Add tab completion

bukkit/src/main/java/me/lucko/luckperms/CommandManagerBukkit.java

@@ -5,19 +5,32 @@ import me.lucko.luckperms.commands.Sender;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandExecutor;
 import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabExecutor;
 
 import java.lang.ref.WeakReference;
 import java.util.Arrays;
+import java.util.List;
 
-class CommandManagerBukkit extends CommandManager implements CommandExecutor {
+class CommandManagerBukkit extends CommandManager implements CommandExecutor, TabExecutor {
     CommandManagerBukkit(LuckPermsPlugin plugin) {
         super(plugin);
     }
 
     @Override
     public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
-        final WeakReference<CommandSender> cs = new WeakReference<>(sender);
+        return onCommand(makeSender(sender), Arrays.asList(args));
-        return onCommand(new Sender() {
+    }
+
+
+    @Override
+    public List<String> onTabComplete(CommandSender sender, Command command, String label, String[] args) {
+        return onTabComplete(makeSender(sender), Arrays.asList(args));
+    }
+
+    private static Sender makeSender(CommandSender sender) {
+        return new Sender() {
+            final WeakReference<CommandSender> cs = new WeakReference<>(sender);
+
             @Override
             public void sendMessage(String s) {
                 final CommandSender c = cs.get();
@@ -31,6 +44,6 @@ class CommandManagerBukkit extends CommandManager implements CommandExecutor {
                 final CommandSender c = cs.get();
                 return c != null && c.hasPermission(node);
             }
-        }, Arrays.asList(args));
+        };
     }
 }

bukkit/src/main/java/me/lucko/luckperms/LPBukkitPlugin.java

@@ -16,12 +16,15 @@ import me.lucko.luckperms.utils.LPConfiguration;
 import me.lucko.luckperms.vaulthooks.VaultHook;
 import org.bukkit.Bukkit;
 import org.bukkit.command.PluginCommand;
+import org.bukkit.entity.Player;
 import org.bukkit.plugin.PluginManager;
 import org.bukkit.plugin.java.JavaPlugin;
 
 import java.io.File;
 import java.util.Arrays;
+import java.util.List;
 import java.util.UUID;
+import java.util.stream.Collectors;
 
 @Getter
 public class LPBukkitPlugin extends JavaPlugin implements LuckPermsPlugin {
@@ -45,6 +48,7 @@ public class LPBukkitPlugin extends JavaPlugin implements LuckPermsPlugin {
         CommandManagerBukkit commandManager = new CommandManagerBukkit(this);
         PluginCommand main = getServer().getPluginCommand("luckperms");
         main.setExecutor(commandManager);
+        main.setTabCompleter(commandManager);
         main.setAliases(Arrays.asList("perms", "lp", "permissions", "p", "perm"));
 
         final String storageMethod = configuration.getStorageMethod();
@@ -123,6 +127,11 @@ public class LPBukkitPlugin extends JavaPlugin implements LuckPermsPlugin {
         return getServer().getOnlinePlayers().size();
     }
 
+    @Override
+    public List<String> getPlayerList() {
+        return getServer().getOnlinePlayers().stream().map(Player::getName).collect(Collectors.toList());
+    }
+
     @Override
     public void runUpdateTask() {
         getServer().getScheduler().runTaskAsynchronously(this, new UpdateTask(this));

bungee/src/main/java/me/lucko/luckperms/LPBungeePlugin.java

@@ -13,10 +13,13 @@ import me.lucko.luckperms.tracks.TrackManager;
 import me.lucko.luckperms.users.BungeeUserManager;
 import me.lucko.luckperms.users.UserManager;
 import me.lucko.luckperms.utils.LPConfiguration;
+import net.md_5.bungee.api.connection.ProxiedPlayer;
 import net.md_5.bungee.api.plugin.Plugin;
 
+import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
 
 @Getter
 public class LPBungeePlugin extends Plugin implements LuckPermsPlugin {
@@ -88,6 +91,11 @@ public class LPBungeePlugin extends Plugin implements LuckPermsPlugin {
         return getProxy().getOnlineCount();
     }
 
