More proper bow item detection

Introduces Projectile2ItemCache to reliably associate fired
projectiles with the item used to shoot them. This replaces
the previous temporary workaround that was vulnerable to player
exploits, ensuring accurate item tracking during damage events.

Author: Krakenied

bukkit/src/main/java/com/leonardobishop/quests/bukkit/BukkitQuestsPlugin.java

@@ -147,6 +147,7 @@
 import com.leonardobishop.quests.bukkit.util.CompatUtils;
 import com.leonardobishop.quests.bukkit.util.FormatUtils;
 import com.leonardobishop.quests.bukkit.util.LogHistory;
+import com.leonardobishop.quests.bukkit.util.Projectile2ItemCache;
 import com.leonardobishop.quests.common.config.ConfigProblem;
 import com.leonardobishop.quests.common.config.ConfigProblemDescriptions;
 import com.leonardobishop.quests.common.config.QuestsConfig;
@@ -226,6 +227,7 @@ public class BukkitQuestsPlugin extends JavaPlugin implements Quests {
     private QuestsBossBar bossBarHandle;
     private QuestsActionBar actionBarHandle;
     private VersionSpecificHandler versionSpecificHandler;
+    private Projectile2ItemCache projectile2ItemCache;
 
     private LogHistory logHistory;
     private WrappedTask questAutoSaveTask;
@@ -370,6 +372,10 @@ public void onEnable() {
             };
         }
 
+        // Instantiate Projectile to ItemStack cache
+        this.projectile2ItemCache = new Projectile2ItemCache();
+        this.getServer().getPluginManager().registerEvents(this.projectile2ItemCache, this);
+
         // Set item getter to be used by Quests config
         this.questsConfig.setItemGetter(this.itemGetter);
 
@@ -972,6 +978,10 @@ public VersionSpecificHandler getVersionSpecificHandler() {
         return versionSpecificHandler;
     }
 
+    public Projectile2ItemCache getProjectile2ItemCache() {
+        return projectile2ItemCache;
+    }
+
     public QuestItemRegistry getQuestItemRegistry() {
         return questItemRegistry;
     }

bukkit/src/main/java/com/leonardobishop/quests/bukkit/hook/versionspecific/VersionSpecificHandler.java

@@ -245,9 +245,13 @@ public interface VersionSpecificHandler {
     /**
      * {@link DamageSource}s were introduced in {@code 1.20.4}.
      */
-    @SuppressWarnings("UnstableApiUsage")
     @Nullable Player getDamager(@Nullable EntityDamageEvent lastDamageCause);
 
+    /**
+     * {@link DamageSource}s were introduced in {@code 1.20.4}.
+     */
+    @Nullable Entity getDirectSource(@Nullable EntityDamageEvent lastDamageCause);
+
     /**
      * {@link Tag#CANDLE_CAKES} was introduced in {@code 1.17}.
      */

bukkit/src/main/java/com/leonardobishop/quests/bukkit/hook/versionspecific/VersionSpecificHandler20.java

@@ -54,7 +54,6 @@ public String getSmithMode(SmithItemEvent event) {
         }
     }
 
-    @SuppressWarnings("UnstableApiUsage")
     @Override
     public @Nullable Player getDamager(@Nullable EntityDamageEvent event) {
         if (!DAMAGE_SOURCE_API) {
@@ -74,4 +73,18 @@ public String getSmithMode(SmithItemEvent event) {
 
         return null;
     }
+
+    @Override
+    public @Nullable Entity getDirectSource(@Nullable EntityDamageEvent event) {
+        if (!DAMAGE_SOURCE_API) {
+            return super.getDamager(event);
+        }
+
+        if (event == null) {
+            return null;
+        }
+
+        DamageSource source = event.getDamageSource();
+        return source.getDirectEntity();
+    }
 }

bukkit/src/main/java/com/leonardobishop/quests/bukkit/hook/versionspecific/VersionSpecificHandler8.java

@@ -226,6 +226,11 @@ public List<Entity> getPassengers(Entity entity) {
         return null;
     }
 
+    @Override
+    public @Nullable Entity getDirectSource(@Nullable EntityDamageEvent lastDamageCause) {
+        return null;
+    }
+
     @Override
     public boolean isCake(Material type) {
         return type == Material.CAKE;

bukkit/src/main/java/com/leonardobishop/quests/bukkit/tasktype/type/DealDamageTaskType.java

@@ -45,9 +45,7 @@ public void onReady() {
 
     @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
     public void onEntityDamage(EntityDamageEvent event) {
-        Entity entity = event.getEntity();
         Player player = plugin.getVersionSpecificHandler().getDamager(event);
-
         if (player == null || player.hasMetadata("NPC")) {
             return;
         }
@@ -57,10 +55,15 @@ public void onEntityDamage(EntityDamageEvent event) {
             return;
         }
 
+        Entity entity = event.getEntity();
         if (!(entity instanceof Damageable damageable)) {
             return;
         }
 
