From 14ea8de7094b97e9f2342690df3be7bfa16268ec Mon Sep 17 00:00:00 2001
From: gianantoniopini <63844628+gianantoniopini@users.noreply.github.com>
Date: Tue, 4 May 2021 11:30:12 +0200
Subject: [PATCH] Modified 'printResume' Firebase cloud function: implemented
 basic retry mechanism with waitUntil 'networkidle0' and 'networkidle2',
 enhanced error handling to return more detailed information

---
 functions/index.js | 125 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 97 insertions(+), 28 deletions(-)

diff --git a/functions/index.js b/functions/index.js
index dc838dc4..0a5319fd 100644
--- a/functions/index.js
+++ b/functions/index.js
@@ -54,42 +54,100 @@ const deleteUserFunctionHandler = async (_, { auth }) => {
   }
 };
 
-exports.deleteUser = functions
-  .runWith({ memory: '256MB' })
-  .https.onCall(deleteUserFunctionHandler);
+/**
+ * Tries to navigate the page to a given URL.
+ *
+ * @param {puppeteer.Page} page Page.
+ * @param {string} url URL to navigate page to.
+ * @param {puppeteer.PuppeteerLifeCycleEvent} waitUntil When to consider navigation succeeded.
+ * @returns {Promise<string>} Returns null if no error occurred, otherwise returns the error message.
+ */
+const tryGotoPage = async (page, url, waitUntil) => {
+  let httpResponse;
 
-exports.printResume = functions
-  .runWith({ memory: '1GB' })
-  .https.onCall(async ({ id, type }, { auth }) => {
-    if (!id) {
-      throw new functions.https.HttpsError(
-        'invalid-argument',
-        'The function must be called with argument "id" containing the resume ID.',
-      );
+  try {
+    httpResponse = await page.goto(url, {
+      waitUntil,
+    });
+  } catch (error) {
+    return `page.goto (waitUntil: "${waitUntil}") threw an error with message "${error.message}"`;
+  }
+
+  if (httpResponse === null) {
+    return `page.goto (waitUntil: "${waitUntil}") returned a null response`;
+  }
+
+  if (!httpResponse.ok()) {
+    return `page.goto (waitUntil: "${waitUntil}") returned a response with HTTP status ${httpResponse.status()} "${httpResponse.statusText()}"`;
+  }
+
+  return null;
+};
+
+/**
+ * Creates a page and navigates to a given URL.
+ *
+ * @param {puppeteer.Browser} browser Browser.
+ * @param {string} url URL to navigate to.
+ * @returns {Promise<{page: puppeteer.Page, errors: string[]}>} Returns an object with the page if no error occurred, otherwise returns an object with the list of error messages.
+ */
+const gotoPage = async (browser, url) => {
+  const errors = [];
+
+  const waitUntilArray = ['networkidle0', 'networkidle2'];
+  for (let index = 0; index < waitUntilArray.length; index++) {
+    /* eslint-disable no-await-in-loop */
+    const waitUntil = waitUntilArray[index];
+
+    const page = await browser.newPage();
+    await page.setCacheEnabled(false);
+
+    const error = await tryGotoPage(page, url, waitUntil);
+    if (!error) {
+      return { page, errors: null };
     }
 
-    if (!type) {
-      throw new functions.https.HttpsError(
-        'invalid-argument',
-        'The function must be called with argument "type" containing the type of resume.',
-      );
-    }
+    errors.push(error);
+    await page.close();
+  }
 
-    if (!auth) {
-      throw new functions.https.HttpsError(
-        'failed-precondition',
-        'The function must be called while authenticated.',
-      );
-    }
+  return { page: null, errors };
+};
 
+const printResumeFunctionHandler = async ({ id, type }, { auth }) => {
+  if (!id) {
+    throw new functions.https.HttpsError(
+      'invalid-argument',
+      'The function must be called with argument "id" containing the resume ID.',
+    );
+  }
+
+  if (!type) {
+    throw new functions.https.HttpsError(
+      'invalid-argument',
+      'The function must be called with argument "type" containing the type of resume.',
+    );
+  }
+
+  if (!auth) {
+    throw new functions.https.HttpsError(
+      'failed-precondition',
+      'The function must be called while authenticated.',
+    );
+  }
+
+  try {
     const browser = await puppeteer.launch({
       headless: true,
       args: ['--no-sandbox'],
     });
-    const page = await browser.newPage();
-    await page.goto(BASE_URL + id, {
-      waitUntil: 'networkidle0',
-    });
+
+    const url = BASE_URL + id;
+    const { page, errors } = await gotoPage(browser, url);
+    if (errors && errors.length > 0) {
+      throw new Error(errors.join(' - '));
+    }
+
     await timeout(6000);
     await page.emulateMediaType('print');
     let pdf;
@@ -124,4 +182,15 @@ exports.printResume = functions
 
     await browser.close();
     return Buffer.from(pdf).toString('base64');
-  });
+  } catch (error) {
+    throw new functions.https.HttpsError('internal', error.message);
+  }
+};
+
+exports.deleteUser = functions
+  .runWith({ memory: '256MB' })
+  .https.onCall(deleteUserFunctionHandler);
+
+exports.printResume = functions
+  .runWith({ memory: '1GB' })
+  .https.onCall(printResumeFunctionHandler);