+    @Override
+    public List<String> getPlayerList() {
+        return getProxy().getPlayers().stream().map(ProxiedPlayer::getName).collect(Collectors.toList());
+    }
+
     @Override
     public void runUpdateTask() {
         doAsync(new UpdateTask(this));

bungee/src/main/java/me/lucko/luckperms/MainCommand.java

@@ -5,11 +5,12 @@ import me.lucko.luckperms.commands.Sender;
 import net.md_5.bungee.api.CommandSender;
 import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.plugin.Command;
+import net.md_5.bungee.api.plugin.TabExecutor;
 
 import java.lang.ref.WeakReference;
 import java.util.Arrays;
 
-class MainCommand extends Command {
+class MainCommand extends Command implements TabExecutor {
     private final CommandManager manager;
 
     public MainCommand(CommandManager manager) {
@@ -20,8 +21,18 @@ class MainCommand extends Command {
 
     @Override
     public void execute(CommandSender sender, String[] args) {
-        final WeakReference<CommandSender> cs = new WeakReference<>(sender);
+        manager.onCommand(makeSender(sender), Arrays.asList(args));
-        manager.onCommand(new Sender() {
+    }
+
+    @Override
+    public Iterable<String> onTabComplete(CommandSender sender, String[] args) {
+        return manager.onTabComplete(makeSender(sender), Arrays.asList(args));
+    }
+
+    private static Sender makeSender(CommandSender sender) {
+        return new Sender() {
+            final WeakReference<CommandSender> cs = new WeakReference<>(sender);
+
             @Override
             public void sendMessage(String s) {
                 final CommandSender c = cs.get();
@@ -35,6 +46,6 @@ class MainCommand extends Command {
                 final CommandSender c = cs.get();
                 return c != null && c.hasPermission(node);
             }
-        }, Arrays.asList(args));
+        };
     }
 }

common/src/main/java/me/lucko/luckperms/LuckPermsPlugin.java

@@ -6,6 +6,7 @@ import me.lucko.luckperms.tracks.TrackManager;
 import me.lucko.luckperms.users.UserManager;
 import me.lucko.luckperms.utils.LPConfiguration;
 
+import java.util.List;
 import java.util.UUID;
 import java.util.logging.Logger;
 
@@ -65,6 +66,12 @@ public interface LuckPermsPlugin {
      */
     int getPlayerCount();
 
+    /**
+     * Gets the usernames of the users online on the platform
+     * @return a {@link List} of usernames
+     */
+    List<String> getPlayerList();
+
     /**
      * Runs an update task
      */

common/src/main/java/me/lucko/luckperms/commands/CommandManager.java

@@ -20,9 +20,11 @@ import me.lucko.luckperms.commands.user.subcommands.*;
 import me.lucko.luckperms.constants.Message;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.logging.Level;
+import java.util.stream.Collectors;
 
 public class CommandManager {
     private final LuckPermsPlugin plugin;
@@ -123,6 +125,31 @@ public class CommandManager {
 
     }
 
+    /**
+     * Generic tab complete method to be called from the command executor object of the platform
+     * @param sender who is tab completing
+     * @param args the arguments provided so far
+     * @return a list of suggestions
+     */
+    public List<String> onTabComplete(Sender sender, List<String> args) {
+        final List<MainCommand> mains = mainCommands.stream().filter(m -> m.canUse(sender)).collect(Collectors.toList());
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return mains.stream().map(MainCommand::getName).map(String::toLowerCase).collect(Collectors.toList());
+            }
+
+            return mains.stream().map(MainCommand::getName).map(String::toLowerCase).filter(s -> s.startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        Optional<MainCommand> o = mains.stream().filter(m -> m.getName().equalsIgnoreCase(args.get(0))).limit(1).findAny();
+        if (!o.isPresent()) {
+            return Collections.emptyList();
+        }
+
+        return o.get().onTabComplete(sender, args.subList(1, args.size()), plugin);
+    }
+
     private void registerMainCommand(MainCommand command) {
         plugin.getLogger().log(Level.INFO, "[CommandManager] Registered main command '" + command.getName() + "'");
         mainCommands.add(command);

common/src/main/java/me/lucko/luckperms/commands/MainCommand.java

@@ -5,7 +5,9 @@ import lombok.Getter;
 import me.lucko.luckperms.LuckPermsPlugin;
 import me.lucko.luckperms.constants.Message;
 
