Use generics for sub commands, fix user lookup bugs

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

@@ -114,7 +114,7 @@ public class CommandManager {
         }
 
         final MainCommand main = o.get();
-        if (!main.canUse(sender)) {
+        if (!main.isAuthorized(sender)) {
             sendCommandUsage(sender, label);
             return true;
         }
@@ -140,8 +140,9 @@ public class CommandManager {
      * @param args the arguments provided so far
      * @return a list of suggestions
      */
+    @SuppressWarnings("unchecked")
     public List<String> onTabComplete(Sender sender, List<String> args) {
-        final List<MainCommand> mains = mainCommands.stream().filter(m -> m.canUse(sender)).collect(Collectors.toList());
+        final List<MainCommand> mains = mainCommands.stream().filter(m -> m.isAuthorized(sender)).collect(Collectors.toList());
 
         if (args.size() <= 1) {
             if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
@@ -169,7 +170,7 @@ public class CommandManager {
         Message.INFO_BRIEF.send(sender, plugin.getVersion());
 
         mainCommands.stream()
-                .filter(c -> c.canUse(sender))
+                .filter(c -> c.isAuthorized(sender))
                 .forEach(c -> Util.sendPluginMessage(sender, "&e-> &d" + String.format(c.getUsage(), label)));
     }
 }

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

@@ -1,27 +1,103 @@
 package me.lucko.luckperms.commands;
 
-import lombok.AllArgsConstructor;
 import lombok.Getter;
+import lombok.RequiredArgsConstructor;
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.api.data.Callback;
 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.stream.Collectors;
 
 @Getter
-@AllArgsConstructor
-public abstract class MainCommand {
+@RequiredArgsConstructor
+public abstract class MainCommand<T> {
 
+    /**
+     * The name of the main command
+     */
     private final String name;
+
+    /**
+     * The command usage
+     */
     private final String usage;
+
+    /**
+     * How many arguments are required for the command to run
+     */
     private final int requiredArgsLength;
 
-    protected abstract void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label);
-    protected abstract List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin);
-    public abstract List<? extends SubCommand> getSubCommands();
+    /**
+     * A list of the sub commands under this main command
+     */
+    @Getter
+    private final List<SubCommand<T>> subCommands = new ArrayList<>();
 
+    /**
+     * Called when this main command is ran
+     * @param plugin a link to the main plugin instance
+     * @param sender the sender to executed the command
+     * @param args the stripped arguments given
+     * @param label the command label used
+     */
+    protected void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label) {
+        if (args.size() < 2) {
+            sendUsage(sender, label);
+            return;
+        }
+
+        Optional<SubCommand<T>> o = subCommands.stream().filter(s -> s.getName().equalsIgnoreCase(args.get(1))).limit(1).findAny();
+
+        if (!o.isPresent()) {
+            Message.COMMAND_NOT_RECOGNISED.send(sender);
+            return;
+        }
+
+        final SubCommand<T> sub = o.get();
+        if (!sub.isAuthorized(sender)) {
+            Message.COMMAND_NO_PERMISSION.send(sender);
+            return;
+        }
+
+        List<String> strippedArgs = new ArrayList<>();
+        if (args.size() > 2) {
+            strippedArgs.addAll(args.subList(2, args.size()));
+        }
+
+        if (sub.getIsArgumentInvalid().test(strippedArgs.size())) {
+            sub.sendUsage(sender, label);
+            return;
+        }
+
+        final String name = args.get(0).toLowerCase();
+        getTarget(name, plugin, sender, t -> sub.execute(plugin, sender, t, strippedArgs, label));
+    }
+
+    /**
+     * Gets the object the command is acting upon, and runs the callback if successful
+     * @param target the name of the object to be looked up
+     * @param plugin a link to the main plugin instance
+     * @param sender the user who send the command (used to send error messages if the lookup was unsuccessful)
+     * @param onSuccess the callback to run when the lookup is completed
+     */
+    protected abstract void getTarget(String target, LuckPermsPlugin plugin, Sender sender, Callback<T> onSuccess);
+
+    /**
+     * Get a list of objects for tab completion
+     * @param plugin a link to the main plugin instance
+     * @return a list of strings
+     */
+    protected abstract List<String> getObjects(LuckPermsPlugin plugin);
+
+    /**
+     * Send the command usage to a sender
+     * @param sender the sender to send the usage to
+     * @param label the command label used
+     */
     protected void sendUsage(Sender sender, String label) {
         if (getSubCommands().isEmpty()) {
             Util.sendPluginMessage(sender, "&e-> &d" + String.format(getUsage(), label));
@@ -41,12 +117,27 @@ public abstract class MainCommand {
         }
     }
 
-    protected boolean canUse(Sender sender) {
+    /**
+     * If a sender has permission to use this command
+     * @param sender the sender trying to use the command
+     * @return true if the sender can use the command
+     */
+    protected boolean isAuthorized(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());
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        final List<String> objects = getObjects(plugin);
+
+        if (args.size() <= 1) {
+            if (args.isEmpty() || args.get(0).equalsIgnoreCase("")) {
+                return objects;
+            }
+
+            return objects.stream().filter(s -> s.toLowerCase().startsWith(args.get(0).toLowerCase())).collect(Collectors.toList());
+        }
+
+        final List<SubCommand<T>> 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());
@@ -56,11 +147,15 @@ public abstract class MainCommand {
                     .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();
+        Optional<SubCommand<T>> 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);
     }
+
+    public void registerSubCommand(SubCommand<T> subCommand) {
+        subCommands.add(subCommand);
+    }
 }

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

@@ -0,0 +1,43 @@
+package me.lucko.luckperms.commands;
+
+import lombok.experimental.UtilityClass;
+
+import java.util.stream.IntStream;
+
+@UtilityClass
+public class Predicate {
+    public static <T> java.util.function.Predicate<T> alwaysFalse() {
+        return t -> false;
+    }
+
+    public static <T> java.util.function.Predicate<T> alwaysTrue() {
+        return t -> true;
+    }
+
+    public static java.util.function.Predicate<Integer> notinRange(Integer start, Integer end) {
+        return inverse(inRange(start, end));
+    }
+
+    public static java.util.function.Predicate<Integer> inRange(Integer start, Integer end) {
+        return isOneOf(IntStream.rangeClosed(start, end).boxed().toArray(Integer[]::new));
+    }
+
+    public static <T> java.util.function.Predicate<T> notOneOf(T[] ts) {
+        return inverse(isOneOf(ts));
+    }
+
+    public static <T> java.util.function.Predicate<T> isOneOf(T[] ta) {
+        return t -> {
+            for (T i : ta) {
+                if (i == t) {
+                    return true;
+                }
+            }
+            return false;
+        };
+    }
+
+    public static <T> java.util.function.Predicate<T> inverse(java.util.function.Predicate<T> t) {
+        return t2 -> !t.test(t2);
+    }
+}

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

@@ -0,0 +1,36 @@
+package me.lucko.luckperms.commands;
+
+import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.api.data.Callback;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * An extension of {@link MainCommand} for implementations without any subcommands
+ */
+public class SingleMainCommand extends MainCommand<Object> {
+    public SingleMainCommand(String name, String usage, int requiredArgsLength) {
+        super(name, usage, requiredArgsLength);
+    }
+
+    @Override
+    protected void getTarget(String target, LuckPermsPlugin plugin, Sender sender, Callback onSuccess) {
+
+    }
+
+    @Override
+    protected List<String> getObjects(LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
+    @Override
+    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public List<SubCommand<Object>> getSubCommands() {
+        return Collections.emptyList();
+    }
+}

