From 6123a7a071c522b012a97ab3d5bc9b0bfa045651 Mon Sep 17 00:00:00 2001
From: Gilles Dubuc <gilles@wikimedia.org>
Date: Thu, 22 Mar 2018 14:06:56 +0100
Subject: [PATCH] mediawiki.user: Implement mw.user.stickyRandomId

This is a sticky version of generateRandomSessionId,
useful to keep track of the pageview between extensions.

Bug: T187299
Change-Id: I0877c399c60d3fb2fdf8e844cad6acecf6f704c9
---
 resources/src/mediawiki/mediawiki.user.js      | 18 ++++++++++++++++--
 .../resources/mediawiki/mediawiki.user.test.js |  8 ++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/resources/src/mediawiki/mediawiki.user.js b/resources/src/mediawiki/mediawiki.user.js
index 65e9e4168d..5fc1990758 100644
--- a/resources/src/mediawiki/mediawiki.user.js
+++ b/resources/src/mediawiki/mediawiki.user.js
@@ -4,7 +4,7 @@
  */
 /* global Uint32Array */
 ( function ( mw, $ ) {
-	var userInfoPromise;
+	var userInfoPromise, stickyRandomSessionId;
 
 	/**
 	 * Get the current user's groups or rights
@@ -48,7 +48,7 @@
 				// Support: IE 11
 				crypto = window.crypto || window.msCrypto;
 
-			if ( crypto && crypto.getRandomValues ) {
+			if ( crypto && crypto.getRandomValues && typeof Uint32Array === 'function' ) {
 				// Fill an array with 2 random values, each of which is 32 bits.
 				// Note that Uint32Array is array-like but does not implement Array.
 				rnds = new Uint32Array( 2 );
@@ -71,6 +71,20 @@
 			return hexRnds.join( '' );
 		},
 
+		/**
+		 * A sticky generateRandomSessionId for the current JS execution context,
+		 * cached within this class.
+		 *
+		 * @return {string} 64 bit integer in hex format, padded
+		 */
+		stickyRandomId: function () {
+			if ( !stickyRandomSessionId ) {
+				stickyRandomSessionId = mw.user.generateRandomSessionId();
+			}
+
+			return stickyRandomSessionId;
+		},
+
 		/**
 		 * Get the current user's database id
 		 *
diff --git a/tests/qunit/suites/resources/mediawiki/mediawiki.user.test.js b/tests/qunit/suites/resources/mediawiki/mediawiki.user.test.js
index bc12642983..814a20753e 100644
--- a/tests/qunit/suites/resources/mediawiki/mediawiki.user.test.js
+++ b/tests/qunit/suites/resources/mediawiki/mediawiki.user.test.js
@@ -97,6 +97,14 @@
 		assert.notEqual( result, result2, 'different when called multiple times' );
 	} );
 
+	QUnit.test( 'stickyRandomId', function ( assert ) {
+		var result = mw.user.stickyRandomId(),
+			result2 = mw.user.stickyRandomId();
+		assert.equal( typeof result, 'string', 'type' );
+		assert.strictEqual( /^[a-f0-9]{16}$/.test( result ), true, '16 HEX symbols string' );
+		assert.equal( result2, result, 'sticky' );
+	} );
+
 	QUnit.test( 'sessionId', function ( assert ) {
 		var result = mw.user.sessionId(),
 			result2 = mw.user.sessionId();
-- 
2.20.1