WikiGameKiller.java - a program for solving Wiki game instances

Intro

I have this GitHub repository. Basically, it is a command-line utility for searching automatically for shortest link paths in the Wikipedia article graph.

Limitations

(As of now, it is possible that the pathfinder in question may discover a link A -> B, but A does not seem to link to B in the article web page. I am still working on how to mitigate this issue.)

Code

com.github.coderodde.wikipedia.game.killer.WikiGameKiller.java:

package com.github.coderodde.wikipedia.game.killer;import com.github.coderodde.graph.pathfinding.delayed.AbstractNodeExpander;import com.github.coderodde.graph.pathfinding.delayed.impl.ThreadPoolBidirectionalBFSPathFinder;import com.github.coderodde.graph.pathfinding.delayed.impl.ThreadPoolBidirectionalBFSPathFinderBuilder;import com.github.coderodde.graph.pathfinding.delayed.impl.ThreadPoolBidirectionalBFSPathFinderSearchBuilder;import com.github.coderodde.wikipedia.graph.expansion.BackwardWikipediaGraphNodeExpander;import com.github.coderodde.wikipedia.graph.expansion.ForwardWikipediaGraphNodeExpander;import java.io.BufferedWriter;import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.net.URLDecoder;import java.net.URLEncoder;import java.nio.charset.Charset;import java.util.ArrayList;import java.util.Arrays;import java.util.HashMap;import java.util.List;import java.util.Locale;import java.util.Map;import java.util.regex.Matcher;import java.util.regex.Pattern;public final class WikiGameKiller {    private static final String WIKIPEDIA_URL_FORMAT ="^((http:\\/\\/)|(https:\\/\\/))?..\\.wikipedia\\.org\\/wiki\\/.+$";    private static final Pattern WIKIPEDIA_URL_FORMAT_PATTERN =             Pattern.compile(WIKIPEDIA_URL_FORMAT);    private static final class CommandLineArguments {        String source           = null;        String target           = null;        String outFileName      = null;        int threads             = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_NUMBER_OF_THREADS;        int trials              = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_NUMBER_OF_MASTER_TRIALS;        int masterSleepDuration = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_MASTER_THREAD_SLEEP_DURATION_MILLIS;        int slaveSleepDuration  = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_SLAVE_THREAD_SLEEP_DURATION_MILLIS;        int expansionTimeout    = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_EXPANSION_JOIN_DURATION_MILLIS;        int lockWaitDuration    = ThreadPoolBidirectionalBFSPathFinder.DEFAULT_LOCK_WAIT_MILLIS;        boolean printHelp       = false;        boolean printStatistics = false;    }    public static void main(String[] args) {        try {            CommandLineArguments commandLineArguments =                     parseCommandLineArguments(args);            if (commandLineArguments.printHelp) {                printHelp();                return;            }            String source = commandLineArguments.source;            String target = commandLineArguments.target;            checkWikipediaArticleFormat(source);            checkWikipediaArticleFormat(target);            String languageCodeSource = getLanguageCode(source);            String languageCodeTarget = getLanguageCode(target);            if (!languageCodeSource.equals(languageCodeTarget)) {                throw new CommandLineException(                        String.format("Language code mismatch: \"%s\" vs \"%s\".",                                 languageCodeSource,                                 languageCodeTarget));            }            // Get the article names:            source = source.substring(source.lastIndexOf("/") + 1);            target = target.substring(target.lastIndexOf("/") + 1);            source = URLDecoder.decode(source, Charset.forName("UTF-8"));            target = URLDecoder.decode(target, Charset.forName("UTF-8"));            ForwardLinkExpander forwardLinkExpander =                     new ForwardLinkExpander(languageCodeSource);            BackwardLinkExpander backwardLinkExpander =                     new BackwardLinkExpander(languageCodeTarget);            validateTerminalNodes(forwardLinkExpander,                                  backwardLinkExpander,                                   source,                                  target);            ThreadPoolBidirectionalBFSPathFinder<String> finder =                     ThreadPoolBidirectionalBFSPathFinderBuilder.