Packt Pub Downloader - Quick hacky script to download all your e-books from packtpub.com. This may not always work, they may change their api calls etc.

readme.md

PacktPub Downloader

This is a script that's intended for bulk downloading all of your books and / or videos listed in the "My Owned Products" section of the PacktPub account pages.

Pre-requisite

You'll have to use either dev-tools, and get the information out of the site cookies, or use the supplied user.js with TamperMonkey / GreaseMonkey to get a valid user session.

Running

TamperMonkey / GreaseMonkey Script:

If you've not already got one of these extensions installed, install TamperMonkey. Ensure you use the correct one for your browser. This should install via each browser's official extension website, to alay at-least some safety concerns.

Follow the guide on how to install a user script for whichever extension you're using:

• TamperMonkey: How to install new scripts
• GreaseMonkey: Installing Scripts

Once you've done this refresh the PacktPub browser tab and login if you aren't already.

Once logged in there should now be an "Authentication Details" button in the bottom right hand corner. Click it and you should get a box which gives you a "Access Token" and "Refresh Token". You'll need these for the PHP downloader script.

PHP Downloader Script

The script can be run using:

php packtPubDownloader.php

or if you want to run inside Docker:

docker build . -t chappy84/packt-pub-downloader
docker run --rm -it -v "`pwd`":/mnt chappy84/packt-pub-downloader

This will fail without authentication details. These can be entered into the script, or passed via environment variables.

• Inside the script: Fill in the $accessToken and $sessionId variables at the top
• Environment Vars: Set PP_ACCESS_TOKEN and PP_SESSION_ID

After which you can run it.

The environment vars can be set on the command line as normal via say export or sourcing a file containing them. With Docker they can be passed to the script in various ways

There's various options that can be passed to the script. These can either be edited in the php script, or passed to the script using command line arguments.

The options are:

• --save-parent-dir - Parent dir of the ebooks and extras directories
• --ebooks-dir - path of the ebooks directory relative to $saveParentDir
• --extras-dir - path of the extras directory relative to $saveParentDir
• --sleep-duration - Time to delay between page requests / different book downloads
• --books-per-list-page - Book details to try requesting from the PacktPub API. This can be max 25
• --file-types-wanted - Different file types you want to download (see script head for available types)
• --download-front-cover - Whether or not you want the book front cover downloading (if available)
• --start-index - If set to a number this will be the first book downloaded of a range
• --end-index - If set to a number this will be the last book downloaded of a range

These can be passed on the command line to either the PHP script, or to the docker image, e.g.

php packtPubDownloader.php --ebooks-dir="my-ebooks"

or when using Docker:

docker run --rm -it -v "`pwd`":/mnt chappy84/packt-pub-downloader --start-index=3 --end-index=7

Dockerfile

FROM php:cli-alpine

RUN mkdir /opt/ppd /mnt/ebooks

COPY packtPubDownloader.php /opt/ppd/

VOLUME /mnt

WORKDIR /mnt

ENTRYPOINT ["/usr/local/bin/php", "/opt/ppd/packtPubDownloader.php"]

packtpub.auth-scraper.user.js

// ==UserScript==
// @name         PacktPub Auth token Scraper
// @version      0.3.1
// @description  Gets the access token and session id for you to use with the packtpub downloader
// @match        https://www.packtpub.com/owned*
// @match        https://account.packtpub.com/*
// @downloadURL  https://gist.github.com/chappy84/c3b1533cec4ac0589b2dcc318b4e6606/raw/packtpub.auth-scraper.user.js
// @updateURL    https://gist.github.com/chappy84/c3b1533cec4ac0589b2dcc318b4e6606/raw/packtpub.auth-scraper.user.js
// @supportURL   https://gist.github.com/chappy84/c3b1533cec4ac0589b2dcc318b4e6606
// @grant        GM_setClipboard
// @grant        GM_cookie
// ==/UserScript==

