Add complete offline-mode support

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

@@ -5,6 +5,7 @@ import me.lucko.luckperms.groups.GroupManager;
 import me.lucko.luckperms.tracks.TrackManager;
 import me.lucko.luckperms.users.UserManager;
 import me.lucko.luckperms.utils.LPConfiguration;
+import me.lucko.luckperms.utils.UuidCache;
 
 import java.util.List;
 import java.util.UUID;
@@ -48,6 +49,12 @@ public interface LuckPermsPlugin {
      */
     Logger getLogger();
 
+    /**
+     * Retrieves the {@link UuidCache} for the plugin
+     * @return the plugin's {@link UuidCache}
+     */
+    UuidCache getUuidCache();
+
     /**
      * @return the version of the plugin
      */

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

@@ -20,7 +20,7 @@ public class InfoCommand extends MainCommand {
     protected void execute(LuckPermsPlugin plugin, Sender sender, List<String> args, String label) {
         final LPConfiguration c = plugin.getConfiguration();
         Message.INFO.send(sender, plugin.getVersion(), plugin.getDatastore().getName(), c.getServer(),
-                c.getDefaultGroupName(), c.getSyncTime(), c.getIncludeGlobalPerms());
+                c.getDefaultGroupName(), c.getSyncTime(), c.getIncludeGlobalPerms(), c.getOnlineMode());
     }
 
     @Override

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

@@ -99,7 +99,8 @@ public enum Message {
             PREFIX + "&eServer Name: &6%s" + "\n" +
             PREFIX + "&eDefault Group: &6%s" + "\n" +
             PREFIX + "&eSync Interval: &6%s minutes" + "\n" +
-            PREFIX + "&eInclude Global Perms: &6%s",
+            PREFIX + "&eInclude Global Perms: &6%s" + "\n" +
+            PREFIX + "&eOnline Mode: &6%s",
             false
     ),
     DEBUG(

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

@@ -61,6 +61,10 @@ public abstract class LPConfiguration<T extends LuckPermsPlugin> {
         return getBoolean("include-global", defaultIncludeGlobal);
     }
 
+    public boolean getOnlineMode() {
+        return getBoolean("online-mode", true);
+    }
+
     public String getDatabaseValue(String value) {
         return getString("sql." + value, null);
     }

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

@@ -0,0 +1,38 @@
+package me.lucko.luckperms.utils;
+
+import lombok.Getter;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class UuidCache {
+
+    private Map<String, UUID> cache;
+
+    @Getter
+    private final boolean onlineMode;
+
+    public UuidCache(boolean onlineMode) {
+        this.onlineMode = onlineMode;
+
+        if (!onlineMode) {
+            cache = new ConcurrentHashMap<>();
+        }
+    }
+
+    public UUID getUUID(String name, UUID fallback) {
+        return onlineMode ? fallback : (cache.containsKey(name) ? cache.get(name) : fallback);
+    }
+
+    public void addToCache(String name, UUID uuid) {
+        if (onlineMode) return;
+        cache.put(name, uuid);
+    }
+
+    public void clearCache(String name) {
+        if (onlineMode) return;
+        cache.remove(name);
+    }
+
+}