarnings())
                messager.nerrors++;
            return CMDERR;
        }

        if (!arguments.validate()) {
            // Arguments does not always increase the error count in the
            // case of errors, so increment the error count only if it has
            // not been updated previously, preventing complaints by callers
            if (!messager.hasErrors() && !messager.hasWarnings())
                messager.nerrors++;
            return CMDERR;
        }

        if (fileManager instanceof BaseFileManager) {
            ((BaseFileManager) fileManager).handleOptions(fileManagerOpts);
        }

        if (fileManager.isSupportedOption(MULTIRELEASE.primaryName) == 1) {
            Target target = Target.instance(context);
            List<String> list = List.of(target.multiReleaseValue());
            fileManager.handleOption(MULTIRELEASE.primaryName, list.iterator());
        }
        compOpts.notifyListeners();
        List<String> modules = (List<String>) jdtoolOpts.computeIfAbsent(ToolOption.MODULE,
                s -> Collections.EMPTY_LIST);

        if (modules.isEmpty()) {
            List<String> subpkgs = (List<String>) jdtoolOpts.computeIfAbsent(ToolOption.SUBPACKAGES,
                    s -> Collections.EMPTY_LIST);
            if (subpkgs.isEmpty()) {
                if (javaNames.isEmpty() && isEmpty(fileObjects)) {
                    String text = messager.getText("main.No_modules_packages_or_classes_specified");
                    throw new ToolException(CMDERR, text);
                }
            }
        }

        JavadocTool comp = JavadocTool.make0(context);
        if (comp == null) return ABNORMAL;

        DocletEnvironment docEnv = comp.getEnvironment(jdtoolOpts,
                javaNames,
                fileObjects);

        // release resources
        comp = null;

        if (breakiterator || !locale.getLanguage().equals(Locale.ENGLISH.getLanguage())) {
            JavacTrees trees = JavacTrees.instance(context);
            trees.setBreakIterator(BreakIterator.getSentenceInstance(locale));
        }
        // pass off control to the doclet
        Result returnStatus = docEnv != null && doclet.run(docEnv)
                ? OK
                : ERROR;

        // We're done.
        if (compOpts.get("-verbose") != null) {
            tm = System.currentTimeMillis() - tm;
            messager.notice("main.done_in", Long.toString(tm));
        }

        return returnStatus;
    }

    boolean matches(List<String> names, String arg) {
        for (String name : names) {
            if (StringUtils.toLowerCase(name).equals(StringUtils.toLowerCase(arg)))
                return true;
        }
        return false;
    }

    boolean matches(Doclet.Option option, String arg) {
        if (matches(option.getNames(), arg))
             return true;
        int sep = arg.indexOf(':');
        String targ = arg.substring(0, sep + 1);
        return matches(option.getNames(), targ);
    }

    Set<? extends Doclet.Option> docletOptions = null;
    int handleDocletOptions(int idx, List<String> args, boolean isToolOption)
            throws OptionException {
        if (docletOptions == null) {
            docletOptions = doclet.getSupportedOptions();
        }
        String arg = args.get(idx);
        String argBase, argVal;
        if (arg.startsWith("--") && arg.contains("=")) {
            int sep = arg.indexOf("=");
            argBase = arg.substring(0, sep);
            argVal = arg.substring(sep + 1);
        } else {
            argBase = arg;
            argVal = null;
        }
        String text = null;
        for (Doclet.Option opt : docletOptions) {
            if (matches(opt, argBase)) {
                if (argVal != null) {
                    switch (opt.getArgumentCount()) {
                        case 0:
                            text = messager.getText("main.unnecessary_arg_provided", argBase);
                            throw new OptionException(ERROR, this::usage, text);
                        case 1:
                            opt.process(arg, Arrays.asList(argVal));
                            break;
                        default:
                            text = messager.getText("main.only_one_argument_with_equals", argBase);
                            throw new OptionException(ERROR, this::usage, text);
                    }
                } else {
                    if (args.size() - idx -1 < opt.getArgumentCount()) {
                        text = messager.getText("main.requires_argument", arg);
                        throw new OptionException(ERROR, this::usage, text);
                    }
                    opt.process(arg, args.subList(idx + 1, args.size()));
                    idx += opt.getArgumentCount();
                }
                return idx;
            }
        }
        // check if arg is accepted by the tool before emitting error
        if (!isToolOption) {
            text = messager.getText("main.invalid_flag", arg);
            throw new OptionException(ERROR, this::usage, text);
        }
        return idx;
    }

    private Class<?> preprocess(JavaFileManager jfm,
            List<String> argv) throws ToolException, OptionException {
        // doclet specifying arguments
        String userDocletPath = null;
        String userDocletName = null;