(function() {

    // I'd prefer these to be constants IN the CookieStore, as that's only where they're used, but JS doesn't support that! :sadpanda:
    const COOKIE_ACCESS_TOKEN_NAME = 'access_token_live';
    const COOKIE_SESSION_NAME = 'packt_session';

    class CookieStore {

        async getAccessToken() {
            return await this.getCookie(COOKIE_ACCESS_TOKEN_NAME);
        }

        async getSessionId() {
            // This cookie is HTTP Only, and accessing HTTP Only cookies only works in the beta versions of TamperMonkey at time of writing
            return await this.getCookie(COOKIE_SESSION_NAME);
        }

        async getCookie(cookieName) {
            const cookie = await GM.cookie.list({name: cookieName});
            return cookie.length == 1
                ? cookie[0].value || ''
                : '';
        }
    }

    // In application code, this'd be split up further into components etc, use jsx, & TS, but it's just a user script
    class TokenUI {

        constructor(store) {
            // define required class properties
            this.dialogBox = null;
            this.displayBtn = null;
            this.accessArea = null;
            this.sessionArea = null;
            this.hiddenClassHash = this.randomHash();

            // Initialise the UI
            this.initBox();
            if (this.isPolyfillRequired()) {
                this.polyfill(this.dialogBox);
            }
            this.initLauncher();
            this.toggleVisibility();
        }

        // Generates hashes. Used with css classes and element IDs
        randomHash() {
            return (Math.random().toString(36).substr(2) + Math.random().toString(36).substr(2)).replace(/^\d+(.+)$/, '$1');
        }

        // Checks if a polyfill is required for dialog element
        isPolyfillRequired() {
            if (window.HTMLDialogElement) {
                return false;
            }
            const dialogEl = document.createElement('dialog');
            return !dialogEl.showModal;
        }

        // Adds the polyfill script tag, then once loaded decorates the generated element
        polyfillDialog(dialogBox) {
            const polyfillScript = document.createElement('script');
            polyfillScript.src = 'https://cdnjs.cloudflare.com/ajax/libs/dialog-polyfill/0.5.4/dialog-polyfill.min.js';
            polyfillScript.addEventListener('load', () => {
                if (dialogPolyfill && dialogBox) {
                    dialogPolyfill.registerDialog(dialogBox);
                }
            });
            polyfillScript.addEventListener('error', (e) => {
                console.error('couldn\'t polyfill dialog, polyfill failed to load: ', e);
            });
            document.head.appendChild(polyfillScript);
        }

        isLoginPage(urlPath = document.location.pathname) {
            return !!urlPath.match(/^(?:\/(?:[#\?].*)?|\/login[#\?]?.*)$/);
        }

        // Toggles wheter or not to display the UI if it's on the login page or not.
        toggleVisibility(urlPath = document.location.pathname) {
            if (this.displayBtn && this.dialogBox) {
                if (this.isLoginPage(urlPath)) {
                    this.displayBtn.classList.add(this.hiddenClassHash);
                    this.dialogBox.classList.add(this.hiddenClassHash);
                    this.dialogBox.close();
                    if (this.accessArea) {
                        this.accessArea.value = '';
                    }
                    if (this.sessionArea) {
                        this.sessionArea.value = '';
                    }
                } else {
                    this.displayBtn.classList.remove(this.hiddenClassHash);
                }
            }
        }

        // Adds the dialog launch button
        initLauncher() {
            if (this.displayBtn) {
                return;
            }

            const authDetHash = this.randomHash();
            this.displayBtn = document.createElement('button');
            this.displayBtn.id = authDetHash;
            this.displayBtn.textContent = 'Authentication Details';
            this.displayBtn.addEventListener('click', async () => {
                if (this.dialogBox && this.dialogBox.showModal) {
                    if (this.accessArea) {
                        this.accessArea.value = await store.getAccessToken();
                    }
                    if (this.sessionArea) {
                        this.sessionArea.value = await store.getSessionId();
                    }
                    this.dialogBox.classList.remove(this.hiddenClassHash);
                    this.dialogBox.showModal();
                }
            });
            this.displayBtn.classList.add(this.hiddenClassHash);