+import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 @Getter
@@ -17,6 +19,7 @@ public abstract class MainCommand {
     private final int requiredArgsLength;
 
     protected abstract void execute(LuckPermsPlugin plugin, Sender sender, List<String> args);
+    protected abstract List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin);
     public abstract List<? extends SubCommand> getSubCommands();
 
     protected void sendUsage(Sender sender) {
@@ -41,4 +44,23 @@ public abstract class MainCommand {
     protected boolean canUse(Sender sender) {
         return getSubCommands().stream().filter(sc -> sc.isAuthorized(sender)).count() != 0;
     }
+
+    protected List<String> onAbstractTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<SubCommand> subs = getSubCommands().stream().filter(s -> s.isAuthorized(sender)).collect(Collectors.toList());
+        if (args.size() == 2) {
+            if (args.get(1).equalsIgnoreCase("")) {
+                return subs.stream().map(SubCommand::getName).map(String::toLowerCase).collect(Collectors.toList());
+            }
+
+            return subs.stream().map(SubCommand::getName).map(String::toLowerCase)
+                    .filter(s -> s.toLowerCase().startsWith(args.get(1).toLowerCase())).collect(Collectors.toList());
+        }
+
+        Optional<SubCommand> o = subs.stream().filter(s -> s.getName().equalsIgnoreCase(args.get(1))).limit(1).findAny();
+        if (!o.isPresent()) {
+            return Collections.emptyList();
+        }
+
+        return o.get().onTabComplete(sender, args.subList(2, args.size()), plugin);
+    }
 }

common/src/main/java/me/lucko/luckperms/commands/SubCommand.java

@@ -2,8 +2,15 @@ package me.lucko.luckperms.commands;
 
 import lombok.AllArgsConstructor;
 import lombok.Getter;
+import me.lucko.luckperms.LuckPermsPlugin;
 import me.lucko.luckperms.constants.Permission;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
 @Getter
 @AllArgsConstructor
 public abstract class SubCommand {
@@ -12,6 +19,34 @@ public abstract class SubCommand {
     private final String usage;
     private final Permission permission;
 
+    protected static List<String> getGroupTabComplete(List<String> args, LuckPermsPlugin plugin) {
+        return getTabComplete(new ArrayList<>(plugin.getGroupManager().getGroups().keySet()), args);
+    }
+
+    protected static List<String> getTrackTabComplete(List<String> args, LuckPermsPlugin plugin) {
+        return getTabComplete(new ArrayList<>(plugin.getTrackManager().getTracks().keySet()), args);
+    }
+
+    private static List<String> getTabComplete(List<String> options, List<String> args) {
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return options;
+            }
+
+            return options.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return Collections.emptyList();
+    }
+
+    protected static List<String> getBoolTabComplete(List<String> args) {
+        if (args.size() == 2) {
+            return Arrays.asList("true", "false");
+        } else {
+            return Collections.emptyList();
+        }
+    }
+
     public boolean isAuthorized(Sender sender) {
         return permission.isAuthorized(sender);
     }
@@ -20,5 +55,9 @@ public abstract class SubCommand {
         Util.sendPluginMessage(sender, "&e-> &d" + getUsage());
     }
 
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     public abstract boolean isArgLengthInvalid(int argLength);
 }

common/src/main/java/me/lucko/luckperms/commands/Util.java

@@ -32,6 +32,10 @@ public class Util {
         return new String(b);
     }
 
+    public static boolean startsWithIgnoreCase(String s, String startsWith) {
+        return s.toLowerCase().startsWith(startsWith);
+    }
+
     public static void sendBoolean(Sender sender, String node, boolean b) {
         if (b) {
             sender.sendMessage(Util.color("&b" + node + ": &atrue"));

common/src/main/java/me/lucko/luckperms/commands/group/CreateGroupCommand.java

@@ -8,7 +8,7 @@ import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.utils.Patterns;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class CreateGroupCommand extends MainCommand {
@@ -51,9 +51,14 @@ public class CreateGroupCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/group/DeleteGroupCommand.java

