Create a hidden revision tag for talk page comments

Bug: T262107
Depends-On: I21159d03eebaf46ad94f4273ba698a59b8019185
Change-Id: Iceddfaf6a4bcc5e8b5c85c8cd5638bf14aa7db03

i18n/en.json

@@ -93,6 +93,8 @@
 	"echo-pref-tooltip-dt-subscription": "Notify me about activity on my talk page subscriptions.",
 	"tag-discussiontools": "-",
 	"tag-discussiontools-description": "Edit made using DiscussionTools",
+	"tag-discussiontools-added-comment": "-",
+	"tag-discussiontools-added-comment-description": "A talk page comment was added in this edit",
 	"tag-discussiontools-edit": "Edit comment",
 	"tag-discussiontools-edit-description": "User edited an existing comment with DiscussionTools",
 	"tag-discussiontools-newtopic": "[{{int:discussiontools-replywidget-newtopic-link}} New topic]",

i18n/qqq.json

@@ -102,6 +102,8 @@
 	"echo-pref-tooltip-dt-subscription": "{{doc-echo-pref-tooltip|title=Echo-category-title-dt-subscription}}",
 	"tag-discussiontools": "{{ignored}}Short description of the discussiontools tag.\n\nShown on lists of changes (history, recentchanges, etc.) for each edit made using DiscussionTools.\n\nSee also:\n* {{msg-mw|Tag-discussiontools-description}}\n{{Related|tag-discussiontools}}",
 	"tag-discussiontools-description": "Long description of the discussiontools tag ({{msg-mw|Tag-discussiontools}}).\n\nShown on [[Special:Tags]].\n\nSee also:\n* {{msg-mw|Tag-discussiontools}}\n{{Related|tag-discussiontools}}",
+	"tag-discussiontools-added-comment": "{{ignored}}Short description of the discussiontools-added-comment tag.\n\nShown on lists of changes (history, recentchanges, etc.) for each edit that adds a talk page comment (or comments), even if it wasn't made using DiscussionTools.\n\nSee also:\n* {{msg-mw|Tag-discussiontools-added-comment-description}}\n{{Related|tag-discussiontools}}",
+	"tag-discussiontools-added-comment-description": "Long description of the discussiontools-added-comment tag ({{msg-mw|Tag-discussiontools-added-comment}}).\n\nShown on [[Special:Tags]].\n\nSee also:\n* {{msg-mw|Tag-discussiontools-added-comment}}\n{{Related|tag-discussiontools}}",
 	"tag-discussiontools-edit": "Short description of the discussiontools-edit tag.\n\nShown on lists of changes (history, recentchanges, etc.) for each edit to an existing comment made using DiscussionTools.\n\nThis message is always shown directly after {{msg-mw|tag-discussiontools}} and a comma.\n\nSee also:\n* {{msg-mw|Tag-discussiontools-edit-description}}\n{{Related|tag-discussiontools}}",
 	"tag-discussiontools-edit-description": "Long description of the discussiontools-edit tag ({{msg-mw|Tag-discussiontools-edit}}).\n\nShown on [[Special:Tags]].\n\nSee also:\n* {{msg-mw|Tag-discussiontools-edit}}\n{{Related|tag-discussiontools}}",
 	"tag-discussiontools-newtopic": "Short description of the discussiontools-newtopic tag.\n\nShown on lists of changes (history, recentchanges, etc.) for each edit made using DiscussionTools to create a new section of a talk page.\n\nThis message is always shown directly after {{msg-mw|tag-discussiontools}} and a comma.\n\nSee also:\n* {{msg-mw|Tag-discussiontools-newtopic-description}}\n{{Related|tag-discussiontools}}",

includes/Hooks/TagHooks.php

@@ -26,6 +26,7 @@ class TagHooks implements
 		'discussiontools-reply',
 		'discussiontools-edit',
 		'discussiontools-newtopic',
+		'discussiontools-added-comment',
 		// Input methods:
 		'discussiontools-source',
 		'discussiontools-visual',

includes/Notifications/EventDispatcher.php

@@ -9,6 +9,8 @@
 
 namespace MediaWiki\Extension\DiscussionTools\Notifications;
 
+use ChangeTags;
+use DeferredUpdates;
 use EchoEvent;
 use Error;
 use IDBAccessObject;
@@ -76,11 +78,6 @@ class EventDispatcher {
 		$userFactory = $services->getUserFactory();
 		$oldRevRecord = $revisionStore->getPreviousRevision( $newRevRecord, IDBAccessObject::READ_LATEST );
 
-		if ( $oldRevRecord === null ) {
-			// TODO: Handle page creation (oldRevRecord = null?)
-			return;
-		}
-
 		$title = Title::newFromLinkTarget(
 			$newRevRecord->getPageAsLinkTarget()
 		);
@@ -96,7 +93,14 @@ class EventDispatcher {
 			return;
 		}
 
-		$oldParser = self::getParsedRevision( $oldRevRecord );
+		if ( $oldRevRecord !== null ) {
+			$oldParser = self::getParsedRevision( $oldRevRecord );
+		} else {
+			// Page creation
+			$doc = DOMUtils::parseHTML( '' );
+			$container = DOMCompat::getBody( $doc );
+			$oldParser = CommentParser::newFromGlobalState( $container );
+		}
 		$newParser = self::getParsedRevision( $newRevRecord );
 
 		self::generateEventsFromParsers( $events, $oldParser, $newParser, $newRevRecord, $title, $user );
@@ -190,6 +194,14 @@ class EventDispatcher {
 			}
 		}
 
+		if ( $addedComments ) {
+			// It's a bit weird to do this here, in the middle of the hook handler for Echo. However:
+			// * Echo calls this from a PageSaveComplete hook handler as a DeferredUpdate,
+			//   which is exactly how we would do this otherwise
+			// * It allows us to reuse the generated comment trees without any annoying caching
+			static::addCommentChangeTag( $newRevRecord );
+		}
+
 		foreach ( $addedComments as $newComment ) {
 			// Ignore comments by other users, e.g. in case of reverts or a discussion being moved.
 			// TODO: But what about someone signing another's comment?
@@ -228,6 +240,19 @@ class EventDispatcher {
 		}
 	}
 
+	/**
+	 * Add our change tag for a revision that adds new comments.
+	 *
+	 * @param RevisionRecord $newRevRecord
+	 */
+	protected static function addCommentChangeTag( RevisionRecord $newRevRecord ) {
+		// Unclear if DeferredUpdates::addCallableUpdate() is needed,
+		// but every extension does it that way.
+		DeferredUpdates::addCallableUpdate( static function () use ( $newRevRecord ) {
+			ChangeTags::addTags( [ 'discussiontools-added-comment' ], null, $newRevRecord->getId() );
+		} );
+	}
+
 	/**
 	 * Return all users subscribed to a comment
 	 *

tests/phpunit/MockEventDispatcher.php

@@ -42,4 +42,12 @@ class MockEventDispatcher extends EventDispatcher {
 		);
 	}
 
+	/**
+	 * No-op for testing
+	 *
+	 * @param RevisionRecord $newRevRecord
+	 */
+	public static function addCommentChangeTag( RevisionRecord $newRevRecord ) {
+	}
+
 }