            const style = document.createElement('style');
            style.textContent = `
                #${this.displayBtn.id} {
                    font-family: Montserrat,Helvetica,sans-serif;
                    font-weight: 400;
                    font-size: 16px;
                    color: #3c3c3b;

                    background-color: #ec6611;
                    cursor: pointer;
                    border: 0;
                    padding: 10px 20px;
                    border-radius: 2px;
                    color: #fff;
                    position: fixed;
                    bottom: 50px;
                    right: 50px;
                    cursor: pointer;
                    z-index: 10;
                }
                #${this.displayBtn.id}:hover {
                    background-color: #c85808;
                }
                #${this.displayBtn.id}.${this.hiddenClassHash} {
                    display: none;
                    visibility: hidden;
                }
            `;
            document.head.appendChild(style);
            document.body.appendChild(this.displayBtn);
        }

        // Adds the dialog box to display the access token and session id
        initBox() {
            if (this.dialogBox) {
                return;
            }

            const xBtnHash = this.randomHash();
            const headerContHash = this.randomHash();
            const copyBtnHash = this.randomHash();
            const accessAreaHash = this.randomHash();
            const sessionAreaHash = this.randomHash();
            const closeBtnHash = this.randomHash();
            const closeContHash = this.randomHash();

            this.dialogBox = document.createElement('dialog');
            this.dialogBox.id = this.randomHash();
            this.dialogBox.classList.add(this.hiddenClassHash);

            this.dialogBox.innerHTML = `
                <button type="button" id="${xBtnHash}">&#215;</button>
                <h4>Authentication Details</h4>
                <div class="${headerContHash}">
                    <label for="${accessAreaHash}">Access Token</label>
                    <button type="button" class="${copyBtnHash}">Copy Access Token to Clipboard</button>
                </div>
                <textarea readonly="readonly" id="${accessAreaHash}"
                    placeholder="If there's no token here, the required cookies have no value, or you're logged out. Login again."
                ></textarea>
                <div class="${headerContHash}">
                    <label for="${sessionAreaHash}">Session ID</label>
                    <button type="button" class="${copyBtnHash}">Copy Session ID to Clipboard</button>
                </div>
                <!-- This cookie is HTTP Only, and accessing HTTP Only cookies only works in the beta versions of TamperMonkey at time of writing -->
                <textarea readonly="readonly" id="${sessionAreaHash}"
                    placeholder="If there's no session ID here, and you're logged in, use the dev tools to get it from the '${COOKIE_SESSION_NAME}' cookie."
                ></textarea>
                <div class="${closeContHash}">
                    <button type="button" id="${closeBtnHash}">Close</button>
                </div>
            `;
            const style = document.createElement('style');
            style.textContent = `
                #${this.dialogBox.id} {
                    font-family: Montserrat,Helvetica,sans-serif;
                    font-weight: 400;
                    font-size: 16px;
                    color: #3c3c3b;

