Moves poll inside GL

app/assets/javascripts/lib/utils/poll.js

+import Vue from 'vue';
+import VueResource from 'vue-resource';
+import httpStatusCodes from './http_status';
+
+Vue.use(VueResource);
+
+/**
+ * Polling utility for handling realtime updates with Vue.Resource get method.
+ *
+ * @example
+ * new poll({
+ *   url: 'endopoint',
+ *   data: {},
+ *   successCallback: () => {}
+ *   errorCallback: () => {}
+ * }).makeRequest();
+ *
+ *
+ * 1. Checks for response and headers before start polling
+ * 2. Interval is provided by `X-Poll-Interval` header.
+ * 3. If `X-Poll-Interval` is -1, we stop polling
+ * 4. If HTTP response is 200, we poll.
+ * 5. If HTTP response is different from 200, we stop polling.
+ *
+ */
+export default class poll {
+  constructor(options) {
+    this.options = options || {};
+
+    this.intervalHeader = 'POLL-INTERVAL';
+  }
+
+  checkConditions(response) {
+    const headers = gl.utils.normalizeHeaders(response.headers);
+    const pollInterval = headers[this.intervalHeader];
+
+    if (pollInterval > 0 && response.status === httpStatusCodes.OK) {
+      this.options.successCallback(response);
+      setTimeout(() => {
+        this.makeRequest()
+          .then(this.checkConditions)
+          .catch(error => this.options.errorCallback(error));
+      }, pollInterval);
+    } else {
+      this.options.successCallback(response);
+    }
+  }
+
+  makeRequest() {
+    return Vue.http.get(this.options.url, this.options.data)
+    .then(this.checkConditions)
+    .catch(error => this.options.errorCallback(error));
+  }
+}