Add more stuff to api

api/src/main/java/me/lucko/luckperms/api/LPConfiguration.java

@@ -0,0 +1,50 @@
+package me.lucko.luckperms.api;
+
+import me.lucko.luckperms.api.data.MySQLConfiguration;
+
+/**
+ * A wrapper interface for the internal LuckPerms configuration, providing read only access.
+ */
+public interface LPConfiguration {
+
+    /**
+     * @return the name of this server
+     */
+    String getServer();
+
+    /**
+     * @return how often a sync task will run in minutes
+     */
+    int getSyncTime();
+
+    /**
+     * @return the default group, in a node representation
+     */
+    String getDefaultGroupNode();
+
+    /**
+     * @return the name of the default group
+     */
+    String getDefaultGroupName();
+
+    /**
+     * @return if the users on this server will have their global permissions applied
+     */
+    boolean getIncludeGlobalPerms();
+
+    /**
+     * @return the online mode setting in the config
+     */
+    boolean getOnlineMode();
+
+    /**
+     * @return the database values set in the configuration
+     */
+    MySQLConfiguration getDatabaseValues();
+
+    /**
+     * @return the storage method string from the configuration
+     */
+    String getStorageMethod();
+
+}

api/src/main/java/me/lucko/luckperms/api/LuckPermsApi.java

@@ -1,5 +1,6 @@
 package me.lucko.luckperms.api;
 
+import java.util.Optional;
 import java.util.UUID;
 
 /**
@@ -18,6 +19,12 @@ public interface LuckPermsApi {
      */
     String getVersion();
 
+    /**
+     * Gets a wrapped {@link LPConfiguration} instance, with read only access
+     * @return a configuration instance
+     */
+    LPConfiguration getConfiguration();
+
     /**
      * Gets a wrapped {@link Datastore} instance, with somewhat limited access
      * @return a datastore instance
@@ -30,6 +37,12 @@ public interface LuckPermsApi {
      */
     Logger getLogger();
 
+    /**
+     * Gets a wrapped {@link UuidCache} instance, providing read access to the LuckPerms internal uuid caching system
+     * @return a uuidcache instance
+     */
+    UuidCache getUuidCache();
+
     /**
      * Gets a wrapped user object from the user storage
      * @param uuid the uuid of the user to get
@@ -37,6 +50,13 @@ public interface LuckPermsApi {
      */
     User getUser(UUID uuid);
 
+    /**
+     * Gets a wrapped user object from the user storage. This method does not return null, unlike {@link #getUser(UUID)}
+     * @param uuid the uuid of the user to get
+     * @return an optional {@link User} object
+     */
+    Optional<User> getUserSafe(UUID uuid);
+
     /**
      * Gets a wrapped user object from the user storage
      * @param name the username of the user to get
@@ -44,6 +64,13 @@ public interface LuckPermsApi {
      */
     User getUser(String name);
 
+    /**
+     * Gets a wrapped user object from the user storage. This method does not return null, unlike {@link #getUser(String)}
+     * @param name the username of the user to get
+     * @return an optional {@link User} object
+     */
+    Optional<User> getUserSafe(String name);
+
     /**
      * Check if a user is loaded in memory
      * @param uuid the uuid to check for
@@ -58,6 +85,13 @@ public interface LuckPermsApi {
      */
     Group getGroup(String name);
 
+    /**
+     * Gets a wrapped group object from the group storage. This method does not return null, unlike {@link #getGroup}
+     * @param name the name of the group to get
+     * @return an optional {@link Group} object
+     */
+    Optional<Group> getGroupSafe(String name);
+
     /**
      * Check if a group is loaded in memory
      * @param name the name to check for
@@ -72,6 +106,13 @@ public interface LuckPermsApi {
      */
     Track getTrack(String name);
 