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

@@ -3,44 +3,78 @@ package me.lucko.luckperms.commands;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
+import me.lucko.luckperms.groups.Group;
+import me.lucko.luckperms.tracks.Track;
 import me.lucko.luckperms.users.User;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 /**
  * Abstract SubCommand class
- * Doesn't declare any abstract onCommand methods, as sub classes declare their own with parameters unique to the sub command type.
- * For example, see: {@link me.lucko.luckperms.commands.user.UserSubCommand#execute(LuckPermsPlugin, Sender, User, List, String)}
- *
- * SubCommand #execute methods are always called from the {@link MainCommand} class related to them, so abstraction is not needed.
  */
 @Getter
 @AllArgsConstructor
-public abstract class SubCommand {
+public abstract class SubCommand<T> {
+
+    /**
+     * The name of the sub command
+     */
     private final String name;
+
+    /**
+     * A brief description of what the sub command does
+     */
     private final String description;
+
+    /**
+     * The command usage
+     */
     private final String usage;
+
+    /**
+     * The permission needed to use this command
+     */
     private final Permission permission;
 
-    public abstract boolean isArgLengthInvalid(int argLength);
+    /**
+     * Predicate to test if the argument length given is invalid
+     */
+    private final Predicate<? super Integer> isArgumentInvalid;
 
-    public boolean isAuthorized(Sender sender) {
-        return permission.isAuthorized(sender);
-    }
+    /**
+     * Called when this sub command is ran
+     * @param plugin a link to the main plugin instance
+     * @param sender the sender to executed the command
+     * @param t the object the command is operating on
+     * @param args the stripped arguments given
+     * @param label the command label used
+     */
+    public abstract void execute(LuckPermsPlugin plugin, Sender sender, T t, List<String> args, String label);
 
+    /**
+     * Send the command usage to a sender
+     * @param sender the sender to send the usage to
+     * @param label the command label used
+     */
     public void sendUsage(Sender sender, String label) {
         Util.sendPluginMessage(sender, "&e-> &d" + String.format(getUsage(), label));
     }
 
-    /*
-     * Returns a list of suggestions, which are empty by default. Sub classes that give tab complete suggestions override
-     * this method to give their own list.
+    /**
+     * If a sender has permission to use this command
+     * @param sender the sender trying to use the command
+     * @return true if the sender can use the command
      */
+    public boolean isAuthorized(Sender sender) {
+        return permission.isAuthorized(sender);
+    }
 
     /**
      * Returns a list of suggestions, which are empty by default. Sub classes that give tab complete suggestions override
@@ -54,7 +88,12 @@ public abstract class SubCommand {
         return Collections.emptyList();
     }
 
-    /* Utility methods used by #onTabComplete implementations in sub classes  */
+    /*
+        ----------------------------------------------------------------------------------
+        Utility methods used by #onTabComplete and #execute implementations in sub classes
+        ----------------------------------------------------------------------------------
+     */
+
     protected static List<String> getGroupTabComplete(List<String> args, LuckPermsPlugin plugin) {
         return getTabComplete(new ArrayList<>(plugin.getGroupManager().getGroups().keySet()), args);
     }
@@ -82,4 +121,40 @@ public abstract class SubCommand {
 
         return Collections.emptyList();
     }
+
+    protected static void saveUser(User user, Sender sender, LuckPermsPlugin plugin) {
+        user.refreshPermissions();
+
+        plugin.getDatastore().saveUser(user, success -> {
+            if (success) {
+                Message.USER_SAVE_SUCCESS.send(sender);
+            } else {
+                Message.USER_SAVE_ERROR.send(sender);
+            }
+        });
+    }
+
+    protected static void saveGroup(Group group, Sender sender, LuckPermsPlugin plugin) {
+        plugin.getDatastore().saveGroup(group, success -> {
+            if (success) {
+                Message.GROUP_SAVE_SUCCESS.send(sender);
+            } else {
+                Message.GROUP_SAVE_ERROR.send(sender);
+            }
+
+            plugin.runUpdateTask();
+        });
+    }
+
+    protected static void saveTrack(Track track, Sender sender, LuckPermsPlugin plugin) {
+        plugin.getDatastore().saveTrack(track, success -> {
+            if (success) {
+                Message.TRACK_SAVE_SUCCESS.send(sender);
+            } else {
+                Message.TRACK_SAVE_ERROR.send(sender);
+            }
+
+            plugin.runUpdateTask();
+        });
+    }
 }

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

@@ -1,17 +1,15 @@
 package me.lucko.luckperms.commands.group;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.utils.Patterns;
 
-import java.util.Collections;
 import java.util.List;
 
-public class CreateGroup extends MainCommand {
+public class CreateGroup extends SingleMainCommand {
     public CreateGroup() {
         super("CreateGroup", "/%s creategroup <group>", 1);
     }
@@ -52,17 +50,7 @@ public class CreateGroup extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.CREATE_GROUP.isAuthorized(sender);
     }
 }

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

@@ -1,9 +1,8 @@
 package me.lucko.luckperms.commands.group;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
@@ -14,7 +13,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class DeleteGroup extends MainCommand {
+public class DeleteGroup extends SingleMainCommand {
     public DeleteGroup() {
         super("DeleteGroup", "/%s deletegroup <group>", 1);
     }
@@ -76,12 +75,7 @@ public class DeleteGroup extends MainCommand {
     }
 
     @Override
-    public List<SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.DELETE_GROUP.isAuthorized(sender);
     }
 }

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

@@ -1,101 +1,46 @@
 package me.lucko.luckperms.commands.group;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.api.data.Callback;
 import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.groups.Group;
 import me.lucko.luckperms.utils.Patterns;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Optional;
-import java.util.stream.Collectors;
-
-public class GroupMainCommand extends MainCommand {
-
-    private final List<GroupSubCommand> subCommands = new ArrayList<>();
 
+public class GroupMainCommand extends MainCommand<Group> {
     public GroupMainCommand() {
         super("Group", "/%s group <group>", 2);
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label) {
-        if (args.size() < 2) {
-            sendUsage(sender, label);
-            return;
-        }
-
-        Optional<GroupSubCommand> o = subCommands.stream().filter(s -> s.getName().equalsIgnoreCase(args.get(1))).limit(1).findAny();
-
-        if (!o.isPresent()) {
-            Message.COMMAND_NOT_RECOGNISED.send(sender);
-            return;
-        }
-
-        final GroupSubCommand sub = o.get();
-        if (!sub.isAuthorized(sender)) {
-            Message.COMMAND_NO_PERMISSION.send(sender);
-            return;
-        }
-
-        List<String> strippedArgs = new ArrayList<>();
-        if (args.size() > 2) {
-            strippedArgs.addAll(args.subList(2, args.size()));
-        }
-
-        if (sub.isArgLengthInvalid(strippedArgs.size())) {
-            sub.sendUsage(sender, label);
-            return;
-        }
-
-        final String groupName = args.get(0).toLowerCase();
-
-        if (Patterns.NON_ALPHA_NUMERIC.matcher(groupName).find()) {
+    protected void getTarget(String target, LuckPermsPlugin plugin, Sender sender, Callback<Group> onSuccess) {
+        if (Patterns.NON_ALPHA_NUMERIC.matcher(target).find()) {
             Message.GROUP_INVALID_ENTRY.send(sender);
             return;
         }
 
