Project import generated by Copybara.

GitOrigin-RevId: d9e9e3fb4e31372ec1fb43b178994ca78fa8fe70
diff --git a/static_src/elements/issue-detail/mr-flipper/mr-flipper.js b/static_src/elements/issue-detail/mr-flipper/mr-flipper.js
new file mode 100644
index 0000000..8159e01
--- /dev/null
+++ b/static_src/elements/issue-detail/mr-flipper/mr-flipper.js
@@ -0,0 +1,151 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import {LitElement, html, css} from 'lit-element';
+import qs from 'qs';
+import {connectStore} from 'reducers/base.js';
+import * as sitewide from 'reducers/sitewide.js';
+import {SHARED_STYLES} from 'shared/shared-styles.js';
+
+/**
+ * Class for displaying a single flipper.
+ * @extends {LitElement}
+ */
+export default class MrFlipper extends connectStore(LitElement) {
+  /** @override */
+  static get properties() {
+    return {
+      currentIndex: {type: Number},
+      totalCount: {type: Number},
+      prevUrl: {type: String},
+      nextUrl: {type: String},
+      listUrl: {type: String},
+      queryParams: {type: Object},
+    };
+  }
+
+  /** @override */
+  constructor() {
+    super();
+    this.currentIndex = null;
+    this.totalCount = null;
+    this.prevUrl = null;
+    this.nextUrl = null;
+    this.listUrl = null;
+
+    this.queryParams = {};
+  }
+
+  /** @override */
+  stateChanged(state) {
+    this.queryParams = sitewide.queryParams(state);
+  }
+
+  /** @override */
+  updated(changedProperties) {
+    if (changedProperties.has('queryParams')) {
+      this.fetchFlipperData(qs.stringify(this.queryParams));
+    }
+  }
+
+  // Eventually this should be replaced with pRPC.
+  fetchFlipperData(query) {
+    const options = {
+      credentials: 'include',
+      method: 'GET',
+    };
+    fetch(`detail/flipper?${query}`, options).then(
+        (response) => response.text(),
+    ).then(
+        (responseBody) => {
+          let responseData;
+          try {
+          // Strip XSSI prefix from response.
+            responseData = JSON.parse(responseBody.substr(5));
+          } catch (e) {
+            console.error(`Error parsing JSON response for flipper: ${e}`);
+            return;
+          }
+          this._populateResponseData(responseData);
+        },
+    );
+  }
+
+  _populateResponseData(data) {
+    this.totalCount = data.total_count;
+    this.currentIndex = data.cur_index;
+    this.prevUrl = data.prev_url;
+    this.nextUrl = data.next_url;
+    this.listUrl = data.list_url;
+  }
+
+  /** @override */
+  static get styles() {
+    return [
+      SHARED_STYLES,
+      css`
+        :host {
+          display: flex;
+          justify-content: center;
+          flex-direction: column;
+        }
+        /* Use visibility instead of display:hidden for hiding in order to
+        * avoid popping when elements are made visible. */
+        .row a[hidden], .counts[hidden] {
+          visibility: hidden;
+        }
+        .counts[hidden] {
+          display: block;
+        }
+        .row a {
+          display: block;
+          padding: 0.25em 0;
+        }
+        .row a, .row div {
+          flex: 1;
+          white-space: nowrap;
+          padding: 0 2px;
+        }
+        .row .counts {
+          padding: 0 16px;
+        }
+        .row {
+          display: flex;
+          align-items: baseline;
+          text-align: center;
+          flex-direction: row;
+        }
+        @media (max-width: 960px) {
+          :host {
+            display: inline-block;
+          }
+        }
+      `,
+    ];
+  }
+
+  /** @override */
+  render() {
+    return html`
+      <div class="row">
+        <a href="${this.prevUrl}" ?hidden="${!this.prevUrl}" title="Prev" class="prev-url">
+          &lsaquo; Prev
+        </a>
+        <div class="counts" ?hidden=${!this.totalCount}>
+          ${this.currentIndex + 1} of ${this.totalCount}
+        </div>
+        <a href="${this.nextUrl}" ?hidden="${!this.nextUrl}" title="Next" class="next-url">
+          Next &rsaquo;
+        </a>
+      </div>
+      <div class="row">
+        <a href="${this.listUrl}" ?hidden="${!this.listUrl}" title="Back to list" class="list-url">
+          Back to list
+        </a>
+      </div>
+    `;
+  }
+}
+
+window.customElements.define('mr-flipper', MrFlipper);
diff --git a/static_src/elements/issue-detail/mr-flipper/mr-flipper.test.js b/static_src/elements/issue-detail/mr-flipper/mr-flipper.test.js
new file mode 100644
index 0000000..183a8d5
--- /dev/null
+++ b/static_src/elements/issue-detail/mr-flipper/mr-flipper.test.js
@@ -0,0 +1,75 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import {assert} from 'chai';
+import MrFlipper from './mr-flipper.js';
+import sinon from 'sinon';
+
+const xssiPrefix = ')]}\'';
+
+let element;
+
+describe('mr-flipper', () => {
+  beforeEach(() => {
+    element = document.createElement('mr-flipper');
+    document.body.appendChild(element);
+
+    sinon.stub(window, 'fetch');
+
+    const response = new window.Response(`${xssiPrefix}{"message": "Ok"}`, {
+      status: 201,
+      headers: {
+        'Content-type': 'application/json',
+      },
+    });
+    window.fetch.returns(Promise.resolve(response));
+  });
+
+  afterEach(() => {
+    document.body.removeChild(element);
+
+    window.fetch.restore();
+  });
+
+  it('initializes', () => {
+    assert.instanceOf(element, MrFlipper);
+  });
+
+  it('renders links', async () => {
+    // Test DOM after properties are updated.
+    element._populateResponseData({
+      cur_index: 4,
+      total_count: 13,
+      prev_url: 'http://prevurl/',
+      next_url: 'http://nexturl/',
+      list_url: 'http://listurl/',
+    });
+
+    await element.updateComplete;
+
+    const prevUrlEl = element.shadowRoot.querySelector('a.prev-url');
+    const nextUrlEl = element.shadowRoot.querySelector('a.next-url');
+    const listUrlEl = element.shadowRoot.querySelector('a.list-url');
+    const countsEl = element.shadowRoot.querySelector('div.counts');
+
+    assert.equal(prevUrlEl.href, 'http://prevurl/');
+    assert.equal(nextUrlEl.href, 'http://nexturl/');
+    assert.equal(listUrlEl.href, 'http://listurl/');
+    assert.include(countsEl.innerText, '5 of 13');
+  });
+
+  it('fetches flipper data when queryParams change', async () => {
+    await element.updateComplete;
+
+    sinon.stub(element, 'fetchFlipperData');
+
+    element.queryParams = {id: 21, q: 'owner:me'};
+
+    sinon.assert.notCalled(element.fetchFlipperData);
+
+    await element.updateComplete;
+
+    sinon.assert.calledWith(element.fetchFlipperData, 'id=21&q=owner%3Ame');
+  });
+});