<?php

use MediaWiki\Linker\LinkTarget;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\ProperPageIdentity;
use MediaWiki\Permissions\Authority;
use MediaWiki\Revision\RenderedRevision;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Storage\EditResult;
use MediaWiki\User\UserIdentity;

/**
 * Functions for the Approved Revs extension called by hooks in the MediaWiki
 * code.
 *
 * @file
 * @ingroup Extensions
 *
 * @author Yaron Koren
 * @author Jeroen De Dauw
 */
class ApprovedRevsHooks {

	private static $mApprovalMagicWords = [
		'MAG_APPROVALYEAR',
		'MAG_APPROVALMONTH',
		'MAG_APPROVALDAY',
		'MAG_APPROVALTIMESTAMP',
		'MAG_APPROVALUSER'
	];

	public static function userRevsApprovedAutomatically( User $user, Title $title ) {
		global $egApprovedRevsAutomaticApprovals, $egApprovedRevsFileAutomaticApprovals;
		if ( $title->getNamespace() == NS_FILE ) {
			$automaticApproval = $egApprovedRevsFileAutomaticApprovals;
		} else {
			$automaticApproval = $egApprovedRevsAutomaticApprovals;
		}
		return ( ApprovedRevs::userCanApprove( $user, $title ) && $automaticApproval );
	}

	/**
	 * "noindex" and "nofollow" meta-tags are added to every revision page,
	 * so that search engines won't index them - remove those if this is
	 * the approved revision.
	 * There doesn't seem to be an ideal MediaWiki hook to use for this
	 * function - it currently uses 'ParserBeforeInternalParse', which works.
	 */
	public static function removeRobotsTag( Parser &$parser, &$text, &$strip_state ) {
		global $wgRequest;

		if ( !ApprovedRevs::isDefaultPageRequest( $wgRequest ) ) {
			return;
		}

		$revisionID = ApprovedRevs::getApprovedRevID( $parser->getTitle() );
		if ( !empty( $revisionID ) ) {
			global $wgOut;
			$wgOut->getMetadata()->setIndexPolicy( 'index' );
			$wgOut->setFollowPolicy( 'follow' );
		}
	}

	/**
	 * Called by updateLinksAfterEdit().
	 */
	public static function getUpdateForTitle( Title $title ) {
		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return null;
		}

		$wikiPage = MediaWikiServices::getInstance()->getWikiPageFactory()->newFromTitle( $title );
		// If this user's revisions get approved automatically, exit
		// now, because this will be the approved revision anyway.
		$userID = $wikiPage->getUser();
		$user = User::newFromId( $userID );
		if ( self::userRevsApprovedAutomatically( $user, $title ) ) {
			return null;
		}

		$content = ApprovedRevs::getApprovedContent( $title );

		// If there's no approved revision, and 'blank if
		// unapproved' is set to true, set the content to blank.
		if ( $content == null ) {
			global $egApprovedRevsBlankIfUnapproved;
			if ( $egApprovedRevsBlankIfUnapproved ) {
				$content = $wikiPage->getContentHandler()->makeEmptyContent();
			} else {
				// If it's an unapproved page and there's no
				// page blanking, exit here.
				return null;
			}
		}

		$editInfo = $wikiPage->prepareContentForEdit( $content, null, $user );
		$luClass = class_exists( 'LinksUpdate' ) ? LinksUpdate::class :
			MediaWiki\Deferred\LinksUpdate\LinksUpdate::class;
		return new $luClass( $title, $editInfo->output );
	}

	/**
	 * Hook: RevisionDataUpdates
	 *
	 * Call LinksUpdate on the text of this page's approved revision,
	 * if there is one.
	 */
	public static function updateLinksAfterEdit(
		Title $title,
		RenderedRevision $renderedRevision,
		array &$updates
	) {
		$update = self::getUpdateForTitle( $title );
		if ( $update !== null ) {
			// Wipe out any existing updates.
			$updates = [ $update ];
		}
	}

	/**
	 * Hook: PageSaveComplete
	 *
	 * If the user saving this page has approval power, and automatic
	 * approvals are enabled, and the page is approvable, and either
	 * (a) this page already has an approved revision, or (b) unapproved
	 * pages are shown as blank on this wiki, automatically set this
	 * latest revision to be the approved one - don't bother logging
	 * the approval, though; the log is reserved for manual approvals.
	 */
	public static function setLatestAsApproved(
		WikiPage $wikiPage,
		UserIdentity $user,
		string $summary,
		int $flags,
		RevisionRecord $revisionRecord,
		EditResult $editResult
	) {
		if ( $revisionRecord === null ) {
			return;
		}

		$title = $wikiPage->getTitle();
		if ( !self::userRevsApprovedAutomatically( $user, $title ) ) {
			return;
		}

		if ( $title->getNamespace() == NS_FILE ) {
			self::setOriginalFileRevAsApproved( $user, $title );
			return;
		}

		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		global $egApprovedRevsBlankIfUnapproved;
		if ( !$egApprovedRevsBlankIfUnapproved ) {
			$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
			if ( empty( $approvedRevID ) ) {
				return;
			}
		}

		// Save approval without logging.
		ApprovedRevs::saveApprovedRevIDInDB( $title, $revisionRecord->getID(), $user, true );
	}

	/**
	 * Hook: PageMoveComplete
	 *
	 * Automatically approve a page move (which, like an edit, also counts
	 * as a revision) if the user has auto-approve rights, and the revision
	 * right before this one was approved - we do this so that page moves
	 * don't lead to unnecessary approval work for anyone.
	 */
	public static function setPageMoveAsApproved(
		LinkTarget $old,
		LinkTarget $new,
		UserIdentity $user,
		int $pageid,
		int $redirid,
		string $reason,
		RevisionRecord $revision
	) {
		if ( $revision === null ) {
			return;
		}

		$approvedRevID = ApprovedRevs::getApprovedRevID( $new );
		if ( empty( $approvedRevID ) ) {
			return;
		}