-        plugin.getDatastore().loadGroup(groupName, success -> {
+        plugin.getDatastore().loadGroup(target, success -> {
             if (!success) {
                 Message.GROUP_NOT_FOUND.send(sender);
                 return;
             }
 
-            Group group = plugin.getGroupManager().getGroup(groupName);
+            Group group = plugin.getGroupManager().getGroup(target);
             if (group == null) {
                 Message.GROUP_NOT_FOUND.send(sender);
                 return;
             }
 
-            sub.execute(plugin, sender, group, strippedArgs, label);
+            onSuccess.onComplete(group);
         });
     }
 
     @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;
+    protected List<String> getObjects(LuckPermsPlugin plugin) {
+        return new ArrayList<>(plugin.getGroupManager().getGroups().keySet());
     }
-
-            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;
-    }
-
-    public void registerSubCommand(GroupSubCommand subCommand) {
-        subCommands.add(subCommand);
-    }
-
 }

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

@@ -1,30 +0,0 @@
-package me.lucko.luckperms.commands.group;
-
-import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
-import me.lucko.luckperms.constants.Message;
-import me.lucko.luckperms.constants.Permission;
-import me.lucko.luckperms.groups.Group;
-
-import java.util.List;
-
-public abstract class GroupSubCommand extends SubCommand {
-    protected GroupSubCommand(String name, String description, String usage, Permission permission) {
-        super(name, description, usage, permission);
-    }
-
-    protected abstract void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label);
-
-    protected void saveGroup(Group group, Sender sender, LuckPermsPlugin plugin) {
-        plugin.getDatastore().saveGroup(group, success -> {
-            if (success) {
-                Message.GROUP_SAVE_SUCCESS.send(sender);
-            } else {
-                Message.GROUP_SAVE_ERROR.send(sender);
-            }
-
-            plugin.runUpdateTask();
-        });
-    }
-}

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

@@ -1,18 +1,16 @@
 package me.lucko.luckperms.commands.group;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.commands.Util;
 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 ListGroups extends MainCommand {
+public class ListGroups extends SingleMainCommand {
     public ListGroups() {
         super("ListGroups", "/%s listgroups", 0);
     }
@@ -29,17 +27,7 @@ public class ListGroups extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.LIST_GROUPS.isAuthorized(sender);
     }
 }

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

@@ -1,29 +1,26 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
 
 import java.util.List;
 
-public class GroupClear extends GroupSubCommand {
+public class GroupClear extends SubCommand<Group> {
     public GroupClear() {
-        super("clear", "Clears a groups permissions", "/%s group <group> clear", Permission.GROUP_CLEAR);
+        super("clear", "Clears a groups permissions", "/%s group <group> clear", Permission.GROUP_CLEAR,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         group.clearNodes();
         Message.CLEAR_SUCCESS.send(sender, group.getName());
 
         saveGroup(group, sender, plugin);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupHasPerm extends GroupSubCommand {
+public class GroupHasPerm extends SubCommand<Group> {
     public GroupHasPerm() {
         super("haspermission", "Checks to see if a group has a certain permission node",
-                "/%s group <group> haspermission <node> [server] [world]", Permission.GROUP_HASPERMISSION);
+                "/%s group <group> haspermission <node> [server] [world]", Permission.GROUP_HASPERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         if (args.size() >= 2) {
             if (Patterns.NON_ALPHA_NUMERIC.matcher(args.get(1)).find()) {
                 Message.SERVER_INVALID_ENTRY.send(sender);
@@ -35,9 +37,4 @@ public class GroupHasPerm extends GroupSubCommand {
             Util.sendBoolean(sender, args.get(0), group.hasPermission(args.get(0), true, "global"));
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,27 +1,24 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
 
 import java.util.List;
 
-public class GroupInfo extends GroupSubCommand {
+public class GroupInfo extends SubCommand<Group> {
     public GroupInfo() {
-        super("info", "Gives info about the group", "/%s group <group> info", Permission.GROUP_INFO);
+        super("info", "Gives info about the group", "/%s group <group> info", Permission.GROUP_INFO,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         Message.GROUP_INFO.send(sender, group.getName(), group.getPermanentNodes().keySet().size(),
                 group.getTemporaryNodes().keySet().size(), label, group.getName());
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupInheritsPerm extends GroupSubCommand {
+public class GroupInheritsPerm extends SubCommand<Group> {
     public GroupInheritsPerm() {
         super("inheritspermission", "Checks to see if a group inherits a certain permission node",
-                "/%s group <group> inheritspermission <node> [server] [world]", Permission.GROUP_INHERITSPERMISSION);
+                "/%s group <group> inheritspermission <node> [server] [world]", Permission.GROUP_INHERITSPERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         if (args.size() >= 2) {
             if (Patterns.NON_ALPHA_NUMERIC.matcher(args.get(1)).find()) {
                 Message.SERVER_INVALID_ENTRY.send(sender);
@@ -35,9 +37,4 @@ public class GroupInheritsPerm extends GroupSubCommand {
             Util.sendBoolean(sender, args.get(0), group.inheritsPermission(args.get(0), true));
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,29 +1,25 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
 
 import java.util.List;
 
-public class GroupListNodes extends GroupSubCommand {
+public class GroupListNodes extends SubCommand<Group> {
     public GroupListNodes() {
         super("listnodes", "Lists the permission nodes the group has", "/%s group <group> listnodes",
-                Permission.GROUP_LISTNODES);
+                Permission.GROUP_LISTNODES, Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         Message.LISTNODES.send(sender, group.getName(), Util.permNodesToString(group.getPermanentNodes()));
         Message.LISTNODES_TEMP.send(sender, group.getName(), Util.tempNodesToString(group.getTemporaryNodes()));
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupSetInherit extends GroupSubCommand {
+public class GroupSetInherit extends SubCommand<Group> {
     public GroupSetInherit() {
         super("setinherit", "Sets another group for this group to inherit permissions from",
-                "/%s group <group> setinherit <group> [server] [world]", Permission.GROUP_SETINHERIT);
+                "/%s group <group> setinherit <group> [server] [world]", Permission.GROUP_SETINHERIT,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -64,9 +66,4 @@ public class GroupSetInherit extends GroupSubCommand {
     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 && argLength != 3;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -11,14 +12,14 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupSetPermission extends GroupSubCommand {
+public class GroupSetPermission extends SubCommand<Group> {
     public GroupSetPermission() {
         super("set", "Sets a permission for a group", "/%s group <group> set <node> <true|false> [server] [world]",
-                Permission.GROUP_SETPERMISSION);
+                Permission.GROUP_SETPERMISSION, Predicate.notinRange(2, 4));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String node = args.get(0);
         String bool = args.get(1).toLowerCase();
 
