Event handling for custom click actions

fabric-networking-api-v1/src/main/java/net/fabricmc/fabric/api/networking/v1/CustomClickActionListener.java

@@ -0,0 +1,11 @@
+package net.fabricmc.fabric.api.networking.v1;
+
+import net.minecraft.nbt.NbtElement;
+import net.minecraft.server.network.ServerPlayerEntity;
+
+import org.jetbrains.annotations.Nullable;
+
+@FunctionalInterface
+public interface CustomClickActionListener {
+	void handleCustomClickAction(ServerPlayerEntity player, @Nullable NbtElement payload);
+}

fabric-networking-api-v1/src/main/java/net/fabricmc/fabric/api/networking/v1/CustomClickActions.java

@@ -0,0 +1,18 @@
+package net.fabricmc.fabric.api.networking.v1;
+
+import java.util.Objects;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.impl.networking.CustomClickEventHandlerRegistry;
+
+import net.minecraft.util.Identifier;
+
+public final class CustomClickActions {
+	public static Event<CustomClickActionListener> getListenerEvent(Identifier id) {
+		Objects.requireNonNull(id, "ID cannot be null");
+		return CustomClickEventHandlerRegistry.getOrCreateListenerEvent(id);
+	}
+
+	private CustomClickActions() {
+	}
+}

fabric-networking-api-v1/src/main/java/net/fabricmc/fabric/impl/networking/CustomClickActionHandlerRegistry.java

@@ -0,0 +1,43 @@
+package net.fabricmc.fabric.impl.networking;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+import net.minecraft.nbt.NbtElement;
+import net.minecraft.server.network.ServerPlayerEntity;
+import net.minecraft.util.Identifier;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.event.EventFactory;
+import net.fabricmc.fabric.api.networking.v1.CustomClickActionListener;
+
+public class CustomClickEventHandlerRegistry {
+	private static final Map<Identifier, Event<CustomClickActionListener>> REGISTRY = new HashMap<>();
+
+	public static Event<CustomClickActionListener> getOrCreateListenerEvent(Identifier id) {
+		return REGISTRY.computeIfAbsent(
+				id,
+				idx -> {
+					return EventFactory.createArrayBacked(
+							CustomClickActionListener.class,
+							listeners -> (player, payload) -> {
+								for (CustomClickActionListener listener : listeners) {
+									listener.handleCustomClickAction(player, payload);
+								}
+							}
+					);
+				}
+		);
+	}
+
+	public static void invokeListenerEvent(Identifier id, ServerPlayerEntity player, Optional<NbtElement> payload) {
+		Event<CustomClickActionListener> event = REGISTRY.get(id);
+		if (event != null) {
+			event.invoker().handleCustomClickAction(player, payload.orElse(null));
+		}
+	}
+
+	private CustomClickEventHandlerRegistry() {
+	}
+}

fabric-networking-api-v1/src/main/java/net/fabricmc/fabric/mixin/networking/ServerCommonNetworkHandlerMixin.java

@@ -16,7 +16,21 @@
 
 package net.fabricmc.fabric.mixin.networking;
 
+import com.llamalad7.mixinextras.injector.wrapmethod.WrapMethod;
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.networking.v1.CustomClickActionListener;
+import net.fabricmc.fabric.impl.networking.CustomClickEventHandlerRegistry;
+
+import net.minecraft.network.packet.c2s.common.CustomClickActionC2SPacket;
+
+import net.minecraft.server.network.ServerPlayNetworkHandler;
+
+import net.minecraft.server.network.ServerPlayerEntity;
+
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
@@ -55,4 +69,21 @@ private void onPlayPong(CommonPongC2SPacket packet, CallbackInfo ci) {
 			addon.onPong(packet.getParameter());
 		}
 	}
+
+	@WrapMethod(method = "onCustomClickAction")
+	protected void overrideCustomClickAction(CustomClickActionC2SPacket packet, Operation<Void> original) {
+		original.call(packet);
+	}
+
+	@Mixin(ServerPlayNetworkHandler.class)
+	private abstract static class ServerPlayNetworkHandlerMixin extends ServerCommonNetworkHandlerMixin {
+		@Shadow
+		public ServerPlayerEntity player;
+
+		@Override
+		protected void overrideCustomClickAction(CustomClickActionC2SPacket packet, Operation<Void> original) {
+			super.overrideCustomClickAction(packet, original);
+			CustomClickEventHandlerRegistry.invokeListenerEvent(packet.id(), this.player, packet.payload());
+		}
+	}
 }

fabric-networking-api-v1/src/main/java/net/fabricmc/fabric/mixin/networking/SignBlockEntityMixin.java

@@ -0,0 +1,38 @@
+package net.fabricmc.fabric.mixin.networking;
+
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
+
+import com.llamalad7.mixinextras.sugar.Local;
+
+import net.fabricmc.fabric.impl.networking.CustomClickEventHandlerRegistry;
+
+import net.minecraft.block.entity.SignBlockEntity;
+
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.nbt.NbtElement;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.network.ServerPlayerEntity;
+import net.minecraft.util.Identifier;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import java.util.Optional;
+
+@Mixin(SignBlockEntity.class)
+public class SignBlockEntityMixin {
+	@WrapOperation(
+			method = "runCommandClickEvent",
+			at = @At(
+					value = "INVOKE",
+					target = "Lnet/minecraft/server/MinecraftServer;handleCustomClickAction(Lnet/minecraft/util/Identifier;Ljava/util/Optional;)V"
+			)
+	)
+	private void hookCustomClickActionListener(MinecraftServer instance, Identifier id, Optional<NbtElement> payload, Operation<Void> original, @Local(argsOnly = true) PlayerEntity player) {
+		original.call(instance, id, payload);
+
+		// base method has a serverworld parameter, so the player should be a server player
+		CustomClickEventHandlerRegistry.invokeListenerEvent(id, (ServerPlayerEntity) player, payload);
+	}
+}

fabric-networking-api-v1/src/main/resources/fabric-networking-api-v1.mixins.json

@@ -16,9 +16,11 @@
     "PlayerManagerMixin",
     "RegistryByteBufMixin",
     "ServerCommonNetworkHandlerMixin",
+    "ServerCommonNetworkHandlerMixin$ServerPlayNetworkHandlerMixin",
     "ServerConfigurationNetworkHandlerMixin",
     "ServerLoginNetworkHandlerMixin",
     "ServerPlayNetworkHandlerMixin",
+    "SignBlockEntityMixin",
     "accessor.EntityTrackerAccessor",
     "accessor.ServerCommonNetworkHandlerAccessor",
     "accessor.ServerLoginNetworkHandlerAccessor",