		$revID = $revision->getID();

		// We need to know if the revision before this current move
		// was approved - unfortunately, there's no convenient function
		// to determine that, so we do a DB query.
		$dbr = ApprovedRevs::getReadDB();
		$lastPreMoveRevID = $dbr->selectField(
			[ 'page', 'revision' ],
			'MAX(rev_id)',
			"rev_page = $pageid AND rev_id < $revID",
			__METHOD__
		);

		if ( $approvedRevID !== $lastPreMoveRevID ) {
			return;
		}

		// Save approval without logging.
		ApprovedRevs::saveApprovedRevIDInDB( $new, $revID, $user, true );
	}

	/**
	 * This method will actually work no matter how many revisions a file has,
	 * but in practice it's only called when the first revision is created.
	 */
	public static function setOriginalFileRevAsApproved( $user, $title ) {
		global $wgLocalFileRepo;

		$fileRepo = new LocalRepo( $wgLocalFileRepo );
		$file = LocalFile::newFromTitle( $title, $fileRepo );
		if ( $file->getTimestamp() == '' ) {
			// Probably a page in the "File:" namespace was created,
			// with no corresponding file upload.
			return;
		}

		if ( defined( 'MW_QUIBBLE_CI' ) ) {
			// FIXME: The actual save doesn't work in CI...
			return;
		}

		ApprovedRevs::setApprovedFileInDB(
			$title, $file->getTimestamp(), $file->getSha1(), $user
		);
	}

	/**
	 * Hook: UploadComplete
	 *
	 * Automatically approve a revision of a file, other than the first
	 * one, if the permissions for it are set.
	 */
	public static function setLatestFileRevAsApproved( UploadBase $image ) {
		$user = RequestContext::getMain()->getUser();
		$file = $image->getLocalFile();
		$title = $file->getTitle();

		// A newly-uploaded file will still have an article ID of 0 -
		// ignore it. (It will get handled by the PageSaveComplete,
		// or PageContentSaveComplete, hook anyway.)
		if ( $title->getArticleID() == 0 ) {
			return;
		}

		if ( !self::userRevsApprovedAutomatically( $user, $title ) ) {
			return;
		}
		ApprovedRevs::setApprovedFileInDB(
			$title, $file->getTimestamp(), $file->getSha1(), $user
		);
	}

	/**
	 * Hook: PageSaveComplete
	 *
	 * Set the text that's stored for the page for standard searches.
	 */
	public static function setSearchText(
		WikiPage $wikiPage,
		UserIdentity $user,
		string $summary,
		int $flags,
		RevisionRecord $revisionRecord,
		EditResult $editResult
	) {
		if ( $revisionRecord === null ) {
			return;
		}

		$title = $wikiPage->getTitle();
		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		$revisionID = ApprovedRevs::getApprovedRevID( $title );
		if ( $revisionID === null ) {
			return;
		}

		// We only need to modify the search text if the approved
		// revision is not the latest one.
		if ( $revisionID != $wikiPage->getLatest() ) {
			$approvedPage = MediaWikiServices::getInstance()->getWikiPageFactory()->newFromTitle( $title );
			$approvedContent = $approvedPage->getContent();
			ApprovedRevs::setPageSearchText( $title, $approvedContent );
		}
	}

	/**
	 * Hook: SearchResultInitFromTitle
	 *
	 * Sets the correct page revision to display the "text snippet" for
	 * a search result.
	 */
	public static function setSearchRevisionID( $title, &$id ) {
		$revisionID = ApprovedRevs::getApprovedRevID( $title );
		if ( $revisionID !== null ) {
			$id = $revisionID;
		}
	}

	/**
	 * Hook: ArticleFromTitle
	 *
	 * Return the approved revision of the page, if there is one, and if
	 * the page is simply being viewed, and if no specific revision has
	 * been requested.
	 */
	public static function showApprovedRevision( &$title, &$article, $context ) {
		$request = $context->getRequest();

		if ( !ApprovedRevs::isDefaultPageRequest( $request ) ) {
			return;
		}

		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		global $egApprovedRevsBlankIfUnapproved;
		$revisionID = ApprovedRevs::getApprovedRevID( $title );

		// Blanking of unapproved pages seems to not work unless code
		// like this is called - possibly because the cache needs to be
		// disabled. There may be a better way to accomplish that than
		// this, but this works, and it doesn't seem to have a
		// noticeable negative impact, so we'll go with it for now, at
		// least.
		if ( !empty( $revisionID ) || $egApprovedRevsBlankIfUnapproved ) {
			$article = new Article( $title, $revisionID );
			// This call is necessary because it
			// causes $article->mRevision to get initialized,
			// which in turn allows "edit section" links to show
			// up if the approved revision is also the latest.
			$article->fetchRevisionRecord();
		}
	}

	/**
	 * Hook: ArticleRevisionViewCustom
	 *
	 * @param RevisionStoreRecord $revisionStoreRecord
	 * @param Title $title
	 * @param int $oldid
	 * @param OutputPage $output
	 */
	public static function showBlankIfUnapproved( $revisionStoreRecord, $title, $oldid, $output ) {
		global $egApprovedRevsBlankIfUnapproved;
		if ( !$egApprovedRevsBlankIfUnapproved ) {
			return true;
		}

		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return true;
		}

		$revisionID = ApprovedRevs::getApprovedRevID( $title );
		if ( !empty( $revisionID ) ) {
			return true;
		}

		// If the user is looking at a specified revision of the page,
		// always show it.
		if ( $oldid > 0 ) {
			return true;
		}

		// We need to do this just to check if we're in the 'view'
		// action, not 'edit', 'history' etc.
		$article = new Article( $title, $oldid );
		$context = $article->getContext();
		$request = $context->getRequest();
		if ( !ApprovedRevs::isDefaultPageRequest( $request ) ) {
			return true;
		}

