[som] Add revision range exapansion.

go/src/infra/appengine/sheriff-o-matic/elements/som-rev-range.html

+<link rel="import" href="/bower_components/polymer/polymer.html">
+
+<link rel="import" href="/bower_components/iron-collapse/iron-collapse.html">
+
+<dom-module id="som-rev-range">
+  <template>
+    <style>
+      .commit {
+        font-family: monospace;
+        font-size: 9pt;
+        margin: 1em;
+      }
+    </style>
+    <div on-tap="_toggleCollapse">
+      [[range.repo]]: <a target="_blank" href$="[[_regressionRangeLink(range)]]">[[_regressionRange(range)]]</a>
+    </div>
+    <iron-collapse id="collapse">
+      <template is="dom-repeat" items="[[_revs]]" as="rev">
+        <div class="commit">
+          <a href$="https://chromium.googlesource.com/chromium/src/+/[[rev.commit]]" target="_blank">[[_shortHash(rev.commit)]]</a>
+          (<a href$="mailto:[[rev.author.email]]">[[rev.author.name]]</a>):
+          [[_firstLine(rev.message)]]
+        </div>
+      </template>
+      <div id="loadingMessage" hidden>Loading revisions...</div>
+    </iron-collapse>
+  </template>
+  <script>
+  (function() {
+    'use strict';
+
+    Polymer({
+      is: 'som-rev-range',
+
+      properties: {
+        range: {
+          type: Object,
+          value: null
+        },
+        _revs: {
+          type: Array,
+          value: null
+        },
+      },
+
+     _toggleCollapse: function() {
+       if (!this._revs) {
+         let start = this._regressionStart(this.range);
+         let end = this._regressionEnd(this.range);
+         let url = `/api/v1/revrange/${start}/${end}`;
+         this.$.loadingMessage.hidden = false;
+         fetch(url).then((resp) => {
+           resp.text().then((bodyJson) => {
+             // remove the )]}' on the first line.
+             bodyJson = bodyJson.substr(')]}\'\n'.length);
+             let body = JSON.parse(bodyJson);
+             this._revs = body.log;
+             this.$.loadingMessage.hidden = true;
+           }, (reject) => {
+             console.error(reject);
+           });
+         }, (reject) => {
+           console.error(reject);
+         });
+       }
+
+       this.$.collapse.toggle();
+     },
+
+     _shortHash: function(hash) {
+       return hash.substring(0, 8);
+     },
+
+     _firstLine: function(message) {
+       return message.split('\n')[0];
+     },
+
+     _regressionStart: function(range) {
+        if (!range.positions || range.positions.length == 0) {
+          return '';
+        }
+
+        return this._parseCommitPosition(range.positions[0]);
+     },
+
+     _regressionEnd: function(range) {
+        if (!range.positions || range.positions.length == 0) {
+          return '';
+        }
+
+        return this._parseCommitPosition(
+            range.positions[range.positions.length - 1]);
+     },
+
+     _regressionRange: function(range) {
+        let start = this._regressionStart(range);
+        let end = this._regressionEnd(range);
+
+        if (start && end) {
+          return `${start} - ${end}`;
+        }
+
+        return start;
+      },
+
+      _regressionRangeLink: function(range) {
+        if (!range.positions) {
+          return '';
+        }
+        let end = this._parseCommitPosition(range.positions[0]);
+        let start = end;
+        if (range.positions.length > 1) {
+          end = this._parseCommitPosition(
+              range.positions[range.positions.length - 1]);
+        }
+        return 'http://test-results.appspot.com/revision_range?start=' +
+            `${start}&end=${end}`;
+      },
+
+      _parseCommitPosition: function(pos) {
+        let groups = /refs\/heads\/master@{#([0-9]+)}/.exec(pos);
+        if (groups && groups.length == 2) {
+          return groups[1];
+        }
+      },
+
+    });
+  })();
+
+  </script>
+</dom-module>