config_service: add last import validation and tests

appengine/config_service/ui/src/config-ui/config-set.html

 <!--
   Copyright 2017 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 -->
 
 <link rel="import" href="config-file-card.html">
 <link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html">
 <link rel="import" href="../../bower_components/paper-item/paper-item.html">
 <link rel="import" href="../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../bower_components/iron-icons/maps-icons.html">
 
 <dom-module id="config-set">
   <template>
     <style>
       .category {
         font-size: 100%;
         font-family: sans-serif;
       }
 
       .center {
         width: 27%;
         margin: auto;
         text-align: left;
       }
 
       .name {
         font-size: 200%;
         font-family: sans-serif;
       }
 
       .title {
         padding-bottom: 1%;
         padding-top: 5%;
       }
     </style>
 
     <iron-ajax
         auto
         id="requestConfigs"
-        url="/_ah/api/config/v1/config-sets?config_set=[[category]]%2F[[name]]&include_files=true"
+        url="/_ah/api/config/v1/config-sets?config_set=[[category]]%2F[[name]][[route.path]]&include_files=true&include_last_import_attempt=true"
         handle-as="json"
         on-response="_onGotConfigFiles">
     </iron-ajax>
 
     <div class="center title">
-      <div class="name">[[name]][[route.path]]</div>
-      <div class="category">[[_formatCategory(category)]]</div>
+      <div class="name">[[name]][[route.path]]
+        <template is="dom-if" if="[[_not(isLoading)]]">
+          <template is="dom-if" if="[[lastImportAttempt.success]]">
+            <iron-icon icon="icons:check-circle"></iron-icon>
+          </template>
+          <template is="dom-if" if="[[_not(lastImportAttempt.success)]]">
+            <iron-icon icon="icons:warning"></iron-icon>
+          </template>
+        </template>
+      </div>
+      <div class="category">
+        [[_formatCategory(category)]] <br>
+        <template is="dom-if" if="[[_not(isLoading)]]">
+          <template is="dom-if" if="[[_not(lastImportAttempt.success)]]">
+            Last import attempt failed: [[lastImportAttempt.message]]
+          </template>
+        </template>
+      </div>      
     </div>
 
     <template is="dom-if" if="[[isLoading]]">
       <div class="center">Fetching config files...</div>
     </template>
     <template is="dom-if" if="[[_not(isLoading)]]">
-      <template is="dom-repeat" items="[[files]]" as="file">
-        <config-file-card
-            name="[[file.path]]" link="[[location]]/[[file.path]]">
-        </config-file-card>
+      <template is="dom-if" if="[[_isEmpty(files)]]">
+        <div class="center" style="font-family: sans-serif;">
+          No config files found.
+        </div>
+      </template>
+      <template is="dom-if" if="[[_not(_isEmpty(files))]]">
+        <template is="dom-repeat" items="[[files]]" as="file">
+          <config-file-card
+              name="[[file.path]]" link="[[location]]/[[file.path]]">
+          </config-file-card>
+        </template>
       </template>
     </template>
   </template>
   <script>
     Polymer({
       is: "config-set",
 
       properties: {
+
+        frontPageIsActive: {
+          type: Boolean,
+          observer: '_frontPageIsActive'
+        },
+
         category: {
           type: String
         },
 
         files: {
           type: Array
         },
 
         isLoading: {
           type: Boolean,
           value: true
         },
 
+        lastImportAttempt: {
+          type: Object
+        },
+
         location: {
           type: String
         },
 
         name: {
           type: String
         }
       },
 
+      _frontPageIsActive: function() {
+        if (this.frontPageIsActive === false) {
+          this.isLoading = true;
+          this.$.requestConfigs.generateRequest();
+        }
+      },
+
+      _isEmpty: function(list) {
+        return list.length === 0;
+      },
+
       _formatCategory: function(category) {
         if (category === "projects") return "Project";
         if (category === "services") return "Service";
       },
 
       _not: function(b) {
         return !b;
       },
 
       _onGotConfigFiles: function(event) {
-        this.files = event.detail.response.config_sets[0].files;
+        this.files = event.detail.response.config_sets[0].files ? 
+            event.detail.response.config_sets[0].files : [];
         this.location = event.detail.response.config_sets[0].location;
+        this.lastImportAttempt = 
+            event.detail.response.config_sets[0].last_import_attempt;
         this.isLoading = false;
       }
     });
   </script>
 </dom-module>