		// We're still here - the page should be blank.
		ApprovedRevs::addCSS();

		// Returning false sets the content to blank.
		return false;
	}

	/**
	 * Sets the subtitle when viewing old revisions of a page.
	 * This function's code is mostly copied from Article::setOldSubtitle(),
	 * and it is meant to serve as a replacement for that function, using
	 * the 'DisplayOldSubtitle' hook.
	 * This display has the following differences from the standard one:
	 * - It includes a link to the approved revision, which goes to the
	 * default page.
	 * - It includes a "diff" link alongside it.
	 * - The "Latest revision" link points to the correct revision ID,
	 * instead of to the default page (unless the latest revision is also
	 * the approved one).
	 *
	 * @author Eli Handel
	 */
	public static function setOldSubtitle( $article, $revisionID ) {
		$title = $article->getTitle();
		$context = $article->getContext();

		$unhide = $context->getRequest()->getInt( 'unhide' ) == 1;

		// Cascade unhide param in links for easy deletion browsing.
		$extraParams = [];
		if ( $unhide ) {
			$extraParams['unhide'] = 1;
		}

		$revisionLookup = MediaWikiServices::getInstance()->getRevisionLookup();
		$rev = $revisionLookup->getRevisionById( $revisionID );
		$timestamp = $rev->getTimestamp();

		$wikiPage = $article->getPage();
		$latestID = $wikiPage->getLatest();
		$current = ( $revisionID == $latestID );
		$approvedID = ApprovedRevs::getApprovedRevID( $title );
		$language = $context->getLanguage();
		$user = $context->getUser();

		$td = $language->userTimeAndDate( $timestamp, $user );
		$tddate = $language->userDate( $timestamp, $user );
		$tdtime = $language->userTime( $timestamp, $user );

		// Show the user links if they're allowed to see them.
		// If hidden, then show them only if requested.
		$userlinks = Linker::revUserTools( $rev, !$unhide );

		$infomsg = $current && !wfMessage( 'revision-info-current' )->isDisabled()
			? 'revision-info-current'
			: 'revision-info';

		$outputPage = $context->getOutput();
		$revUser = $rev->getUser();
		$userText = $revUser ? $revUser->getName() : '';
		$comment = MediaWikiServices::getInstance()->getCommentFormatter()
			->formatRevision( $rev, $user, true, true );
		$revisionInfo = "<div id=\"mw-{$infomsg}\">" .
			$context->msg( $infomsg, $td )
				->rawParams( $userlinks )
				->params( $revisionID, $tddate, $tdtime, $userText )
				->rawParams( $comment )
				->parse() .
			"</div>";
		$outputPage->addSubtitle( $revisionInfo );

		// Created for Approved Revs
		$latestLinkParams = [];
		if ( $latestID != $approvedID ) {
			$latestLinkParams['oldid'] = $latestID;
		}
		$linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
		$lnk = $current
			? wfMessage( 'currentrevisionlink' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'currentrevisionlink' )->escaped(),
				[],
				$latestLinkParams + $extraParams
			);
		$curdiff = $current
			? wfMessage( 'diff' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'diff' )->escaped(),
				[],
				[
					'diff' => 'cur',
					'oldid' => $revisionID
				] + $extraParams
			);
		$prev = $revisionLookup->getPreviousRevision( $rev );
		$prevlink = $prev
			? $linkRenderer->makeLink(
				$title,
				wfMessage( 'previousrevision' )->escaped(),
				[],
				[
					'direction' => 'prev',
					'oldid' => $revisionID
				] + $extraParams
			)
			: wfMessage( 'previousrevision' )->escaped();
		$prevdiff = $prev
			? $linkRenderer->makeLink(
				$title,
				wfMessage( 'diff' )->escaped(),
				[],
				[
					'diff' => 'prev',
					'oldid' => $revisionID
				] + $extraParams
			)
			: wfMessage( 'diff' )->escaped();
		$nextlink = $current
			? wfMessage( 'nextrevision' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'nextrevision' )->escaped(),
				[],
				[
					'direction' => 'next',
					'oldid' => $revisionID
				] + $extraParams
			);
		$nextdiff = $current
			? wfMessage( 'diff' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'diff' )->escaped(),
				[],
				[
					'diff' => 'next',
					'oldid' => $revisionID
				] + $extraParams
			);

		// Added for Approved Revs
		$approved = ( $approvedID != null && $revisionID == $approvedID );
		$approvedlink = $approved
			? wfMessage( 'approvedrevs-approvedrevision' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'approvedrevs-approvedrevision' )->escaped(),
				[],
				$extraParams
			);
		$approveddiff = $approved
			? wfMessage( 'diff' )->escaped()
			: $linkRenderer->makeLink(
				$title,
				wfMessage( 'diff' )->escaped(),
				[],
				[
					'diff' => $approvedID,
					'oldid' => $revisionID
				] + $extraParams
			);

		$cdel = Linker::getRevDeleteLink( $user, $rev, $title );
		if ( $cdel !== '' ) {
			$cdel .= ' ';
		}

		// Modified for Approved Revs
		$outputPage->addSubtitle( "<div id=\"mw-revision-nav\">" . $cdel .
			wfMessage( 'approvedrevs-revision-nav' )->rawParams(
				$prevdiff, $prevlink, $approvedlink, $approveddiff, $lnk, $curdiff, $nextlink, $nextdiff
			)->escaped() . "</div>" );
	}

	/**
	 * If user is viewing the page via its main URL, and what they're
	 * seeing is the approved revision of the page, remove the standard
	 * subtitle shown for all non-latest revisions, and replace it with
	 * either nothing or a message explaining the situation, depending
	 * on the user's rights.
	 */
	public static function setSubtitle( &$article, &$revisionID ) {
		$title = $article->getTitle();
		if ( !ApprovedRevs::hasApprovedRevision( $title ) ) {
			return true;
		}

