Add Dynamic CSS Classes extension

This extension adds the current referrer's domains as classes to the
HTML element. If the current document is inside a viewer, it'll add a
viewer CSS class ass well.

extensions/amp-dynamic-css-classes/0.1/amp-dynamic-css-classes.js

@@ -0,0 +1,101 @@
+/**
+ * Copyright 2015 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {parseUrl} from '../../../src/url';
+import {viewerFor} from '../../../src/viewer';
+import {log} from '../../../src/log';
+import {isExperimentOn} from '../../../src/experiments';
+
+/** @const */
+const TAG = 'AmpDynamicCssClasses';
+
+/** @const */
+const EXPERIMENT = 'dynamic-css-classes';
+
+/**
+ * Returns an array of referrers which vary in level of subdomain specificity.
+ *
+ * @param {string} referrer
+ * @return {!Array<string>}
+ * @private Visible for testing only!
+ */
+export function referrers_(referrer) {
+  referrer = parseUrl(referrer).hostname;
+  const domains = referrer.split('.');
+  let domainBase = '';
+
+  return domains.reduceRight((referrers, domain) => {
+    if (domainBase) {
+      domain += '-' + domainBase;
+    }
+    domainBase = domain;
+    referrers.push(domain);
+    return referrers;
+  }, []);
+}
+
+/**
+ * Adds CSS classes onto the HTML element.
+ * @param {!Window} win
+ * @param {!Array<string>} classes
+ */
+function addDynamicCssClasses(win, classes) {
+  const documentElement = win.document.documentElement;
+  const classList = documentElement.classList;
+
+  for (let i = 0; i < classes.length; i++) {
+    classList.add(classes[i]);
+  }
+}
+
+
+/**
+ * Adds dynamic css classes based on the referrer, with a separate class for
+ * each level of subdomain specificity.
+ * @param {!Window} win
+ */
+function addReferrerClasses(win) {
+  const classes = referrers_(win.document.referrer).map(referrer => {
+    return `amp-referrer-${referrer}`;
+  });
+  addDynamicCssClasses(win, classes);
+}
+
+
+/**
+ * Adds a dynamic css class `amp-viewer` if this document is inside a viewer.
+ * @param {!Window} win
+ */
+function addViewerClass(win) {
+  const viewer = viewerFor(win);
+  if (viewer.isEmbedded()) {
+    addDynamicCssClasses(win, ['amp-viewer']);
+  }
+}
+
+/**
+ * @param {!Window} win
+ */
+function addRuntimeClasses(win) {
+  if (isExperimentOn(win, EXPERIMENT)) {
+    addReferrerClasses(win);
+    addViewerClass(win);
+  } else {
+    log.warn(TAG, `Experiment ${EXPERIMENT} disabled`);
+  }
+}
+
+addRuntimeClasses(AMP.win);

extensions/amp-dynamic-css-classes/0.1/test/test-dynamic-classes.js

@@ -0,0 +1,65 @@
+/**
+ * Copyright 2015 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {referrers_} from '../amp-dynamic-css-classes';
+
+describe('amp-dynamic-css-classes', () => {
+  describe('referrers_', () => {
+    describe('when referrer is TLD-less', () => {
+      const referrer = 'http://localhost/test/ing?this#referrer';
+
+      it('contains the domain', () => {
+        expect(referrers_(referrer)).to.deep.equal(['localhost']);
+      });
+    });
+
+    describe('when referrer has no subdomains', () => {
+      const referrer = 'http://google.com/test/ing?this#referrer';
+      const referrers = referrers_(referrer);
+
+      it('contains the TLD', () => {
+        expect(referrers).to.contain('com');
+      });
+
+      it('contains the domain', () => {
+        expect(referrers).to.contain('google-com');
+        expect(referrers.length).to.equal(2);
+      });
+    });
+
+    describe('when referrer has subdomains', () => {
+      const referrer = 'http://a.b.c.google.com/test/ing?this#referrer';
+      const referrers = referrers_(referrer);
+
+      it('contains the TLD', () => {
+        expect(referrers).to.contain('com');
+      });
+
+      it('contains the domain', () => {
+        expect(referrers).to.contain('google-com');
+      });
+
+      it('contains each subdomain', () => {
+        expect(referrers).to.include.members([
+          'c-google-com',
+          'b-c-google-com',
+          'a-b-c-google-com'
+        ]);
+        expect(referrers.length).to.equal(5);
+      });
+    });
+  });
+});

