Paper-only event player tracks|untracks <entity>

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

@@ -64,6 +64,7 @@ public static void init() {
         ScriptEvent.registerScriptEvent(PlayerSelectsStonecutterRecipeScriptEvent.class);
         ScriptEvent.registerScriptEvent(PlayerSpectatesEntityScriptEvent.class);
         ScriptEvent.registerScriptEvent(PlayerStopsSpectatingScriptEvent.class);
+        ScriptEvent.registerScriptEvent(PlayerTracksEntityScriptEvent.class);
         ScriptEvent.registerScriptEvent(PlayerTradesWithMerchantScriptEvent.class);
         ScriptEvent.registerScriptEvent(PreEntitySpawnScriptEvent.class);
         ScriptEvent.registerScriptEvent(ProjectileCollideScriptEvent.class);

paper/src/main/java/com/denizenscript/denizen/paper/events/PlayerTracksEntityScriptEvent.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.LocationTag;
+import com.denizenscript.denizen.utilities.implementation.BukkitScriptEntryData;
+import com.denizenscript.denizencore.objects.ObjectTag;
+import com.denizenscript.denizencore.scripts.ScriptEntryData;
+import io.papermc.paper.event.player.PlayerTrackEntityEvent;
+import io.papermc.paper.event.player.PlayerUntrackEntityEvent;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+
+public class PlayerTracksEntityScriptEvent extends BukkitScriptEvent implements Listener {
+
+    // <--[event]
+    // @Events
+    // player tracks|untracks <entity>
+    //
+    // @Location true
+    //
+    // @Group Paper
+    //
+    // @Plugin Paper
+    //
+    // @Warning This event may fire very rapidly.
+    //
+    // @Triggers when a player starts or stop tracking an entity. An entity is tracked when it is visible to the client. An entity will be untracked when it is no longer visible, e.g. it despawns, dies, or is unloaded.
+    //
+    // @Context
+    // <context.entity> returns an EntityTag of the entity being tracked.
+    // <context.location> returns a LocationTag of the entity.
+    //
+    // @Player Always.
+    //
+    // @Example
+    // # Narrate when the player tracks all entities except for item frames.
+    // on player tracks !item_frame:
+    // - narrate "You are now tracking <context.entity.name> at <context.location.simple>"
+    //
+    // @Example
+    // on player untracks chicken:
+    // - narrate "CHICKEN: No! Come back! :("
+    // -->
+
+    public PlayerTracksEntityScriptEvent() {
+        registerCouldMatcher("player tracks|untracks <entity>");
+    }
+
+    public String type;
+    public Player player;
+    public EntityTag entity;
+    public LocationTag location;
+
+    @Override
+    public boolean matches(ScriptPath path) {
+        if (!runInCheck(path, location)) {
+            return false;
+        }
+        if (!path.eventArgLowerAt(1).equals(type)) {
+            return false;
+        }
+        if (!path.tryArgObject(2, entity)) {
+            return false;
+        }
+        return super.matches(path);
+    }
+
+    @Override
+    public ScriptEntryData getScriptEntryData() {
+        return new BukkitScriptEntryData(player);
+    }
+
+    @Override
+    public ObjectTag getContext(String name) {
+        return switch (name) {
+            case "entity" -> entity;
+            case "location" -> location;
+            default -> super.getContext(name);
+        };
+    }
+
+    @EventHandler
+    public void playerTracksEntityEvent(PlayerTrackEntityEvent event) {
+        entity = new EntityTag(event.getEntity());
+        location = new LocationTag(event.getEntity().getLocation());
+        player = event.getPlayer();
+        type = "tracks";
+        fire(event);
+    }
+
+    @EventHandler
+    public void playerUntracksEntityEvent(PlayerUntrackEntityEvent event) {
+        entity = new EntityTag(event.getEntity());
+        location = new LocationTag(event.getEntity().getLocation());
+        player = event.getPlayer();
+        type = "untracks";
+        fire(event);
+    }
+}