		$context = $article->getContext();
		$request = $context->getRequest();
		if ( $request->getCheck( 'oldid' ) ) {
			// If the user is looking at the latest revision,
			// disable caching, to avoid the wiki getting the
			// contents from the cache, and thus getting the
			// approved contents instead.
			if ( $revisionID == $article->getPage()->getLatest() ) {
				global $wgEnableParserCache;
				$wgEnableParserCache = false;
			}
			self::setOldSubtitle( $article, $revisionID );
			// Don't show default Article::setOldSubtitle().
			return false;
		}

		$text = "";
		ApprovedRevs::addCSS();

		$user = $context->getUser();
		if ( ApprovedRevs::checkPermission( $user, $title, "viewlinktolatest" ) ) {
			if ( $revisionID == $article->getPage()->getLatest() ) {
				$text .= Xml::element(
					'span',
					[ 'class' => 'approvedAndLatestMsg' ],
					wfMessage( 'approvedrevs-approvedandlatest' )->text()
				);
			} else {
				$text .= wfMessage( 'approvedrevs-notlatest' )->parse();

				$linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
				$text .= ' ' . $linkRenderer->makeLink(
					$title,
					wfMessage( 'approvedrevs-viewlatestrev' )->parse(),
					[],
					[ 'oldid' => $article->getPage()->getLatest() ]
				);

				$text = Xml::tags(
					'span',
					[ 'class' => 'notLatestMsg' ],
					$text
				);
			}
		}

		if ( ApprovedRevs::checkPermission( $user, $title, "viewapprover" ) ) {
			$revisionUser = ApprovedRevs::getRevApprover( $title );
			if ( $revisionUser ) {
				$text .= Html::rawElement(
					'span',
					[ 'class' => 'approvingUser' ],
					wfMessage( 'approvedrevs-approver' )->rawParams(
						Linker::userLink( $revisionUser->getId(), $revisionUser->getName() )
					)->escaped()
				);
			}
		}

		if ( $text !== "" ) {
			$out = $context->getOutput();
			if ( $out->getSubtitle() != '' ) {
				$out->addSubtitle( '<br />' . $text );
			} else {
				$out->setSubtitle( $text );
			}
		}

		return false;
	}

	/**
	 * Hook: TitleGetEditNotices
	 *
	 * Add an edit notice if the approved revision
	 * is not the same as the latest one, so that users don't
	 * get confused, since they'll be seeing the latest one.
	 * Also add an edit notice if the user can't automatically
	 * approve.
	 *
	 * @param Title $title
	 * @param int $oldid
	 * @param array &$notices
	 */
	public static function addEditNotice( Title $title, $oldid, array &$notices ) {
		$editPage = new EditPage( new Article( $title, $oldid ) );
		$editPage->oldid = $oldid;
		$article = $editPage->getArticle();
		$context = $article->getContext();
		$request = $context->getRequest();
		$user = $context->getUser();
		$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
		$latestRevID = $title->getLatestRevID();

		if ( empty( $approvedRevID ) ) {
			return true;
		}

		if ( $approvedRevID != $latestRevID && !$request->getCheck( 'oldid' ) ) {
			// MediaWiki 1.40+
			if ( class_exists( 'MediaWiki\Html\Html' ) ) {
				$notices['approvedrevs-editwarning'] = MediaWiki\Html\Html::warningBox(
					$context->msg( 'approvedrevs-editwarning',
					$title->getFullURL( [
						'diff' => $latestRevID,
						'oldid' => $approvedRevID,
					] )
				)->parse() );
			} else {
				$notices['approvedrevs-editwarning'] = Html::warningBox(
					$context->msg( 'approvedrevs-editwarning',
					$title->getFullURL( [
						'diff' => $latestRevID,
						'oldid' => $approvedRevID,
					] )
				)->parse() );
			}
		}

		if ( !self::userRevsApprovedAutomatically( $user, $title ) ) {
			if ( class_exists( 'MediaWiki\Html\Html' ) ) {
				$notices['approvedrevs-editwarning-pending'] =
					MediaWiki\Html\Html::warningBox( $context->msg( 'approvedrevs-editwarning-pending' )->escaped() );
			} else {
				$notices['approvedrevs-editwarning-pending'] =
					Html::warningBox( $context->msg( 'approvedrevs-editwarning-pending' )->escaped() );
			}
		}

		return true;
	}

	/**
	 * Hook: PageForms::HTMLBeforeForm
	 *
	 * Same as addWarningToEditPage(), but for the Page Forms
	 * 'edit with form' tab.
	 */
	public static function addWarningToPFForm( &$title, &$preFormHTML ) {
		if ( $title == null || !$title->exists() ) {
			return true;
		}

		$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
		$latestRevID = $title->getLatestRevID();
		if ( !empty( $approvedRevID ) && $approvedRevID != $latestRevID ) {
			ApprovedRevs::addCSS();
			$preFormHTML .= Xml::element( 'p',
				[ 'class' => 'approvedRevsEditWarning' ],
				wfMessage( 'approvedrevs-editwarning' )->text() ) . "\n";
		}
	}

	/**
	 * Hook: SkinTemplateNavigation::Universal
	 *
	 * If user is looking at a revision through a main 'view' URL (no
	 * revision specified), have the 'edit' tab link to the basic
	 * 'action=edit' URL (i.e., the latest revision), no matter which
	 * revision they're actually on.
	 */
	public static function changeEditLink( SkinTemplate &$skinTemplate, &$links ) {
		$context = $skinTemplate->getContext();
		$request = $context->getRequest();

		if ( $request->getCheck( 'oldid' ) ) {
			return;
		}

		$title = $skinTemplate->getTitle();
		if ( ApprovedRevs::hasApprovedRevision( $title ) ) {
			$contentActions = &$links['views'];
			// The URL is the same regardless of whether the tab
			// is 'edit' or 'view source', but the "action" is
			// different.
			if ( array_key_exists( 'edit', $contentActions ) ) {
				$contentActions['edit']['href'] = $title->getLocalUrl( [ 'action' => 'edit' ] );
			}
			if ( array_key_exists( 've-edit', $contentActions ) ) {
				$contentActions['ve-edit']['href'] = $title->getLocalUrl( [ 'veaction' => 'edit' ] );
			}
			if ( array_key_exists( 'viewsource', $contentActions ) ) {
				$contentActions['viewsource']['href'] = $title->getLocalUrl( [ 'action' => 'edit' ] );
				$skinTemplate->getOutput()->addJsConfigVars( 'wgEditLatestRevision', true );
			}
		}
	}