extensions/amp-dynamic-css-classes/0.1/test/test-runtime-classes.js

@@ -0,0 +1,60 @@
+/**
+ * Copyright 2015 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {createServedIframe} from '../../../../testing/iframe';
+import {toggleExperiment} from '../../../../src/experiments';
+
+const iframeSrc = '/base/test/fixtures/served/amp-dynamic-css-classes.html';
+
+describe('dynamic classes are inserted at runtime', () => {
+  let documentElement, win;
+  beforeEach(() => {
+    return createServedIframe(iframeSrc).then(fixture => {
+      win = fixture.win;
+      documentElement = fixture.doc.documentElement;
+    });
+  });
+
+  describe('when experiment is disabled', () => {
+    beforeEach(() => {
+      toggleExperiment(win, 'dynamic-css-classes', false);
+      return win.insertDynamicCssScript();
+    });
+
+    it('should not include referrer classes', () => {
+      expect(documentElement).not.to.have.class('amp-referrer-localhost');
+    });
+
+    it('should not include viewer class', () => {
+      expect(documentElement).not.to.have.class('amp-viewer');
+    });
+  });
+
+  describe('when experiment is enabled', () => {
+    beforeEach(() => {
+      toggleExperiment(win, 'dynamic-css-classes', true);
+      return win.insertDynamicCssScript();
+    });
+
+    it('should include referrer classes', () => {
+      expect(documentElement).to.have.class('amp-referrer-localhost');
+    });
+
+    it('should include viewer class', () => {
+      expect(documentElement).to.have.class('amp-viewer');
+    });
+  });
+});

extensions/amp-dynamic-css-classes/amp-dynamic-css-classes.md

@@ -0,0 +1,37 @@
+<!---
+Copyright 2015 The AMP HTML Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS-IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+### <a name="amp-dynamic-css-classes"></a> AMP Dynamic CSS Classes
+
+The AMP Dynamic CSS Classes extension adds several dynamic CSS class
+names onto the HTML element.
+
+#### Behavior
+
+The AMP Dynamic CSS Classes extension adds the following CSS classes
+onto the HTML element:
+
+**amp-referrer-***
+
+One or more referrer classes will be set, one for each level of
+subdomain specificity. For example, `www.google.com` will add three
+classes: `amp-referrer-www-google-com`, `amp-referrer-google-com`, and
+`amp-referrer-com`.
+
+**amp-viewer**
+
+The `amp-viewer` class will be set if the current document is being
+displayed inside a Viewer.

gulpfile.js

@@ -74,6 +74,7 @@ function buildExtensions(options) {
   buildExtension('amp-audio', '0.1', false, options);
   buildExtension('amp-brightcove', '0.1', false, options);
   buildExtension('amp-carousel', '0.1', true, options);
+  buildExtension('amp-dynamic-css-classes', '0.1', false, options);
   buildExtension('amp-fit-text', '0.1', true, options);
   buildExtension('amp-font', '0.1', false, options);
   buildExtension('amp-iframe', '0.1', false, options);

test/fixtures/served/amp-dynamic-css-classes.html

@@ -0,0 +1,25 @@
+<!doctype html>
+<html ⚡>
+<head>
+  <meta charset="utf-8">
+  <title>AMP #0</title>
+  <link rel="canonical" href="amps.html" >
+  <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
+  <style>body {opacity: 0}</style><noscript><style>body {opacity: 1}</style></noscript>
+  <script async src="/base/dist/amp.js"></script>
+  <script>
+      function insertDynamicCssScript() {
+          return new Promise((resolve, reject) => {
+              var script = document.createElement('script');
+              script.src = '/base/dist/v0/amp-dynamic-css-classes-0.1.max.js';
+              script.onload = resolve;
+              script.onerror = reject;
+              document.getElementsByTagName('head')[0].appendChild(script);
+          });
+      }
+  </script>
+</head>
+<body>
+
+</body>
+</html>

testing/iframe.js

@@ -196,6 +196,27 @@ export function createIframePromise(opt_runtimeOff, opt_beforeLayoutCallback) {
   });
 }
 
+export function createServedIframe(src) {
+  return new Promise(function(resolve, reject) {
+    const iframe = document.createElement('iframe');
+    iframe.name = 'test_' + iframeCount++;
+    iframe.src = src;
+    iframe.onload = function() {
+      const win = iframe.contentWindow;
+      win.AMP_TEST = true;
+      installCoreServices(win);
+      registerForUnitTest(win);
+      resolve({
+        win: win,
+        doc: win.document,
+        iframe: iframe
+      });
+    };
+    iframe.onerror = reject;
+    document.body.appendChild(iframe);
+  });
+}
+
 /**
  * Returns a promise for when the condition becomes true.
  * @param {string} description

tools/experiments/experiments.js

@@ -79,6 +79,14 @@ const EXPERIMENTS = [
     spec: 'https://github.com/ampproject/amphtml/blob/master/extensions/' +
         'amp-user-notification/amp-user-notification.md',
   },
+
+  // Dynamic CSS Classes
+  {
+    id: 'dynamic-css-classes',
+    name: 'Dynamic CSS Classes',
+    spec: 'https://github.com/ampproject/amphtml/blob/master/extensions/' +
+        'amp-dynamic-css-classes/amp-dynamic-css-classes.md',
+  },
 ];