Implement regex-based nickname blacklist

Adds `nick-blacklist` list to config which takes phrases or regexes. Users with essentials.nick.blacklist.bypass can bypass the blacklist.

Essentials/src/com/earth2me/essentials/ISettings.java

@@ -15,6 +15,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.function.Predicate;
 import java.util.regex.Pattern;
 
 
@@ -332,4 +333,6 @@ public interface ISettings extends IConf {
     boolean isSafeUsermap();
 
     boolean logCommandBlockCommands();
+
+    Set<Predicate<String>> getNickBlacklist();
 }

Essentials/src/com/earth2me/essentials/Settings.java

@@ -35,6 +35,7 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.function.Predicate;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
@@ -555,6 +556,7 @@ public class Settings implements net.ess3.api.ISettings {
         isWaterSafe = _isWaterSafe();
         isSafeUsermap = _isSafeUsermap();
         logCommandBlockCommands = _logCommandBlockCommands();
+        nickBlacklist = _getNickBlacklist();
     }
 
     void _lateLoadItemSpawnBlacklist() {
@@ -1588,4 +1590,25 @@ public class Settings implements net.ess3.api.ISettings {
     public boolean logCommandBlockCommands() {
         return logCommandBlockCommands;
     }
+
+    private Set<Predicate<String>> nickBlacklist;
+
+    private Set<Predicate<String>> _getNickBlacklist() {
+        Set<Predicate<String>> blacklist = new HashSet<>();
+
+        config.getStringList("nick-blacklist").forEach(entry -> {
+            try {
+                blacklist.add(Pattern.compile(entry).asPredicate());
+            } catch (PatternSyntaxException e) {
+                logger.warning("Invalid nickname blacklist regex: " + entry);
+            }
+        });
+
+        return blacklist;
+    }
+
+    @Override
+    public Set<Predicate<String>> getNickBlacklist() {
+        return nickBlacklist;
+    }
 }

Essentials/src/com/earth2me/essentials/commands/Commandnick.java

@@ -83,10 +83,17 @@ public class Commandnick extends EssentialsLoopCommand {
             throw new Exception(tl("nickNamesAlpha"));
         } else if (user != null && (user.isAuthorized("essentials.nick.changecolors") && !user.isAuthorized("essentials.nick.changecolors.bypass")) && !FormatUtil.stripFormat(newNick).equals(user.getName())) {
             throw new Exception(tl("nickNamesOnlyColorChanges"));
+        } else if (user != null && !user.isAuthorized("essentials.nick.blacklist.bypass") && isNickBanned(newNick)) {
+            throw new Exception(tl("nickNameBlacklist", nick));
         }
         return newNick;
     }
 
+    private boolean isNickBanned(String newNick) {
+        return ess.getSettings().getNickBlacklist().stream()
+            .anyMatch(entry -> entry.test(newNick));
+    }
+
     private int getNickLength(final String nick) {
         return ess.getSettings().ignoreColorsInMaxLength() ? ChatColor.stripColor(nick).length() : nick.length();
     }

Essentials/src/config.yml

@@ -32,6 +32,12 @@ nickname-prefix: '~'
 # The maximum length allowed in nicknames. The nickname prefix is included in this.
 max-nick-length: 15
 
+# A list of phrases that cannot be used in nicknames. You can include regular expressions here.
+# Users with essentials.nick.blacklist.bypass will be able to bypass this filter.
+nick-blacklist:
+#- Notch
+#- '^Dinnerbone'
+
 # When this option is enabled, nickname length checking will exclude color codes in player names.
 # ie: "&6Notch" has 7 characters (2 are part of a color code), a length of 5 is used when this option is set to true
 ignore-colors-in-max-nick-length: false

Essentials/src/messages.properties

@@ -323,6 +323,7 @@ negativeBalanceError=\u00a74User is not allowed to have a negative balance.
 nickChanged=\u00a76Nickname changed.
 nickDisplayName=\u00a74You have to enable change-displayname in Essentials config.
 nickInUse=\u00a74That name is already in use.
+nickNameBlacklist=\u00a74That nickname is not allowed.
 nickNamesAlpha=\u00a74Nicknames must be alphanumeric.
 nickNamesOnlyColorChanges=\u00a74Nicknames can only have their colors changed.
 nickNoMore=\u00a76You no longer have a nickname.