	/**
	 * Hook: PageHistoryLineEnding
	 *
	 * If the user is allowed to make revision approvals, add either an
	 * 'approve' or 'unapprove' link to the end of this row in the page
	 * history, depending on whether or not this is already the approved
	 * revision. If it's the approved revision also add on a "star"
	 * icon, regardless of the user.
	 */
	public static function addApprovalLink( $historyPage, &$row, &$s, &$classes ) {
		$title = $historyPage->getTitle();
		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		$context = $historyPage->getContext();
		$user = $context->getUser();

		$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
		if ( $row->rev_id == $approvedRevID ) {
			$s .= ' &#9733;';

			// add class to this line to highlight the approved rev with CSS
			if ( is_array( $classes ) ) {
				$classes[] = "approved-revision";
			} else {
				$classes = [ "approved-revision" ];
			}

			// We also need to add the CSS.
			ApprovedRevs::addCSS();
		}
		if ( ApprovedRevs::userCanApprove( $user, $title ) ) {
			if ( $row->rev_id == $approvedRevID ) {
				$url = $title->getLocalUrl(
					[ 'action' => 'unapprove' ]
				);
				$msg = wfMessage( 'approvedrevs-unapprove' )->text();
			} else {
				$url = $title->getLocalUrl(
					[ 'action' => 'approve', 'oldid' => $row->rev_id ]
				);
				$msg = wfMessage( 'approvedrevs-approve' )->text();
			}
			$s .= ' (' . Xml::element(
				'a',
				[ 'href' => $url ],
				$msg
			) . ')';
		}
	}

	public static function addApprovalDiffLink(
		RevisionRecord $newRevision,
		array &$links,
		?RevisionRecord $prevRevision,
		UserIdentity $userIdentity
	) {
		$title = Title::castFromLinkTarget( $newRevision->getPageAsLinkTarget() );

		if ( $prevRevision === null || $title === null || !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		$approvedRevID = ApprovedRevs::getApprovedRevID( $title );

		if ( ApprovedRevs::userCanApprove( $userIdentity, $title ) && $prevRevision->getID() == $approvedRevID ) {
			// array key is class applied to <span> wrapping around link
			// default if blank is mw-diff-tool; add that along with extension-specific class
			$links['mw-diff-tool ext-approved-revs-approval-span'] = HTML::element(
				'a',
				[
					'href' => $title->getLocalUrl( [
						'action' => 'approve',
						'oldid' => $newRevision->getId()
					] ),
					'class' => 'ext-approved-revs-approval-link',
					'title' => wfMessage( 'approvedrevs-approvethisrev' )->text()
				],
				wfMessage( 'approvedrevs-approve' )->text()
			);
		}
	}

	/**
	 * @see https://www.mediawiki.org/wiki/Manual:Hooks/BeforeParserFetchTemplateRevisionRecord
	 *
	 * Use the approved revision, if it exists, for templates and other
	 * transcluded pages.
	 */
	public static function setTranscludedPageRev(
		?LinkTarget $contextTitle,
		LinkTarget $titleTarget,
		bool &$skip,
		?RevisionRecord &$revRecord
	) {
		$title = Title::castFromLinkTarget( $titleTarget );
		$revisionID = ApprovedRevs::getApprovedRevID( $title );
		if ( !empty( $revisionID ) ) {
			$revLookup = MediaWikiServices::getInstance()->getRevisionLookup();
			$revRecord = $revLookup->getRevisionById( $revisionID );
		}
	}

	/**
	 * Hook: PageDeleteComplete
	 *
	 * Delete the approval record in the database if the page itself is
	 * deleted.
	 */
	public static function deleteRevisionApproval(
		ProperPageIdentity $page, Authority $deleter, string $reason, int $pageID,
		RevisionRecord $deletedRev, ManualLogEntry $logEntry, int $archivedRevisionCount
	) {
		ApprovedRevs::unsetApprovalInDB( $page->getTitle() );
	}

	/**
	 * @see https://www.mediawiki.org/wiki/Manual:Hooks/GetMagicVariableIDs
	 *
	 * Register magic-word variable IDs
	 */
	public static function addMagicWordVariableIDs( &$magicWordVariableIDs ) {
		$magicWordVariableIDs[] = 'MAG_APPROVEDREVS';
		$magicWordVariableIDs = array_merge( $magicWordVariableIDs, self::$mApprovalMagicWords );
	}

	/**
	 * Hook: ParserAfterTidy
	 *
	 * Set values in the page_props table based on the presence of the
	 * 'APPROVEDREVS' magic word in a page
	 */
	public static function handleMagicWords( &$parser, &$text ) {
		$factory = MediaWikiServices::getInstance()->getMagicWordFactory();
		$mw_hide = $factory->get( 'MAG_APPROVEDREVS' );
		if ( $mw_hide->matchAndRemove( $text ) ) {
			$parserOutput = $parser->getOutput();
			$parserOutput->setPageProperty( 'approvedrevs', 'y' );
		}
	}

	/**
	 * Hook: ParserGetVariableValueSwitch
	 *
	 * Assign a value to our variable.
	 *
	 * @param Parser $parser
	 * @param array &$variableCache
	 * @param string $magicWordId
	 * @param string &$ret
	 */
	public static function assignAValue( $parser, &$variableCache, $magicWordId, &$ret ) {
		if ( !in_array( $magicWordId, self::$mApprovalMagicWords ) ) {
			return;
		}

