docs: fix problems with multiple versions

docs/processors/version-data.js

@@ -0,0 +1,43 @@
+var _ = require('lodash');
+var fs = require('fs');
+var semver = require('semver');
+var path = require('canonical-path');
+
+var basePath;
+var outputFolder;
+var currentVersion;
+module.exports = {
+  name: 'version-data',
+  description: 'Give a list of all available versions to the template',
+  runBefore: ['pages-data'],
+  init: function(config) {
+    basePath = config.get('basePath');
+    outputFolder = config.get('rendering.outputFolder');
+    currentVersion = config.get('currentVersion');
+  },
+  process: function(docs, extraData) {
+    var docsBaseFolder = path.resolve(basePath, outputFolder, 'docs');
+
+    //Array of versions sorted backwards
+    var versions = fs.readdirSync(docsBaseFolder)
+      .filter(semver.valid)
+      .sort(semver.rcompare);
+
+    //Add current version to the top of the list if not exists
+    !_.contains(versions, currentVersion) && versions.unshift(currentVersion);
+
+    //Add nightly to the top of the list if not exists
+    !_.contains(versions, 'nightly') && versions.unshift('nightly');
+
+    versions = versions.map(function(ver) {
+      return {
+        href: '/docs/' + ver,
+        name: ver
+      };
+    });
+    extraData.version = {
+      list: versions,
+      current: _.find(versions, { name: currentVersion })
+    };
+  }
+};