Many many changes related to inventory transactions, fixed item dropping, fixed creative menu

src/pocketmine/inventory/transaction/action/InventoryAction.php

@@ -0,0 +1,102 @@
+<?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\inventory\transaction\action;
+
+use pocketmine\item\Item;
+use pocketmine\Player;
+
+/**
+ * Represents an action involving a change that applies in some way to an inventory or other item-source.
+ */
+abstract class InventoryAction{
+
+	/** @var float */
+	private $creationTime;
+	/** @var Item */
+	protected $sourceItem;
+	/** @var Item */
+	protected $targetItem;
+
+	public function __construct(Item $sourceItem, Item $targetItem){
+		$this->sourceItem = $sourceItem;
+		$this->targetItem = $targetItem;
+
+		$this->creationTime = microtime(true);
+	}
+
+	public function getCreationTime() : float{
+		return $this->creationTime;
+	}
+
+	/**
+	 * Returns the item that was present before the action took place.
+	 * @return Item
+	 */
+	public function getSourceItem() : Item{
+		return clone $this->sourceItem;
+	}
+
+	/**
+	 * Returns the item that the action attempted to replace the source item with.
+	 * @return Item
+	 */
+	public function getTargetItem() : Item{
+		return clone $this->targetItem;
+	}
+
+	/**
+	 * Returns whether this action is currently valid. This should perform any necessary sanity checks.
+	 *
+	 * @param Player $source
+	 *
+	 * @return bool
+	 */
+	abstract public function isValid(Player $source) : bool;
+
+	/**
+	 * Performs actions needed to complete the inventory-action server-side. Returns if it was successful. Will return
+	 * false if plugins cancelled events. This will only be called if the transaction which it is part of is considered
+	 * valid.
+	 *
+	 * @param Player $source
+	 *
+	 * @return bool
+	 */
+	abstract public function execute(Player $source) : bool;
+
+	/**
+	 * Performs additional actions when this inventory-action completed successfully.
+	 *
+	 * @param Player $source
+	 */
+	abstract public function onExecuteSuccess(Player $source);
+
+	/**
+	 * Performs additional actions when this inventory-action did not complete successfully.
+	 *
+	 * @param Player $source
+	 */
+	abstract public function onExecuteFail(Player $source);
+
+}