@@ -71,9 +72,4 @@ public class GroupSetPermission extends GroupSubCommand {
     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 && argLength != 4;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,14 +13,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupSetTempInherit extends GroupSubCommand {
+public class GroupSetTempInherit extends SubCommand<Group> {
     public GroupSetTempInherit() {
         super("settempinherit", "Sets another group for this group to inherit permissions from temporarily",
-                "/%s group <group> settempinherit <group> <duration> [server] [world]", Permission.GROUP_SET_TEMP_INHERIT);
+                "/%s group <group> settempinherit <group> <duration> [server] [world]",
+                Permission.GROUP_SET_TEMP_INHERIT, Predicate.notinRange(2, 4));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -80,9 +82,4 @@ public class GroupSetTempInherit extends GroupSubCommand {
     public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
         return getGroupTabComplete(args, plugin);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 2 && argLength != 3 && argLength != 4;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,14 +13,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupSetTempPermission extends GroupSubCommand {
+public class GroupSetTempPermission extends SubCommand<Group> {
     public GroupSetTempPermission() {
         super("settemp", "Sets a temporary permission for a group",
-                "/%s group <group> settemp <node> <true|false> <duration> [server] [world]", Permission.GROUP_SET_TEMP_PERMISSION);
+                "/%s group <group> settemp <node> <true|false> <duration> [server] [world]",
+                Permission.GROUP_SET_TEMP_PERMISSION, Predicate.notinRange(3, 5));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String node = args.get(0);
         String bool = args.get(1).toLowerCase();
 
@@ -87,9 +89,4 @@ public class GroupSetTempPermission extends GroupSubCommand {
     public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
         return getBoolTabComplete(args);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 3 && argLength != 4 && argLength != 5;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
@@ -12,13 +13,14 @@ import me.lucko.luckperms.tracks.Track;
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class GroupShowTracks extends GroupSubCommand {
+public class GroupShowTracks extends SubCommand<Group> {
     public GroupShowTracks() {
-        super("showtracks", "Lists the tracks that this group features on", "/%s group <group> showtracks", Permission.GROUP_SHOWTRACKS);
+        super("showtracks", "Lists the tracks that this group features on", "/%s group <group> showtracks",
+                Permission.GROUP_SHOWTRACKS, Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         plugin.getDatastore().loadAllTracks(success -> {
             if (!success) {
                 Message.TRACKS_LOAD_ERROR.send(sender);
@@ -29,9 +31,4 @@ public class GroupShowTracks extends GroupSubCommand {
                     plugin.getTrackManager().getApplicableTracks(group.getName()).stream().map(Track::getName).collect(Collectors.toList())));
         });
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,14 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupUnSetPermission extends GroupSubCommand {
+public class GroupUnSetPermission extends SubCommand<Group> {
     public GroupUnSetPermission() {
-        super("unset", "Unsets a permission for a group",
-                "/%s group <group> unset <node> [server] [world]", Permission.GROUP_UNSETPERMISSION);
+        super("unset", "Unsets a permission for a group", "/%s group <group> unset <node> [server] [world]",
+                Permission.GROUP_UNSETPERMISSION, Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String node = args.get(0);
 
         if (node.contains("/") || node.contains("$")) {
@@ -58,9 +59,4 @@ public class GroupUnSetPermission extends GroupSubCommand {
             Message.DOES_NOT_HAVEPERMISSION.send(sender, group.getName());
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupUnsetInherit extends GroupSubCommand {
+public class GroupUnsetInherit extends SubCommand<Group> {
     public GroupUnsetInherit() {
         super("unsetinherit", "Unsets another group for this group to inherit permissions from",
-                "/%s group <group> unsetinherit <group> [server] [world]", Permission.GROUP_UNSETINHERIT);
+                "/%s group <group> unsetinherit <group> [server] [world]", Permission.GROUP_UNSETINHERIT,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -58,9 +60,4 @@ public class GroupUnsetInherit extends GroupSubCommand {
     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 && argLength != 3;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupUnsetTempInherit extends GroupSubCommand {
+public class GroupUnsetTempInherit extends SubCommand<Group> {
     public GroupUnsetTempInherit() {
         super("unsettempinherit", "Unsets another group for this group to inherit permissions from",
-                "/%s group <group> unsettempinherit <group> [server] [world]", Permission.GROUP_UNSET_TEMP_INHERIT);
+                "/%s group <group> unsettempinherit <group> [server] [world]", Permission.GROUP_UNSET_TEMP_INHERIT,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -58,9 +60,4 @@ public class GroupUnsetTempInherit extends GroupSubCommand {
     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 && argLength != 3;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.group.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.group.GroupSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class GroupUnsetTempPermission extends GroupSubCommand {
+public class GroupUnsetTempPermission extends SubCommand<Group> {
     public GroupUnsetTempPermission() {
         super("unsettemp", "Unsets a temporary permission for a group",
-                "/%s group <group> unsettemp <node> [server] [world]", Permission.GROUP_UNSET_TEMP_PERMISSION);
+                "/%s group <group> unsettemp <node> [server] [world]", Permission.GROUP_UNSET_TEMP_PERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Group group, List<String> args, String label) {
         String node = args.get(0);
 
         if (node.contains("/") || node.contains("$")) {
@@ -58,9 +60,4 @@ public class GroupUnsetTempPermission extends GroupSubCommand {
             Message.DOES_NOT_HAVE_TEMP_PERMISSION.send(sender, group.getName());
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,16 +1,14 @@
 package me.lucko.luckperms.commands.misc;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
-import java.util.Collections;
 import java.util.List;
 
-public class DebugCommand extends MainCommand {
+public class DebugCommand extends SingleMainCommand {
     public DebugCommand() {
         super("Debug", "/%s debug", 0);
     }
@@ -23,17 +21,7 @@ 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 Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.DEBUG.isAuthorized(sender);
     }
 }

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

@@ -1,17 +1,15 @@
 package me.lucko.luckperms.commands.misc;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.utils.LPConfiguration;
 
-import java.util.Collections;
 import java.util.List;
 
-public class InfoCommand extends MainCommand {
+public class InfoCommand extends SingleMainCommand {
     public InfoCommand() {
         super("Info", "/%s info", 0);
     }
@@ -24,17 +22,7 @@ public class InfoCommand extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<? extends SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.INFO.isAuthorized(sender);
     }
 }

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

@@ -1,16 +1,14 @@
 package me.lucko.luckperms.commands.misc;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 
-import java.util.Collections;
 import java.util.List;
 
-public class SyncCommand extends MainCommand {
+public class SyncCommand extends SingleMainCommand {
     public SyncCommand() {
         super("Sync", "/%s sync", 0);
     }
@@ -22,17 +20,7 @@ public class SyncCommand extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<? extends SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.SYNC.isAuthorized(sender);
     }
 }

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

@@ -1,17 +1,15 @@
 package me.lucko.luckperms.commands.track;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.utils.Patterns;
 
-import java.util.Collections;
 import java.util.List;
 
-public class CreateTrack extends MainCommand {
+public class CreateTrack extends SingleMainCommand {
     public CreateTrack() {
         super("CreateTrack", "/%s createtrack <track>", 1);
     }
@@ -52,17 +50,7 @@ public class CreateTrack extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<? extends SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.CREATE_TRACK.isAuthorized(sender);
     }
 }

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

@@ -1,9 +1,8 @@
 package me.lucko.luckperms.commands.track;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
@@ -14,7 +13,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class DeleteTrack extends MainCommand {
+public class DeleteTrack extends SingleMainCommand {
     public DeleteTrack() {
         super("DeleteTrack", "/%s deletetrack <track>", 1);
     }
@@ -71,12 +70,7 @@ public class DeleteTrack extends MainCommand {
     }
 
     @Override
-    public List<SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.DELETE_TRACK.isAuthorized(sender);
     }
 }

