From 27cc87cd67a5cd5d3428339243347dd94a7bcdf5 Mon Sep 17 00:00:00 2001
From: Alexander Ebert <ebert@woltlab.com>
Date: Tue, 26 Jun 2018 12:19:11 +0200
Subject: [PATCH] Discussion provider support for articles

See #2615
See #2585
See WoltLab/com.woltlab.wbb#299
See WoltLab/com.woltlab.wbb#301
---
 com.woltlab.wcf/objectType.xml                |  5 ++
 com.woltlab.wcf/objectTypeDefinition.xml      |  5 ++
 com.woltlab.wcf/templates/article.tpl         | 21 +-----
 com.woltlab.wcf/templates/articleComments.tpl | 12 +++
 .../templates/articleListItems.tpl            |  6 +-
 com.woltlab.wcf/templates/boxArticleList.tpl  |  4 +-
 .../files/lib/data/article/Article.class.php  | 75 +++++++++++++++++++
 .../article/ViewableArticleList.class.php     |  7 +-
 .../lib/page/AbstractArticlePage.class.php    |  1 +
 .../files/lib/page/ArticlePage.class.php      | 14 ++--
 ...bstractArticleDiscussionProvider.class.php | 43 +++++++++++
 ...CommentArticleDiscussionProvider.class.php | 58 ++++++++++++++
 .../IArticleDiscussionProvider.class.php      | 54 +++++++++++++
 .../VoidArticleDiscussionProvider.class.php   | 44 +++++++++++
 14 files changed, 320 insertions(+), 29 deletions(-)
 create mode 100644 com.woltlab.wcf/templates/articleComments.tpl
 create mode 100644 wcfsetup/install/files/lib/system/article/discussion/AbstractArticleDiscussionProvider.class.php
 create mode 100644 wcfsetup/install/files/lib/system/article/discussion/CommentArticleDiscussionProvider.class.php
 create mode 100644 wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
 create mode 100644 wcfsetup/install/files/lib/system/article/discussion/VoidArticleDiscussionProvider.class.php

diff --git a/com.woltlab.wcf/objectType.xml b/com.woltlab.wcf/objectType.xml
index 20a83cd7c8..30445adad8 100644
--- a/com.woltlab.wcf/objectType.xml
+++ b/com.woltlab.wcf/objectType.xml
@@ -81,6 +81,11 @@
 			<definitionname>com.woltlab.wcf.label.objectType</definitionname>
 			<classname>wcf\system\label\object\type\ArticleCategoryLabelObjectTypeHandler</classname>
 		</type>
+		<type>
+			<name>com.woltlab.wcf.article.comment</name>
+			<definitionname>com.woltlab.wcf.article.discussionProvider</definitionname>
+			<classname>wcf\system\article\discussion\CommentArticleDiscussionProvider</classname>
+		</type>
 		<!-- /articles -->
 		
 		<type>
diff --git a/com.woltlab.wcf/objectTypeDefinition.xml b/com.woltlab.wcf/objectTypeDefinition.xml
index 8fcb1f0b50..61a6f0227b 100644
--- a/com.woltlab.wcf/objectTypeDefinition.xml
+++ b/com.woltlab.wcf/objectTypeDefinition.xml
@@ -236,6 +236,11 @@
 			<name>com.woltlab.wcf.sitemap.object</name>
 			<interfacename>wcf\system\sitemap\object\ISitemapObjectObjectType</interfacename>
 		</definition>
+		
+		<definition>
+			<name>com.woltlab.wcf.article.discussionProvider</name>
+			<interfacename>wcf\system\article\discussion\IArticleDiscussionProvider</interfacename>
+		</definition>
 	</import>
 	
 	<delete>
diff --git a/com.woltlab.wcf/templates/article.tpl b/com.woltlab.wcf/templates/article.tpl
index 4e0fde5bfd..1bc906b4e6 100644
--- a/com.woltlab.wcf/templates/article.tpl
+++ b/com.woltlab.wcf/templates/article.tpl
@@ -36,12 +36,12 @@
 					<meta itemprop="dateModified" content="{@$article->time|date:'c'}">
 				</li>
 				
-				{if $article->enableComments}
+				{if $article->getDiscussionProvider()->getDiscussionCountPhrase()}
 					<li itemprop="interactionStatistic" itemscope itemtype="http://schema.org/InteractionCounter">
 						<span class="icon icon16 fa-comments"></span>
-						<span>{lang}wcf.article.articleComments{/lang}</span>
+						<span>{$article->getDiscussionProvider()->getDiscussionCountPhrase()}</span>
 						<meta itemprop="interactionType" content="http://schema.org/CommentAction">
-						<meta itemprop="userInteractionCount" content="{@$article->comments}">
+						<meta itemprop="userInteractionCount" content="{@$article->getDiscussionProvider()->getDiscussionCount()}">
 					</li>
 				{/if}
 				