                    min-width: 50%;
                    border: 0;
                    box-shadow: 0 11px 15px -7px rgba(0,0,0,.2), 0 24px 38px 3px rgba(0,0,0,.14), 0 9px 46px 8px rgba(0,0,0,.12);
                    margin: auto;
                    padding: 20px;
                }
                #${this.dialogBox.id}.${this.hiddenClassHash} {
                    display: none;
                    visibility: hidden;
                }
                #${this.dialogBox.id} h4 {
                    font-size: 2.5rem;
                    font-weight: bold;
                }
                #${xBtnHash} {
                    box-shadow: 0 3px 5px -1px rgba(0,0,0,.2), 0 6px 10px 0 rgba(0,0,0,.14), 0 1px 18px 0 rgba(0,0,0,.12);
                    border-radius: 50%;
                    border: 0;
                    width: 40px;
                    height: 40px;
                    cursor: pointer;
                    position: absolute;
                    top: 35px;
                    right: 35px;
                    font-size: 3ex;
                }
                .${closeContHash}, #${this.dialogBox.id} h4, #${this.dialogBox.id} .${headerContHash}, #${this.dialogBox.id} textarea {
                    display: block;
                    width: 95%;
                    margin: 20px auto;
                }
                #${this.dialogBox.id} h4 {
                    padding-right: 60px;
                }
                #${this.dialogBox.id} .${headerContHash} {
                    margin-top: 40px;
                }
                #${this.dialogBox.id} .${headerContHash} label {
                    margin-top: 10px;
                }
                #${this.dialogBox.id} textarea {
                    background-color: #e5eaee;
                    border: 0;
                    padding: 10px;
                }
                #${accessAreaHash} {
                    height: 18em;
                }
                #${closeBtnHash}, .${copyBtnHash} {
                    cursor: pointer;
                    border: 0;
                    padding: 10px 20px;
                    border-radius: 2px;
                }
                #${closeBtnHash} {
                    background-color: #e5eaee;
                    margin: 20px auto;
                }
                #${closeBtnHash}:hover {
                    background-color: #dbe1e5;
                }
                #${this.dialogBox.id} .${copyBtnHash} {
                    background-color: #ec6611;
                    color: #fff;
                }
                #${this.dialogBox.id} .${copyBtnHash}:hover {
                    background-color: #c85808;
                }
                #${this.dialogBox.id} .${headerContHash} {
                    display: flex;
                    justify-content: space-between;
                }
            `;
            document.head.appendChild(style);
            document.body.appendChild(this.dialogBox);
            const closeFn = () => {
                this.dialogBox.close();
                this.dialogBox.classList.add(this.hiddenClassHash);
            };
            document.getElementById(xBtnHash).addEventListener('click', closeFn);
            document.getElementById(closeBtnHash).addEventListener('click', closeFn);
            this.dialogBox.querySelectorAll(`.${copyBtnHash}`).forEach((el) => {
                el.addEventListener('click', (e) => {
                    const textArea = document.getElementById(e.target.parentNode.querySelector('label[for]').htmlFor);
                    if (textArea) {
                        GM_setClipboard(textArea.value, 'text');
                    }
                })
            });

            this.accessArea = document.getElementById(accessAreaHash);
            this.sessionArea = document.getElementById(sessionAreaHash);
        }
    }

    const store = new CookieStore();
    const ui = new TokenUI(store);

    // Clear the token values on logout, and hide the UI
    window.history.pushState = new Proxy(window.history.pushState, {
        apply: (target, thisArg, argumentsList) => {
            // pushState arguments: state, title, url
            const retVal = target.apply(thisArg, argumentsList);
            ui.toggleVisibility(argumentsList[2]); // url from arguments
            return retVal;
        }
    });

})();

packtPubDownloader.php

<?php

define('DS', DIRECTORY_SEPARATOR);
// Check if in Docker Container
define('CGROUP_FILE', '/proc/1/cgroup');
define('IN_DOCKER', file_exists(CGROUP_FILE) && false !== preg_match('#\:/docker/#', file_get_contents(CGROUP_FILE)));

// config values
$saveParentDir = __DIR__; // Parent dir of the ebooks and extras directories
$ebooksDir = 'ebooks'; // path of the ebooks directory relative to $saveParentDir
$extrasDir = 'ebooks' . DS . 'extras'; // path of the extras directory relative to $saveParentDir
$sleepDuration = 4; // Time to delay between page requests / different book downloads
$booksPerListPage = 24; // Book details to try requesting from the PacktPub API. This can be max 25
$fileTypesWanted = ['epub', 'mobi', 'pdf', 'code', 'video']; // Different file types from BOOK_FORMATS_URL you want to download
$downloadFrontCover = true; // Whether or not you want the book front cover downloading (if available)
$startIndex = false; // If set to a number this will be the first book downloaded of a range
$endIndex = false; // If set to a number this will be the last book downloaded of a range