+    /**
+     * Gets a wrapped tracj object from the track storage. This method does not return null, unlike {@link #getTrack}
+     * @param name the name of the track to get
+     * @return an optional {@link Track} object
+     */
+    Optional<Track> getTrackSafe(String name);
+
     /**
      * Check if a track is loaded in memory
      * @param name the name to check for

api/src/main/java/me/lucko/luckperms/api/UuidCache.java

@@ -0,0 +1,32 @@
+package me.lucko.luckperms.api;
+
+import java.util.UUID;
+
+/**
+ * This UuidCache is a means of allowing users to have the same internal UUID across a network of offline mode servers
+ * or mixed offline mode and online mode servers. Platforms running in offline mode generate a random UUID for a user when
+ * they first join the server, but this UUID will then not be consistent across the network. LuckPerms will instead check
+ * the datastore cache, to get a UUID for a user that is consistent across an entire network.
+ *
+ * If you want to get a user object from the datastore using the api on a server in offline mode, you will need to use this cache,
+ * OR use Datastore#getUUID, for users that are not online.
+ *
+ * WARNING: THIS IS ONLY EFFECTIVE FOR ONLINE PLAYERS. USE THE DATASTORE METHODS FOR OFFLINE PLAYERS.
+ */
+public interface UuidCache {
+
+    /**
+     * Gets a users internal "LuckPerms" UUID, from the one given by the server.
+     * @param external the UUID assigned by the server, through Player#getUniqueId or ProxiedPlayer#getUniqueId
+     * @return the corresponding internal UUID
+     */
+    UUID getUUID(UUID external);
+
+    /**
+     * Gets a users external, server assigned or Mojang assigned unique id, from the internal one used within LuckPerms.
+     * @param internal the UUID used within LuckPerms, through User#getUuid
+     * @return the corresponding external UUID
+     */
+    UUID getExternalUUID(UUID internal);
+
+}

api/src/main/java/me/lucko/luckperms/api/data/MySQLConfiguration.java

@@ -0,0 +1,9 @@
+package me.lucko.luckperms.api.data;
+
+public interface MySQLConfiguration {
+
+    String getAddress();
+    String getDatabase();
+    String getUsername();
+    String getPassword();
+}

bukkit/src/main/java/me/lucko/luckperms/api/vault/VaultPermissionHook.java

@@ -10,9 +10,6 @@ import me.lucko.luckperms.users.User;
 import me.lucko.luckperms.utils.PermissionHolder;
 import net.milkbowl.vault.permission.Permission;
 
-/**
- *
- */
 class VaultPermissionHook extends Permission {
 
     @Setter

common/src/main/java/me/lucko/luckperms/api/implementation/ApiProvider.java

@@ -4,11 +4,9 @@ import lombok.AllArgsConstructor;
 import lombok.NonNull;
 import me.lucko.luckperms.LuckPermsPlugin;
 import me.lucko.luckperms.api.*;
-import me.lucko.luckperms.api.implementation.internal.DatastoreLink;
+import me.lucko.luckperms.api.implementation.internal.*;
-import me.lucko.luckperms.api.implementation.internal.GroupLink;
-import me.lucko.luckperms.api.implementation.internal.TrackLink;
-import me.lucko.luckperms.api.implementation.internal.UserLink;
 
+import java.util.Optional;
 import java.util.UUID;
 
 /**
@@ -28,11 +26,21 @@ public class ApiProvider implements LuckPermsApi {
         return plugin.getVersion();
     }
 
+    @Override
+    public LPConfiguration getConfiguration() {
+        return new LPConfigurationLink(plugin.getConfiguration());
+    }
+
     @Override
     public Datastore getDatastore() {
         return new DatastoreLink(plugin.getDatastore());
     }
 
+    @Override
+    public UuidCache getUuidCache() {
+        return new UuidCacheLink(plugin.getUuidCache());
+    }
+
     @Override
     public Logger getLogger() {
         return plugin.getLog();
@@ -48,6 +56,11 @@ public class ApiProvider implements LuckPermsApi {
         return new UserLink(user);
     }
 
