Add VaultEffect to cycle crate prizes on Vault blocks

paper/src/main/java/com/badbones69/crazycrates/paper/CrazyCrates.java

@@ -18,6 +18,7 @@
 import com.badbones69.crazycrates.paper.listeners.crates.types.QuadCrateListener;
 import com.badbones69.crazycrates.paper.listeners.crates.types.WarCrateListener;
 import com.badbones69.crazycrates.paper.listeners.other.EntityDamageListener;
+import com.badbones69.crazycrates.paper.tasks.crates.effects.VaultEffect;
 import com.badbones69.crazycrates.paper.support.holograms.HologramManager;
 import com.badbones69.crazycrates.paper.support.placeholders.PlaceholderAPISupport;
 import com.badbones69.crazycrates.paper.managers.BukkitUserManager;
@@ -141,7 +142,10 @@ public void onEnable() {
                 new CrateControlListener(),
                 new CrateOpenListener(),
 
-                new PaperInteractListener()
+                new PaperInteractListener(),
+
+                // Vault block item display effect
+                new VaultEffect()
         ).forEach(listener -> manager.registerEvents(listener, this));
 
         this.crateManager.loadCustomItems();

paper/src/main/java/com/badbones69/crazycrates/paper/tasks/crates/effects/VaultEffect.java

@@ -0,0 +1,93 @@
+package com.badbones69.crazycrates.paper.tasks.crates.effects;
+
+import com.badbones69.crazycrates.paper.CrazyCrates;
+import com.badbones69.crazycrates.paper.api.objects.Crate;
+import com.badbones69.crazycrates.paper.api.objects.Prize;
+import com.badbones69.crazycrates.paper.api.objects.crates.CrateLocation;
+import com.badbones69.crazycrates.paper.tasks.crates.CrateManager;
+import org.bukkit.Location;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.block.VaultDisplayItemEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Handles the Vault block's item display to show crate prizes.
+ * When a Vault block is placed at a crate location, it will cycle through
+ * displaying the prizes available in that crate.
+ */
+public class VaultEffect implements Listener {
+
+    private final CrazyCrates plugin = CrazyCrates.getPlugin();
+    private final CrateManager crateManager = this.plugin.getCrateManager();
+    private final Random random = new Random();
+
+    // Track the current display index for each vault location to enable cycling
+    private final Map<String, Integer> displayIndexes = new ConcurrentHashMap<>();
+
+    @EventHandler
+    public void onVaultDisplayItem(@NotNull final VaultDisplayItemEvent event) {
+        final Location location = event.getBlock().getLocation();
+        final CrateLocation crateLocation = this.crateManager.getCrateLocation(location);
+
+        // If this vault is not at a crate location, let vanilla handle it
+        if (crateLocation == null) return;
+
+        final Crate crate = crateLocation.getCrate();
+        final List<Prize> prizes = crate.getPrizes();
+
+        // If the crate has no prizes, let vanilla handle it
+        if (prizes.isEmpty()) return;
+
+        // Get or initialize the display index for this location
+        final String locationKey = getLocationKey(location);
+        final int currentIndex = this.displayIndexes.getOrDefault(locationKey, 0);
+
+        // Get the prize at the current index (cycling through)
+        final Prize prize = prizes.get(currentIndex % prizes.size());
+
+        // Get the display item for this prize
+        final ItemStack displayItem = prize.getDisplayItem(crate);
+
+        // Set the display item on the vault
+        event.setDisplayItem(displayItem);
+
+        // Increment the index for next time (cycle through prizes)
+        this.displayIndexes.put(locationKey, (currentIndex + 1) % prizes.size());
+    }
+
+    /**
+     * Creates a unique key for a location to track display cycling.
+     *
+     * @param location the location to create a key for
+     * @return a string key representing the location
+     */
+    private String getLocationKey(@NotNull final Location location) {
+        return location.getWorld().getName() + "_" + location.getBlockX() + "_" + location.getBlockY() + "_" + location.getBlockZ();
+    }
+
+    /**
+     * Clears the display index tracking for a specific location.
+     * Call this when a crate location is removed.
+     *
+     * @param location the location to clear
+     */
+    public void clearLocation(@NotNull final Location location) {
+        this.displayIndexes.remove(getLocationKey(location));
+    }
+
+    /**
+     * Clears all tracked display indexes.
+     * Call this on plugin disable or reload.
+     */
+    public void clearAll() {
+        this.displayIndexes.clear();
+    }
+}
+