// These are required from the website cookies to correctly authenticate
$accessToken = ''; // Access Token. Obtain using associated user.js with TamperMonkey, or use dev-tools console
$sessionId = ''; // Packt Session. Obtain using associated user.js with TamperMonkey, or use dev-tools console

define(
    'OWNED_BOOKS_URL',
    'https://www.packtpub.com/api/entitlements/users/me/owned?sort=createdAt:desc&search=&limit=%d&offset=%d'
);
define('BOOK_FORMATS_URL', 'https://services.packtpub.com/products-v1/products/%d/types');
define('FILE_DOWNLOAD_DETAILS_URL', 'https://services.packtpub.com/products-v1/products/%d/files/%s');
define('BOOK_SUMMARY_URL', 'https://static.packt-cdn.com/products/%d/summary');

$defaultCurlOptions = [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36',
];

// Used to clear the current output line
// pinched from symfony console: https://github.com/symfony/console/blob/master/Helper/ProgressIndicator.php#L211
define('CLEAR_LINE', "\x0D\x1B[2K");
// I might write this properly, and use symfony console someday!

echo 'Confiruration Options:', PHP_EOL;

$cliOptMap = [
    'save-parent-dir:' => 'saveParentDir',
    'ebooks-dir:' => 'ebooksDir',
    'extras-dir:' => 'extrasDir',
    'sleep-duration:' => 'sleepDuration',
    'books-per-list-page:' => 'booksPerListPage',
    'file-types-wanted:' => 'fileTypesWanted',
    'download-front-cover:' => 'downloadFrontCover',
    'start-index:' => 'startIndex',
    'end-index:' => 'endIndex',
];

$cliOptValues = getopt('', array_keys($cliOptMap));

if (IN_DOCKER) {
    if (!empty($cliOptValues['save-parent-dir'])) {
        echo 'Ignoring --save-parent-dir as running inside docker container. Mount a volume to /mnt instead.', PHP_EOL;
        unset($cliOptValues['save-parent-dir']);
    }
    $saveParentDir = '/mnt';
}

foreach ($cliOptMap as $cliOptName => $varName) {
    $nameToUse = str_replace(':', '', $cliOptName);
    if (!empty($cliOptValues[$nameToUse])) {
        $valToAssign = $cliOptValues[$nameToUse];
        if ($varName == 'fileTypesWanted' && !is_array($valToAssign)) {
            $valToAssign = [$valToAssign];
        }
        // I know, variable variables are awful, but it's got some protection as they're known
        // variable names, and at-least it's not PHP 4/5's register_globals! I'm just being lazy ;-P
        $$varName = $valToAssign;
    }
    echo $nameToUse, ' = ', var_export($$varName), PHP_EOL;
}

// These are env vars rather than arguments due to their sensitive nature. If using docker run, use --env, -e or --env-file
$envVarMap = [
    'PP_ACCESS_TOKEN' => 'accessToken',
    'PP_SESSION_ID' => 'sessionId'
];

foreach ($envVarMap as $envVarName => $varName) {
    if (!empty($_ENV[$envVarName])) {
        // see above note on variable variables
        $$varName = $_ENV[$envVarName];
    }
    echo $varName, ' = ', var_export($$varName), PHP_EOL;
}

function errorAndDie($message)
{
    echo $message, PHP_EOL;
    die;
}

function getAccessTokenExpiry($accessToken)
{
    // It's a JWT, so we can easily extract it out
    list(, $tokenDataBase64, ) = explode('.', $accessToken);
    $tokenData = json_decode(base64_decode($tokenDataBase64));
    return $tokenData->exp;
}