        // taglet specifying arguments, since tagletpath is a doclet
        // functionality, assume they are repeated and inspect all.
        List<File> userTagletPath = new ArrayList<>();
        List<String> userTagletNames = new ArrayList<>();

        // Step 1: loop through the args, set locale early on, if found.
        for (int i = 0 ; i < argv.size() ; i++) {
            String arg = argv.get(i);
            if (arg.equals(ToolOption.DUMPONERROR.primaryName)) {
                dumpOnError = true;
            } else if (arg.equals(ToolOption.LOCALE.primaryName)) {
                checkOneArg(argv, i++);
                String lname = argv.get(i);
                locale = getLocale(lname);
            } else if (arg.equals(ToolOption.DOCLET.primaryName)) {
                checkOneArg(argv, i++);
                if (userDocletName != null) {
                    if (apiMode) {
                        throw new IllegalArgumentException("More than one doclet specified (" +
                                userDocletName + " and " + argv.get(i) + ").");
                    }
                    String text = messager.getText("main.more_than_one_doclet_specified_0_and_1",
                            userDocletName, argv.get(i));
                    throw new ToolException(CMDERR, text);
                }
                if (docletName != null) {
                    if (apiMode) {
                        throw new IllegalArgumentException("More than one doclet specified (" +
                                docletName + " and " + argv.get(i) + ").");
                    }
                    String text = messager.getText("main.more_than_one_doclet_specified_0_and_1",
                            docletName, argv.get(i));
                    throw new ToolException(CMDERR, text);
                }
                userDocletName = argv.get(i);
            } else if (arg.equals(ToolOption.DOCLETPATH.primaryName)) {
                checkOneArg(argv, i++);
                if (userDocletPath == null) {
                    userDocletPath = argv.get(i);
                } else {
                    userDocletPath += File.pathSeparator + argv.get(i);
                }
            } else if ("-taglet".equals(arg)) {
                userTagletNames.add(argv.get(i + 1));
            } else if ("-tagletpath".equals(arg)) {
                for (String pathname : argv.get(i + 1).split(File.pathSeparator)) {
                    userTagletPath.add(new File(pathname));
                }
            }
        }

        // Step 2: a doclet is provided, nothing more to do.
        if (docletClass != null) {
            return docletClass;
        }

        // Step 3: doclet name specified ? if so find a ClassLoader,
        // and load it.
        if (userDocletName != null) {
            ClassLoader cl = classLoader;
            if (cl == null) {
                if (!fileManager.hasLocation(DOCLET_PATH)) {
                    List<File> paths = new ArrayList<>();
                    if (userDocletPath != null) {
                        for (String pathname : userDocletPath.split(File.pathSeparator)) {
                            paths.add(new File(pathname));
                        }
                    }
                    try {
                        ((StandardJavaFileManager)fileManager).setLocation(DOCLET_PATH, paths);
                    } catch (IOException ioe) {
                        if (apiMode) {
                            throw new IllegalArgumentException("Could not set location for " +
                                    userDocletPath, ioe);
                        }
                        String text = messager.getText("main.doclet_could_not_set_location",
                                userDocletPath);
                        throw new ToolException(CMDERR, text, ioe);
                    }
                }
                cl = fileManager.getClassLoader(DOCLET_PATH);
                if (cl == null) {
                    // despite doclet specified on cmdline no classloader found!
                    if (apiMode) {
                        throw new IllegalArgumentException("Could not obtain classloader to load "
                                + userDocletPath);
                    }
                    String text = messager.getText("main.doclet_no_classloader_found",
                            userDocletName);
                    throw new ToolException(CMDERR, text);
                }
            }
            try {
                return cl.loadClass(userDocletName);
            } catch (ClassNotFoundException cnfe) {
                if (apiMode) {
                    throw new IllegalArgumentException("Cannot find doclet class " + userDocletName,
                            cnfe);
                }
                String text = messager.getText("main.doclet_class_not_found", userDocletName);
                throw new ToolException(CMDERR, text, cnfe);
            }
        }

        // Step 4: we have a doclet, try loading it
        if (docletName != null) {
            return loadDocletClass(docletName);
        }