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

@@ -1,18 +1,16 @@
 package me.lucko.luckperms.commands.track;
 
 import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
+import me.lucko.luckperms.commands.SingleMainCommand;
 import me.lucko.luckperms.commands.Util;
 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 ListTracks extends MainCommand {
+public class ListTracks extends SingleMainCommand {
     public ListTracks() {
         super("ListTracks", "/%s listtracks", 0);
     }
@@ -29,17 +27,7 @@ public class ListTracks extends MainCommand {
     }
 
     @Override
-    protected List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
-        return Collections.emptyList();
-    }
-
-    @Override
-    public List<SubCommand> getSubCommands() {
-        return Collections.emptyList();
-    }
-
-    @Override
-    protected boolean canUse(Sender sender) {
+    protected boolean isAuthorized(Sender sender) {
         return Permission.LIST_TRACKS.isAuthorized(sender);
     }
 }

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

@@ -1,101 +1,40 @@
 package me.lucko.luckperms.commands.track;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.api.data.Callback;
 import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.tracks.Track;
-import me.lucko.luckperms.utils.Patterns;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Optional;
-import java.util.stream.Collectors;
-
-public class TrackMainCommand extends MainCommand {
-
-    private final List<TrackSubCommand> subCommands = new ArrayList<>();
 
+public class TrackMainCommand extends MainCommand<Track> {
     public TrackMainCommand() {
         super("Track", "/%s track <track>", 2);
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label) {
-        if (args.size() < 2) {
-            sendUsage(sender, label);
-            return;
-        }
-
-        Optional<TrackSubCommand> o = subCommands.stream().filter(s -> s.getName().equalsIgnoreCase(args.get(1))).limit(1).findAny();
-
-        if (!o.isPresent()) {
-            Message.COMMAND_NOT_RECOGNISED.send(sender);
-            return;
-        }
-
-        final TrackSubCommand sub = o.get();
-        if (!sub.isAuthorized(sender)) {
-            Message.COMMAND_NO_PERMISSION.send(sender);
-            return;
-        }
-
-        List<String> strippedArgs = new ArrayList<>();
-        if (args.size() > 2) {
-            strippedArgs.addAll(args.subList(2, args.size()));
-        }
-
-        if (sub.isArgLengthInvalid(strippedArgs.size())) {
-            sub.sendUsage(sender, label);
-            return;
-        }
-
-        final String trackName = args.get(0).toLowerCase();
-
-        if (Patterns.NON_ALPHA_NUMERIC.matcher(trackName).find()) {
-            Message.TRACK_INVALID_ENTRY.send(sender);
-            return;
-        }
-
-        plugin.getDatastore().loadTrack(trackName, success -> {
+    protected void getTarget(String target, LuckPermsPlugin plugin, Sender sender, Callback<Track> onSuccess) {
+        plugin.getDatastore().loadTrack(target, success -> {
             if (!success) {
                 Message.TRACK_NOT_FOUND.send(sender);
                 return;
             }
 
-            Track track = plugin.getTrackManager().getTrack(trackName);
+            Track track = plugin.getTrackManager().getTrack(target);
             if (track == null) {
                 Message.TRACK_NOT_FOUND.send(sender);
                 return;
             }
 
-            sub.execute(plugin, sender, track, strippedArgs, label);
+            onSuccess.onComplete(track);
         });
     }
 
     @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;
+    protected List<String> getObjects(LuckPermsPlugin plugin) {
+        return new ArrayList<>(plugin.getTrackManager().getTracks().keySet());
     }
-
-            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;
-    }
-
-    public void registerSubCommand(TrackSubCommand subCommand) {
-        subCommands.add(subCommand);
-    }
-
 }

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

@@ -1,30 +0,0 @@
-package me.lucko.luckperms.commands.track;
-
-import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
-import me.lucko.luckperms.constants.Message;
-import me.lucko.luckperms.constants.Permission;
-import me.lucko.luckperms.tracks.Track;
-
-import java.util.List;
-
-public abstract class TrackSubCommand extends SubCommand {
-    public TrackSubCommand(String name, String description, String usage, Permission permission) {
-        super(name, description, usage, permission);
-    }
-
-    protected abstract void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label);
-
-    protected void saveTrack(Track track, Sender sender, LuckPermsPlugin plugin) {
-        plugin.getDatastore().saveTrack(track, success -> {
-            if (success) {
-                Message.TRACK_SAVE_SUCCESS.send(sender);
-            } else {
-                Message.TRACK_SAVE_ERROR.send(sender);
-            }
-
-            plugin.runUpdateTask();
-        });
-    }
-}

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.track.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.track.TrackSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,13 +13,14 @@ import me.lucko.luckperms.tracks.Track;
 
 import java.util.List;
 
-public class TrackAppend extends TrackSubCommand {
+public class TrackAppend extends SubCommand<Track> {
     public TrackAppend() {
-        super("append", "Appends a group onto the end of the track", "/%s track <track> append <group>", Permission.TRACK_APPEND);
+        super("append", "Appends a group onto the end of the track", "/%s track <track> append <group>",
+                Permission.TRACK_APPEND, Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         plugin.getDatastore().loadGroup(groupName, success -> {
@@ -47,9 +49,4 @@ public class TrackAppend extends TrackSubCommand {
     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/TrackClear.java

@@ -1,28 +1,25 @@
 package me.lucko.luckperms.commands.track.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.track.TrackSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
 
 import java.util.List;
 
-public class TrackClear extends TrackSubCommand {
+public class TrackClear extends SubCommand<Track> {
     public TrackClear() {
-        super("clear", "Clears the groups on the track", "/%s track <track> clear", Permission.TRACK_CLEAR);
+        super("clear", "Clears the groups on the track", "/%s track <track> clear", Permission.TRACK_CLEAR,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
         track.clearGroups();
         Message.TRACK_CLEAR.send(sender, track.getName());
         saveTrack(track, sender, plugin);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,27 +1,24 @@
 package me.lucko.luckperms.commands.track.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.track.TrackSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
 
 import java.util.List;
 
-public class TrackInfo extends TrackSubCommand {
+public class TrackInfo extends SubCommand<Track> {
     public TrackInfo() {
-        super("info", "Gives info about the track", "/%s track <track> info", Permission.TRACK_INFO);
+        super("info", "Gives info about the track", "/%s track <track> info", Permission.TRACK_INFO,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
         Message.TRACK_INFO.send(sender, track.getName(), Util.listToArrowSep(track.getGroups()));
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.track.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.track.TrackSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,14 +13,14 @@ import me.lucko.luckperms.tracks.Track;
 
 import java.util.List;
 
-public class TrackInsert extends TrackSubCommand {
+public class TrackInsert extends SubCommand<Track> {
     public TrackInsert() {
         super("insert", "Inserts a group at a given position along the track",
-                "/%s track <track> insert <group> <position>", Permission.TRACK_INSERT);
+                "/%s track <track> insert <group> <position>", Permission.TRACK_INSERT, Predicate.notOneOf(new Integer[]{2}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
         int pos;
         try {
@@ -57,9 +58,4 @@ public class TrackInsert extends TrackSubCommand {
     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/TrackRemove.java

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.track.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.track.TrackSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -10,13 +11,14 @@ import me.lucko.luckperms.tracks.Track;
 
 import java.util.List;
 
