Implemented a proper way to handle items cooldown (#6405)

src/item/ChorusFruit.php

@@ -88,4 +88,8 @@ class ChorusFruit extends Food{
 	public function getCooldownTicks() : int{
 		return 20;
 	}
+
+	public function getCooldownTag() : ?string{
+		return ItemCooldownTags::CHORUS_FRUIT;
+	}
 }

src/item/EnderPearl.php

@@ -45,4 +45,8 @@ class EnderPearl extends ProjectileItem{
 	public function getCooldownTicks() : int{
 		return 20;
 	}
+
+	public function getCooldownTag() : ?string{
+		return ItemCooldownTags::ENDER_PEARL;
+	}
 }

src/item/Item.php

@@ -654,6 +654,20 @@ class Item implements \JsonSerializable{
 		return 0;
 	}
 
+	/**
+	 * Returns a tag that identifies a group of items that should have cooldown at the same time
+	 * regardless of their state or type.
+	 * When cooldown starts, any other items with the same cooldown tag can't be used until the cooldown expires.
+	 * Such behaviour can be seen in goat horns and shields.
+	 *
+	 * If tag is null, item state id will be used to store cooldown.
+	 *
+	 * @see ItemCooldownTags
+	 */
+	public function getCooldownTag() : ?string{
+		return null;
+	}
+
 	/**
 	 * Compares an Item to this Item and check if they match.
 	 *

src/item/ItemCooldownTags.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+ */
+
+declare(strict_types=1);
+
+namespace pocketmine\item;
+
+/**
+ * Tags used by items to determine their cooldown group.
+ *
+ * These tag values are not related to Minecraft internal IDs.
+ * They only share a visual similarity because these are the most obvious values to use.
+ * Any arbitrary string can be used.
+ *
+ * @see Item::getCooldownTag()
+ */
+final class ItemCooldownTags{
+
+	private function __construct(){
+		//NOOP
+	}
+
+	public const CHORUS_FRUIT = "chorus_fruit";
+	public const ENDER_PEARL = "ender_pearl";
+	public const SHIELD = "shield";
+	public const GOAT_HORN = "goat_horn";
+}