Adding a bunch of hooks from wikiHow into DifferenceEngine

These hooks allow things such as:
* adding CSS(/JS) into the OutputPage when viewing diffs
* adding extra HTML content (such as avatars) into diff views
* hiding the bottom "mark as patrolled" link
* altering the parser output that is used by DifferenceEngine
* and more

Example extension using these hooks is wikiHow's
/extensions/wikihow/hooks/, specifically the file DiffHooks.php (but the
hooks are setup in WikihowHooks.php).

Live example of the DiffHooks stuff in action can be found at wikiHow.com,
for example:
http://www.wikihow.com/index.php?title=Set-Your-Homepage&diff=17112892&oldid=15888129
(user avatars, additional CSS, changes to the old/new revision header
texts/links)

Change-Id: Icbc987fa4806e7bfc66743375301912b428dc348

diff --git a/docs/hooks.txt b/docs/hooks.txt
index fa664c3..2e7a299 100644 (file)
--- a/docs/hooks.txt
+++ b/docs/hooks.txt
@@ -1135,6 +1135,85 @@ $page: SpecialPage object for DeletedContributions
 $row: the DB row for this line
 &$classes: the classes to add to the surrounding <li>
 
+'DifferenceEngineMarkPatrolledLink': Allows extensions to change the "mark as patrolled" link
+which is shown both on the diff header as well as on the bottom of a page, usually
+wrapped in a span element which has class="patrollink".
+$differenceEngine: DifferenceEngine object
+&$markAsPatrolledLink: The "mark as patrolled" link HTML (string)
+$rcid: Recent change ID (rc_id) for this change (int)
+$token: Patrol token; $rcid is used in generating this variable
+
+'DifferenceEngineMarkPatrolledRCID': Allows extensions to possibly change the rcid parameter.
+For example the rcid might be set to zero due to the user being the same as the
+performer of the change but an extension might still want to show it under certain
+conditions.
+&$rcid: rc_id (int) of the change or 0
+$differenceEngine: DifferenceEngine object
+$change: RecentChange object
+$user: User object representing the current user
+
+'DifferenceEngineNewHeader': Allows extensions to change the $newHeader variable, which
+contains information about the new revision, such as the revision's author, whether
+the revision was marked as a minor edit or not, etc.
+$differenceEngine: DifferenceEngine object
+&$newHeader: The string containing the various #mw-diff-otitle[1-5] divs, which
+include things like revision author info, revision comment, RevisionDelete link and more
+$formattedRevisionTools: Array containing revision tools, some of which may have
+been injected with the DiffRevisionTools hook
+$nextlink: String containing the link to the next revision (if any); also included in $newHeader
+$rollback: Rollback link (string) to roll this revision back to the previous one, if any
+$newminor: String indicating if the new revision was marked as a minor edit
+$diffOnly: Boolean parameter passed to DifferenceEngine#showDiffPage, indicating
+whether we should show just the diff; passed in as a query string parameter to the
+various URLs constructed here (i.e. $nextlink)
+$rdel: RevisionDelete link for the new revision, if the current user is allowed
+to use the RevisionDelete feature
+$unhide: Boolean parameter indicating whether to show RevisionDeleted revisions
+
+'DifferenceEngineOldHeader': Allows extensions to change the $oldHeader variable, which
+contains information about the old revision, such as the revision's author, whether
+the revision was marked as a minor edit or not, etc.
+$differenceEngine: DifferenceEngine object
+&$oldHeader: The string containing the various #mw-diff-otitle[1-5] divs, which
+include things like revision author info, revision comment, RevisionDelete link and more
+$prevlink: String containing the link to the previous revision (if any); also included in $oldHeader
+$oldminor: String indicating if the old revision was marked as a minor edit
+$diffOnly: Boolean parameter passed to DifferenceEngine#showDiffPage, indicating
+whether we should show just the diff; passed in as a query string parameter to the
+various URLs constructed here (i.e. $prevlink)
+$ldel: RevisionDelete link for the old revision, if the current user is allowed
+to use the RevisionDelete feature
+$unhide: Boolean parameter indicating whether to show RevisionDeleted revisions
+
+'DifferenceEngineOldHeaderNoOldRev': Change the $oldHeader variable in cases when
+there is no old revision
+&$oldHeader: empty string by default
+
+'DifferenceEngineRenderRevisionAddParserOutput': Allows extensions to change the parser output.
+Return false to not add parser output via OutputPage's addParserOutput method.
+$differenceEngine: DifferenceEngine object
+$out: OutputPage object
+$parserOutput: ParserOutput object
+$wikiPage: WikiPage object
+
+'DifferenceEngineRenderRevisionShowFinalPatrolLink': An extension can hook into this hook
+point and return false to not show the final "mark as patrolled" link on the bottom
+of a page.
+This hook has no arguments.
+
+'DifferenceEngineShowDiff': Allows extensions to affect the diff text which
+eventually gets sent to the OutputPage object.
+$differenceEngine: DifferenceEngine object
+
+'DifferenceEngineShowEmptyOldContent': Allows extensions to change the diff table
+body (without header) in cases when there is no old revision or the old and new
+revisions are identical.
+$differenceEngine: DifferenceEngine object
+
+'DifferenceEngineShowDiffPage': Add additional output via the available OutputPage
+object into the diff view
+$out: OutputPage object
+
 'DiffRevisionTools': Override or extend the revision tools available from the
 diff view, i.e. undo, etc.
 $newRev: Revision object of the "new" revision