+    @Override
+    public Optional<User> getUserSafe(UUID uuid) {
+        return Optional.ofNullable(getUser(uuid));
+    }
+
     @Override
     public User getUser(@NonNull String name) {
         final me.lucko.luckperms.users.User user = plugin.getUserManager().getUser(name);
@@ -58,6 +71,11 @@ public class ApiProvider implements LuckPermsApi {
         return new UserLink(user);
     }
 
+    @Override
+    public Optional<User> getUserSafe(String name) {
+        return Optional.ofNullable(getUser(name));
+    }
+
     @Override
     public boolean isUserLoaded(@NonNull UUID uuid) {
         return plugin.getUserManager().isLoaded(uuid);
@@ -73,6 +91,11 @@ public class ApiProvider implements LuckPermsApi {
         return new GroupLink(group);
     }
 
+    @Override
+    public Optional<Group> getGroupSafe(String name) {
+        return Optional.ofNullable(getGroup(name));
+    }
+
     @Override
     public boolean isGroupLoaded(@NonNull String name) {
         return plugin.getGroupManager().isLoaded(name);
@@ -88,6 +111,11 @@ public class ApiProvider implements LuckPermsApi {
         return new TrackLink(track);
     }
 
+    @Override
+    public Optional<Track> getTrackSafe(String name) {
+        return Optional.ofNullable(getTrack(name));
+    }
+
     @Override
     public boolean isTrackLoaded(@NonNull String name) {
         return plugin.getTrackManager().isLoaded(name);

common/src/main/java/me/lucko/luckperms/api/implementation/internal/DatastoreLink.java

@@ -7,10 +7,11 @@ import me.lucko.luckperms.api.Group;
 import me.lucko.luckperms.api.Track;
 import me.lucko.luckperms.api.User;
 import me.lucko.luckperms.api.data.Callback;
-import me.lucko.luckperms.utils.Patterns;
 
 import java.util.UUID;
 
+import static me.lucko.luckperms.api.implementation.internal.Utils.*;
+
 /**
  * Provides a link between {@link Datastore} and {@link me.lucko.luckperms.data.Datastore}
  */
@@ -27,22 +28,6 @@ public class DatastoreLink implements Datastore {
         this.sync = new Sync(master);
     }
 
-    private static String checkUsername(String s) {
-        if (s.length() > 16 || Patterns.NON_USERNAME.matcher(s).find()) {
-            throw new IllegalArgumentException("Invalid username entry '" + s + "'. Usernames must be less than 16 chars" +
-                    " and only contain 'a-z A-Z 1-9 _'.");
-        }
-        return s;
-    }
-
-    private static String checkName(String s) {
-        if (s.length() > 36 || Patterns.NON_ALPHA_NUMERIC.matcher(s).find()) {
-            throw new IllegalArgumentException("Invalid name entry '" + s + "'. Names must be less than 37 chars" +
-                    " and only contain 'a-z A-Z 1-9'.");
-        }
-        return s.toLowerCase();
-    }
-
     private static <T> Callback<T> checkCallback(Callback<T> c) {
         // If no callback was given, just send an empty one
         if (c == null) {
@@ -87,7 +72,7 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public void saveUser(@NonNull User user, Callback<Boolean> callback) {
-            Utils.checkUser(user);
+            checkUser(user);
             master.saveUser(((UserLink) user).getMaster(), checkCallback(callback));
         }
 
@@ -108,13 +93,13 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public void saveGroup(@NonNull Group group, Callback<Boolean> callback) {
-            Utils.checkGroup(group);
+            checkGroup(group);
             master.saveGroup(((GroupLink) group).getMaster(), checkCallback(callback));
         }
 
         @Override
         public void deleteGroup(@NonNull Group group, Callback<Boolean> callback) {
-            Utils.checkGroup(group);
+            checkGroup(group);
             master.deleteGroup(((GroupLink) group).getMaster(), checkCallback(callback));
         }
 