@@ -331,20 +331,7 @@
 
 {event name='beforeComments'}
 
-{if $article->enableComments}
-	{if $commentList|count || $commentCanAdd}
-		<section id="comments" class="section sectionContainerList">
-			<h2 class="sectionTitle">{lang}wcf.global.comments{/lang}{if $article->comments} <span class="badge">{#$article->comments}</span>{/if}</h2>
-			
-			{include file='__commentJavaScript' commentContainerID='articleCommentList'}
-			
-			<ul id="articleCommentList" class="commentList containerList" data-can-add="{if $commentCanAdd}true{else}false{/if}" data-object-id="{@$articleContentID}" data-object-type-id="{@$commentObjectTypeID}" data-comments="{@$commentList->countObjects()}" data-last-comment-time="{@$lastCommentTime}">
-				{if $commentCanAdd}{include file='commentListAddComment' wysiwygSelector='articleCommentListAddComment'}{/if}
-				{include file='commentList'}
-			</ul>
-		</section>
-	{/if}
-{/if}
+{@$article->getDiscussionProvider()->renderDiscussions()}
 
 {if MODULE_LIKE && ARTICLE_ENABLE_LIKE}
 	<script data-relocate="true">
diff --git a/com.woltlab.wcf/templates/articleComments.tpl b/com.woltlab.wcf/templates/articleComments.tpl
new file mode 100644
index 0000000000..dcb3879b16
--- /dev/null
+++ b/com.woltlab.wcf/templates/articleComments.tpl
@@ -0,0 +1,12 @@
+{if $commentList|count || $commentCanAdd}
+	<section id="comments" class="section sectionContainerList">
+		<h2 class="sectionTitle">{lang}wcf.global.comments{/lang}{if $article->comments} <span class="badge">{#$article->comments}</span>{/if}</h2>
+		
+		{include file='__commentJavaScript' commentContainerID='articleCommentList'}
+		
+		<ul id="articleCommentList" class="commentList containerList" data-can-add="{if $commentCanAdd}true{else}false{/if}" data-object-id="{@$articleContentID}" data-object-type-id="{@$commentObjectTypeID}" data-comments="{@$commentList->countObjects()}" data-last-comment-time="{@$lastCommentTime}">
+			{if $commentCanAdd}{include file='commentListAddComment' wysiwygSelector='articleCommentListAddComment'}{/if}
+			{include file='commentList'}
+		</ul>
+	</section>
+{/if}
diff --git a/com.woltlab.wcf/templates/articleListItems.tpl b/com.woltlab.wcf/templates/articleListItems.tpl
index f5badadbb2..072e06d7fc 100644
--- a/com.woltlab.wcf/templates/articleListItems.tpl
+++ b/com.woltlab.wcf/templates/articleListItems.tpl
@@ -27,10 +27,10 @@
 									{@$article->time|time}
 								</li>
 								
-								{if $article->enableComments}
+								{if $article->getDiscussionProvider()->getDiscussionCountPhrase()}
 									<li>
 										<span class="icon icon16 fa-comments"></span>
-										{lang}wcf.article.articleComments{/lang}
+										{$article->getDiscussionProvider()->getDiscussionCountPhrase()}
 									</li>
 								{/if}
 								
@@ -63,4 +63,4 @@
 			</a>
 		</li>
 	{/foreach}
-</ul>
\ No newline at end of file
+</ul>
diff --git a/com.woltlab.wcf/templates/boxArticleList.tpl b/com.woltlab.wcf/templates/boxArticleList.tpl
index b562cbc35d..881d56121f 100644
--- a/com.woltlab.wcf/templates/boxArticleList.tpl
+++ b/com.woltlab.wcf/templates/boxArticleList.tpl
@@ -13,7 +13,7 @@
 							{elseif $boxSortField == 'views'}
 								{lang article=$boxArticle}wcf.article.articleViews{/lang}
 							{elseif $boxSortField == 'comments'}
-								{lang article=$boxArticle}wcf.article.articleComments{/lang}
+								{$boxArticle->getDiscussionProvider()->getDiscussionCountPhrase()}
 							{elseif $boxSortField == 'cumulativeLikes'}
 								{if MODULE_LIKE && $__wcf->getSession()->getPermission('user.like.canViewLike') && ($boxArticle->likes || $boxArticle->dislikes)}
 									<span class="wcfLikeCounter{if $boxArticle->cumulativeLikes > 0} likeCounterLiked{elseif $boxArticle->cumulativeLikes < 0}likeCounterDisliked{/if}">
@@ -45,7 +45,7 @@
 						