<String>begin()                    .withJoinDurationMillis(commandLineArguments.expansionTimeout)                    .withLockWaitMillis(commandLineArguments.lockWaitDuration)                    .withMasterThreadSleepDurationMillis(commandLineArguments.masterSleepDuration)                    .withSlaveThreadSleepDurationMillis(commandLineArguments.slaveSleepDuration)                    .withNumberOfMasterTrials(commandLineArguments.trials)                    .withNumberOfRequestedThreads(commandLineArguments.threads)                    .end();            List<String> path =                     ThreadPoolBidirectionalBFSPathFinderSearchBuilder                            .<String>withPathFinder(finder)                            .withSourceNode(source)                            .withTargetNode(target)                            .withForwardNodeExpander(forwardLinkExpander)                            .withBackwardNodeExpander(backwardLinkExpander)                            .search();            if (commandLineArguments.printStatistics) {                System.out.printf("[STATISTICS] Duration: %d milliseconds, " +"expanded nodes: %d nodes.\n",                        finder.getDurationMillis(),                        finder.getNumberOfExpandedNodes());            }            for (int i = 0; i < path.size(); i++) {                final String title = path.get(i);                final String url = wrapToUrl(title, languageCodeTarget);                path.set(i, url);            }            for (final String articleTitle : path) {                System.out.println(articleTitle);            }            if (commandLineArguments.outFileName != null) {                saveFile(commandLineArguments.outFileName,                         path,                         commandLineArguments.printStatistics,                         finder.getDuration(),                         finder.getNumberOfExpandedNodes());            }        } catch (final CommandLineException ex) {            System.out.printf("ERROR: %s\n", ex.getMessage());            System.exit(1);        }    }    private static void saveFile(final String fileName,                                 final List<String> path,                                 final boolean showStats,                                 final long duration,                                 final int numberOfExpandedNodes) {        File file = new File(fileName);        if (!file.exists()) {            try {                if (!file.createNewFile()) {                    throw new CommandLineException(                            String.format("Could not create file \"%s\".",                                     fileName));                }            } catch (IOException ex) {                throw new CommandLineException(                        String.format("Could not create file \"%s\".",                                 fileName));            }        }        String html;        if (showStats) {            html = String.format(                    HTML_TEMPLATE,                    String.format("Duration: %d milliseconds, expanded %d nodes.",                             duration,                             numberOfExpandedNodes),                    getPathListHtml(path));        } else {            html = String.format(HTML_TEMPLATE, "", getPathListHtml(path));        }        try {            final BufferedWriter bufferedWriter =                     new BufferedWriter(new FileWriter(fileName));            bufferedWriter.write(html);            bufferedWriter.close();        } catch (IOException ex) {            throw new CommandLineException("Could not create a buffered writer.");        }    }    private static String getPathListHtml(final List<String> articleUrlPath) {        StringBuilder stringBuilder = new StringBuilder();        stringBuilder.append("<ol>\n");        for (final String articleUrl : articleUrlPath) {            stringBuilder.append("                <li><a href=\"")                         .append(articleUrl)                         .append("\">")                         .append(articleUrl)                         .append("</a></li>\n");        }        stringBuilder.append("            </ol>\n");        return stringBuilder.toString();    }    private static String wrapToUrl(final String articleTitle,                                     final String languageCode) {        return String.format("https://%s.wikipedia.org/wiki/%s",                              languageCode,                              URLEncoder.encode(                                     articleTitle,                                      Charset.forName("UTF-8")));    }    private static String getLanguageCode(String url) {        final String secureProtocol = "https://";        final String insecureProtocol = "http://";        if (url.startsWith(secureProtocol)) {            url = url.substring(secureProtocol.length());        } else if (url.startsWith(insecureProtocol)) {            url = url.substring(insecureProtocol.length());        }        final String languageCode = url.substring(0, 2);        if (!Arrays.asList(Locale.getISOLanguages()).contains(languageCode)) {            throw new CommandLineException(                    String.format("Unknown language code: %s",                            languageCode));        }        return languageCode;    }    private static void validateTerminalNodes(            final AbstractNodeExpander<String> forwardExpander,            final AbstractNodeExpander<String> backwardExpander,            String source,             String target) {        if (!forwardExpander.isValidNode(source)) {            throw new CommandLineException(                    String.format("The source node \"%s\" is not a valid node.",                            source));        }        if (!backwardExpander.isValidNode(target)) {            throw new CommandLineException(                    String.format("The target node \"%s\" is not a valid node.",                            target));        }    }    private static final String HTML_TEMPLATE = """<!DOCTYPE html><html><head><title>WikiGameKiller.java</title></head><body><div>%s</div><div><h3>Shortest path:</h3>                        %s</div><body></html>""";    private static void printHelp() {        System.out.printf("""        usage: %s            --source SOURCE_ARTICLE_URL            --target TARGET_ARTICLE_URL           [--threads NUMBER_OF_THREADS]           [--master-trials TRIALS]           [--master-sleep-duration MASTER_SLEEP_MILLIS]           [--slave-sleep-duration SLAVE_SLEEP_MILLIS]           [--expansion-timeout EXPANSION_TIMEOUT_MILLIS]           [--lock-wait-timeout LOCK_WAIT_MILLIS]           [--help]           [--stats]           [--out OUTPUT_HTML_FILE_NAME]            where:                NUMBER_OF_THREADS        - the total number of threads.        Default is %d.                TRIALS                   - the number of master thread trials. Default is %d.                MASTER_SLEEP_MILLIS      - the number of milliseconds.         Default is %d.                SLAVE_SLEEP_MILLIS       - the number of milliseconds.         Default is %d.                EXPANSION_TIMEOUT_MILLIS - the number of milliseconds.         Default is %d.                LOCK_WAIT_MILLIS         - the number of milliseconds.         Default is %d.                --help  - Print this help message.                --stats - Print the search statistics after the search.""",        getPath(),        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_NUMBER_OF_THREADS,        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_NUMBER_OF_MASTER_TRIALS,        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_MASTER_THREAD_SLEEP_DURATION_MILLIS,        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_SLAVE_THREAD_SLEEP_DURATION_MILLIS,        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_EXPANSION_JOIN_DURATION_MILLIS,        ThreadPoolBidirectionalBFSPathFinder.DEFAULT_LOCK_WAIT_MILLIS        );    }    private static CommandLineArguments parseCommandLineArguments(String[] args) {        Map<String, Integer> map = computeArgumentMap(args);        if (map.containsKey("--help")) {            if (map.size() > 1) {                throw new CommandLineException("--help must be the only argument.");            }            CommandLineArguments commandLineSettings = new CommandLineArguments();            commandLineSettings.printHelp = true;            return commandLineSettings;        }        if (!map.containsKey("--source")) {            throw new CommandLineException("--source option is missing.");        }        if (!map.containsKey("--target")) {            throw new CommandLineException("--target option is missing.");        }        CommandLineArguments commandLineArguments = new CommandLineArguments();        commandLineArguments.source =                 getArgumentStringValue(args, map.get("--source") + 1);        commandLineArguments.target =                 getArgumentStringValue(args, map.get("--target") + 1);        if (map.containsKey("--out")) {            commandLineArguments.outFileName =                 getArgumentStringValue(args, map.get("--out") + 1);        }        if (map.containsKey("--stats")) {            commandLineArguments.printStatistics = true;        }        if (map.containsKey("--threads")) {            int index = map.get("--threads");            commandLineArguments.threads = getArgumentIntValue(args, index + 1);        }        if (map.containsKey("--master-trials")) {            int index = map.get("--master-trials");            commandLineArguments.trials = getArgumentIntValue(args, index + 1);        }        if (map.containsKey("--master-sleep-duration")) {            int index = map.get("--master-sleep-duration");            commandLineArguments.masterSleepDuration =                     getArgumentIntValue(args, index + 1);        }        if (map.containsKey("--slave-sleep-duration")) {            int index = map.get("--slave-sleep-duration");            commandLineArguments.slaveSleepDuration =                     getArgumentIntValue(args, index + 1);        }        if (map.containsKey("--expansion-timeout")) {            int index = map.get("--expansion-timeout");            commandLineArguments.expansionTimeout =                     getArgumentIntValue(args, index + 1);        }        if (map.containsKey("--lock-wait-timeout")) {            int index = map.get("--lock-wait-timeout");            commandLineArguments.lockWaitDuration =                     getArgumentIntValue(args, index + 1);        }        return commandLineArguments;    }    private static Map<String, Integer> computeArgumentMap(String[] args) {        Map<String, Integer> map = new HashMap<>(args.length);        for (int i = 0; i < args.length; i++) {            map.put(args[i], i);        }        return map;    }    private static String getArgumentStringValue(String[] args, int index) {        checkValueFitsInCommandLine(args, index);        return args[index];    }    private static int getArgumentIntValue(String[] args, int index) {        checkValueFitsInCommandLine(args, index);        try {            return Integer.parseInt(args[index]);        } catch (final NumberFormatException ex) {            throw new CommandLineException(                    String.format("\"%s\" is not an integer.",                            args[index + 1]));        }    }    private static void checkValueFitsInCommandLine(String[] args, int index) {        if (index >= args.length) {            throw new CommandLineException(                    String.format("The argument \"%s\" has no value.",                             args[index]));        }    }    public static final class CommandLineException extends RuntimeException {        CommandLineException(final String exceptionMessage) {            super(exceptionMessage);        }    }    private static String getPath() {        return new java.io.File(WikiGameKiller.class.getProtectionDomain()          .getCodeSource()          .getLocation()          .getPath())          .getName();    }    static void checkWikipediaArticleFormat(final String url) {        Matcher matcher = WIKIPEDIA_URL_FORMAT_PATTERN.matcher(url);        if (!matcher.find()) {            throw new CommandLineException(                    String.format("URL \"%s\" is not a valid Wikipedia URL.",                            url));        }    }    private static List<String> stripHostAddress(final List<String> urlList) {        List<String> result = new ArrayList<>(urlList.size());        for (final String url : urlList) {            result.add(url.substring(url.lastIndexOf("/") + 1));        }        return result;    }    private static final class ForwardLinkExpander             extends AbstractNodeExpander<String> {        private final ForwardWikipediaGraphNodeExpander expander;        public ForwardLinkExpander(final String languageCode) {            this.expander = new ForwardWikipediaGraphNodeExpander(languageCode);        }        @Override        public List<String> generateSuccessors(final String article) {            List<String> urlList = expander.generateSuccessors(article);            return stripHostAddress(urlList);        }        @Override        public boolean isValidNode(final String article) {            return expander.isValidNode(article);        }    }    private static final class BackwardLinkExpander             extends AbstractNodeExpander<String> {        private final BackwardWikipediaGraphNodeExpander expander;        public BackwardLinkExpander(final String languageCode) {            this.expander =                     new BackwardWikipediaGraphNodeExpander(languageCode);        }        @Override        public List<String> generateSuccessors(final String article) {            List<String> urlList = expander.generateSuccessors(article);            return stripHostAddress(urlList);        }        @Override        public boolean isValidNode(final String article) {            return expander.isValidNode(article);        }    }}

Example output

java -jar WikiGameKiller.java-1.0.0.jar --source https://en.wikipedia.org/wiki/Bugatti --target https://en.wikipedia.org/wiki/Java_(programming_language) --threads 128 --stats --out ..\index.html --expansion-timeout 4000[STATISTICS] Duration: 4383 milliseconds, expanded nodes: 931 nodes.https://en.wikipedia.org/wiki/Bugattihttps://en.wikipedia.org/wiki/2024_Formula_One_World_Championshiphttps://en.wikipedia.org/wiki/Oracle_Corporationhttps://en.wikipedia.org/wiki/Java_%28programming_language%29