		$approvalInfo = ARParserFunctions::getApprovalInfo( $parser->getTitle() );
		if ( $approvalInfo == null ) {
			$variableCache[$magicWordId] = '';
			$ret = '';
			return;
		}
		switch ( $magicWordId ) {
			case 'MAG_APPROVALYEAR':
				$ret = date( 'Y', $approvalInfo[0] );
				break;
			case 'MAG_APPROVALMONTH':
				$ret = date( 'm', $approvalInfo[0] );
				break;
			case 'MAG_APPROVALDAY':
				$ret = date( 'd', $approvalInfo[0] );
				break;
			case 'MAG_APPROVALTIMESTAMP':
				$ret = date( 'YmdHis', $approvalInfo[0] );
				break;
			case 'MAG_APPROVALUSER':
				$userID = $approvalInfo[1];
				$user = User::newFromID( $userID );
				$ret = $user->getName();
				break;
			default:
				return;
		}

		$variableCache[$magicWordId] = $ret;
	}

	/**
	 * Hook: ParserFirstCallInit
	 *
	 * Register parser function(s).
	 *
	 * @param Parser &$parser
	 * @since 1.0
	 */
	public static function registerFunctions( &$parser ) {
		$parser->setFunctionHook(
			'approvable_by',
			'ARParserFunctions::renderApprovableBy',
			Parser::SFH_OBJECT_ARGS
		);
		$parser->setFunctionHook(
			'MAG_APPROVALYEAR',
			'ARParserFunctions::renderApprovalYear',
			Parser::SFH_NO_HASH
		);
		$parser->setFunctionHook(
			'MAG_APPROVALMONTH',
			'ARParserFunctions::renderApprovalMonth',
			Parser::SFH_NO_HASH
		);
		$parser->setFunctionHook(
			'MAG_APPROVALDAY',
			'ARParserFunctions::renderApprovalDay',
			Parser::SFH_NO_HASH
		);
		$parser->setFunctionHook(
			'MAG_APPROVALTIMESTAMP',
			'ARParserFunctions::renderApprovalTimestamp',
			Parser::SFH_NO_HASH
		);
		$parser->setFunctionHook(
			'MAG_APPROVALUSER',
			'ARParserFunctions::renderApprovalUser',
			Parser::SFH_NO_HASH
		);
	}

	/**
	 * Hook: AdminLinks
	 *
	 * Add a link to Special:ApprovedPages to the page
	 * Special:AdminLinks, defined by the Admin Links extension.
	 */
	public static function addToAdminLinks( &$admin_links_tree ) {
		$general_section = $admin_links_tree->getSection( wfMessage( 'adminlinks_general' )->text() );
		$extensions_row = $general_section->getRow( 'extensions' );
		if ( $extensions_row === null ) {
			$extensions_row = new ALRow( 'extensions' );
			$general_section->addRow( $extensions_row );
		}
		$extensions_row->addItem( ALItem::newFromSpecialPage( 'ApprovedRevs' ) );
	}

	public static function describeDBSchema( DatabaseUpdater $updater ) {
		$dir = __DIR__;

		// DB updates
		// For now, there's just a single SQL file for all DB types.
		//if ( $updater->getDB()->getType() == 'mysql' ) {
		$updater->addExtensionUpdate( [
			'addTable', 'approved_revs', "$dir/../sql/ApprovedRevs.sql", true
		] );
		$updater->addExtensionUpdate( [
			'addField', 'approved_revs', 'approver_id', "$dir/../sql/patch-approver_id.sql", true
		] );
		$updater->addExtensionUpdate( [
			'addField', 'approved_revs', 'approval_date', "$dir/../sql/patch-approval_date.sql", true
		] );
		$updater->addExtensionUpdate( [
			'addTable', 'approved_revs_files', "$dir/../sql/ApprovedFiles.sql", true
		] );
		// }
	}

	/**
	 * Hook: ArticleViewHeader
	 *
	 * Display a message to the user if (a) "blank if unapproved" is set,
	 * (b) the page is approvable, (c) the user has 'viewlinktolatest'
	 * permission, and (d) either the page has no approved revision, or
	 * the user is looking at a revision that's not the latest - the
	 * displayed message depends on which of those cases it is.
	 * @todo - this should probably get split up into two methods.
	 *
	 * @since 0.5.6
	 *
	 * @param Article $article
	 * @param bool &$outputDone
	 * @param bool &$useParserCache
	 */
	public static function setArticleHeader( Article $article, &$outputDone, &$useParserCache ) {
		global $egApprovedRevsBlankIfUnapproved;

		// For now, we only set the header if "blank if unapproved"
		// is set.
		if ( !$egApprovedRevsBlankIfUnapproved ) {
			return;
		}

		$title = $article->getTitle();
		$context = $article->getContext();
		$user = $context->getUser();
		$out = $context->getOutput();
		$request = $context->getRequest();

		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}

		// If the user isn't supposed to see these kinds of
		// messages, exit.
		if ( !ApprovedRevs::checkPermission( $user, $title, "viewlinktolatest" ) ) {
			return;
		}

		// If there's an approved revision for this page, and the
		// user is looking at it - either by simply going to the page,
		// or by looking at the revision that happens to be approved -
		// don't display anything.
		$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
		if ( !empty( $approvedRevID ) &&
			( !$request->getCheck( 'oldid' ) ||
			$request->getInt( 'oldid' ) == $approvedRevID ) ) {
			return;
		}

		// Disable caching, so that if it's a specific ID being shown
		// that happens to be the latest, it doesn't show a blank page.
		$useParserCache = false;
		$out->addHTML( '<span style="margin-left: 10.75px">' );

