org.bukkit.command.defaults.HelpCommand Maven / Gradle / Ivy

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package org.bukkit.command.defaults;

import com.google.common.collect.ImmutableList;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.Validate;
import org.apache.commons.lang.math.NumberUtils;
import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.command.CommandSender;
import org.bukkit.command.ConsoleCommandSender;
import org.bukkit.help.HelpMap;
import org.bukkit.help.HelpTopic;
import org.bukkit.help.HelpTopicComparator;
import org.bukkit.help.IndexHelpTopic;
import org.bukkit.util.ChatPaginator;

import java.util.*;

public class HelpCommand extends VanillaCommand {
  public HelpCommand() {
    super("help");
    this.description = "Shows the help menu";
    this.usageMessage = "/help \n/help \n/help  ";
    this.setAliases(Arrays.asList("?"));
    this.setPermission("bukkit.command.help");
  }

  /**
   * Computes the Dameraur-Levenshtein Distance between two strings. Adapted
   * from the algorithm at Wikipedia: Damerau–Levenshtein distance
   *
   * @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 sd = new HashMap();
    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];
  }

  @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 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 matchedTopics = new ArrayList();
      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 possibleMatches = new TreeSet(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;
    }
  }
}