Fix invoking handler

Author: surajkumar

cache/src/main/java/com/javadiscord/jdi/internal/cache/Cache.java

@@ -20,7 +20,9 @@ public CacheInterface<Object> getCacheForGuild(long guildId) {
         if (!cache.containsKey(guildId)) {
             return cache.put(guildId, getCacheForType());
         }
-        return cache.get(guildId);
+        return cache.get(guildId) == null
+            ? cache.put(guildId, getCacheForType())
+            : cache.get(guildId);
     }
 
     public boolean isGuildCached(long guildId) {

core/src/main/java/com/javadiscord/jdi/core/interaction/InteractionEventHandler.java

@@ -3,7 +3,9 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.Parameter;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import com.javadiscord.jdi.core.Discord;
 import com.javadiscord.jdi.core.EventListener;
@@ -19,6 +21,8 @@ public class InteractionEventHandler implements EventListener {
     private final Object slashCommandLoader;
     private final Discord discord;
 
+    private final Map<String, Object> cachedInstances = new HashMap<>();
+
     public InteractionEventHandler(Object slashCommandLoader, Discord discord) {
         this.slashCommandLoader = slashCommandLoader;
         this.discord = discord;
@@ -46,7 +50,9 @@ public void onInteractionCreate(Interaction interaction, Guild guild) {
                 (Class<?>) commandClassMethodInstance.getClass().getMethod("clazz")
                     .invoke(commandClassMethodInstance);
 
-            Method method = commandClassMethodInstance.getClass().getMethod("method");
+            Method method =
+                (Method) commandClassMethodInstance.getClass().getMethod("method")
+                    .invoke(commandClassMethodInstance);
 
             List<Object> paramOrder = new ArrayList<>();
             Parameter[] parameters = method.getParameters();
@@ -71,10 +77,12 @@ public void onInteractionCreate(Interaction interaction, Guild guild) {
                 );
             }
 
-            method.invoke(commandClassMethodInstance, paramOrder.toArray());
-
-            Object handlerInstance = handler.getDeclaredConstructor().newInstance();
-            method.invoke(handlerInstance);
+            if (cachedInstances.containsKey(handler.getName())) {
+                method.invoke(cachedInstances.get(handler.getName()), paramOrder.toArray());
+            } else {
+                Object handlerInstance = handler.getDeclaredConstructor().newInstance();
+                method.invoke(handlerInstance, paramOrder.toArray());
+            }
 
         } catch (Exception e) {
             LOGGER.error("Failed to invoke handler for /{}", command, e);