(bug 43270) Add wgPostEdit to show if user just saved this page

* Sets short-lived cookie in EditPage
* Adds JS module, 'mediawiki.action.view.postEdit', to all views to
  convert cookie to wgPostEdit.  This avoids caching the variable in the
  HTML.
* Based in part on PostEdit extension

Change-Id: Ie89507f8e98c365df9d93a7633223103b9025790

includes/Article.php

@@ -767,6 +767,8 @@ class Article implements Page {
 		$this->showViewFooter();
 		$this->mPage->doViewUpdates( $user );
 
+		$outputPage->addModules( 'mediawiki.action.view.postEdit' );
+
 		wfProfileOut( __METHOD__ );
 	}
 

includes/EditPage.php

@@ -165,6 +165,26 @@ class EditPage {
 	 */
 	const EDITFORM_ID                  = 'editform';
 
+	/**
+	 * Prefix of key for cookie used to pass post-edit state.
+	 * The revision id edited is added after this
+	 */
+	const POST_EDIT_COOKIE_KEY_PREFIX = 'PostEditRevision';
+
+	/**
+	 * Duration of PostEdit cookie, in seconds.
+	 * The cookie will be removed instantly if the JavaScript runs.
+	 *
+	 * Otherwise, though, we don't want the cookies to accumulate.
+	 * RFC 2109 ( https://www.ietf.org/rfc/rfc2109.txt ) specifies a possible limit of only 20 cookies per domain.
+	 * This still applies at least to some versions of IE without full updates:
+	 * https://blogs.msdn.com/b/ieinternals/archive/2009/08/20/wininet-ie-cookie-internals-faq.aspx
+	 *
+	 * A value of 20 minutes should be enough to take into account slow loads and minor
+	 * clock skew while still avoiding cookie accumulation when JavaScript is turned off.
+	 */
+	const POST_EDIT_COOKIE_DURATION = 1200;
+
 	/**
 	 * @var Article
 	 */
@@ -1127,6 +1147,33 @@ class EditPage {
 		return $this->mTokenOk;
 	}
 
+	/**
+	 * Sets post-edit cookie indicating the user just saved a particular revision.
+	 *
+	 * This uses a temporary cookie for each revision ID so separate saves will never
+	 * interfere with each other.
+	 *
+	 * The cookie is deleted in the mediawiki.action.view.postEdit JS module after
+	 * the redirect.  It must be clearable by JavaScript code, so it must not be
+	 * marked HttpOnly. The JavaScript code converts the cookie to a wgPostEdit config
+	 * variable.
+	 *
+	 * Since WebResponse::setcookie does not allow forcing HttpOnly for a single
+	 * cookie, we have to use PHP's setcookie() directly.
+	 *
+	 * We use a path of '/' since wgCookiePath is not exposed to JS
+	 *
+	 * If the variable were set on the server, it would be cached, which is unwanted
+	 * since the post-edit state should only apply to the load right after the save.
+	 */
+	protected function setPostEditCookie() {
+		global $wgCookiePrefix, $wgCookieDomain;;
+		$revisionId = $this->mArticle->getLatest();
+		$postEditKey = self::POST_EDIT_COOKIE_KEY_PREFIX . $revisionId;
+
+		setcookie( $wgCookiePrefix . $postEditKey, '1', time() + self::POST_EDIT_COOKIE_DURATION, '/', $wgCookieDomain );
+	}
+
 	/**
 	 * Attempt submission
 	 * @throws UserBlockedError|ReadOnlyError|ThrottledError|PermissionsError
@@ -1142,6 +1189,7 @@ class EditPage {
 		// FIXME: once the interface for internalAttemptSave() is made nicer, this should use the message in $status
 		if ( $status->value == self::AS_SUCCESS_UPDATE || $status->value == self::AS_SUCCESS_NEW_ARTICLE ) {
 			$this->didSave = true;
+			$this->setPostEditCookie();
 		}
 
 		switch ( $status->value ) {

resources/Resources.php

@@ -735,6 +735,10 @@ return array(
 			'metadata-collapse',
 		),
 	),
+	'mediawiki.action.view.postEdit' => array(
+		'scripts' => 'resources/mediawiki.action/mediawiki.action.view.postEdit.js',
+		'dependencies' => 'jquery.cookie'
+	),
 	'mediawiki.action.view.rightClickEdit' => array(
 		'scripts' => 'resources/mediawiki.action/mediawiki.action.view.rightClickEdit.js',
 	),

resources/mediawiki.action/mediawiki.action.view.postEdit.js

@@ -0,0 +1,10 @@
+( function ( mw, $ ) {
+	// Matches EditPage::POST_EDIT_COOKIE_KEY_PREFIX
+	var cookieKey = mw.config.get( 'wgCookiePrefix' ) + 'PostEditRevision' + mw.config.get( 'wgCurRevisionId' );
+
+	if ( $.cookie( cookieKey ) === '1' ) {
+		// We just saved this page
+		$.cookie( cookieKey, null, { path: '/' } );
+		mw.config.set( 'wgPostEdit', true );
+	}
+} ( mediaWiki, jQuery ) );