// Human readable format, taken from here: https://stackoverflow.com/questions/15188033/human-readable-file-size#answer-23888858
function sizeToHuman($bytes)
{
    $size   = array('B', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB');
    $factor = floor((strlen($bytes) - 1) / 3);
    $dec = ($bytes > 0) ? 2 : 0;

    return sprintf("%.{$dec}f %s", $bytes / (1000 ** $factor), @$size[$factor]);
}

$checkAccessTokenExpiry = function(bool $outputExpiry = false) use (&$accessToken)
{
    $expiryTimestamp = getAccessTokenExpiry($accessToken);

    if ($expiryTimestamp <= time()) {
        errorAndDie('Current Access Token has expired');
    }
    if ($outputExpiry) {
        echo 'Access Token expires at ', date('Y/m/d H:i:s T', $expiryTimestamp), PHP_EOL;
    }

    return $expiryTimestamp;
};

$getJson = function ($url, $errorMessage, $extraOptions = []) use ($checkAccessTokenExpiry, $defaultCurlOptions, &$accessToken, &$sessionId)
{
    if (!empty($accessToken)) {
        $checkAccessTokenExpiry();
        if (!isset($extraOptions[CURLOPT_HTTPHEADER])) {
            $extraOptions[CURLOPT_HTTPHEADER] = [];
        }
        $extraOptions[CURLOPT_HTTPHEADER][] = 'Authorization: Bearer ' . $accessToken;
        $extraOptions[CURLOPT_COOKIE] = 'packt_session=' . $sessionId . '; path=/';
    }

    $ch = curl_init($url);
    curl_setopt_array($ch, $defaultCurlOptions + $extraOptions);

    $response = curl_exec($ch);
    $responseCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($responseCode !== 200) {
        errorAndDie($errorMessage. ': '. $responseCode);
    }

    if (null === ($decodedJson = json_decode($response))) {
        errorAndDie($errorMessage);
    }

    return $decodedJson;
};

$downloadFile = function ($url, $savePath, $errorMessage) use ($defaultCurlOptions)
{
    $fh = fopen($savePath, 'w+');

    $filesize = 0;

    $ch = curl_init($url);
    curl_setopt_array(
        $ch,
        $defaultCurlOptions + [
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_RETURNTRANSFER => false,
            CURLOPT_FILE => $fh,
            CURLOPT_HEADERFUNCTION => function($ch, $header) use (&$filesize) {
                static $setFilesize = false;
                if (!$setFilesize) {
                    $headerParts = explode(':', $header, 2);
                    if (2 == count($headerParts) && 'content-length' == strtolower(trim($headerParts[0]))) {
                        $filesize = intval(trim($headerParts[1]));
                        echo ' , filesize: ', sizeToHuman($filesize), PHP_EOL;
                        $setFilesize = true;
                    }
                }
                return strlen($header);
            },
            CURLOPT_WRITEFUNCTION => function($ch, $data) use ($fh, &$filesize) {
                if ($filesize > 0) {
                    static $downloadedSize = 0;
                    $downloadedSize += strlen($data);
                    $downloadedPercentage = $downloadedSize / $filesize;
                    echo CLEAR_LINE;
                    if ($downloadedPercentage < 1) {
                        echo 'Downloaded ', number_format($downloadedPercentage * 100, 2, '.', ''), '%';
                    }
                    return fwrite($fh, $data);
                }
                return false;
            }
        ]
    );
    curl_exec($ch);
    $responseCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
    fclose($fh);

    if ($responseCode !== 200 || !filesize($savePath)) {
        echo $errorMessage, ': ', $responseCode, PHP_EOL;
        return false;
    }
    return true;
};

if (empty($accessToken)) {
    errorAndDie('Missing auth token. Stopping script.');
}

$checkAccessTokenExpiry(true);

echo 'Sleeping for ', $sleepDuration, ' seconds', PHP_EOL;
sleep($sleepDuration);

