config_service: improve landing page

appengine/config_service/ui/src/config-ui/front-page.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="../../bower_components/app-layout/app-layout.html">
+<link rel="import" href="config-card.html">
+<link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html">
+<link rel="import" href="../../bower_components/paper-button/paper-button.html">
+<link rel="import" href="../../bower_components/paper-search/paper-search-bar.html">
+<link rel="import" href="../../bower_components/polymer/polymer.html">
+
+<dom-module id="front-page">
+  <template>
+    <style>
+      app-toolbar {
+        background-color: #efefef;
+        color: #232323;
+      }
+
+      app-header {
+        @apply --layout-fixed-top;
+      }
+
+      .center {
+        width: 50%;
+        margin: auto;
+        text-align: center;
+      }
+
+      .logo {
+        height: 100%;
+      }
+
+      .title {
+        padding-left: 1%;
+        font-size: 150%;
+        font-family: sans-serif;
+      }
+
+      .search-bar {
+        padding-top: 7%;
+        padding-bottom: 2%;
+      }
+
+      paper-search-bar {
+        border-style: solid;
+        border-width: 2px;
+        width: 40%;
+        height: 100%;
+        margin: auto;
+      }
+    </style>
+
+    <app-header reveals>
+      <app-toolbar>
+        <image class="logo" src="/static/images/chromium.png"/>
+        <div class="title" main-title>Configuration Service (not fully implemented)</div>
+      </app-toolbar>
+    </app-header>
+
+    <iron-ajax
+        auto
+        id="requestConfigs"
+        url="https://luci-config.appspot.com/_ah/api/config/v1/config-sets"

[nodir, 2017/06/13 16:48:22]

this is probably slow.
currently this loads information that you don't need and loading that
information is expensive.
i can add parameters to limit the response only to names of config sets and it
will work faster

no action needed in this CL though

+        handle-as="json"
+        on-response="_onGotConfigs">

[nodir, 2017/06/13 16:48:22]

apologies, I realized that a better name would be "_onGotConfigSets" since it is
the config sets we are getting here

+    </iron-ajax>
+
+    <div class="search-bar">
+      <paper-search-bar query="{{query}}"></paper-search-bar>
+    </div>
+    
+    <div class="config-list">
+      <template is="dom-if" if="[[isLoading]]">
+        <div class="center">Fetching config sets...</div>
+      </template>
+      <template is="dom-if" if="[[_not(isLoading)]]">
+        <template is="dom-if" if="[[isEmpty]]">
+          <config-card name="No config sets found."></config-card>
+        </template>
+        <template is="dom-if" if="[[_not(isEmpty)]]">
+          <template is="dom-repeat" items="[[searchResults]]" as="config">
+            <config-card name="[[config.config_set]]"></config-card>
+          </template>
+        </template>
+      </template>
+    </div>
+  </template>
+
+  <script>
+    Polymer({
+      is: 'front-page',
+
+      properties: {
+        configList: {
+          type: Array,
+          value: []
+        },
+
+        isEmpty: {
+          type: Boolean,
+          value: true
+        },
+
+        isLoading: {
+          type: Boolean,
+          value: true
+        },
+
+        query: {
+          type: String,
+          observer: '_updateSearchResults'
+        },
+
+        searchResults: {
+          type: Array,
+          value: () => { return []; }
+        }
+      },
+
+      _onGotConfigs: function(event) {
+        this.configList = event.detail.response.config_sets;
+        this._updateSearchResults();
+        this.isEmpty = this.searchResults.length === 0;

[nodir, 2017/06/13 16:48:22]

_updateSearchResults already updates isEmpty, so this line is unnecessary

+        this.isLoading = false;
+      },
+
+      _not: function(bool) {
+        return (!(bool));
+      },
+
+      _updateSearchResults: function() {
+        var query = this.query;
+        this.searchResults = this.configList.filter(function(elem) {
+          return elem.config_set.includes(query);
+        });

[nodir, 2017/06/13 16:48:22]

arrow functions are best for this kind of inline functions for 2 reasons:
1) return is implied if you don't put {}
2) it captures "this" correctly, so L135 is unnecessary

this.searchResults = this.configList.filter(e =>
e.config_set.includes(this.query))

+        this.isEmpty = this.searchResults.length === 0;
+      }
+    });
+  </script>
+</dom-module>