@@ -135,13 +120,13 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public void saveTrack(@NonNull Track track, Callback<Boolean> callback) {
-            Utils.checkTrack(track);
+            checkTrack(track);
             master.saveTrack(((TrackLink) track).getMaster(), checkCallback(callback));
         }
 
         @Override
         public void deleteTrack(@NonNull Track track, Callback<Boolean> callback) {
-            Utils.checkTrack(track);
+            checkTrack(track);
             master.deleteTrack(((TrackLink) track).getMaster(), checkCallback(callback));
         }
 
@@ -172,7 +157,7 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public boolean saveUser(@NonNull User user) {
-            Utils.checkUser(user);
+            checkUser(user);
             return master.saveUser(((UserLink) user).getMaster());
         }
 
@@ -193,13 +178,13 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public boolean saveGroup(@NonNull Group group) {
-            Utils.checkGroup(group);
+            checkGroup(group);
             return master.saveGroup(((GroupLink) group).getMaster());
         }
 
         @Override
         public boolean deleteGroup(@NonNull Group group) {
-            Utils.checkGroup(group);
+            checkGroup(group);
             return master.deleteGroup(((GroupLink) group).getMaster());
         }
 
@@ -220,13 +205,13 @@ public class DatastoreLink implements Datastore {
 
         @Override
         public boolean saveTrack(@NonNull Track track) {
-            Utils.checkTrack(track);
+            checkTrack(track);
             return master.saveTrack(((TrackLink) track).getMaster());
         }
 
         @Override
         public boolean deleteTrack(@NonNull Track track) {
-            Utils.checkTrack(track);
+            checkTrack(track);
             return master.deleteTrack(((TrackLink) track).getMaster());
         }
 

common/src/main/java/me/lucko/luckperms/api/implementation/internal/GroupLink.java

@@ -9,6 +9,8 @@ import me.lucko.luckperms.exceptions.ObjectLacksException;
 
 import java.util.List;
 
+import static me.lucko.luckperms.api.implementation.internal.Utils.*;
+
 /**
  * Provides a link between {@link Group} and {@link me.lucko.luckperms.groups.Group}
  */
@@ -30,91 +32,91 @@ public class GroupLink extends PermissionHolderLink implements Group {
 
     @Override
     public boolean inheritsGroup(@NonNull Group group) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.inheritsGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public boolean inheritsGroup(@NonNull Group group, @NonNull String server) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.inheritsGroup(((GroupLink) group).getMaster(), server);
     }
 
     @Override
     public boolean inheritsGroup(@NonNull Group group, @NonNull String server, @NonNull String world) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.inheritsGroup(((GroupLink) group).getMaster(), server, world);
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group, @NonNull String server) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster(), checkServer(server));
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group, @NonNull String server, @NonNull String world) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster(), checkServer(server), world);
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster(), checkTime(expireAt));
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group, @NonNull String server, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster(), checkServer(server), checkTime(expireAt));
     }
 
     @Override
     public void setInheritGroup(@NonNull Group group, @NonNull String server, @NonNull String world, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.setInheritGroup(((GroupLink) group).getMaster(), checkServer(server), world, checkTime(expireAt));
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster(), temporary);
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group, @NonNull String server) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster(), checkServer(server));
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group, @NonNull String server, @NonNull String world) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster(), checkServer(server), world);
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group, @NonNull String server, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster(), checkServer(server), temporary);
     }
 
     @Override
     public void unsetInheritGroup(@NonNull Group group, @NonNull String server, @NonNull String world, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.unsetInheritGroup(((GroupLink) group).getMaster(), checkServer(server), world, temporary);
     }
 

common/src/main/java/me/lucko/luckperms/api/implementation/internal/LPConfigurationLink.java

