feat: nicknames_must_be_unique

Author: John-Paul-R

docs/Config-Documentation.md

@@ -66,6 +66,7 @@ The config file can be found at `config/EssentialCommands.properties`
 | nickname_prefix                                        | {"text":"~","color":"red"} | MinecraftText                |
 | nicknames_as_command_arg                               | Never                      | NicknameCommandArgMode       |
 | nicknames_in_player_list                               | true                       | boolean                      |
+| nicknames_must_be_unique                               | false                      | boolean                      |
 | ops_bypass_teleport_rules                              | true                       | boolean                      |
 | persist_back_location                                  | false                      | boolean                      |
 | print_teleport_coordinates                             | true                       | boolean                      |

docs/Feature-Guide.md

@@ -216,6 +216,7 @@ Customize player display names.
   - `Never` - Nicknames are not resolved in any command argument
   - `EssentialCommandsOnly` - Nicknames resolve and suggest only in Essential Commands
   - `Everywhere` - Nicknames resolve and suggest in all commands (e.g. `/tp`, `/give`)
+- `nicknames_must_be_unique` - Block nicknames that duplicate another player's nickname or match an existing username (case-insensitive) - Default: `false`
 
 ## Utility Commands
 

src/main/java/com/fibermc/essentialcommands/commands/NicknameSetCommand.java

@@ -74,6 +74,10 @@ public static int exec(CommandContext<CommandSourceStack> context, Component raw
                     ecText.accent(String.valueOf(nicknameText.getString().length())),
                     ecText.accent(String.valueOf(CONFIG.NICKNAME_MAX_LENGTH))
                 );
+                case -3 -> ecText.getText(
+                    "cmd.nickname.set.error.taken", TextFormatType.Error,
+                    ecText.accent(nicknameText.getString())
+                );
                 default -> ecText.getText("generic.error.unknown", TextFormatType.Error);
             };
             senderFeedbackReceiver.sendCommandError("cmd.nickname.set.error", nicknameText, failReason);

src/main/java/com/fibermc/essentialcommands/config/EssentialCommandsConfig.java

@@ -6,12 +6,7 @@
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
-import net.minecraft.ChatFormatting;
-import net.minecraft.network.chat.Component;
-import net.minecraft.network.chat.Style;
-import net.minecraft.resources.Identifier;
-import net.minecraft.resources.ResourceKey;
-import net.minecraft.world.level.Level;
+
 import com.fibermc.essentialcommands.ECPerms;
 import com.fibermc.essentialcommands.EssentialCommands;
 import com.fibermc.essentialcommands.ManagerLocator;
@@ -20,6 +15,14 @@
 import com.fibermc.essentialcommands.types.RespawnCondition;
 import com.fibermc.essentialcommands.types.RtpCenter;
 import org.jetbrains.annotations.NotNull;
+
+import net.minecraft.ChatFormatting;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.Style;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.world.level.Level;
+
 import dev.jpcode.eccore.config.Config;
 import dev.jpcode.eccore.config.ConfigOption;
 import dev.jpcode.eccore.config.ConfigUtil;
@@ -87,6 +90,7 @@ public final class EssentialCommandsConfig extends Config<EssentialCommandsConfi
     @ConfigOption public final Option<Boolean> NICKNAMES_IN_PLAYER_LIST =   new Option<>("nicknames_in_player_list", true, Boolean::parseBoolean);
     @ConfigOption public final Option<Integer> NICKNAME_MAX_LENGTH =    new Option<>("nickname_max_length", 32, ConfigUtil::parseInt);
     @ConfigOption public final Option<NicknameCommandArgMode> NICKNAMES_AS_COMMAND_ARG = new Option<>("nicknames_as_command_arg", NicknameCommandArgMode.Never, NicknameCommandArgMode::valueOf);
+    @ConfigOption public final Option<Boolean> NICKNAMES_MUST_BE_UNIQUE = new Option<>("nicknames_must_be_unique", false, Boolean::parseBoolean);
     @ConfigOption public final Option<Boolean> NICKNAME_ABOVE_HEAD =    new Option<>("nickname_above_head", false, Boolean::parseBoolean);
     @ConfigOption public final Option<RtpCenter> RTP_CENTER =           new Option<>("rtp_center", RtpCenter.spawn(), RtpCenter::parse, RtpCenter::serialize);
     @ConfigOption public final Option<Integer> RTP_RADIUS =             new Option<>("rtp_radius", 1000, ConfigUtil::parseInt);

src/main/java/com/fibermc/essentialcommands/config/EssentialCommandsConfigSnapshot.java

