Adding writable and written books. (#1397)

* Adding writable and written books.
* Added a PlayerEditBookEvent.
* Changed BookEditPacket field names.

src/pocketmine/item/WritableBook.php

@@ -0,0 +1,228 @@
+<?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;
+
+use pocketmine\nbt\tag\CompoundTag;
+use pocketmine\nbt\tag\ListTag;
+use pocketmine\nbt\tag\StringTag;
+
+class WritableBook extends Item{
+
+	public function __construct(int $meta = 0){
+		parent::__construct(self::WRITABLE_BOOK, $meta, "Book & Quill");
+	}
+
+	/**
+	 * Returns whether the given page exists in this book.
+	 *
+	 * @param int $pageId
+	 *
+	 * @return bool
+	 */
+	public function pageExists(int $pageId) : bool{
+		return isset($this->getNamedTag()->pages->{$pageId});
+	}
+
+	/**
+	 * Returns a string containing the content of a page (which could be empty), or null if the page doesn't exist.
+	 *
+	 * @param int $pageId
+	 *
+	 * @return string|null
+	 */
+	public function getPageText(int $pageId) : ?string{
+		if(!$this->pageExists($pageId)){
+			return null;
+		}
+		return $this->getNamedTag()->pages->{$pageId}->text->getValue();
+	}
+
+	/**
+	 * Sets the text of a page in the book. Adds the page if the page does not yet exist.
+	 *
+	 * @param int    $pageId
+	 * @param string $pageText
+	 *
+	 * @return bool indicating whether the page was created or not.
+	 */
+	public function setPageText(int $pageId, string $pageText) : bool{
+		$created = false;
+		if(!$this->pageExists($pageId)){
+			$this->addPage($pageId);
+			$created = true;
+		}
+
+		$namedTag = $this->getNamedTag();
+		$namedTag->pages->{$pageId}->text->setValue($pageText);
+		$this->setNamedTag($namedTag);
+
+		return $created;
+	}
+
+	/**
+	 * Adds a new page with the given page ID.
+	 * Creates a new page for every page between the given ID and existing pages that doesn't yet exist.
+	 *
+	 * @param int $pageId
+	 */
+	public function addPage(int $pageId) : void{
+		if($pageId < 0){
+			throw new \InvalidArgumentException("Page number \"$pageId\" is out of range");
+		}
+		$namedTag = $this->getCorrectedNamedTag();
+
+		if(!isset($namedTag->pages) or !($namedTag->pages instanceof ListTag)){
+			$namedTag->pages = new ListTag("pages", []);
+		}
+
+		for($id = 0; $id <= $pageId; $id++){
+			if(!$this->pageExists($id)){
+				$namedTag->pages->{$id} = new CompoundTag("", [
+					new StringTag("text", ""),
+					new StringTag("photoname", "")
+				]);
+			}
+		}
+
+		$this->setNamedTag($namedTag);
+	}
+
+	/**
+	 * Deletes an existing page with the given page ID.
+	 *
+	 * @param int $pageId
+	 *
+	 * @return bool indicating success
+	 */
+	public function deletePage(int $pageId) : bool{
+		if(!$this->pageExists($pageId)){
+			return false;
+		}
+
+		$namedTag = $this->getNamedTag();
+		unset($namedTag->pages->{$pageId});
+		$this->pushPages($pageId, $namedTag);
+		$this->setNamedTag($namedTag);
+
+		return true;
+	}
+
+	/**
+	 * Inserts a new page with the given text and moves other pages upwards.
+	 *
+	 * @param int $pageId
+	 * @param string $pageText
+	 *
+	 * @return bool indicating success
+	 */
+	public function insertPage(int $pageId, string $pageText = "") : bool{
+		$namedTag = $this->getCorrectedNamedTag();
+		if(!isset($namedTag->pages) or !($namedTag->pages instanceof ListTag)){
+			$namedTag->pages = new ListTag("pages", []);
+		}
+		$this->pushPages($pageId, $namedTag, false);
+
+		$namedTag->pages->{$pageId}->text->setValue($pageText);
+		$this->setNamedTag($namedTag);
+		return true;
+	}
+
+	/**
+	 * Switches the text of two pages with each other.
+	 *
+	 * @param int $pageId1
+	 * @param int $pageId2
+	 *
+	 * @return bool indicating success
+	 */
+	public function swapPage(int $pageId1, int $pageId2) : bool{
+		if(!$this->pageExists($pageId1) or !$this->pageExists($pageId2)){
+			return false;
+		}
+
+		$pageContents1 = $this->getPageText($pageId1);
+		$pageContents2 = $this->getPageText($pageId2);
+		$this->setPageText($pageId1, $pageContents2);
+		$this->setPageText($pageId2, $pageContents1);
+
+		return true;
+	}
+
+	/**
+	 * @return CompoundTag
+	 */
+	protected function getCorrectedNamedTag() : CompoundTag{
+		return $this->getNamedTag() ?? new CompoundTag();
+	}
+
+	public function getMaxStackSize() : int{
+		return 1;
+	}
+
+	/**
+	 * @param int         $pageId
+	 * @param CompoundTag $namedTag
+	 * @param bool        $downwards
+	 *
+	 * @return bool
+	 */
+	private function pushPages(int $pageId, CompoundTag $namedTag, bool $downwards = true) : bool{
+		if(empty($this->getPages())){
+			return false;
+		}
+
+		$pages = $this->getPages();
+		$type = $downwards ? -1 : 1;
+		foreach($pages as $key => $page){
+			if(($key <= $pageId and $downwards) or ($key < $pageId and !$downwards)){
+				continue;
+			}
+
+			if($downwards){
+				unset($namedTag->pages->{$key});
+			}
+			$namedTag->pages->{$key + $type} = new CompoundTag("", [
+				new StringTag("text", $page->text->getValue()),
+				new StringTag("photoname", "")
+			]);
+		}
+		return true;
+	}
+
+	/**
+	 * Returns an array containing all pages of this book.
+	 *
+	 * @return CompoundTag[]
+	 */
+	public function getPages() : array{
+		$namedTag = $this->getCorrectedNamedTag();
+		if(!isset($namedTag->pages)){
+			return [];
+		}
+
+		return array_filter((array) $namedTag->pages, function(string $key){
+			return is_numeric($key);
+		}, ARRAY_FILTER_USE_KEY);
+	}
+}