		// If the user is looking at a specific revision, show an
		// "approve this revision" message - otherwise, it means
		// there's no approved revision (we would have exited out if
		// there were), so show a message explaining why the page is
		// blank, with a link to the latest revision.
		if ( $request->getCheck( 'oldid' ) ) {
			if ( ApprovedRevs::userCanApprove( $user, $title ) ) {
				// @TODO - why is this message being shown
				// at all? Aren't the "approve this revision"
				// links in the history page always good
				// enough?
				$out->addHTML( Xml::tags( 'span', [ 'id' => 'contentSub2' ],
					Xml::element( 'a',
					[ 'href' => $title->getLocalUrl(
						[
							'action' => 'approve',
							'oldid' => $request->getInt( 'oldid' )
						]
					) ],
					wfMessage( 'approvedrevs-approvethisrev' )->text()
				) ) );
			}
		} else {
			$out->addSubtitle(
				htmlspecialchars( wfMessage( 'approvedrevs-blankpageshown' )->text() ) . '&#160;' .
				Xml::element( 'a',
					[ 'href' => $title->getLocalUrl(
						[
							'oldid' => $article->getRevIdFetched()
						]
					) ],
					wfMessage( 'approvedrevs-viewlatestrev' )->text()
				)
			);
		}

		$out->addHTML( '</span>' );
	}

	/**
	 * Hook: ArticleViewHeader
	 *
	 * If this page is approvable, but has no approved revision, display
	 * a header message stating that, if the setting to display this
	 * message is activated.
	 */
	public static function displayNotApprovedHeader( Article $article, &$outputDone, &$useParserCache ) {
		global $egApprovedRevsShowNotApprovedMessage;
		if ( !$egApprovedRevsShowNotApprovedMessage ) {
			return;
		}

		// If we're looking at an old revision of the page, no need to
		// display anything.
		if ( $article->mOldId !== 0 ) {
			return;
		}

		$title = $article->getTitle();
		if ( !ApprovedRevs::pageIsApprovable( $title ) ) {
			return;
		}
		if ( ApprovedRevs::hasApprovedRevision( $title ) ) {
			return;
		}

		$text = wfMessage( 'approvedrevs-noapprovedrevision' )->escaped();

		$context = $article->getContext();
		$out = $context->getOutput();
		if ( $out->getSubtitle() != '' ) {
			$out->addSubtitle( '<br />' . $text );
		} else {
			$out->setSubtitle( $text );
		}
	}

	/**
	 * Add a class to the <body> tag indicating the approval status
	 * of this page, so it can be styled accordingly.
	 */
	public static function addBodyClass( $out, $skin, &$bodyAttrs ) {
		$title = $skin->getTitle();
		$context = $skin->getContext();
		$request = $context->getRequest();

		if ( !ApprovedRevs::hasApprovedRevision( $title ) ) {
			// This page has no approved rev.
			$bodyAttrs['class'] .= " approvedRevs-noapprovedrev";
		} else {
			// The page has an approved rev - see if this is it.
			$approvedRevID = ApprovedRevs::getApprovedRevID( $title );
			if ( !empty( $approvedRevID ) &&
				( !$request->getCheck( 'oldid' ) ||
				$request->getInt( 'oldid' ) == $approvedRevID ) ) {
				// This is the approved rev.
				$bodyAttrs['class'] .= " approvedRevs-approved";
			} else {
				// This is not the approved rev.
				$bodyAttrs['class'] .= " approvedRevs-notapproved";
			}
		}
	}

	/**
	 * Hook: ImagePageFileHistoryLine
	 *
	 * On image pages (pages in NS_FILE), modify each line in the file history
	 * (file history, not history of wikitext on file page). Add
	 * "approved-revision" class to the appropriate row. For users with
	 * approve permissions on this page add "approve" and "unapprove" links as
	 * required.
	 */
	public static function onImagePageFileHistoryLine( $hist, $file, &$s, &$rowClass ) {
		$fileTitle = $file->getTitle();

		if ( !ApprovedRevs::fileIsApprovable( $fileTitle ) ) {
			return;
		}

		$rowTimestamp = $file->getTimestamp();
		$rowSha1 = $file->getSha1();

		[ $approvedRevTimestamp, $approvedRevSha1 ] =
			ApprovedRevs::getApprovedFileInfo( $file->getTitle() );

		ApprovedRevs::addCSS();

		// Apply class to row of approved revision
		// Note: both here and below in the "userCanApprove" section, if the
		// timestamp condition is removed then all rows with the same sha1 as
		// the approved rev will be given the class "approved-revision", and
		// highlighted. Only the actual approved rev will be given the
		// star icon and approved revision label, though.
		if ( $rowSha1 == $approvedRevSha1 && $rowTimestamp == $approvedRevTimestamp ) {
			if ( $rowClass ) {
				$rowClass .= ' ';
			}
			$rowClass .= "approved-revision";

			$pattern = "/<td[^>]+filehistory-selected+[^>]+>/";
			$replace = "$0 &#9733; " . wfMessage( 'approvedrevs-approvedrevision' )->escaped() . "<br />";
			$s = preg_replace( $pattern, $replace, $s );
		}

		$user = $hist->getContext()->getUser();
		if ( ApprovedRevs::userCanApprove( $user, $fileTitle ) ) {
			if ( $rowSha1 == $approvedRevSha1 && $rowTimestamp == $approvedRevTimestamp ) {
				$url = $fileTitle->getLocalUrl(
					[ 'action' => 'unapprovefile' ]
				);
				$msg = wfMessage( 'approvedrevs-unapprove' )->text();
			} else {
				$url = $fileTitle->getLocalUrl(
					[
						'action' => 'approvefile',
						'ts' => $rowTimestamp,
						'sha1' => $rowSha1
					]
				);
				$msg = wfMessage( 'approvedrevs-approve' )->text();
			}
			$s .= '<td>' . Xml::element(
				'a',
				[ 'href' => $url ],
				$msg
			) . '</td>';
		}
	}

