diff --git a/src/pocketmine/inventory/BaseInventory.php b/src/pocketmine/inventory/BaseInventory.php
new file mode 100644
index 000000000..4fda1504d
--- /dev/null
+++ b/src/pocketmine/inventory/BaseInventory.php
@@ -0,0 +1,293 @@
+<?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/
+ *
+ *
+*/
+
+namespace pocketmine\inventory;
+
+use pocketmine\Player;
+use pocketmine\item\Item;
+
+abstract class BaseInventory implements Inventory{
+
+	/** @var InventoryType */
+	protected $type;
+	/** @var int */
+	protected $maxStackSize = Inventory::MAX_STACK;
+	/** @var int */
+	protected $size;
+	/** @var string */
+	protected $name;
+	/** @var string */
+	protected $title;
+	/** @var Item[] */
+	protected $slots = [];
+	/** @var \SplObjectStorage<Player> */
+	protected $viewers = [];
+	/** @var InventoryHolder */
+	protected $holder;
+
+	/**
+	 * @param InventoryHolder $holder
+	 * @param InventoryType   $type
+	 * @param Item[]          $items
+	 * @param int             $overrideSize
+	 * @param string          $overrideTitle
+	 */
+	public function __construct(InventoryHolder $holder, InventoryType $type, array $items = [], $overrideSize = null, $overrideTitle = null){
+		$this->holder = $holder;
+		$this->viewers = new \SplObjectStorage();
+
+		//A holder can be a plugin, or an entity
+		if($this->holder instanceof Player){
+			$this->viewers->attach($this->holder);
+		}
+
+
+		$this->type = $type;
+		if($overrideSize !== null){
+			$this->size = (int) $overrideSize;
+		}else{
+			$this->size = $this->type->getDefaultSize();
+		}
+
+		if($overrideTitle !== null){
+			$this->title = $overrideTitle;
+		}else{
+			$this->title = $this->type->getDefaultTitle();
+		}
+
+		$this->name = $this->type->getDefaultTitle();
+
+		$this->setContents($items);
+	}
+
+	public function getSize(){
+		return $this->size;
+	}
+
+	public function getMaxStackSize(){
+		return $this->maxStackSize;
+	}
+
+	public function getName(){
+		return $this->name;
+	}
+
+	public function getTitle(){
+		return $this->title;
+	}
+
+	public function getItem($index){
+		return isset($this->slots[$index]) ? $this->slots[$index] : null;
+	}
+
+	public function getContents(){
+		return $this->slots;
+	}
+
+	/**
+	 * @param Item[] $items
+	 */
+	public function setContents(array $items){
+		if(count($items) > $this->size){
+			$items = array_slice($items, 0, $this->size, true);
+		}
+
+		for($i = 0; $i < $this->size; ++$i){
+			if(!isset($items[$i])){
+				if(isset($this->slots[$i])){
+					$this->clear($i);
+				}
+			}else{
+				$this->setItem($i, $items[$i]);
+			}
+		}
+	}
+
+	public function setItem($index, Item $item){
+		if($index < 0 or $index >= $this->size or $item->getID() === 0){
+			return;
+		}
+		$old = $this->slots[$index];
+		$this->slots[$index] = clone $item;
+		$this->onSlotChange($index, $old);
+	}
+
+	public function contains(Item $item){
+		$count = max(1, $item->getCount());
+		$checkDamage = $item->getDamage() === null ? false : true;
+		foreach($this->slots as $i){
+			if($item->equals($i, $checkDamage)){
+				$count -= $i->getCount();
+				if($count <= 0){
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
+	public function all(Item $item){
+		$slots = [];
+		$checkDamage = $item->getDamage() === null ? false : true;
+		foreach($this->slots as $index => $i){
+			if($item->equals($i, $checkDamage)){
+				$slots[$index] = $i;
+			}
+		}
+
+		return $slots;
+	}
+
+	public function remove(Item $item){
+		$checkDamage = $item->getDamage() === null ? false : true;
+		foreach($this->slots as $index => $i){
+			if($item->equals($i, $checkDamage)){
+				$this->clear($index);
+			}
+		}
+	}
+
+	public function first(Item $item){
+		$count = max(1, $item->getCount());
+		$checkDamage = $item->getDamage() === null ? false : true;
+		foreach($this->slots as $index => $i){
+			if($item->equals($i, $checkDamage) and $i->getCount() >= $count){
+				return $index;
+			}
+		}
+
+		return -1;
+	}
+
+	public function firstEmpty(){
+		for($i = 0; $i < $this->size; ++$i){
+			if(!isset($this->slots[$i])){
+				return $i;
+			}elseif(!($this->slots[$i] instanceof Item) or $this->slots[$i]->getID() === 0 or $this->slots[$i]->getCount() <= 0){
+				unset($this->slots[$i]);
+				return $i;
+			}
+		}
+
+		return -1;
+	}
+
+	public function addItem(){
+		/** @var Item[] $slots */
+		$slots = func_get_args();
+		for($i = 0; $i < $this->size; ++$i){
+			if(!isset($this->slots[$i])){
+				$item = $this->slots[$i] = array_shift($slots);
+				$this->onSlotChange($i, null);
+			}else{
+				$item = $this->slots[$i];
+			}
+
+			foreach($slots as $index => $slot){
+				if($slot->equals($item, $slot->getDamage() === null ? false : true)){
+					if($item->getCount() < $item->getMaxStackSize()){
+						$amount = min($item->getMaxStackSize() - $item->getCount(), $slot->getCount());
+						$slot->setCount($slot->getCount() - $amount);
+						$old = clone $item;
+						$item->setCount($item->getCount() + $amount);
+						$this->onSlotChange($i, $old);
+						if($slot->getCount() <= 0){
+							unset($slots[$index]);
+						}
+					}
+				}
+			}
+
+			if(count($slots) === 0){
+				break;
+			}
+		}
+
+		return $slots;
+	}
+
+	public function removeItem(){
+		/** @var Item[] $slots */
+		$slots = func_get_args();
+		for($i = 0; $i < $this->size; ++$i){
+			if(!isset($this->slots[$i])){
+				continue;
+			}else{
+				$item = $this->slots[$i];
+			}
+
+			foreach($slots as $index => $slot){
+				if($slot->equals($item, $slot->getDamage() === null ? false : true)){
+					$amount = min($item->getCount(), $slot->getCount());
+					$slot->setCount($slot->getCount() - $amount);
+					$old = clone $item;
+					$item->setCount($item->getCount() - $amount);
+					if($slot->getCount() <= 0){
+						unset($slots[$index]);
+					}
+					if($item->getCount() <= 0){
+						$this->clear($i);
+					}else{
+						$this->onSlotChange($i, $old);
+					}
+				}
+			}
+
+			if(count($slots) === 0){
+				break;
+			}
+		}
+
+		return $slots;
+	}
+
+	public function clear($index){
+		if(isset($this->slots[$index])){
+			$old = $this->slots[$index];
+			unset($this->slots[$index]);
+			$this->onSlotChange($index, $old);
+		}
+	}
+
+	public function clearAll(){
+		foreach($this->slots as $index => $i){
+			$this->clear($index);
+		}
+	}
+
+	public function getViewers(){
+		$viewers = [];
+		foreach($this->viewers as $viewer){
+			$viewers[] = $viewer;
+		}
+		return $viewers;
+	}
+
+	public function getHolder(){
+		return $this->holder;
+	}
+
+	public function setMaxStackSize($size){
+		$this->setMaxStackSize($size);
+	}
+
+}
\ No newline at end of file
diff --git a/src/pocketmine/inventory/Inventory.php b/src/pocketmine/inventory/Inventory.php
index fd56c7b71..d602a5974 100644
--- a/src/pocketmine/inventory/Inventory.php
+++ b/src/pocketmine/inventory/Inventory.php
@@ -58,21 +58,21 @@ interface Inventory{
 	 *
 	 * Returns the Items that did not fit
 	 *
-	 * @param Item|Item[] $items
+	 * @param Item ...$item
 	 *
 	 * @return Item[]
 	 */
-	public function addItem($items);
+	public function addItem();
 