@@ -2,13 +2,16 @@
 
 import java.util.List;
 import java.util.Set;
+
+import com.fibermc.essentialcommands.types.NicknameCommandArgMode;
+import com.fibermc.essentialcommands.types.RespawnCondition;
+import com.fibermc.essentialcommands.types.RtpCenter;
+
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.chat.Style;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.world.level.Level;
-import com.fibermc.essentialcommands.types.NicknameCommandArgMode;
-import com.fibermc.essentialcommands.types.RespawnCondition;
-import com.fibermc.essentialcommands.types.RtpCenter;
+
 import dev.jpcode.eccore.config.expression.Expression;
 import dev.jpcode.eccore.util.TimeUtil;
 
@@ -66,6 +69,7 @@ public final class EssentialCommandsConfigSnapshot {
     public final boolean NICKNAMES_IN_PLAYER_LIST;
     public final int NICKNAME_MAX_LENGTH;
     public final NicknameCommandArgMode NICKNAMES_AS_COMMAND_ARG;
+    public final boolean NICKNAMES_MUST_BE_UNIQUE;
     public final boolean NICKNAME_ABOVE_HEAD;
     public final RtpCenter RTP_CENTER;
     public final int RTP_RADIUS;
@@ -146,6 +150,7 @@ private EssentialCommandsConfigSnapshot(EssentialCommandsConfig config) {
         this.NICKNAMES_IN_PLAYER_LIST           = config.NICKNAMES_IN_PLAYER_LIST.getValue();
         this.NICKNAME_MAX_LENGTH                = config.NICKNAME_MAX_LENGTH.getValue();
         this.NICKNAMES_AS_COMMAND_ARG           = config.NICKNAMES_AS_COMMAND_ARG.getValue();
+        this.NICKNAMES_MUST_BE_UNIQUE           = config.NICKNAMES_MUST_BE_UNIQUE.getValue();
         this.NICKNAME_ABOVE_HEAD                = config.NICKNAME_ABOVE_HEAD.getValue();
         this.RTP_CENTER                         = config.RTP_CENTER.getValue();
         this.RTP_RADIUS                         = config.RTP_RADIUS.getValue();

src/main/java/com/fibermc/essentialcommands/playerdata/PlayerData.java

@@ -547,9 +547,27 @@ public int setNickname(Component nickname) {
                 );
             }
 
+            String candidateNormalized = normalizeNickname(nickname.getString());
+
+            if (CONFIG.NICKNAMES_MUST_BE_UNIQUE) {
+                List<PlayerData> existing = PlayerDataManager.getInstance().getByNickname(candidateNormalized);
+                boolean takenByOther = existing.stream().anyMatch(pd -> pd != this);
+                if (takenByOther) {
+                    return -3;
+                }
+
+                var nameCache = this.player.level().getServer().services().nameToIdCache();
+                boolean matchesOtherUsername = nameCache.get(candidateNormalized)
+                    .filter(profile -> !profile.id().equals(this.player.getUUID()))
+                    .isPresent();
+                if (matchesOtherUsername) {
+                    return -3;
+                }
+            }
+
             // Set nickname
             this.nickname = nickname;
-            this.normalizedNickname = normalizeNickname(nickname.getString());
+            this.normalizedNickname = candidateNormalized;
         }
 
         reloadFullNickname();

src/main/resources/data/essential_commands/lang/en_us.json

@@ -24,6 +24,7 @@
   "cmd.nickname.set.error": "Nickname could not be set to '%1$s'. Reason: %2$s",
   "cmd.nickname.set.error.perms": "Player has insufficient permissions for specified nickname.",
   "cmd.nickname.set.error.length": "Length of supplied nickname (%1$s) exceeded max nickname length (%2$s)",
+  "cmd.nickname.set.error.taken": "The nickname ('%1$s') is already in use or conflicts with an existing username.",
   "cmd.rtp.error.pre": "Could not execute command '/rtp'. Reason: ",
   "cmd.rtp.error.world_not_enabled": "RTP is not enabled in the world '%1$s'",
   "cmd.rtp.error.cooldown": "Command is on cooldown. (%1$s seconds remaining.)",