	/**
	 * Hook: BeforeParserFetchFileAndTitle
	 *
	 * Changes links and thumbnails of files to point to the approved
	 * revision in all cases except the primary file on file pages (e.g.
	 * the big image in the top left on File:My File.png). To modify that
	 * image, see self::onImagePageFindFile().
	 */
	public static function modifyFileLinks( $parser, Title $fileTitle, &$options, &$query ) {
		if ( $fileTitle->getNamespace() == NS_MEDIA ) {
			$fileTitle = Title::makeTitle( NS_FILE, $fileTitle->getDBkey() );
			// avoid extra queries
			$fileTitle->resetArticleId( $fileTitle->getArticleID() );

			// Media link redirects don't get caught by the normal
			// redirect check, so this extra check is required
			$fileWikiPage = MediaWikiServices::getInstance()->getWikiPageFactory()
				->newFromID( $fileTitle->getArticleID() );
			if ( $fileWikiPage && $fileWikiPage->getRedirectTarget() ) {
				$fileTitle = $fileWikiPage->getTitle();
			}
		}

		if ( $fileTitle->isRedirect() ) {
			$page = MediaWikiServices::getInstance()->getWikiPageFactory()
				->newFromID( $fileTitle->getArticleID() );
			$fileTitle = $page->getRedirectTarget();
			// avoid extra queries
			$fileTitle->resetArticleId( $fileTitle->getArticleID() );
		}

		# Tell Parser what file version to use
		[ $approvedRevTimestamp, $approvedRevSha1 ] =
			ApprovedRevs::getApprovedFileInfo( $fileTitle );

		// No approved version of this file - just exit here, and
		// possibly make it look like the file doesn't exist.
		if ( ( !$approvedRevTimestamp ) || ( !$approvedRevSha1 ) ) {
			global $egApprovedRevsBlankFileIfUnapproved;
			if ( $egApprovedRevsBlankFileIfUnapproved ) {
				$options['broken'] = true;
			}
			return true;
		}

		$options['time'] = wfTimestampOrNull( TS_MW, $approvedRevTimestamp );
		$options['sha1'] = $approvedRevSha1;

		# Stabilize the file link
		if ( $query != '' ) {
			$query .= '&';
		}
		$query .= "filetimestamp=" . urlencode(
			wfTimestamp( TS_MW, $approvedRevTimestamp )
		);
	}

	/**
	 * Hook: ImagePageFindFile
	 *
	 * Applicable on image pages only, this changes the primary image
	 * on the page from the most recent to the approved revision.
	 */
	public static function onImagePageFindFile( $imagePage, &$normalFile, &$displayFile ) {
		[ $approvedRevTimestamp, $approvedRevSha1 ] =
			ApprovedRevs::getApprovedFileInfo( $imagePage->getFile()->getTitle() );

		if ( ( !$approvedRevTimestamp ) || ( !$approvedRevSha1 ) ) {
			return;
		}

		$repo = MediaWikiServices::getInstance()->getRepoGroup();
		$title = $imagePage->getTitle();
		$displayFile = $repo->findFile(
			$title, [ 'time' => $approvedRevTimestamp ]
		);

		# If none found, try current
		if ( !$displayFile ) {
			wfDebug( __METHOD__ . ": {$title->getPrefixedDBkey()}: " .
				"$approvedRevTimestamp not found, using current\n" );
			$displayFile = $repo->findFile( $title );
			// If still none found, use a valid local placeholder.
			if ( !$displayFile ) {
				// fallback to current
				$displayFile = $repo->getLocalRepo()->newFile( $title );
			}
			$normalFile = $displayFile;
		# If found, set $normalFile
		} else {
			wfDebug( __METHOD__ . ": {$title->getPrefixedDBkey()}: " .
				"using timestamp $approvedRevTimestamp\n" );
			$normalFile = $repo->findFile( $title );
		}
	}

	/**
	 * Hook: FileDeleteComplete
	 *
	 * If a file is deleted, check if the sha1 (and timestamp?) exist in the
	 * approved_revs_files table, and delete that row accordingly. A deleted
	 * version of a file should not be the approved version!
	 */
	public static function onFileDeleteComplete( File $file, $oldimage, $article, $user, $reason ) {
		$dbr = ApprovedRevs::getReadDB();
		// check if this file has an approved revision
		$approvedFile = $dbr->selectRow(
			'approved_revs_files',
			[ 'approved_timestamp', 'approved_sha1' ],
			[ 'file_title' => $file->getTitle()->getDBkey() ],
			__METHOD__
		);

		// If an approved revision exists, loop through all files in
		// history. Since this hook happens AFTER deletion (there is
		// no hook before deletion), check to see if the sha1 of the
		// approved revision is NOT in the history. If it is not in
		// the history, then it has no business being in the
		// approved_revs_files table, and should be deleted.
		if ( $approvedFile ) {

			$revs = [];
			$approvedExists = false;

			$hist = $file->getHistory();
			foreach ( $hist as $OldLocalFile ) {
				// need to check both sha1 and timestamp, since
				// reverted files can have the same sha1, but
				// different timestamps
				if (
					$OldLocalFile->getTimestamp() == $approvedFile->approved_timestamp
					&& $OldLocalFile->getSha1() == $approvedFile->approved_sha1 ) {
					$approvedExists = true;
				}

			}

			if ( !$approvedExists ) {
				ApprovedRevs::unsetApprovedFileInDB( $file->getTitle(), $user );
			}

		}
	}

	/**
	 * Hook: wgQueryPages
	 *
	 * @param array &$qp
	 */
	public static function onwgQueryPages( &$qp ) {
		$qp['SpecialApprovedRevsPage'] = 'ApprovedRevs';
	}

	public static function onMpdfGetArticle( $title, &$article ) {
		$revisionID = ApprovedRevs::getApprovedRevID( $title );
		if ( $revisionID === null ) {
			return;
		}
		$article = new Article( $title, $revisionID );
	}

}