Cache the options token for preferences system

Change-Id: I2e9a4326119db390aba36cc5bc6da20c5c16eed1

resources/js/ext.uls.preferences.js

@@ -21,7 +21,90 @@
 ( function ( $, mw, undefined ) {
 	'use strict';
 
-	var ULSPreferences = function () {
+	var ULSPreferences,
+		cachedOptionsToken = null;
+
+	/**
+	 * Post to options API with correct token.
+	 * If we have no token, get one and try to post.
+	 * If we have a cached token try using that, and if it fails, blank out the
+	 * cached token and start over.
+	 *
+	 * @param params {Object} API parameters
+	 * @param ok {Function} callback for success
+	 * @param err {Function} [optional] error callback
+	 * @return {jqXHR}
+	 */
+	function saveOptionsWithToken ( params, ok, err ) {
+		var useTokenToPost, getTokenIfBad;
+		if ( cachedOptionsToken === null ) {
+			// We don't have a valid cached token, so get a fresh one and try posting.
+			// We do not trap any 'badtoken' or 'notoken' errors, because we don't want
+			// an infinite loop. If this fresh token is bad, something else is very wrong.
+			useTokenToPost = function ( token ) {
+				params.token = token;
+				new mw.Api().post( params, ok, err );
+			};
+			return getOptionToken( useTokenToPost, err );
+		} else {
+			// We do have a token, but it might be expired. So if it is 'bad' then
+			// start over with a new token.
+			params.token = cachedOptionsToken;
+			getTokenIfBad = function ( code, result ) {
+				if ( code === 'badtoken' ) {
+					// force a new token, clear any old one
+					cachedOptionsToken = null;
+					saveOptionsWithToken( params, ok, err );
+				} else {
+					err( code, result );
+				}
+			};
+			return new mw.Api().post( params, { ok : ok, err : getTokenIfBad });
+		}
+	}
+
+	/**
+	 * Api helper to grab an options token
+	 *
+	 * token callback has signature ( String token )
+	 * error callback has signature ( String code, Object results, XmlHttpRequest xhr, Exception exception )
+	 * Note that xhr and exception are only available for 'http_*' errors
+	 * code may be any http_* error code (see mw.Api), or 'token_missing'
+	 *
+	 * @param tokenCallback {Function} received token callback
+	 * @param err {Function} error callback
+	 * @return {jqXHR}
+	 */
+	function getOptionToken ( tokenCallback, err ) {
+		var parameters = {
+				action: 'tokens',
+				type: 'options'
+			},
+			ok = function ( data ) {
+				var token;
+				// If token type is not available for this user,
+				// key 'translationreviewtoken' is missing or can contain Boolean false
+				if ( data.tokens && data.tokens.optionstoken ) {
+					token = data.tokens.optionstoken;
+					cachedOptionsToken = token;
+					tokenCallback( token );
+				} else {
+					err( 'token-missing', data );
+				}
+			},
+			ajaxOptions = {
+				ok: ok,
+				err: err,
+				// Due to the API assuming we're logged out if we pass the callback-parameter,
+				// we have to disable jQuery's callback system, and instead parse JSON string,
+				// by setting 'jsonp' to false.
+				jsonp: false
+			};
+
+		return new mw.Api().get( parameters, ajaxOptions );
+	}
+
+	ULSPreferences = function () {
 		this.preferenceName = 'uls-preferences';
 		this.username = mw.user.getName();
 		this.isAnon = mw.user.isAnon();
@@ -68,8 +151,7 @@
 		 * @param callback
 		 */
 		save: function ( callback ) {
-			var ulsPreferences = this,
-				api;
+			var ulsPreferences = this;
 
 			callback = callback || $.noop;
 			if ( this.isAnon ) {
@@ -78,25 +160,13 @@
 				callback.call( this, true );
 			} else {
 				// Logged in user. Use MW apis to change preferences
-				api = new mw.Api();
-
-				api.post( {
-					action: 'tokens',
-					type: 'options'
-				} ).done( function ( tokenresult ) {
-					var token = tokenresult.tokens.optionstoken;
-
-					api.post( {
-						action: 'options',
-						optionname: ulsPreferences.preferenceName,
-						optionvalue: $.toJSON( ulsPreferences.preferences ),
-						token: token
-					} ).done( function ( data ) {
-						callback.call( this, true );
-					} ).fail( function ( data ) {
-						callback.call( this, false );
-					} );
-				} ).fail( function () {
+				saveOptionsWithToken( {
+					action: 'options',
+					optionname: ulsPreferences.preferenceName,
+					optionvalue: $.toJSON( ulsPreferences.preferences )
+				}, function () {
+					callback.call( this, true );
+				}, function () {
 					callback.call( this, false );
 				} );
 			}