+        Entity directSource = plugin.getVersionSpecificHandler().getDirectSource(event);
+        ItemStack bowItem = directSource != null ? plugin.getProjectile2ItemCache().getItem(directSource) : null;
+        ItemStack item = bowItem != null ? bowItem : plugin.getVersionSpecificHandler().getItemInMainHand(player);
+
         // Clamp entity damage as getDamage() returns Float.MAX_VALUE for killing a parrot with a cookie
         // https://github.com/LMBishop/Quests/issues/753
         double finalDamage = event.getFinalDamage();
@@ -87,7 +90,6 @@ public void onEntityDamage(EntityDamageEvent event) {
             }
 
             if (task.hasConfigKey("item")) {
-                ItemStack item = plugin.getVersionSpecificHandler().getItemInMainHand(player);
                 if (item == null) {
                     super.debug("Specific item is required, player has no item in hand; continuing...", quest.getId(), task.getId(), player.getUniqueId());
                     continue;

bukkit/src/main/java/com/leonardobishop/quests/bukkit/tasktype/type/MobkillingTaskType.java

@@ -99,6 +99,11 @@ private void handle(Player player, LivingEntity entity, int eventAmount) {
             return;
         }
 
+        EntityDamageEvent lastDamageCause = entity.getLastDamageCause();
+        Entity directSource = plugin.getVersionSpecificHandler().getDirectSource(lastDamageCause);
+        ItemStack bowItem = directSource != null ? plugin.getProjectile2ItemCache().getItem(directSource) : null;
+        ItemStack item = bowItem != null ? bowItem : plugin.getVersionSpecificHandler().getItemInMainHand(player);
+
         //noinspection deprecation
         String customName = entity.getCustomName();
 
@@ -137,7 +142,6 @@ private void handle(Player player, LivingEntity entity, int eventAmount) {
             }
 
             if (task.hasConfigKey("item")) {
-                ItemStack item = plugin.getVersionSpecificHandler().getItemInMainHand(player);
                 if (item == null) {
                     super.debug("Specific item is required, player has no item in hand; continuing...", quest.getId(), task.getId(), player.getUniqueId());
                     continue;

bukkit/src/main/java/com/leonardobishop/quests/bukkit/tasktype/type/dependent/MythicMobsDealDamageTaskType.java

@@ -100,7 +100,6 @@ public void onEntityDamage(EntityDamageEvent event) {
     }
 
     private void handle(final EntityDamageEvent event, final String mobName, final double level) {
-        Entity entity = event.getEntity();
         Player player = plugin.getVersionSpecificHandler().getDamager(event);
 
         if (player == null || player.hasMetadata("NPC")) {
@@ -112,10 +111,15 @@ private void handle(final EntityDamageEvent event, final String mobName, final d
             return;
         }
 
+        Entity entity = event.getEntity();
         if (!(entity instanceof Damageable damageable)) {
             return;
         }
 
+        Entity directSource = plugin.getVersionSpecificHandler().getDirectSource(event);
+        ItemStack bowItem = directSource != null ? plugin.getProjectile2ItemCache().getItem(directSource) : null;
+        ItemStack item = bowItem != null ? bowItem : plugin.getVersionSpecificHandler().getItemInMainHand(player);
+
         // Clamp entity damage as getDamage() returns Float.MAX_VALUE for killing a parrot with a cookie
         // https://github.com/LMBishop/Quests/issues/753
         double finalDamage = event.getFinalDamage();
@@ -147,7 +151,6 @@ private void handle(final EntityDamageEvent event, final String mobName, final d
             }
 
             if (task.hasConfigKey("item")) {
-                ItemStack item = plugin.getVersionSpecificHandler().getItemInMainHand(player);
                 if (item == null) {
                     super.debug("Specific item is required, player has no item in hand; continuing...", quest.getId(), task.getId(), player.getUniqueId());
                     continue;

bukkit/src/main/java/com/leonardobishop/quests/bukkit/util/Projectile2ItemCache.java

@@ -0,0 +1,50 @@
+package com.leonardobishop.quests.bukkit.util;
+
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityShootBowEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+/**
+ * Provides a cache that links projectiles to the item used to fire them.
+ *
+ * <p>This cache exists because damage-related events do not expose
+ * information about the item from which a projectile was fired.
+ * By capturing this association at the time the projectile is created,
+ * the item can later be retrieved when handling damage events.</p>
+ */
+@NullMarked
+public final class Projectile2ItemCache implements Listener {
+
+    private final Map<Entity, @Nullable ItemStack> backingMap;
+
+    public Projectile2ItemCache() {
+        this.backingMap = WeakHashMap.newWeakHashMap(1024);
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onEntityShootBow(final EntityShootBowEvent event) {
+        final LivingEntity shooter = event.getEntity();
+        final Entity projectile = event.getProjectile();
+        final ItemStack bow = event.getBow();
+
+        // Currently there are no advantages of caching projectiles for non-player arrows.
+        // It would be needed to cache these if we needed a task to take damage from mobs.
+        if (shooter instanceof Player) {
+            this.backingMap.put(projectile, bow);
+        }
+    }
+
+    public @Nullable ItemStack getItem(final Entity projectile) {
+        return this.backingMap.get(projectile);
+    }
+}