-public class TrackRemove extends TrackSubCommand {
+public class TrackRemove extends SubCommand<Track> {
     public TrackRemove() {
-        super("remove", "Removes a group from the track", "/%s track <track> remove <group>", Permission.TRACK_REMOVE);
+        super("remove", "Removes a group from the track", "/%s track <track> remove <group>", Permission.TRACK_REMOVE,
+                Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, Track track, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
         try {
             track.removeGroup(groupName);
@@ -31,9 +33,4 @@ public class TrackRemove extends TrackSubCommand {
     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

@@ -1,104 +1,53 @@
 package me.lucko.luckperms.commands.user;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.api.data.Callback;
 import me.lucko.luckperms.commands.MainCommand;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.users.User;
 import me.lucko.luckperms.utils.Patterns;
 
-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 {
-
-    private final List<UserSubCommand> subCommands = new ArrayList<>();
 
+public class UserMainCommand extends MainCommand<User> {
     public UserMainCommand() {
         super("User", "/%s user <user>", 2);
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label) {
-        if (args.size() < 2) {
-            sendUsage(sender, label);
-            return;
-        }
-
-        Optional<UserSubCommand> o = subCommands.stream().filter(s -> s.getName().equalsIgnoreCase(args.get(1))).limit(1).findAny();
-
-        if (!o.isPresent()) {
-            Message.COMMAND_NOT_RECOGNISED.send(sender);
-            return;
-        }
-
-        final UserSubCommand sub = o.get();
-        if (!sub.isAuthorized(sender)) {
-            Message.COMMAND_NO_PERMISSION.send(sender);
-            return;
-        }
-
-        // The arguments to be passed onto the sub command
-        List<String> strippedArgs = new ArrayList<>();
-        if (args.size() > 2) {
-            strippedArgs.addAll(args.subList(2, args.size()));
-        }
-
-        if (sub.isArgLengthInvalid(strippedArgs.size())) {
-            sub.sendUsage(sender, label);
-            return;
-        }
-
-        final String user = args.get(0);
-
-        if (Patterns.NON_USERNAME.matcher(user).find()) {
-            Message.USER_INVALID_ENTRY.send(sender, user);
-            return;
-        }
-
-        UUID u = Util.parseUuid(user);
+    protected void getTarget(String target, LuckPermsPlugin plugin, Sender sender, Callback<User> onSuccess) {
+        UUID u = Util.parseUuid(target);
         if (u != null) {
-            runSub(plugin, sender, u, sub, strippedArgs, label);
+            runSub(plugin, sender, u, onSuccess);
+            return;
+        }
+
+        if (target.length() <= 16) {
+            if (Patterns.NON_USERNAME.matcher(target).find()) {
+                Message.USER_INVALID_ENTRY.send(sender, target);
                 return;
             }
 
-        if (user.length() <= 16) {
             Message.USER_ATTEMPTING_LOOKUP.send(sender);
 
-            plugin.getDatastore().getUUID(user, uuid -> {
+            plugin.getDatastore().getUUID(target, uuid -> {
                 if (uuid == null) {
                     Message.USER_NOT_FOUND.send(sender);
                     return;
                 }
-                runSub(plugin, sender, uuid, sub, strippedArgs, label);
+
+                runSub(plugin, sender, uuid, onSuccess);
             });
             return;
         }
 
-        Message.USER_INVALID_ENTRY.send(sender, user);
+        Message.USER_INVALID_ENTRY.send(sender, target);
     }
 
-    @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, String label) {
+    private void runSub(LuckPermsPlugin plugin, Sender sender, UUID uuid, Callback<User> onSuccess) {
         plugin.getDatastore().loadUser(uuid, success -> {
             if (!success) {
                 Message.USER_NOT_FOUND.send(sender);
@@ -108,19 +57,16 @@ public class UserMainCommand extends MainCommand {
             User user = plugin.getUserManager().getUser(uuid);
             if (user == null) {
                 Message.USER_NOT_FOUND.send(sender);
+                return;
             }
 
-            command.execute(plugin, sender, user, strippedArgs, label);
+            onSuccess.onComplete(user);
             plugin.getUserManager().cleanupUser(user);
         });
     }
 
     @Override
-    public List<? extends SubCommand> getSubCommands() {
-        return subCommands;
-    }
-
-    public void registerSubCommand(UserSubCommand subCommand) {
-        subCommands.add(subCommand);
+    protected List<String> getObjects(LuckPermsPlugin plugin) {
+        return plugin.getPlayerList();
     }
 }

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

@@ -1,30 +0,0 @@
-package me.lucko.luckperms.commands.user;
-
-import me.lucko.luckperms.LuckPermsPlugin;
-import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.SubCommand;
-import me.lucko.luckperms.constants.Message;
-import me.lucko.luckperms.constants.Permission;
-import me.lucko.luckperms.users.User;
-
-import java.util.List;
-
-public abstract class UserSubCommand extends SubCommand {
-    protected UserSubCommand(String name, String description, String usage, Permission permission) {
-        super(name, description, usage, permission);
-    }
-
-    protected abstract void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label);
-
-    protected void saveUser(User user, Sender sender, LuckPermsPlugin plugin) {
-        user.refreshPermissions();
-
-        plugin.getDatastore().saveUser(user, success -> {
-            if (success) {
-                Message.USER_SAVE_SUCCESS.send(sender);
-            } else {
-                Message.USER_SAVE_ERROR.send(sender);
-            }
-        });
-    }
-}

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,13 +13,14 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserAddGroup extends UserSubCommand {
+public class UserAddGroup extends SubCommand<User> {
     public UserAddGroup() {
-        super("addgroup", "Adds the user to a group", "/%s user <user> addgroup <group> [server] [world]", Permission.USER_ADDGROUP);
+        super("addgroup", "Adds the user to a group", "/%s user <user> addgroup <group> [server] [world]",
+                Permission.USER_ADDGROUP, Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -70,9 +72,4 @@ public class UserAddGroup extends UserSubCommand {
     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 && argLength != 3);
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -13,14 +14,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserAddTempGroup extends UserSubCommand {
+public class UserAddTempGroup extends SubCommand<User> {
     public UserAddTempGroup() {
         super("addtempgroup", "Adds the user to a group temporarily",
-                "/%s user <user> addtempgroup <group> <duration> [server] [world]", Permission.USER_ADDTEMPGROUP);
+                "/%s user <user> addtempgroup <group> <duration> [server] [world]", Permission.USER_ADDTEMPGROUP,
+                Predicate.notinRange(2, 4));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -87,9 +89,4 @@ public class UserAddTempGroup extends UserSubCommand {
     public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
         return getGroupTabComplete(args, plugin);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return (argLength != 2 && argLength != 3 && argLength != 4);
-    }
 }

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

@@ -1,30 +1,27 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserClear extends UserSubCommand {
+public class UserClear extends SubCommand<User> {
     public UserClear() {
-        super("clear", "Clears a users permissions and groups", "/%s user <user> clear", Permission.USER_CLEAR);
+        super("clear", "Clears a users permissions and groups", "/%s user <user> clear", Permission.USER_CLEAR,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         user.clearNodes();
         plugin.getUserManager().giveDefaults(user);
         Message.CLEAR_SUCCESS.send(sender, user.getName());
 
         saveUser(user, sender, plugin);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -14,13 +15,14 @@ import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserDemote extends UserSubCommand {
+public class UserDemote extends SubCommand<User> {
     public UserDemote() {
-        super("demote", "Demotes a user along a track", "/%s user <user> demote <track>", Permission.USER_DEMOTE);
+        super("demote", "Demotes a user along a track", "/%s user <user> demote <track>", Permission.USER_DEMOTE,
+                Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         final String trackName = args.get(0).toLowerCase();
 
         plugin.getDatastore().loadTrack(trackName, success -> {
@@ -85,9 +87,4 @@ public class UserDemote extends UserSubCommand {
     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/UserGetUUID.java