@@ -0,0 +1,53 @@
+package me.lucko.luckperms.api.implementation.internal;
+
+import lombok.AllArgsConstructor;
+import me.lucko.luckperms.api.LPConfiguration;
+import me.lucko.luckperms.api.data.MySQLConfiguration;
+
+/**
+ * Provides a link between {@link me.lucko.luckperms.api.LPConfiguration} and {@link me.lucko.luckperms.utils.LPConfiguration}
+ */
+@AllArgsConstructor
+public class LPConfigurationLink implements LPConfiguration {
+    private final me.lucko.luckperms.utils.LPConfiguration master;
+
+    @Override
+    public String getServer() {
+        return master.getServer();
+    }
+
+    @Override
+    public int getSyncTime() {
+        return master.getSyncTime();
+    }
+
+    @Override
+    public String getDefaultGroupNode() {
+        return master.getDefaultGroupNode();
+    }
+
+    @Override
+    public String getDefaultGroupName() {
+        return master.getDefaultGroupName();
+    }
+
+    @Override
+    public boolean getIncludeGlobalPerms() {
+        return master.getIncludeGlobalPerms();
+    }
+
+    @Override
+    public boolean getOnlineMode() {
+        return master.getOnlineMode();
+    }
+
+    @Override
+    public MySQLConfiguration getDatabaseValues() {
+        return master.getDatabaseValues();
+    }
+
+    @Override
+    public String getStorageMethod() {
+        return master.getStorageMethod();
+    }
+}

common/src/main/java/me/lucko/luckperms/api/implementation/internal/PermissionHolderLink.java

@@ -6,13 +6,13 @@ import lombok.NonNull;
 import me.lucko.luckperms.api.PermissionHolder;
 import me.lucko.luckperms.exceptions.ObjectAlreadyHasException;
 import me.lucko.luckperms.exceptions.ObjectLacksException;
-import me.lucko.luckperms.utils.DateUtil;
-import me.lucko.luckperms.utils.Patterns;
 
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
+import static me.lucko.luckperms.api.implementation.internal.Utils.*;
+
 /**
  * Provides a link between {@link PermissionHolder} and {@link me.lucko.luckperms.utils.PermissionHolder}
  */
@@ -23,27 +23,6 @@ class PermissionHolderLink implements PermissionHolder {
     @NonNull
     private final me.lucko.luckperms.utils.PermissionHolder master;
 
-    static String checkServer(String s) {
-        if (Patterns.NON_ALPHA_NUMERIC.matcher(s).find()) {
-            throw new IllegalArgumentException("Invalid server entry '" + s + "'. Server names can only contain alphanumeric characters.");
-        }
-        return s;
-    }
-
-    private static String checkNode(String s) {
-        if (s.contains("/") || s.contains("$")) {
-            throw new IllegalArgumentException("Invalid node entry '" + s + "'. Nodes cannot contain '/' or '$' characters.");
-        }
-        return s;
-    }
-
-    static long checkTime(long l) {
-        if (DateUtil.shouldExpire(l)) {
-            throw new IllegalArgumentException("Unix time '" + l + "' is invalid, as it has already passed.");
-        }
-        return l;
-    }
-
     @Override
     public String getObjectName() {
         return master.getObjectName();

common/src/main/java/me/lucko/luckperms/api/implementation/internal/TrackLink.java

@@ -11,6 +11,8 @@ import me.lucko.luckperms.exceptions.ObjectLacksException;
 
 import java.util.List;
 
+import static me.lucko.luckperms.api.implementation.internal.Utils.checkGroup;
+
 /**
  * Provides a link between {@link Track} and {@link me.lucko.luckperms.tracks.Track}
  */
@@ -39,31 +41,31 @@ public class TrackLink implements Track {
 
     @Override
     public String getNext(@NonNull Group current) throws ObjectLacksException {
-        Utils.checkGroup(current);
+        checkGroup(current);
         return master.getNext(((GroupLink) current).getMaster());
     }
 
     @Override
     public String getPrevious(@NonNull Group current) throws ObjectLacksException {
-        Utils.checkGroup(current);
+        checkGroup(current);
         return master.getPrevious(((GroupLink) current).getMaster());
     }
 
