From 6e3df970fab216d9a660276149a3d38d6f70f6ac Mon Sep 17 00:00:00 2001
From: Felix Cravic <themode@outlook.fr>
Date: Wed, 9 Dec 2020 22:31:20 +0100
Subject: [PATCH] Added GlobalEventHandler

---
 .../net/minestom/server/MinecraftServer.java  | 14 +++++++++++
 .../server/event/GlobalEventHandler.java      | 23 +++++++++++++++++++
 .../server/event/handler/EventHandler.java    | 22 ++++++++++++++----
 3 files changed, 54 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/net/minestom/server/event/GlobalEventHandler.java

diff --git a/src/main/java/net/minestom/server/MinecraftServer.java b/src/main/java/net/minestom/server/MinecraftServer.java
index b6e97e810..4c3450394 100644
--- a/src/main/java/net/minestom/server/MinecraftServer.java
+++ b/src/main/java/net/minestom/server/MinecraftServer.java
@@ -9,6 +9,7 @@ import net.minestom.server.data.SerializableData;
 import net.minestom.server.entity.EntityManager;
 import net.minestom.server.entity.EntityType;
 import net.minestom.server.entity.Player;
+import net.minestom.server.event.GlobalEventHandler;
 import net.minestom.server.extensions.Extension;
 import net.minestom.server.extensions.ExtensionManager;
 import net.minestom.server.fluids.Fluid;
@@ -133,6 +134,7 @@ public final class MinecraftServer {
     private static ResponseDataConsumer responseDataConsumer;
     private static String brandName = "Minestom";
     private static Difficulty difficulty = Difficulty.NORMAL;
+    private static GlobalEventHandler globalEventHandler = new GlobalEventHandler();
     private static LootTableManager lootTableManager;
     private static TagManager tagManager;
 
@@ -282,6 +284,18 @@ public final class MinecraftServer {
         PacketUtils.sendGroupedPacket(connectionManager.getOnlinePlayers(), serverDifficultyPacket);
     }
 
+    /**
+     * Gets the global event handler.
+     * <p>
+     * Used to register event callback at a global scale.
+     *
+     * @return the global event handler
+     */
+    @NotNull
+    public static GlobalEventHandler getGlobalEventListener() {
+        return globalEventHandler;
+    }
+
     /**
      * Gets the manager handling all incoming packets
      *
diff --git a/src/main/java/net/minestom/server/event/GlobalEventHandler.java b/src/main/java/net/minestom/server/event/GlobalEventHandler.java
new file mode 100644
index 000000000..dd9da088c
--- /dev/null
+++ b/src/main/java/net/minestom/server/event/GlobalEventHandler.java
@@ -0,0 +1,23 @@
+package net.minestom.server.event;
+
+import net.minestom.server.event.handler.EventHandler;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Object containing all the global event listeners.
+ */
+public final class GlobalEventHandler implements EventHandler {
+
+    // Events
+    private final Map<Class<? extends Event>, Collection<EventCallback>> eventCallbacks = new ConcurrentHashMap<>();
+
+    @NotNull
+    @Override
+    public Map<Class<? extends Event>, Collection<EventCallback>> getEventCallbacksMap() {
+        return eventCallbacks;
+    }
+}
diff --git a/src/main/java/net/minestom/server/event/handler/EventHandler.java b/src/main/java/net/minestom/server/event/handler/EventHandler.java
index 47080e812..52529252f 100644
--- a/src/main/java/net/minestom/server/event/handler/EventHandler.java
+++ b/src/main/java/net/minestom/server/event/handler/EventHandler.java
@@ -1,9 +1,11 @@
 package net.minestom.server.event.handler;
 
+import net.minestom.server.MinecraftServer;
 import net.minestom.server.entity.Entity;
 import net.minestom.server.event.CancellableEvent;
 import net.minestom.server.event.Event;
 import net.minestom.server.event.EventCallback;
+import net.minestom.server.event.GlobalEventHandler;
 import net.minestom.server.instance.Instance;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
@@ -89,17 +91,21 @@ public interface EventHandler {
      * @param <E>        the event type
      */
     default <E extends Event> void callEvent(@NotNull Class<E> eventClass, @NotNull E event) {
-        // TODO global event
-        final Collection<EventCallback> eventCallbacks = getEventCallbacks(eventClass);
-        for (EventCallback<E> eventCallback : eventCallbacks) {
-            eventCallback.run(event);
+
+        // Global listeners
+        if (!(this instanceof GlobalEventHandler)) {
+            MinecraftServer.getGlobalEventListener().callEvent(eventClass, event);
         }
 
+        // Local listeners
+        final Collection<EventCallback> eventCallbacks = getEventCallbacks(eventClass);
+        runEvent(eventCallbacks, event);
+
         // Call the same event for the current entity instance
         if (this instanceof Entity) {
             final Instance instance = ((Entity) this).getInstance();
             if (instance != null) {
-                instance.callEvent(eventClass, event);
+                runEvent(instance.getEventCallbacks(eventClass), event);
             }
         }
     }
@@ -122,4 +128,10 @@ public interface EventHandler {
         }
     }
 
+    private <E extends Event> void runEvent(@NotNull Collection<EventCallback> eventCallbacks, @NotNull E event) {
+        for (EventCallback<E> eventCallback : eventCallbacks) {
+            eventCallback.run(event);
+        }
+    }
+
 }