Add method for reading session cookie

Assumes the session cookie is stored as JSON which may or may not have been compressed via zlib (indicated by a leading `.`), which is then base64-encoded, and made URL-safe by replacing all `+` and `/` characters with `-` and `_` respectively.

package.json

@@ -52,6 +52,7 @@
     "lodash.range": "3.0.1",
     "minilog": "2.0.8",
     "node-sass": "3.3.3",
+    "pako": "0.2.8",
     "po2icu": "git://github.com/LLK/po2icu.git#develop",
     "react-addons-test-utils": "0.14.7",
     "react-modal": "0.6.1",

src/lib/jar.js

 var cookie = require('cookie');
 var xhr = require('xhr');
+var pako = require('pako');
 
 /**
  * Module that handles coookie interactions.
@@ -10,6 +11,33 @@ var xhr = require('xhr');
  * use(name, uri, callback) – can by sync or async, gets cookie from the uri if not there.
  */
 var Jar = {
+    unsign: function (value, callback) {
+        // Return the usable content portion of a signed, compressed cookie
+        if (!value) return callback('No value to unsign');
+        try {
+            var b64Data = value.split(':')[0];
+            var decompress = false;
+            if (b64Data[0] === '.') {
+                decompress = true;
+                b64Data = b64Data.substring(1);
+            }
+
+            // Django makes its base64 strings url safe by replacing + and / with - and _ respectively
+            b64Data = b64Data.replace(/[-_]/g, function (c) {return {'-':'+', '_':'/'}[c]; });
+            var strData = atob(b64Data);
+
+            if (decompress) {
+                var charData = strData.split('').map(function (c) { return c.charCodeAt(0); });
+                var binData = new Uint8Array(charData);
+                var data = pako.inflate(binData);
+                strData = String.fromCharCode.apply(null, new Uint16Array(data));
+            }
+
+            return callback(null, strData);
+        } catch (e) {
+            return callback(e);
+        }
+    },
     get: function (name, callback) {
     // Get cookie by name
     var obj = cookie.parse(document.cookie) || {};

static/js/lib/polyfill.min.js

@@ -26,6 +26,12 @@
  */
 (function(){try{new e("test")}catch(t){var e=function(t,e){var n;return e=e||{bubbles:!1,cancelable:!1,detail:void 0},n=document.createEvent("CustomEvent"),n.initCustomEvent(t,e.bubbles,e.cancelable,e.detail),n};e.prototype=window.Event.prototype,window.CustomEvent=e}})();
 
+/*!
+ * https://github.com/davidchambers/Base64.js
+ * see https://github.com/davidchambers/Base64.js/blob/master/LICENSE
+ */
+!function(){function t(t){this.message=t}var r="undefined"!=typeof exports?exports:this,e="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";t.prototype=new Error,t.prototype.name="InvalidCharacterError",r.btoa||(r.btoa=function(r){for(var o,n,a=String(r),i=0,c=e,d="";a.charAt(0|i)||(c="=",i%1);d+=c.charAt(63&o>>8-i%1*8)){if(n=a.charCodeAt(i+=.75),n>255)throw new t("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");o=o<<8|n}return d}),r.atob||(r.atob=function(r){var o=String(r).replace(/=+$/,"");if(o.length%4==1)throw new t("'atob' failed: The string to be decoded is not correctly encoded.");for(var n,a,i=0,c=0,d="";a=o.charAt(c++);~a&&(n=i%4?64*n+a:a,i++%4)?d+=String.fromCharCode(255&n>>(-2*i&6)):0)a=e.indexOf(a);return d})}();
+
 /*!
  * https://github.com/andyearnshaw/Intl.js
  * @license  The MIT License (MIT) Copyright (c) 2013 Andy Earnshaw