@@ -9,7 +9,9 @@ import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public class DeleteGroupCommand extends MainCommand {
     public DeleteGroupCommand() {
@@ -52,9 +54,24 @@ public class DeleteGroupCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> groups = new ArrayList<>(plugin.getGroupManager().getGroups().keySet());
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return groups;
+            }
+
+            return groups.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return Collections.emptyList();
+    }
+
     @Override
     public List<SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/group/GroupMainCommand.java

@@ -10,6 +10,7 @@ import me.lucko.luckperms.groups.Group;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 public class GroupMainCommand extends MainCommand {
 
@@ -66,6 +67,21 @@ public class GroupMainCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> groups = new ArrayList<>(plugin.getGroupManager().getGroups().keySet());
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return groups;
+            }
+
+            return groups.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return onAbstractTabComplete(sender, args, plugin);
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
         return subCommands;

common/src/main/java/me/lucko/luckperms/commands/group/ListGroupsCommand.java

@@ -9,6 +9,7 @@ import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class ListGroupsCommand extends MainCommand {
@@ -27,9 +28,14 @@ public class ListGroupsCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/group/subcommands/GroupSetInheritCommand.java

@@ -42,6 +42,11 @@ public class GroupSetInheritCommand extends GroupSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1 && argLength != 2;

common/src/main/java/me/lucko/luckperms/commands/group/subcommands/GroupSetPermissionCommand.java

@@ -55,6 +55,11 @@ public class GroupSetPermissionCommand extends GroupSubCommand {
         }
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getBoolTabComplete(args);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 2 && argLength != 3;

common/src/main/java/me/lucko/luckperms/commands/group/subcommands/GroupUnsetInheritCommand.java

@@ -36,6 +36,11 @@ public class GroupUnsetInheritCommand extends GroupSubCommand {
         }
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1 && argLength != 2;

common/src/main/java/me/lucko/luckperms/commands/misc/DebugCommand.java

@@ -7,7 +7,7 @@ import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class DebugCommand extends MainCommand {
@@ -22,9 +22,14 @@ public class DebugCommand extends MainCommand {
         );
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/misc/InfoCommand.java

@@ -7,7 +7,7 @@ import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class InfoCommand extends MainCommand {
@@ -20,9 +20,14 @@ public class InfoCommand extends MainCommand {
         Message.INFO.send(sender, plugin.getVersion(), plugin.getDatastore().getName());
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/misc/SyncCommand.java

@@ -7,7 +7,7 @@ import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class SyncCommand extends MainCommand {
@@ -21,9 +21,14 @@ public class SyncCommand extends MainCommand {
         plugin.runUpdateTask();
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/track/CreateTrackCommand.java

@@ -8,7 +8,7 @@ import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.utils.Patterns;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class CreateTrackCommand extends MainCommand {
@@ -51,9 +51,14 @@ public class CreateTrackCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/track/DeleteTrackCommand.java

@@ -9,7 +9,9 @@ import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public class DeleteTrackCommand extends MainCommand {
     public DeleteTrackCommand() {
@@ -47,9 +49,24 @@ public class DeleteTrackCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> tracks = new ArrayList<>(plugin.getTrackManager().getTracks().keySet());
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return tracks;
+            }
+
+            return tracks.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return Collections.emptyList();
+    }
+
     @Override
     public List<SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/track/ListTracksCommand.java

@@ -9,6 +9,7 @@ import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class ListTracksCommand extends MainCommand {
@@ -27,9 +28,14 @@ public class ListTracksCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
     @Override
     public List<SubCommand> getSubCommands() {
-        return new ArrayList<>();
+        return Collections.emptyList();
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/commands/track/TrackMainCommand.java