        // finally
        return StdDoclet;
    }

    private Class<?> loadDocletClass(String docletName) throws ToolException {
        try {
            return Class.forName(docletName, true, getClass().getClassLoader());
        } catch (ClassNotFoundException cnfe) {
            if (apiMode) {
                throw new IllegalArgumentException("Cannot find doclet class " + docletName);
            }
            String text = messager.getText("main.doclet_class_not_found", docletName);
            throw new ToolException(CMDERR, text, cnfe);
        }
    }

    private void parseArgs(List<String> args, List<String> javaNames) throws ToolException,
            OptionException, com.sun.tools.javac.main.Option.InvalidValueException {
        for (int i = 0 ; i < args.size() ; i++) {
            String arg = args.get(i);
            ToolOption o = ToolOption.get(arg);
            if (o != null) {
                // handle a doclet argument that may be needed however
                // don't increment the index, and allow the tool to consume args
                handleDocletOptions(i, args, true);
                if (o.hasArg) {
                    if (arg.startsWith("--") && arg.contains("=")) {
                        o.process(this, arg.substring(arg.indexOf('=') + 1));
                    } else {
                        checkOneArg(args, i++);
                        o.process(this, args.get(i));
                    }
                } else if (o.hasSuffix) {
                    o.process(this, arg);
                } else {
                    o.process(this);
                }
            } else if (arg.startsWith("-XD")) {
                // hidden javac options
                String s = arg.substring("-XD".length());
                int eq = s.indexOf('=');
                String key = (eq < 0) ? s : s.substring(0, eq);
                String value = (eq < 0) ? s : s.substring(eq+1);
                compOpts.put(key, value);
            } else if (arg.startsWith("-")) {
                i = handleDocletOptions(i, args, false);
            } else {
                javaNames.add(arg);
            }
        }
    }

    private <T> boolean isEmpty(Iterable<T> iter) {
        return !iter.iterator().hasNext();
    }

    
Check the one arg option.
Error and exit if one argument is not provided.
/**
     * Check the one arg option.
     * Error and exit if one argument is not provided.
     */
    private void checkOneArg(List<String> args, int index) throws OptionException {
        if ((index + 1) >= args.size() || args.get(index + 1).startsWith("-d")) {
            String text = messager.getText("main.requires_argument", args.get(index));
            throw new OptionException(CMDERR, this::usage, text);
        }
    }

    void error(String key, Object... args) {
        messager.printErrorUsingKey(key, args);
    }

    void warn(String key, Object... args)  {
        messager.printWarningUsingKey(key, args);
    }

    
Get the locale if specified on the command line
else return null and if locale option is not used
then return default locale.
/**
     * Get the locale if specified on the command line
     * else return null and if locale option is not used
     * then return default locale.
     */
    private Locale getLocale(String localeName) throws ToolException {
        try {
            // Tolerate, at least for a while, the older syntax accepted by javadoc,
            // using _ as the separator
            localeName = localeName.replace("_", "-");
            Locale l =  new Locale.Builder().setLanguageTag(localeName).build();
            // Ensure that a non-empty language is available for the <HTML lang=...> element
            return (l.getLanguage().isEmpty()) ? Locale.ENGLISH : l;
        } catch (IllformedLocaleException e) {
            String text = messager.getText("main.malformed_locale_name", localeName);
            throw new ToolException(CMDERR, text);
        }
    }

    
Search the locale for specified language, specified country and
specified variant.
/**
     * Search the locale for specified language, specified country and
     * specified variant.
     */
    private Locale searchLocale(String language, String country,
                                String variant) {
        for (Locale loc : Locale.getAvailableLocales()) {
            if (loc.getLanguage().equals(language) &&
                (country == null || loc.getCountry().equals(country)) &&
                (variant == null || loc.getVariant().equals(variant))) {
                return loc;
            }
        }
        return null;
    }

    @Override
    OptionHelper getOptionHelper() {
        return new GrumpyHelper(messager) {
            @Override
            public String get(com.sun.tools.javac.main.Option option) {
                return compOpts.get(option);
            }

            @Override
            public void put(String name, String value) {
                compOpts.put(name, value);
            }

            @Override
            public void remove(String name) {
                compOpts.remove(name);
            }

            @Override
            public boolean handleFileManagerOption(com.sun.tools.javac.main.Option option, String value) {
                fileManagerOpts.put(option, value);
                return true;
            }
        };
    }

    @Override
    String getLocalizedMessage(String msg, Object... args) {
        return messager.getText(msg, args);
    }
}