Implement mod implementation interface for use in downstream mods

src/main/java/net/hypixel/modapi/HypixelModAPI.java

@@ -16,11 +16,11 @@
 import net.hypixel.modapi.packet.impl.serverbound.ServerboundRegisterPacket;
 import net.hypixel.modapi.serializer.PacketSerializer;
 import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.function.Predicate;
 
 public class HypixelModAPI {
     private static final HypixelModAPI INSTANCE = new HypixelModAPI();
@@ -33,12 +33,12 @@ public static HypixelModAPI getInstance() {
     private final Map<String, Collection<RegisteredHandlerImpl<?>>> handlers = new ConcurrentHashMap<>();
     private final Set<String> subscribedEvents = ConcurrentHashMap.newKeySet();
     private Set<String> lastSubscribedEvents = Collections.emptySet();
-    private Predicate<HypixelPacket> packetSender = null;
+    @Nullable
+    private HypixelModAPIImplementation modImplementation;
 
     private HypixelModAPI() {
         registerHypixelPackets();
         registerEventPackets();
-        registerDefaultHandler();
     }
 
     private void registerHypixelPackets() {
@@ -77,8 +77,8 @@ private void registerDefaultHandler() {
     }
 
     private void sendRegisterPacket(boolean alwaysSendIfNotEmpty) {
-        if (packetSender == null) {
-            // Allow registering events before the mod has fully initialized
+        if (modImplementation == null || !modImplementation.isConnectedToHypixel()) {
+            // Allow registering events when not connected to Hypixel
             return;
         }
 
@@ -144,11 +144,18 @@ public void handleError(String identifier, ErrorReason reason) {
     }
 
     @ApiStatus.Internal
-    public void setPacketSender(Predicate<HypixelPacket> packetSender) {
-        if (this.packetSender != null) {
-            throw new IllegalArgumentException("Packet sender already set");
+    public void setModImplementation(HypixelModAPIImplementation modImplementation) {
+        if (this.modImplementation != null) {
+            throw new IllegalStateException("Mod implementation already set");
+        }
+
+        if (modImplementation == null) {
+            throw new NullPointerException("modImplementation cannot be null");
         }
-        this.packetSender = packetSender;
+
+        this.modImplementation = modImplementation;
+        this.modImplementation.onInit();
+        registerDefaultHandler();
     }
 
     /**
@@ -184,11 +191,11 @@ public void subscribeToEventPacket(Class<? extends EventPacket> packet) {
      * @return whether the packet was sent successfully
      */
     public boolean sendPacket(HypixelPacket packet) {
-        if (packetSender == null) {
-            throw new IllegalStateException("Packet sender not set");
+        if (modImplementation == null) {
+            throw new IllegalStateException("Mod implementation not set");
         }
 
-        return packetSender.test(packet);
+        return modImplementation.sendPacket(packet);
     }
 
     private static class RegisteredHandlerImpl<T extends ClientboundHypixelPacket> implements RegisteredHandler<T> {

src/main/java/net/hypixel/modapi/HypixelModAPIImplementation.java

@@ -0,0 +1,15 @@
+package net.hypixel.modapi;
+
+import net.hypixel.modapi.packet.HypixelPacket;
+import org.jetbrains.annotations.ApiStatus;
+
+@ApiStatus.Internal
+public interface HypixelModAPIImplementation {
+
+    void onInit();
+
+    boolean sendPacket(HypixelPacket packet);
+
+    boolean isConnectedToHypixel();
+
+}