 						<li>
 							<span class="icon icon16 fa-comments"></span>
-							{lang article=$boxArticle}wcf.article.articleComments{/lang}
+							{$boxArticle->getDiscussionProvider()->getDiscussionCountPhrase()}
 						</li>
 					</ul>
 				</a>
diff --git a/wcfsetup/install/files/lib/data/article/Article.class.php b/wcfsetup/install/files/lib/data/article/Article.class.php
index 0318fd0853..5806e17ad6 100644
--- a/wcfsetup/install/files/lib/data/article/Article.class.php
+++ b/wcfsetup/install/files/lib/data/article/Article.class.php
@@ -5,6 +5,10 @@ use wcf\data\article\category\ArticleCategory;
 use wcf\data\article\content\ArticleContent;
 use wcf\data\DatabaseObject;
 use wcf\data\ILinkableObject;
+use wcf\data\object\type\ObjectTypeCache;
+use wcf\system\article\discussion\CommentArticleDiscussionProvider;
+use wcf\system\article\discussion\IArticleDiscussionProvider;
+use wcf\system\article\discussion\VoidArticleDiscussionProvider;
 use wcf\system\WCF;
 
 /**
@@ -65,6 +69,12 @@ class Article extends DatabaseObject implements ILinkableObject {
 	 */
 	protected $category;
 	
+	/**
+	 * @var IArticleDiscussionProvider
+	 * @since 3.2
+	 */
+	protected $discussionProvider;
+	
 	/**
 	 * Returns true if the active user can delete this article.
 	 *
@@ -241,4 +251,69 @@ class Article extends DatabaseObject implements ILinkableObject {
 		
 		return $this->category;
 	}
+	
+	/**
+	 * Sets the discussion provider for this article.
+	 * 
+	 * @param       IArticleDiscussionProvider      $discussionProvider
+	 * @since       3.2
+	 */
+	public function setDiscussionProvider(IArticleDiscussionProvider $discussionProvider) {
+		$this->discussionProvider = $discussionProvider;
+	}
+	
+	/**
+	 * Returns the responsible discussion provider for this article.
+	 * 
+	 * @return      IArticleDiscussionProvider
+	 * @since       3.2
+	 */
+	public function getDiscussionProvider() {
+		if ($this->discussionProvider === null) {
+			foreach (self::getAllDiscussionProviders() as $discussionProvider) {
+				if (call_user_func([$discussionProvider, 'isResponsible'], $this)) {
+					$this->setDiscussionProvider(new $discussionProvider($this));
+					break;
+				}
+			}
+			
+			if ($this->discussionProvider === null) {
+				throw new \RuntimeException('No discussion provider has claimed to be responsible for the article #' . $this->articleID);
+			}
+		}
+		
+		return $this->discussionProvider;
+	}
+	
+	/**
+	 * Returns the list of the available discussion providers.
+	 * 
+	 * @return      string[]
+	 * @since       3.2
+	 */
+	public static function getAllDiscussionProviders(): array {
+		/** @var string[] $discussionProviders */
+		static $discussionProviders;
+		
+		if ($discussionProviders === null) {
+			$discussionProviders = [];
+			
+			$objectTypes = ObjectTypeCache::getInstance()->getObjectTypes('com.woltlab.wcf.article.discussionProvider');
+			$commentProvider = '';
+			foreach ($objectTypes as $objectType) {
+				// the comment and the "void" provider should always be the last in the list
+				if ($objectType->className === CommentArticleDiscussionProvider::class) {
+					$commentProvider = $objectType->className;
+					continue;
+				}
+				
+				$discussionProviders[] = $objectType->className;
+			}
+			
+			$discussionProviders[] = $commentProvider;
+			$discussionProviders[] = VoidArticleDiscussionProvider::class;
+		}
+		
+		return $discussionProviders;
+	}
 }
diff --git a/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php b/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
index 5d1acce046..c6278d2252 100644
--- a/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
+++ b/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
@@ -81,7 +81,12 @@ class ViewableArticleList extends ArticleList {
 			$contentList->getConditionBuilder()->add('(article_content.languageID IS NULL OR article_content.languageID = ?)', [WCF::getLanguage()->languageID]);
 			$contentList->readObjects();
 			foreach ($contentList as $articleContent) {
-				$this->objects[$articleContent->articleID]->setArticleContent($articleContent);
+				$article = $this->objects[$articleContent->articleID];
+				$article->setArticleContent($articleContent);
+				
+				// Some providers do pre-populate internal caches in order to retrieve the data
+				// for many objects in a single step.
+				$article->getDiscussionProvider();
 			}
 		}
 		
