Add entity teleported by portal Paper-only event (#2441)

* Add `entity teleported by portal` event

* Properly handle null target world in switch

paper/src/main/java/com/denizenscript/denizen/paper/PaperModule.java

@@ -38,6 +38,9 @@ public static void init() {
         ScriptEvent.registerScriptEvent(EntityPathfindScriptEvent.class);
         ScriptEvent.registerScriptEvent(EntityRemoveFromWorldScriptEvent.class);
         ScriptEvent.registerScriptEvent(EntityStepsOnScriptEvent.class);
+        if (NMSHandler.getVersion().isAtLeast(NMSVersion.v1_19)) {
+            ScriptEvent.registerScriptEvent(EntityTeleportedByPortalScriptEvent.class);
+        }
         ScriptEvent.registerScriptEvent(ExperienceOrbMergeScriptEvent.class);
         ScriptEvent.registerScriptEvent(PlayerAbsorbsExperienceScriptEvent.class);
         ScriptEvent.registerScriptEvent(PlayerBeaconEffectScriptEvent.class);

paper/src/main/java/com/denizenscript/denizen/paper/events/EntityTeleportedByPortalScriptEvent.java

@@ -0,0 +1,101 @@
+package com.denizenscript.denizen.paper.events;
+
+import com.denizenscript.denizen.events.BukkitScriptEvent;
+import com.denizenscript.denizen.objects.EntityTag;
+import com.denizenscript.denizen.objects.WorldTag;
+import com.denizenscript.denizencore.objects.ObjectTag;
+import com.denizenscript.denizencore.objects.core.ElementTag;
+import com.denizenscript.denizencore.utilities.CoreUtilities;
+import io.papermc.paper.event.entity.EntityPortalReadyEvent;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+
+public class EntityTeleportedByPortalScriptEvent extends BukkitScriptEvent implements Listener {
+
+    // <--[event]
+    // @Events
+    // <entity> teleported by portal
+    //
+    // @Switch to:<world> to only process the event if the world the entity is being teleported to matches the specified WorldTag matcher.
+    // @Switch portal_type:<type> to only process the event if the portal's type matches the specified portal type.
+    //
+    // @Plugin Paper
+    //
+    // @Group Paper
+    //
+    // @Location true
+    //
+    // @Cancellable true
+    //
+    // @Triggers When an entity is about to be teleported by a portal (currently only fires for nether portals).
+    //
+    // @Context
+    // <context.entity> returns an EntityTag of the entity being teleported.
+    // <context.target_world> returns a WorldTag of the world the entity is being teleported to.
+    // <context.portal_type> returns an ElementTag of the portal's type. Will be one of <@link url https://jd.papermc.io/paper/1.19/org/bukkit/PortalType.html>.
+    //
+    // @Determine
+    // "TARGET_WORLD:" + WorldTag to set the world the entity will be teleported to.
+    // "REMOVE_TARGET_WORLD" to remove the target world. Should usually cancel the event instead of using this.
+    //
+    // -->
+
+    public EntityTeleportedByPortalScriptEvent() {
+        registerCouldMatcher("<entity> teleported by portal");
+        registerSwitches("to", "portal_type");
+    }
+
+    EntityPortalReadyEvent event;
+
+    @Override
+    public boolean matches(ScriptPath path) {
+        if (!path.tryObjectSwitch("to", WorldTag.mirrorBukkitWorld(event.getTargetWorld()))) {
+            return false;
+        }
+        if (!runGenericSwitchCheck(path, "portal_type", event.getPortalType().name())) {
+            return false;
+        }
+        if (!path.tryArgObject(0, new EntityTag(event.getEntity()))) {
+            return false;
+        }
+        if (!runInCheck(path, event.getEntity().getLocation())) {
+            return false;
+        }
+        return super.matches(path);
+    }
+
+    @Override
+    public ObjectTag getContext(String name) {
+        return switch (name) {
+            case "entity" -> new EntityTag(event.getEntity());
+            case "target_world" -> event.getTargetWorld() != null ? new WorldTag(event.getTargetWorld()) : null;
+            case "portal_type" -> new ElementTag(event.getPortalType());
+            default -> super.getContext(name);
+        };
+    }
+
+    @Override
+    public boolean applyDetermination(ScriptPath path, ObjectTag determinationObj) {
+        if (determinationObj instanceof ElementTag) {
+            String determination = CoreUtilities.toLowerCase(determinationObj.toString());
+            if (determination.startsWith("target_world:")) {
+                WorldTag world = WorldTag.valueOf(determination.substring("target_world:".length()), getTagContext(path));
+                if (world != null) {
+                    event.setTargetWorld(world.getWorld());
+                    return true;
+                }
+            }
+            else if (determination.equals("remove_target_world")) {
+                event.setTargetWorld(null);
+                return true;
+            }
+        }
+        return super.applyDetermination(path, determinationObj);
+    }
+
+    @EventHandler
+    public void onEntityPortalReady(EntityPortalReadyEvent event) {
+        this.event = event;
+        fire(event);
+    }
+}