public HelpCommand() {

        super("help");

        this.description = "Shows the help menu";

        this.usageMessage = "/help <pageNumber>\n/help <topic>\n/help <topic> <pageNumber>";

        this.setAliases(Arrays.asList(new String[] { "?" }));

        this.setPermission("bukkit.command.help");

    }

    @Override

    public boolean execute(CommandSender sender, String currentAlias, String[] args) {

        if (!testPermission(sender)) return true;

        String command;

        int pageNumber;

        int pageHeight;

        int pageWidth;

        if (args.length == 0) {

            command = "";

            pageNumber = 1;

        } else if (NumberUtils.isDigits(args[args.length - 1])) {

            command = StringUtils.join(ArrayUtils.subarray(args, 0, args.length - 1), " ");

            try {

                pageNumber = NumberUtils.createInteger(args[args.length - 1]);

            } catch (NumberFormatException exception) {

                pageNumber = 1;

            }

            if (pageNumber <= 0) {

                pageNumber = 1;

            }

        } else {

            command = StringUtils.join(args, " ");

            pageNumber = 1;

        }

        if (sender instanceof ConsoleCommandSender) {

            pageHeight = ChatPaginator.UNBOUNDED_PAGE_HEIGHT;

            pageWidth = ChatPaginator.UNBOUNDED_PAGE_WIDTH;

        } else {

            pageHeight = ChatPaginator.CLOSED_CHAT_PAGE_HEIGHT - 1;

            pageWidth = ChatPaginator.GUARANTEED_NO_WRAP_CHAT_PAGE_WIDTH;

        }

        HelpMap helpMap = Bukkit.getServer().getHelpMap();

        HelpTopic topic = helpMap.getHelpTopic(command);

        if (topic == null) {

            topic = helpMap.getHelpTopic("/" + command);

        }

        if (topic == null) {

            topic = findPossibleMatches(command);

        }

        if (topic == null || !topic.canSee(sender)) {

            sender.sendMessage(ChatColor.RED + "No help for " + command);

            return true;

        }

        ChatPaginator.ChatPage page = ChatPaginator.paginate(topic.getFullText(sender), pageNumber, pageWidth, pageHeight);

        StringBuilder header = new StringBuilder();

        header.append(ChatColor.YELLOW);

        header.append("--------- ");

        header.append(ChatColor.WHITE);

        header.append("Help: ");

        header.append(topic.getName());

        header.append(" ");

        if (page.getTotalPages() > 1) {

            header.append("(");

            header.append(page.getPageNumber());

            header.append("/");

            header.append(page.getTotalPages());

            header.append(") ");

        }

        header.append(ChatColor.YELLOW);

        for (int i = header.length(); i < ChatPaginator.GUARANTEED_NO_WRAP_CHAT_PAGE_WIDTH; i++) {

            header.append("-");

        }

        sender.sendMessage(header.toString());

        sender.sendMessage(page.getLines());

        return true;

    }

    @Override

    public List<String> tabComplete(CommandSender sender, String alias, String[] args) {

        Validate.notNull(sender, "Sender cannot be null");

        Validate.notNull(args, "Arguments cannot be null");

        Validate.notNull(alias, "Alias cannot be null");

        if (args.length == 1) {

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

            String searchString = args[0];

            for (HelpTopic topic : Bukkit.getServer().getHelpMap().getHelpTopics()) {

                String trimmedTopic = topic.getName().startsWith("/") ? topic.getName().substring(1) : topic.getName();

                if (trimmedTopic.startsWith(searchString)) {

                    matchedTopics.add(trimmedTopic);

                }

            }

            return matchedTopics;

        }

        return ImmutableList.of();

    }

    protected HelpTopic findPossibleMatches(String searchString) {

        int maxDistance = (searchString.length() / 5) + 3;

        Set<HelpTopic> possibleMatches = new TreeSet<HelpTopic>(HelpTopicComparator.helpTopicComparatorInstance());

        if (searchString.startsWith("/")) {

            searchString = searchString.substring(1);

        }

        for (HelpTopic topic : Bukkit.getServer().getHelpMap().getHelpTopics()) {

            String trimmedTopic = topic.getName().startsWith("/") ? topic.getName().substring(1) : topic.getName();

            if (trimmedTopic.length() < searchString.length()) {

                continue;

            }

            if (Character.toLowerCase(trimmedTopic.charAt(0)) != Character.toLowerCase(searchString.charAt(0))) {

                continue;

            }

            if (damerauLevenshteinDistance(searchString, trimmedTopic.substring(0, searchString.length())) < maxDistance) {

                possibleMatches.add(topic);

            }

        }

        if (possibleMatches.size() > 0) {

            return new IndexHelpTopic("Search", null, null, possibleMatches, "Search for: " + searchString);

        } else {

            return null;

        }

    }

    /**

     * Computes the Dameraur-Levenshtein Distance between two strings. Adapted

     * from the algorithm at <a href="http://en.wikipedia.org/wiki/Damerau–Levenshtein_distance">Wikipedia: Damerau–Levenshtein distance</a>

     *

     * @param s1 The first string being compared.

     * @param s2 The second string being compared.

     * @return The number of substitutions, deletions, insertions, and

     * transpositions required to get from s1 to s2.

     */

    protected static int damerauLevenshteinDistance(String s1, String s2) {

        if (s1 == null && s2 == null) {

            return 0;

        }

        if (s1 != null && s2 == null) {

            return s1.length();

        }

        if (s1 == null && s2 != null) {

            return s2.length();

        }

        int s1Len = s1.length();

        int s2Len = s2.length();

        int[][] H = new int[s1Len + 2][s2Len + 2];

        int INF = s1Len + s2Len;

        H[0][0] = INF;

        for (int i = 0; i <= s1Len; i++) {

            H[i + 1][1] = i;

            H[i + 1][0] = INF;

        }

        for (int j = 0; j <= s2Len; j++) {

            H[1][j + 1] = j;

            H[0][j + 1] = INF;

        }

        Map<Character, Integer> sd = new HashMap<Character, Integer>();

        for (char Letter : (s1 + s2).toCharArray()) {

            if (!sd.containsKey(Letter)) {

                sd.put(Letter, 0);

            }

        }

        for (int i = 1; i <= s1Len; i++) {

            int DB = 0;

            for (int j = 1; j <= s2Len; j++) {

                int i1 = sd.get(s2.charAt(j - 1));

                int j1 = DB;

                if (s1.charAt(i - 1) == s2.charAt(j - 1)) {

                    H[i + 1][j + 1] = H[i][j];

                    DB = j;

                } else {

                    H[i + 1][j + 1] = Math.min(H[i][j], Math.min(H[i + 1][j], H[i][j + 1])) + 1;

                }

                H[i + 1][j + 1] = Math.min(H[i + 1][j + 1], H[i1][j1] + (i - i1 - 1) + 1 + (j - j1 - 1));

            }

            sd.put(s1.charAt(i - 1), i);

        }

        return H[s1Len + 1][s2Len + 1];

    }

}