     @Override
     public void appendGroup(@NonNull Group group) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.appendGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public void insertGroup(@NonNull Group group, @NonNull int position) throws ObjectAlreadyHasException, IndexOutOfBoundsException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.insertGroup(((GroupLink) group).getMaster(), position);
     }
 
     @Override
     public void removeGroup(@NonNull Group group) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster());
     }
 
@@ -74,7 +76,7 @@ public class TrackLink implements Track {
 
     @Override
     public boolean containsGroup(@NonNull Group group) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.containsGroup(((GroupLink) group).getMaster());
     }
 

common/src/main/java/me/lucko/luckperms/api/implementation/internal/UserLink.java

@@ -11,6 +11,8 @@ import me.lucko.luckperms.exceptions.ObjectLacksException;
 import java.util.List;
 import java.util.UUID;
 
+import static me.lucko.luckperms.api.implementation.internal.Utils.*;
+
 /**
  * Provides a link between {@link User} and {@link me.lucko.luckperms.users.User}
  */
@@ -60,91 +62,91 @@ public class UserLink extends PermissionHolderLink implements User {
 
     @Override
     public boolean isInGroup(@NonNull Group group) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.isInGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public boolean isInGroup(@NonNull Group group, @NonNull String server) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.isInGroup(((GroupLink) group).getMaster(), server);
     }
 
     @Override
     public boolean isInGroup(@NonNull Group group, @NonNull String server, @NonNull String world) {
-        Utils.checkGroup(group);
+        checkGroup(group);
         return master.isInGroup(((GroupLink) group).getMaster(), server, world);
     }
 
     @Override
     public void addGroup(@NonNull Group group) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public void addGroup(@NonNull Group group, @NonNull String server) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster(), checkServer(server));
     }
 
     @Override
     public void addGroup(@NonNull Group group, @NonNull String server, @NonNull String world) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster(), checkServer(server), world);
     }
 
     @Override
     public void addGroup(@NonNull Group group, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster(), checkTime(expireAt));
     }
 
     @Override
     public void addGroup(@NonNull Group group, @NonNull String server, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster(), checkServer(server), checkTime(expireAt));
     }
 
     @Override
     public void addGroup(@NonNull Group group, @NonNull String server, @NonNull String world, @NonNull long expireAt) throws ObjectAlreadyHasException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.addGroup(((GroupLink) group).getMaster(), checkServer(server), world, checkTime(expireAt));
     }
 
     @Override
     public void removeGroup(@NonNull Group group) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster());
     }
 
     @Override
     public void removeGroup(@NonNull Group group, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster(), temporary);
     }
 
     @Override
     public void removeGroup(@NonNull Group group, @NonNull String server) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster(), checkServer(server));
     }
 
     @Override
     public void removeGroup(@NonNull Group group, @NonNull String server, @NonNull String world) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster(), checkServer(server), world);
     }
 
     @Override
     public void removeGroup(@NonNull Group group, @NonNull String server, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster(), checkServer(server), temporary);
     }
 
     @Override
     public void removeGroup(@NonNull Group group, @NonNull String server, @NonNull String world, @NonNull boolean temporary) throws ObjectLacksException {
-        Utils.checkGroup(group);
+        checkGroup(group);
         master.removeGroup(((GroupLink) group).getMaster(), checkServer(server), world, temporary);
     }
 

common/src/main/java/me/lucko/luckperms/api/implementation/internal/Utils.java

@@ -4,6 +4,8 @@ import lombok.experimental.UtilityClass;
 import me.lucko.luckperms.api.Group;
 import me.lucko.luckperms.api.Track;
 import me.lucko.luckperms.api.User;
+import me.lucko.luckperms.utils.DateUtil;
+import me.lucko.luckperms.utils.Patterns;
 
