✨Analytics: CookieWriter

build-system/conformance-config.textproto

@@ -289,6 +289,7 @@ requirement: {
   whitelist: 'src/experiments.js'
   whitelist: 'src/service/cid-api.js'
   whitelist: 'src/service/cid-impl.js'
+  whitelist: 'extensions/amp-analytics/0.1/cookie-writer.js'
 }
 
 # Function

build-system/dep-check-config.js

@@ -255,6 +255,8 @@ exports.rules = [
           'src/service/position-observer/position-observer-worker.js',
       'extensions/amp-analytics/0.1/amp-analytics.js->' +
           'src/service/cid-impl.js',
+      'extensions/amp-analytics/0.1/cookie-writer.js->' +
+          'src/service/cid-impl.js',
       'extensions/amp-next-page/0.1/next-page-service.js->' +
           'src/service/position-observer/position-observer-impl.js',
       'extensions/amp-next-page/0.1/next-page-service.js->' +

build-system/tasks/presubmit-checks.js

@@ -818,6 +818,7 @@ const forbiddenTermsSrcInclusive = {
     whitelist: [
       'extensions/amp-form/0.1/amp-form.js',
       'src/service/url-replacements-impl.js',
+      'extensions/amp-analytics/0.1/cookie-writer.js',
     ],
   },
   '\\.expandInputValueSync\\(': {

extensions/amp-analytics/0.1/amp-analytics.js

@@ -17,6 +17,7 @@
 import {Activity} from './activity-impl';
 import {AnalyticsConfig, mergeObjects} from './config';
 import {AnalyticsEventType} from './events';
+import {CookieWriter} from './cookie-writer';
 import {
   ExpansionOptions,
   installVariableService,
@@ -211,6 +212,10 @@ export class AmpAnalytics extends AMP.BaseElement {
             })
             .then(config => {
               this.config_ = config;
+              return new CookieWriter(this.win,
+                  this.element, this.config_).write();
+            })
+            .then(() => {
               this.transport_ =
                   new Transport(this.win, this.config_['transport'] || {});
             })

extensions/amp-analytics/0.1/cookie-writer.js

@@ -0,0 +1,155 @@
+/**
+ * Copyright 2018 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 {BASE_CID_MAX_AGE_MILLIS} from '../../../src/service/cid-impl';
+import {Services} from '../../../src/services';
+import {getMode} from '../../../src/mode';
+import {getNameArgs} from './variables';
+import {hasOwn} from '../../../src/utils/object';
+import {isInFie} from '../../../src/friendly-iframe-embed';
+import {isObject} from '../../../src/types';
+import {isProxyOrigin} from '../../../src/url';
+import {setCookie} from '../../../src/cookies';
+import {user} from '../../../src/log';
+
+
+const TAG = 'amp-analytics/cookie-writer';
+
+const EXPAND_WHITELIST = {
+  'QUERY_PARAM': true,
+  // TODO: Add linker_param
+};
+
+export class CookieWriter {
+
+  /**
+   * @param {!Window} win
+   * @param {!Element} element
+   * @param {!JsonObject} config
+   */
+  constructor(win, element, config) {
+    /** @private {!Window} */
+    this.win_ = win;
+
+    /** @private {!Element} */
+    this.element_ = element;
+
+    /** @private {!../../../src/service/url-replacements-impl.UrlReplacements} */
+    this.urlReplacementService_ = Services.urlReplacementsForDoc(element);
+
+    /** @private {?Promise} */
+    this.writePromise_ = null;
+
+    /** @private {!JsonObject} */
+    this.config_ = config;
+  }
+
+  /**
+   * @return {!Promise}
+   */
+  write() {
+    if (!this.writePromise_) {
+      this.writePromise_ = this.init_();
+    }
+
+    return this.writePromise_;
+  }
+
+  /**
+   * Parse the config and write to cookie
+   * @return {!Promise}
+   */
+  init_() {
+    // TODO: Need the consider the case for shadow doc.
+    if (isInFie(this.element_) || isProxyOrigin(this.win_.location) ||
+        getMode(this.win_).runtime == 'inabox') {
+      // Disable cookie writer in friendly iframe and proxy origin and inabox.
+      // Note: It's important to check origin here so that setCookie doesn't
+      // throw error "should not attempt ot set cookie on proxy origin"
+      return Promise.resolve();
+    }
+
+
+    if (!hasOwn(this.config_, 'writeCookies')) {
+      return Promise.resolve();
+    }
+
+    if (!isObject(this.config_['writeCookies'])) {
+      user().error(TAG, 'writeCookies config must be an object');
+      return Promise.resolve();
+    }
+
+    const inputConfig = this.config_['writeCookies'];
+    const ids = Object.keys(inputConfig);
+    const promises = [];
+    for (let i = 0; i < ids.length; i++) {
+      const cookieName = ids[i];
+      const cookieValue = inputConfig[cookieName];
+      if (this.isCookieValueStringValid_(cookieValue)) {
+        promises.push(this.expandAndWrite_(cookieName, cookieValue));
+      }
+    }
+
+    return Promise.all(promises);
+  }
+
+  /**
+   * Check whether the cookie value is supported. Currently only support
+   * QUERY_PARAM(***)
+   * @param {*} str
+   * @return {boolean}
+   */
+  isCookieValueStringValid_(str) {
+    if (typeof str !== 'string') {
+      user().error(TAG, 'cookie value needs to be a string');
+      return false;
+    }
+
+    // Make sure that only QUERY_PARAM and LINKER_PARAM is supported
+    const {name} = getNameArgs(str);
+    if (!EXPAND_WHITELIST[name]) {
+      user().error(TAG, `cookie value ${str} not supported. ` +
+        'Only QUERY_PARAM is supported');
+      return false;
+    }
+
+    return true;
+  }
+
+  /**
+   * Expand the value and write to cookie if necessary
+   * @param {string} cookieName
+   * @param {string} cookieValue
+   * @return {!Promise}
+   */
+  expandAndWrite_(cookieName, cookieValue) {
+    // Note: Have to use `expandStringAsync` because QUERY_PARAM can wait for
+    // trackImpressionPromise and resolve async
+    return this.urlReplacementService_.expandStringAsync(cookieValue,
+        /* TODO: Add opt_binding */ undefined, EXPAND_WHITELIST).then(
+        value => {
+        // Note: We ignore empty cookieValue, that means currently we don't
+        // provide a way to overwrite or erase existing cookie
+          if (value) {
+            const expireDate = Date.now() + BASE_CID_MAX_AGE_MILLIS;
+            setCookie(this.win_, cookieName, value, expireDate);
+          }
+        }).catch(e => {
+      user().error(TAG, 'Error expanding cookie string', e);
+    });
+  }
+}
+