Add a Firebase Analytics "Send Survey on app update" sample

Change-Id: I392b18c93f9cdeca0b503b3eca0fd70ded5ac0a8

survey-app-update/README.md

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+# Send a survey when users update your app
+
+This sample shows how to send a survey to your users who have updated your app. App Update is detected using a Firebase Analytics event.
+
+
+## Functions Code
+
+See file [functions/index.js](functions/index.js) for the trigger and the email sending code.
+
+Sending emails is performed using [nodemailer](https://www.npmjs.com/package/nodemailer) a node based Email client with comprehensive EMail server setup. For simplicity, in this sample we're showing how to send email through SMTP using a Gmail account. Be aware that Gmail has an [email sending quota](https://support.google.com/mail/answer/22839). If you are planning on sending a large number of emails you should use a professional email sending platform such as [Sendgrid](https://console.cloud.google.com/launcher/details/sendgrid-app/sendgrid-email), [Mailjet](https://www.mailjet.com/google) or [Mailgun](http://www.mailgun.com/google).
+
+The dependencies are listed in [functions/package.json](functions/package.json).
+
+
+## Trigger rules
+
+The function triggers on changes to `app_update` Firebase Analytics event..
+
+
+## Setting up the sample
+
+Set the `gmail.email` and `gmail.password` Google Cloud environment variables to match the email and password of the Gmail account used to send emails. For this use:
+
+```bash
+firebase functions:config:set gmail.email="myusername@gmail.com" gmail.password="secretpassword"
+```
+
+
+## Deploy and test
+
+This sample can be tested on your Android and iOS app. To test it out:
+
+ - Set the project to your Firebase project using `firebase use --add` then select your projec tin the list.
+ - Deploy your project using `firebase deploy`
+ - Have users update your app, for instance through the play store.
+ - Within a few hours the emails to the survey will be sent.

survey-app-update/firebase.json

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+{}

survey-app-update/functions/index.js

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+/**
+ * Copyright 2016 Google Inc. 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.
+ */
+'use strict';
+
+const functions = require('firebase-functions');
+const admin = require('firebase-admin');
+admin.initializeApp(functions.config().firebase);
+const nodemailer = require('nodemailer');
+// Configure the email transport using the default SMTP transport and a GMail account.
+// For other types of transports such as Sendgrid see https://nodemailer.com/transports/
+// TODO: Configure the `gmail.email` and `gmail.password` Google Cloud environment variables.
+const gmailEmail = encodeURIComponent(functions.config().gmail.email);
+const gmailPassword = encodeURIComponent(functions.config().gmail.password);
+const mailTransport = nodemailer.createTransport(
+    `smtps://${gmailEmail}:${gmailPassword}@smtp.gmail.com`);
+
+// TODO: Create yor own survey.
+const LINK_TO_SURVEY = 'https://goo.gl/forms/IdurnOZ66h3FtlO33';
+
+/**
+ * After a user has updated the app. Send them a survey to compare the app with the old version.
+ */
+exports.sendAppUpdateSurvey = functions.analytics.event('app_update').onLog(event => {
+  const uid = event.data.user.userId;
+
+  // Fetch the email of the user. In this sample we assume that the app is using Firebase Auth and
+  // has set the Firebase Analytics User ID to be the same as the Firebase Auth uid using the
+  // setUserId API.
+  return admin.auth().getUser(uid).then(user => {
+    const email = user.email;
+    const name = user.displayName;
+    return sendSurveyEmail(email, name);
+  });
+});
+
+/**
+ * Sends an email pointing to the Upgraded App survey.
+ */
+function sendSurveyEmail(email, name) {
+  const mailOptions = {
+    from: '"MyCoolApp" <noreply@firebase.com>',
+    to: email,
+    subject: 'How did you like our new app?',
+    text: `Hey ${name}, We've seen that you have upgraded to the new version of our app!
+           It would be awesome if you could tell us how you like it.
+           Fill out our survey: ${LINK_TO_SURVEY}`
+  };
+
+  return mailTransport.sendMail(mailOptions).then(() => {
+    console.log('Upgrade App Survey email sent to:', email);
+  });
+}

survey-app-update/functions/package.json

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+{
+  "name": "bigquery-import-functions",
+  "description": "Import data to BigQuery Firebase Functions sample",
+  "dependencies": {
+    "nodemailer": "^2.4.1",
+    "firebase-admin": "^4.1.1",
+    "firebase-functions": "https://storage.googleapis.com/firebase-preview-drop/node/firebase-functions/firebase-functions-0.5.1-preview1.tgz"
+  }
+}