@@ -10,6 +10,7 @@ import me.lucko.luckperms.tracks.Track;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 public class TrackMainCommand extends MainCommand {
 
@@ -66,6 +67,21 @@ public class TrackMainCommand extends MainCommand {
         });
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> tracks = new ArrayList<>(plugin.getTrackManager().getTracks().keySet());
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return tracks;
+            }
+
+            return tracks.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return onAbstractTabComplete(sender, args, plugin);
+    }
+
     @Override
     public List<? extends SubCommand> getSubCommands() {
         return subCommands;

common/src/main/java/me/lucko/luckperms/commands/track/subcommands/TrackAppendCommand.java

@@ -43,6 +43,11 @@ public class TrackAppendCommand extends TrackSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/commands/track/subcommands/TrackInsertCommand.java

@@ -53,6 +53,11 @@ public class TrackInsertCommand extends TrackSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 2;

common/src/main/java/me/lucko/luckperms/commands/track/subcommands/TrackRemoveCommand.java

@@ -27,6 +27,11 @@ public class TrackRemoveCommand extends TrackSubCommand {
         }
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/commands/user/UserMainCommand.java

@@ -12,8 +12,9 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.stream.Collectors;
 
-public class UserMainCommand extends MainCommand{
+public class UserMainCommand extends MainCommand {
 
     private final List<UserSubCommand> subCommands = new ArrayList<>();
 
@@ -75,6 +76,21 @@ public class UserMainCommand extends MainCommand{
         Message.USER_INVALID_ENTRY.send(sender, user);
     }
 
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> onlinePlayers = plugin.getPlayerList();
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return onlinePlayers;
+            }
+
+            return onlinePlayers.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        return onAbstractTabComplete(sender, args, plugin);
+    }
+
     private void runSub(LuckPermsPlugin plugin, Sender sender, UUID uuid, UserSubCommand command, List<String> strippedArgs) {
         plugin.getDatastore().loadUser(uuid, success -> {
             if (!success) {

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserAddGroupCommand.java

@@ -48,6 +48,11 @@ public class UserAddGroupCommand extends UserSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return (argLength != 1 && argLength != 2);

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserDemoteCommand.java

@@ -79,6 +79,11 @@ public class UserDemoteCommand extends UserSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getTrackTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserPromoteCommand.java

@@ -79,6 +79,11 @@ public class UserPromoteCommand extends UserSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getTrackTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserRemoveGroupCommand.java

@@ -41,6 +41,11 @@ public class UserRemoveGroupCommand extends UserSubCommand {
         }
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return (argLength != 1 && argLength != 2);

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserSetPermissionCommand.java

@@ -55,6 +55,11 @@ public class UserSetPermissionCommand extends UserSubCommand {
         }
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getBoolTabComplete(args);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 2 && argLength != 3;

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserSetPrimaryGroupCommand.java

@@ -40,6 +40,11 @@ public class UserSetPrimaryGroupCommand extends UserSubCommand {
         saveUser(user, sender, plugin);
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getGroupTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/commands/user/subcommands/UserShowPosCommand.java

@@ -45,6 +45,11 @@ public class UserShowPosCommand extends UserSubCommand {
         });
     }
 
+    @Override
+    public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return getTrackTabComplete(args, plugin);
+    }
+
     @Override
     public boolean isArgLengthInvalid(int argLength) {
         return argLength != 1;

common/src/main/java/me/lucko/luckperms/constants/Message.java

@@ -29,7 +29,7 @@ public enum Message {
     USER_NOT_FOUND("&eUser could not be found.", true),
     USER_SAVE_SUCCESS("&7(User data was saved to the datastore)", true),
     USER_SAVE_ERROR("There was an error whilst saving the user.", true),
-    USER_ATTEMPTING_LOOKUP("&7(Attempting UUID lookup, since you specified a user)", true),
+    USER_ATTEMPTING_LOOKUP("&7(Attempting UUID lookup, since you specified a username)", true),
 
     GROUP_NOT_FOUND("&eGroup could not be found.", true),
     GROUP_SAVE_SUCCESS("&7(Group data was saved to the datastore)", true),