@@ -1,26 +1,23 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserGetUUID extends UserSubCommand {
+public class UserGetUUID extends SubCommand<User> {
     public UserGetUUID() {
-        super("getuuid", "Get the UUID of a user", "/%s user <user> getuuid", Permission.USER_GETUUID);
+        super("getuuid", "Get the UUID of a user", "/%s user <user> getuuid", Permission.USER_GETUUID,
+                Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         Message.USER_GETUUID.send(sender, user.getName(), user.getUuid().toString());
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserHasPerm extends UserSubCommand {
+public class UserHasPerm extends SubCommand<User> {
     public UserHasPerm() {
         super("haspermission", "Checks to see if a user has a certain permission node",
-                "/%s user <user> haspermission <node> [server] [world]", Permission.USER_HASPERMISSION);
+                "/%s user <user> haspermission <node> [server] [world]", Permission.USER_HASPERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         if (args.size() >= 2) {
             if (Patterns.NON_ALPHA_NUMERIC.matcher(args.get(1)).find()) {
                 Message.SERVER_INVALID_ENTRY.send(sender);
@@ -35,9 +37,4 @@ public class UserHasPerm extends UserSubCommand {
             Util.sendBoolean(sender, args.get(0), user.hasPermission(args.get(0), true, "global"));
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,30 +1,26 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserInfo extends UserSubCommand {
+public class UserInfo extends SubCommand<User> {
     public UserInfo() {
-        super("info", "Gives info about the user", "/%s user <user> info", Permission.USER_INFO);
+        super("info", "Gives info about the user", "/%s user <user> info", Permission.USER_INFO, Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         Message.USER_INFO.send(sender, user.getName(), user.getUuid(), plugin.getPlayerStatus(user.getUuid()),
                 Util.listToCommaSep(user.getGroupNames()), user.getPrimaryGroup(),
                 user.getPermanentNodes().keySet().size(), user.getTemporaryNodes().keySet().size(), label, user.getName()
         );
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserInheritsPerm extends UserSubCommand {
+public class UserInheritsPerm extends SubCommand<User> {
     public UserInheritsPerm() {
         super("inheritspermission", "Checks to see if a user inherits a certain permission node",
-                "/%s user <user> inheritspermission <node> [server] [world]", Permission.USER_INHERITSPERMISSION);
+                "/%s user <user> inheritspermission <node> [server] [world]", Permission.USER_INHERITSPERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         if (args.size() >= 2) {
             if (Patterns.NON_ALPHA_NUMERIC.matcher(args.get(1)).find()) {
                 Message.SERVER_INVALID_ENTRY.send(sender);
@@ -35,9 +37,4 @@ public class UserInheritsPerm extends UserSubCommand {
             Util.sendBoolean(sender, args.get(0), user.inheritsPermission(args.get(0), true));
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,28 +1,25 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserListNodes extends UserSubCommand {
+public class UserListNodes extends SubCommand<User> {
     public UserListNodes() {
-        super("listnodes", "Lists the permission nodes the user has", "/%s user <user> listnodes", Permission.USER_LISTNODES);
+        super("listnodes", "Lists the permission nodes the user has", "/%s user <user> listnodes",
+                Permission.USER_LISTNODES, Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         Message.LISTNODES.send(sender, user.getName(), Util.permNodesToString(user.getPermanentNodes()));
         Message.LISTNODES_TEMP.send(sender, user.getName(), Util.tempNodesToString(user.getTemporaryNodes()));
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -14,13 +15,14 @@ import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserPromote extends UserSubCommand {
+public class UserPromote extends SubCommand<User> {
     public UserPromote() {
-        super("promote", "Promotes the user along a track", "/%s user <user> promote <track>", Permission.USER_PROMOTE);
+        super("promote", "Promotes the user along a track", "/%s user <user> promote <track>", Permission.USER_PROMOTE,
+                Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         final String trackName = args.get(0).toLowerCase();
 
         plugin.getDatastore().loadTrack(trackName, success -> {
@@ -85,9 +87,4 @@ public class UserPromote extends UserSubCommand {
     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/UserRemoveGroup.java

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,13 +12,14 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserRemoveGroup extends UserSubCommand {
+public class UserRemoveGroup extends SubCommand<User> {
     public UserRemoveGroup() {
-        super("removegroup", "Removes a user from a group", "/%s user <user> removegroup <group> [server] [world]", Permission.USER_REMOVEGROUP);
+        super("removegroup", "Removes a user from a group", "/%s user <user> removegroup <group> [server] [world]",
+                Permission.USER_REMOVEGROUP, Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -63,9 +65,4 @@ public class UserRemoveGroup extends UserSubCommand {
     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 && argLength != 3);
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserRemoveTempGroup extends UserSubCommand {
+public class UserRemoveTempGroup extends SubCommand<User> {
     public UserRemoveTempGroup() {
         super("removetempgroup", "Removes a user from a temporary group",
-                "/%s user <user> removetempgroup <group> [server] [world]", Permission.USER_REMOVETEMPGROUP);
+                "/%s user <user> removetempgroup <group> [server] [world]", Permission.USER_REMOVETEMPGROUP,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String groupName = args.get(0).toLowerCase();
 
         if (groupName.contains("/") || groupName.contains("$")) {
@@ -58,9 +60,4 @@ public class UserRemoveTempGroup extends UserSubCommand {
     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 && argLength != 3);
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserSetPermission extends UserSubCommand {
+public class UserSetPermission extends SubCommand<User> {
     public UserSetPermission() {
         super("set", "Sets a permission for a user",
-                "/%s user <user> set <node> <true|false> [server] [world]", Permission.USER_SETPERMISSION);
+                "/%s user <user> set <node> <true|false> [server] [world]", Permission.USER_SETPERMISSION,
+                Predicate.notinRange(2, 4));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String node = args.get(0);
         String bool = args.get(1).toLowerCase();
 
@@ -71,9 +73,4 @@ public class UserSetPermission extends UserSubCommand {
     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 && argLength != 4;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.groups.Group;
@@ -10,14 +11,14 @@ import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserSetPrimaryGroup extends UserSubCommand {
+public class UserSetPrimaryGroup extends SubCommand<User> {
     public UserSetPrimaryGroup() {
         super("setprimarygroup", "Sets a users primary group",
-                "/%s user <user> setprimarygroup <group>", Permission.USER_SETPRIMARYGROUP);
+                "/%s user <user> setprimarygroup <group>", Permission.USER_SETPRIMARYGROUP, Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         Group group = plugin.getGroupManager().getGroup(args.get(0).toLowerCase());
         if (group == null) {
             Message.GROUP_DOES_NOT_EXIST.send(sender);
@@ -44,9 +45,4 @@ public class UserSetPrimaryGroup extends UserSubCommand {
     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/UserSetTempPermission.java

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
@@ -12,14 +13,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserSetTempPermission extends UserSubCommand {
+public class UserSetTempPermission extends SubCommand<User> {
     public UserSetTempPermission() {
         super("settemp", "Sets a temporary permission for a user",
-                "/%s user <user> settemp <node> <true|false> <duration> [server] [world]", Permission.USER_SET_TEMP_PERMISSION);
+                "/%s user <user> settemp <node> <true|false> <duration> [server] [world]",
+                Permission.USER_SET_TEMP_PERMISSION, Predicate.notinRange(3, 5));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String node = args.get(0);
         String bool = args.get(1).toLowerCase();
 