diff --git a/wcfsetup/install/files/lib/page/AbstractArticlePage.class.php b/wcfsetup/install/files/lib/page/AbstractArticlePage.class.php
index ea5675d339..8aed647262 100644
--- a/wcfsetup/install/files/lib/page/AbstractArticlePage.class.php
+++ b/wcfsetup/install/files/lib/page/AbstractArticlePage.class.php
@@ -85,6 +85,7 @@ abstract class AbstractArticlePage extends AbstractPage {
 		}
 		
 		$this->article = ViewableArticle::getArticle($this->articleContent->articleID, false);
+		$this->article->getDiscussionProvider()->setArticleContent($this->articleContent->getDecoratedObject());
 		$this->category = $this->article->getCategory();
 		
 		// update interface language
diff --git a/wcfsetup/install/files/lib/page/ArticlePage.class.php b/wcfsetup/install/files/lib/page/ArticlePage.class.php
index 3bbfe0da3e..ffcfeb933b 100644
--- a/wcfsetup/install/files/lib/page/ArticlePage.class.php
+++ b/wcfsetup/install/files/lib/page/ArticlePage.class.php
@@ -139,12 +139,14 @@ class ArticlePage extends AbstractArticlePage {
 		WCF::getTPL()->assign([
 			'previousArticle' => $this->previousArticle,
 			'nextArticle' => $this->nextArticle,
-			'commentCanAdd' => WCF::getSession()->getPermission('user.article.canAddComment'),
-			'commentList' => $this->commentList,
-			'commentObjectTypeID' => $this->commentObjectTypeID,
-			'lastCommentTime' => $this->commentList ? $this->commentList->getMinCommentTime() : 0,
-			'likeData' => (MODULE_LIKE && $this->commentList) ? $this->commentList->getLikeData() : [],
-			'articleLikeData' => $this->articleLikeData
+			'articleLikeData' => $this->articleLikeData,
+			
+			// nullified values for backwards-compatibility
+			'commentCanAdd' => 0,
+			'commentList' => null,
+			'commentObjectTypeID' => 0,
+			'lastCommentTime' => 0,
+			'likeData' => [],
 		]);
 	}
 }
diff --git a/wcfsetup/install/files/lib/system/article/discussion/AbstractArticleDiscussionProvider.class.php b/wcfsetup/install/files/lib/system/article/discussion/AbstractArticleDiscussionProvider.class.php
new file mode 100644
index 0000000000..03855552bd
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/article/discussion/AbstractArticleDiscussionProvider.class.php
@@ -0,0 +1,43 @@
+<?php
+declare(strict_types=1);
+namespace wcf\system\article\discussion;
+use wcf\data\article\Article;
+use wcf\data\article\content\ArticleContent;
+
+/**
+ * Default implementation for discussion provider for articles. Any actual implementation
+ * should derive from this class for forwards-compatibility.
+ *
+ * @author      Alexander Ebert
+ * @copyright   2001-2018 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Article\Discussion
+ * @since       3.2
+ */
+abstract class AbstractArticleDiscussionProvider implements IArticleDiscussionProvider {
+	/**
+	 * @var Article
+	 */
+	protected $article;
+	
+	/**
+	 * @var ArticleContent 
+	 */
+	protected $articleContent;
+	
+	/**
+	 * AbstractArticleDiscussionProvider constructor.
+	 *
+	 * @param       Article         $article
+	 */
+	public function __construct(Article $article) {
+		$this->article = $article;
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function setArticleContent(ArticleContent $articleContent) {
+		$this->articleContent = $articleContent;
+	}
+}
diff --git a/wcfsetup/install/files/lib/system/article/discussion/CommentArticleDiscussionProvider.class.php b/wcfsetup/install/files/lib/system/article/discussion/CommentArticleDiscussionProvider.class.php
new file mode 100644
index 0000000000..9f521a4dd6
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/article/discussion/CommentArticleDiscussionProvider.class.php
@@ -0,0 +1,58 @@
+<?php
+declare(strict_types=1);
+namespace wcf\system\article\discussion;
+use wcf\data\article\Article;
+use wcf\system\comment\CommentHandler;
+use wcf\system\WCF;
+
+/**
+ * The built-in discussion provider using the native comment system.
+ *
+ * @author      Alexander Ebert
+ * @copyright   2001-2018 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Article\Discussion
+ * @since       3.2
+ */
+class CommentArticleDiscussionProvider extends AbstractArticleDiscussionProvider {
+	/**
+	 * @inheritDoc
+	 */
+	public function getDiscussionCount(): int {
+		return $this->article->comments;
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function getDiscussionCountPhrase(): string {