diff --git a/includes/diff/DifferenceEngine.php b/includes/diff/DifferenceEngine.php
index f35356c..c5e94c5 100644 (file)
--- a/includes/diff/DifferenceEngine.php
+++ b/includes/diff/DifferenceEngine.php
@@ -236,12 +236,14 @@ class DifferenceEngine extends ContextSource {
        }
 
        public function showDiffPage( $diffOnly = false ) {
-
                # Allow frames except in certain special cases
                $out = $this->getOutput();
                $out->allowClickjacking();
                $out->setRobotPolicy( 'noindex,nofollow' );
 
+               // Allow extensions to add any extra output here
+               Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
+
                if ( !$this->loadRevisionData() ) {
                        $this->showMissingRevision();
 
@@ -283,6 +285,8 @@ class DifferenceEngine extends ContextSource {
                        $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
                        $samePage = true;
                        $oldHeader = '';
+                       // Allow extensions to change the $oldHeader variable
+                       Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
                } else {
                        Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 
@@ -352,6 +356,10 @@ class DifferenceEngine extends ContextSource {
                                '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
                                '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 
+                       // Allow extensions to change the $oldHeader variable
+                       Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
+                               $diffOnly, $ldel, $this->unhide ] );
+
                        if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
                                $deleted = true; // old revisions text is hidden
                                if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
@@ -413,6 +421,10 @@ class DifferenceEngine extends ContextSource {
                        '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
                        '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 
+               // Allow extensions to change the $newHeader variable
+               Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
+                       $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
+
                if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
                        $deleted = true; // new revisions text is hidden
                        if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
@@ -485,6 +497,9 @@ class DifferenceEngine extends ContextSource {
                                                        'token' => $linkInfo['token'],
                                                ]
                                        ) . ']</span>';
+                               // Allow extensions to change the markpatrolled link
+                               Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
+                                       &$this->mMarkPatrolledLink, $linkInfo['rcid'], $linkInfo['token'] ] );
                        }
                }
                return $this->mMarkPatrolledLink;
@@ -528,6 +543,13 @@ class DifferenceEngine extends ContextSource {
                                // If the user could patrol this it already would be patrolled
                                $rcid = 0;
                        }
+
+                       // Allow extensions to possibly change the rcid here
+                       // For example the rcid might be set to zero due to the user
+                       // being the same as the performer of the change but an extension
+                       // might still want to show it under certain conditions
+                       Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
+
                        // Build the link
                        if ( $rcid ) {
                                $this->getOutput()->preventClickjacking();
@@ -615,15 +637,20 @@ class DifferenceEngine extends ContextSource {
 
                                # WikiPage::getParserOutput() should not return false, but just in case
                                if ( $parserOutput ) {
-                                       $out->addParserOutput( $parserOutput );
+                                       // Allow extensions to change parser output here
+                                       if ( !Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput', [ $this, $out, $parserOutput, $wikiPage ] ) ) {
+                                               $out->addParserOutput( $parserOutput );
+                                       }
                                }
                        }
                }
                # @codingStandardsIgnoreEnd
 
-               # Add redundant patrol link on bottom...
-               $out->addHTML( $this->markPatrolledLink() );
-
+               // Allow extensions to optionally not show the final patrolled link
+               if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
+                       # Add redundant patrol link on bottom...
+                       $out->addHTML( $this->markPatrolledLink() );
+               }
        }
 
        protected function getParserOutput( WikiPage $page, Revision $rev ) {
@@ -649,6 +676,9 @@ class DifferenceEngine extends ContextSource {
         * @return bool
         */
        public function showDiff( $otitle, $ntitle, $notice = '' ) {
+               // Allow extensions to affect the output here
+               Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
+
                $diff = $this->getDiff( $otitle, $ntitle, $notice );
                if ( $diff === false ) {
                        $this->showMissingRevision();
@@ -718,7 +748,9 @@ class DifferenceEngine extends ContextSource {
                if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
                        && $this->mOldRev->getId() == $this->mNewRev->getId() )
                ) {
-                       return '';
+                       if ( !Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
+                               return '';
+                       }
                }
                // Cacheable?
                $key = false;