Implemented Totems, close #2198

Totem usage can be detected using the MODIFIER_TOTEM constant of EntityDamageEvent.

This does not currently support using the totem in the offhand because offhand is not implemented yet.

src/pocketmine/entity/Human.php

@@ -35,6 +35,7 @@ use pocketmine\inventory\PlayerInventory;
 use pocketmine\item\Consumable;
 use pocketmine\item\FoodSource;
 use pocketmine\item\Item;
+use pocketmine\item\Totem;
 use pocketmine\level\Level;
 use pocketmine\nbt\NBT;
 use pocketmine\nbt\tag\ByteArrayTag;
@@ -43,6 +44,7 @@ use pocketmine\nbt\tag\IntTag;
 use pocketmine\nbt\tag\ListTag;
 use pocketmine\nbt\tag\StringTag;
 use pocketmine\network\mcpe\protocol\AddPlayerPacket;
+use pocketmine\network\mcpe\protocol\EntityEventPacket;
 use pocketmine\network\mcpe\protocol\LevelEventPacket;
 use pocketmine\network\mcpe\protocol\LevelSoundEventPacket;
 use pocketmine\network\mcpe\protocol\PlayerSkinPacket;
@@ -673,6 +675,41 @@ class Human extends Creature implements ProjectileSource, InventoryHolder{
 		return $this->getNameTag();
 	}
 
+	public function applyDamageModifiers(EntityDamageEvent $source) : void{
+		parent::applyDamageModifiers($source);
+
+		$type = $source->getCause();
+		if($type !== EntityDamageEvent::CAUSE_SUICIDE and $type !== EntityDamageEvent::CAUSE_VOID
+			and $this->inventory->getItemInHand() instanceof Totem){ //TODO: check offhand as well (when it's implemented)
+
+			$compensation = $this->getHealth() - $source->getFinalDamage() - 1;
+			if($compensation < 0){
+				$source->setModifier($compensation, EntityDamageEvent::MODIFIER_TOTEM);
+			}
+		}
+	}
+
+	protected function applyPostDamageEffects(EntityDamageEvent $source) : void{
+		parent::applyPostDamageEffects($source);
+		$totemModifier = $source->getModifier(EntityDamageEvent::MODIFIER_TOTEM);
+		if($totemModifier < 0){ //Totem prevented death
+			$this->removeAllEffects();
+
+			$this->addEffect(new EffectInstance(Effect::getEffect(Effect::REGENERATION), 40 * 20, 1));
+			$this->addEffect(new EffectInstance(Effect::getEffect(Effect::FIRE_RESISTANCE), 40 * 20, 1));
+			$this->addEffect(new EffectInstance(Effect::getEffect(Effect::ABSORPTION), 5 * 20, 1));
+
+			$this->broadcastEntityEvent(EntityEventPacket::CONSUME_TOTEM);
+			$this->level->broadcastLevelEvent($this->add(0, $this->eyeHeight, 0), LevelEventPacket::EVENT_SOUND_TOTEM);
+
+			$hand = $this->inventory->getItemInHand();
+			if($hand instanceof Totem){
+				$hand->pop(); //Plugins could alter max stack size
+				$this->inventory->setItemInHand($hand);
+			}
+		}
+	}
+
 	public function getDrops() : array{
 		return array_merge(
 			$this->inventory !== null ? array_values($this->inventory->getContents()) : [],

src/pocketmine/event/entity/EntityDamageEvent.php

@@ -37,6 +37,7 @@ class EntityDamageEvent extends EntityEvent implements Cancellable{
 	public const MODIFIER_ABSORPTION = 5;
 	public const MODIFIER_ARMOR_ENCHANTMENTS = 6;
 	public const MODIFIER_CRITICAL = 7;
+	public const MODIFIER_TOTEM = 8;
 
 	public const CAUSE_CONTACT = 0;
 	public const CAUSE_ENTITY_ATTACK = 1;

src/pocketmine/item/ItemFactory.php

@@ -228,7 +228,7 @@ class ItemFactory{
 		self::registerItem(new Item(Item::SHULKER_SHELL, 0, "Shulker Shell"));
 		self::registerItem(new Banner());
 
-		//TODO: TOTEM
+		self::registerItem(new Totem());
 
 		self::registerItem(new Item(Item::IRON_NUGGET, 0, "Iron Nugget"));
 

src/pocketmine/item/Totem.php

@@ -0,0 +1,34 @@
+<?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;
+
+class Totem extends Item{
+	public function __construct(int $meta = 0){
+		parent::__construct(self::TOTEM, $meta, "Totem of Undying");
+	}
+
+	public function getMaxStackSize() : int{
+		return 1;
+	}
+}