 	/**
 	 * Removes the given Item from the inventory.
 	 * It will return the Items that couldn't be removed.
 	 *
-	 * @param Item|Item[] $items
+	 * @param Item ...$item
 	 *
 	 * @return Item[]
 	 */
-	public function removeItem($items);
+	public function removeItem();
 
 	/**
 	 * @return Item[]
@@ -90,7 +90,8 @@ interface Inventory{
 	public function contains(Item $item);
 
 	/**
-	 * Will return all the Items that has the same id and metadata (if not null)
+	 * Will return all the Items that has the same id and metadata (if not null).
+	 * Won't check amount
 	 *
 	 * @param Item $item
 	 *
@@ -100,7 +101,7 @@ interface Inventory{
 
 	/**
 	 * Will return the first slot has the same id and metadata (if not null) as the Item.
-	 * -1 if not found
+	 * -1 if not found, will check amount
 	 *
 	 * @param Item $item
 	 *
@@ -152,7 +153,19 @@ interface Inventory{
 	 */
 	public function getHolder();
 
+	/**
+	 * @param Player $who
+	 */
 	public function onOpen(Player $who);
 
+	/**
+	 * @param Player $who
+	 */
 	public function onClose(Player $who);
+
+	/**
+	 * @param int $index
+	 * @param Item|null $before
+	 */
+	public function onSlotChange($index, $before);
 }