@@ -85,9 +87,4 @@ public class UserSetTempPermission extends UserSubCommand {
     public List<String> onTabComplete(Sender sender, List<String> args, LuckPermsPlugin plugin) {
         return getBoolTabComplete(args);
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 3 && argLength != 4 && argLength != 5;
-    }
 }

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

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
@@ -11,13 +12,14 @@ import me.lucko.luckperms.users.User;
 
 import java.util.List;
 
-public class UserShowPos extends UserSubCommand {
+public class UserShowPos extends SubCommand<User> {
     public UserShowPos() {
-        super("showpos", "Shows a users position on a track", "/%s user <user> showpos <track>", Permission.USER_SHOWPOS);
+        super("showpos", "Shows a users position on a track", "/%s user <user> showpos <track>", Permission.USER_SHOWPOS,
+                Predicate.notOneOf(new Integer[]{1}));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         final String trackName = args.get(0).toLowerCase();
 
         plugin.getDatastore().loadTrack(trackName, success -> {
@@ -49,9 +51,4 @@ public class UserShowPos extends UserSubCommand {
     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/UserShowTracks.java

@@ -1,9 +1,10 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.commands.Util;
-import me.lucko.luckperms.commands.user.UserSubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.tracks.Track;
@@ -12,14 +13,14 @@ import me.lucko.luckperms.users.User;
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class UserShowTracks extends UserSubCommand {
+public class UserShowTracks extends SubCommand<User> {
     public UserShowTracks() {
         super("showtracks", "Lists the tracks that this user's primary group features on", "/%s user <user> showtracks",
-                Permission.USER_SHOWTRACKS);
+                Permission.USER_SHOWTRACKS, Predicate.alwaysFalse());
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         plugin.getDatastore().loadAllTracks(success -> {
             if (!success) {
                 Message.TRACKS_LOAD_ERROR.send(sender);
@@ -31,9 +32,4 @@ public class UserShowTracks extends UserSubCommand {
                     plugin.getTrackManager().getApplicableTracks(user.getPrimaryGroup()).stream().map(Track::getName).collect(Collectors.toList())));
         });
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return false;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,14 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserUnSetPermission extends UserSubCommand {
+public class UserUnSetPermission extends SubCommand<User> {
     public UserUnSetPermission() {
         super("unset", "Unsets a permission for a user",
-                "/%s user <user> unset <node> [server] [world]", Permission.USER_UNSETPERMISSION);
+                "/%s user <user> unset <node> [server] [world]", Permission.USER_UNSETPERMISSION, Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String node = args.get(0);
 
         if (node.contains("/") || node.contains("$")) {
@@ -58,9 +59,4 @@ public class UserUnSetPermission extends UserSubCommand {
             Message.DOES_NOT_HAVEPERMISSION.send(sender, user.getName());
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

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

@@ -1,8 +1,9 @@
 package me.lucko.luckperms.commands.user.subcommands;
 
 import me.lucko.luckperms.LuckPermsPlugin;
+import me.lucko.luckperms.commands.Predicate;
 import me.lucko.luckperms.commands.Sender;
-import me.lucko.luckperms.commands.user.UserSubCommand;
+import me.lucko.luckperms.commands.SubCommand;
 import me.lucko.luckperms.constants.Message;
 import me.lucko.luckperms.constants.Permission;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
@@ -11,14 +12,15 @@ import me.lucko.luckperms.utils.Patterns;
 
 import java.util.List;
 
-public class UserUnsetTempPermission extends UserSubCommand {
+public class UserUnsetTempPermission extends SubCommand<User> {
     public UserUnsetTempPermission() {
         super("unsettemp", "Unsets a temporary permission for a user",
-                "/%s user <user> unsettemp <node> [server] [world]", Permission.USER_UNSET_TEMP_PERMISSION);
+                "/%s user <user> unsettemp <node> [server] [world]", Permission.USER_UNSET_TEMP_PERMISSION,
+                Predicate.notinRange(1, 3));
     }
 
     @Override
-    protected void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
+    public void execute(LuckPermsPlugin plugin, Sender sender, User user, List<String> args, String label) {
         String node = args.get(0);
 
         if (node.contains("/") || node.contains("$")) {
@@ -58,9 +60,4 @@ public class UserUnsetTempPermission extends UserSubCommand {
             Message.DOES_NOT_HAVE_TEMP_PERMISSION.send(sender, user.getName());
         }
     }
-
-    @Override
-    public boolean isArgLengthInvalid(int argLength) {
-        return argLength != 1 && argLength != 2 && argLength != 3;
-    }
 }

common/src/main/java/me/lucko/luckperms/data/methods/FlatfileDatastore.java

@@ -503,12 +503,14 @@ public class FlatfileDatastore extends Datastore {
 
     @Override
     public boolean saveUUIDData(String username, UUID uuid) {
+        username = username.toLowerCase();
         uuidCache.put(username, uuid.toString());
         return true;
     }
 
     @Override
     public UUID getUUID(String username) {
+        username = username.toLowerCase();
         if (uuidCache.get(username) == null) return null;
         return UUID.fromString(uuidCache.get(username));
     }

common/src/main/java/me/lucko/luckperms/data/methods/SQLDatastore.java

@@ -80,7 +80,7 @@ abstract class SQLDatastore extends Datastore {
         boolean success = false;
         try {
             @Cleanup Connection connection = getConnection();
-            if (connection == null) {
+            if (connection == null || connection.isClosed()) {
                 throw new IllegalStateException("SQL connection is null");
             }
 
@@ -396,10 +396,11 @@ abstract class SQLDatastore extends Datastore {
 
     @Override
     public boolean saveUUIDData(String username, UUID uuid) {
+        final String u = username.toLowerCase();
         boolean success = runQuery(new QueryRS(UUIDCACHE_SELECT) {
             @Override
             void onRun(PreparedStatement preparedStatement) throws SQLException {
-                preparedStatement.setString(1, username);
+                preparedStatement.setString(1, u);
             }
 
             @Override
@@ -410,14 +411,14 @@ abstract class SQLDatastore extends Datastore {
                         @Override
                         void onRun(PreparedStatement preparedStatement) throws SQLException {
                             preparedStatement.setString(1, uuid.toString());
-                            preparedStatement.setString(2, username);
+                            preparedStatement.setString(2, u);
                         }
                     });
                 } else {
                     success = runQuery(new QueryPS(UUIDCACHE_INSERT) {
                         @Override
                         void onRun(PreparedStatement preparedStatement) throws SQLException {
-                            preparedStatement.setString(1, username);
+                            preparedStatement.setString(1, u);
                             preparedStatement.setString(2, uuid.toString());
                         }
                     });
@@ -431,12 +432,13 @@ abstract class SQLDatastore extends Datastore {
 
     @Override
     public UUID getUUID(String username) {
+        final String u = username.toLowerCase();
         final UUID[] uuid = {null};
 
         boolean success = runQuery(new QueryRS(UUIDCACHE_SELECT) {
             @Override
             void onRun(PreparedStatement preparedStatement) throws SQLException {
-                preparedStatement.setString(1, username);
+                preparedStatement.setString(1, u);
             }
 
             @Override