 @UtilityClass
 class Utils {
@@ -26,4 +28,41 @@ class Utils {
         }
     }
 
+    static String checkUsername(String s) {
+        if (s.length() > 16 || Patterns.NON_USERNAME.matcher(s).find()) {
+            throw new IllegalArgumentException("Invalid username entry '" + s + "'. Usernames must be less than 16 chars" +
+                    " and only contain 'a-z A-Z 1-9 _'.");
+        }
+        return s;
+    }
+
+    static String checkName(String s) {
+        if (s.length() > 36 || Patterns.NON_ALPHA_NUMERIC.matcher(s).find()) {
+            throw new IllegalArgumentException("Invalid name entry '" + s + "'. Names must be less than 37 chars" +
+                    " and only contain 'a-z A-Z 1-9'.");
+        }
+        return s.toLowerCase();
+    }
+
+    static String checkServer(String s) {
+        if (Patterns.NON_ALPHA_NUMERIC.matcher(s).find()) {
+            throw new IllegalArgumentException("Invalid server entry '" + s + "'. Server names can only contain alphanumeric characters.");
+        }
+        return s;
+    }
+
+    static String checkNode(String s) {
+        if (s.contains("/") || s.contains("$")) {
+            throw new IllegalArgumentException("Invalid node entry '" + s + "'. Nodes cannot contain '/' or '$' characters.");
+        }
+        return s;
+    }
+
+    static long checkTime(long l) {
+        if (DateUtil.shouldExpire(l)) {
+            throw new IllegalArgumentException("Unix time '" + l + "' is invalid, as it has already passed.");
+        }
+        return l;
+    }
+
 }

common/src/main/java/me/lucko/luckperms/api/implementation/internal/UuidCacheLink.java

@@ -0,0 +1,24 @@
+package me.lucko.luckperms.api.implementation.internal;
+
+import lombok.AllArgsConstructor;
+import me.lucko.luckperms.api.UuidCache;
+
+import java.util.UUID;
+
+/**
+ * Provides a link between {@link me.lucko.luckperms.api.UuidCache} and {@link me.lucko.luckperms.utils.UuidCache}
+ */
+@AllArgsConstructor
+public class UuidCacheLink implements UuidCache {
+    private final me.lucko.luckperms.utils.UuidCache master;
+
+    @Override
+    public UUID getUUID(UUID external) {
+        return master.getUUID(external);
+    }
+
+    @Override
+    public UUID getExternalUUID(UUID internal) {
+        return master.getExternalUUID(internal);
+    }
+}

common/src/main/java/me/lucko/luckperms/data/MySQLConfiguration.java

@@ -5,7 +5,7 @@ import lombok.Getter;
 
 @Getter
 @AllArgsConstructor
-public class MySQLConfiguration {
+public class MySQLConfiguration implements me.lucko.luckperms.api.data.MySQLConfiguration {
 
     private final String address;
     private final String database;

common/src/main/java/me/lucko/luckperms/utils/AbstractListener.java

@@ -35,14 +35,6 @@ public class AbstractListener {
         }
     }
 
-    protected void onLogin(UUID uuid, String username) {
-
-    }
-
-    protected void onJoin(UUID uuid, String username) {
-
-    }
-
     protected void onLeave(UUID uuid) {
         final UuidCache cache = plugin.getUuidCache();
 

common/src/main/java/me/lucko/luckperms/utils/UuidCache.java

@@ -7,6 +7,15 @@ import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
+/**
+ * This UuidCache is a means of allowing users to have the same internal UUID across a network of offline mode servers
+ * or mixed offline mode and online mode servers. Platforms running in offline mode generate a random UUID for a user when
+ * they first join the server, but this UUID will then not be consistent across the network. LuckPerms will instead check
+ * the datastore cache, to get a UUID for a user that is consistent across an entire network.
+ *
+ * If you want to get a user object from the datastore using the api on a server in offline mode, you will need to use this cache,
+ * OR use Datastore#getUUID, for users that are not online.
+ */
 public class UuidCache {
 
     // External UUID --> Internal UUID