+		return WCF::getLanguage()->getDynamicVariable('wcf.article.articleComments', ['article' => $this->article]);
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function renderDiscussions(): string {
+		$commentCanAdd = WCF::getSession()->getPermission('user.article.canAddComment');
+		$commentObjectTypeID = CommentHandler::getInstance()->getObjectTypeID('com.woltlab.wcf.articleComment');
+		$commentManager = CommentHandler::getInstance()->getObjectType($commentObjectTypeID)->getProcessor();
+		$commentList = CommentHandler::getInstance()->getCommentList($commentManager, $commentObjectTypeID, $this->articleContent->articleContentID);
+		
+		WCF::getTPL()->assign([
+			'commentCanAdd' => $commentCanAdd,
+			'commentList' => $commentList,
+			'commentObjectTypeID' => $commentObjectTypeID,
+			'lastCommentTime' => $commentList->getMinCommentTime(),
+			'likeData' => (MODULE_LIKE) ? $commentList->getLikeData() : [],
+		]);
+		
+		return WCF::getTPL()->fetch('articleComments');
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public static function isResponsible(Article $article): bool {
+		return !!$article->enableComments;
+	}
+}
diff --git a/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php b/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
new file mode 100644
index 0000000000..e9e5877468
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
@@ -0,0 +1,54 @@
+<?php
+declare(strict_types=1);
+namespace wcf\system\article\discussion;
+use wcf\data\article\Article;
+use wcf\data\article\content\ArticleContent;
+
+/**
+ * Discussion provider for articles.
+ * 
+ * @author      Alexander Ebert
+ * @copyright   2001-2018 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Article\Discussion
+ * @since       3.2
+ */
+interface IArticleDiscussionProvider {
+	/**
+	 * Returns the number of discussion items.
+	 * 
+	 * @return      int
+	 */
+	public function getDiscussionCount(): int;
+	
+	/**
+	 * Returns the simple phrase "X <discussions>" that is used for both the statistics
+	 * and the meta data in the article's headline.
+	 * 
+	 * @return      string
+	 */
+	public function getDiscussionCountPhrase(): string;
+	
+	/**
+	 * Renders the input and display section of the associated discussion.
+	 * 
+	 * @return      string
+	 */
+	public function renderDiscussions(): string;
+	
+	/**
+	 * Sets the content object required for the separate discussions per article language.
+	 * 
+	 * @param       ArticleContent          $articleContent
+	 */
+	public function setArticleContent(ArticleContent $articleContent);
+	
+	/**
+	 * Returning true will assign this provider to the article, otherwise the next
+	 * possible provider is being evaluated.
+	 *
+	 * @param       Article         $article
+	 * @return      bool
+	 */
+	public static function isResponsible(Article $article): bool;
+}
diff --git a/wcfsetup/install/files/lib/system/article/discussion/VoidArticleDiscussionProvider.class.php b/wcfsetup/install/files/lib/system/article/discussion/VoidArticleDiscussionProvider.class.php
new file mode 100644
index 0000000000..8e5e960df1
--- /dev/null
+++ b/wcfsetup/install/files/lib/system/article/discussion/VoidArticleDiscussionProvider.class.php
@@ -0,0 +1,44 @@
+<?php
+declare(strict_types=1);
+namespace wcf\system\article\discussion;
+use wcf\data\article\Article;
+
+/**
+ * Represents a non-existing discussion provider and is used when there is no other
+ * type of discussion being available. This provider is always being evaluated last.
+ * 
+ * @author      Alexander Ebert
+ * @copyright   2001-2018 WoltLab GmbH
+ * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package     WoltLabSuite\Core\System\Article\Discussion
+ * @since       3.2
+ */
+class VoidArticleDiscussionProvider extends AbstractArticleDiscussionProvider {
+	/**
+	 * @inheritDoc
+	 */
+	public function getDiscussionCount(): int {
+		return 0;
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function getDiscussionCountPhrase(): string {
+		return '';
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public function renderDiscussions(): string {
+		return '';
+	}
+	
+	/**
+	 * @inheritDoc
+	 */
+	public static function isResponsible(Article $article): bool {
+		return true;
+	}
+}
-- 
2.20.1