$bookCount = 0;
echo 'Getting list of eBooks', PHP_EOL;
$booksInfo = $getJson(
    sprintf(OWNED_BOOKS_URL, $booksPerListPage, $bookCount),
    'Couldn\'t retrieve list of books'
);
$totalNumberOfBooks = $booksInfo->count;
$noOfPages = ceil($totalNumberOfBooks / $booksPerListPage);

echo 'Total number of books: ', $totalNumberOfBooks, ', Total number of pages: ', $noOfPages, PHP_EOL;

for ($pageCount = 1; $pageCount <= $noOfPages; $pageCount++) {

    if ($pageCount > 1) {
        $booksInfo = $getJson(
            sprintf(OWNED_BOOKS_URL, $booksPerListPage, $bookCount),
            'Couldn\'t retrieve list of books'
        );
    }

    $pageBooksCount = count($booksInfo->data);

    echo 'Found ', $pageBooksCount, ' books on page ', $pageCount, PHP_EOL;

    if (count($booksInfo->data)) {
        if (!file_exists($saveParentDir . DS . $ebooksDir)) {
            mkdir($saveParentDir . DS . $ebooksDir);
        }
        if (!file_exists($saveParentDir . DS . $extrasDir)) {
            mkdir($saveParentDir . DS . $extrasDir);
        }
        foreach ($booksInfo->data as $bookData) {
            $bookCount++;

            if ($startIndex !== false && $bookCount < $startIndex) {
                continue;
            }

            $name = $bookData->productName;
            echo $bookCount, '. Examining "', $name, '"', PHP_EOL;
            $fileName = preg_replace(['/[\<\>\:\"\/\\\|\?\*\%]+/', '/\s+/', '/[\[\]]/'], ['-', '_', ''], $name);

            $downloadFormatInfo = $getJson(
                sprintf(BOOK_FORMATS_URL, $bookData->productId),
                'Couldn\'t retrieve available book formats'
            );

            $downloadLinks = [];
            foreach ($downloadFormatInfo->data[0]->fileTypes as $fileType) {
                if (in_array($fileType, $fileTypesWanted)) {
                    $downloadLinks[$fileType] = sprintf(FILE_DOWNLOAD_DETAILS_URL, $bookData->productId, $fileType);
                }
            }

            if (0 === count($downloadLinks)) {
                echo 'No Downloadable Books / Code', PHP_EOL;
                continue;
            }
            foreach ($downloadLinks as $format => $downloadHref) {
                $downloadLinkInfo = $getJson(
                    $downloadHref,
                    'Couldn\'t retrieve book download link'
                );
                $savePath = ('code' === $format)
                    ? $saveParentDir . DS . $extrasDir . DS . $fileName . '.zip'
                    : $saveParentDir . DS . $ebooksDir . DS . $fileName . '.' . (('video' === $format) ? 'zip' : $format);
                echo 'Downloading ', $format, ' to ', $savePath;

                $downloadFile($downloadLinkInfo->data, $savePath, $format . ' download failed');
            }
            if ($downloadFrontCover) {
                $frontCoverLinkInfo = $getJson(
                    sprintf(BOOK_SUMMARY_URL, $bookData->productId),
                    'Couldn\'t retrieve book summary link'
                );
                if (!empty($frontCoverLinkInfo->coverImage)) {
                    $fileExt = preg_replace('/^.+\.([^\.]+)$/', '$1', $frontCoverLinkInfo->coverImage);
                    $savePath = $saveParentDir . DS . $extrasDir . DS . $fileName . '.' . $fileExt;
                    echo 'Downloading Front Cover to: ', $savePath;
                    $downloadFile(
                        $frontCoverLinkInfo->coverImage,
                        $savePath,
                        'Front cover download failed'
                    );
                }
            }

            if ($endIndex !== false && $bookCount >= $endIndex) {
                break 2;
            }

            echo 'Sleeping for ', $sleepDuration, ' seconds', PHP_EOL;
            sleep($sleepDuration);
        }
    }
}

No longer works due to changes in site - quick hack I put together here you can look at to see new method against their new REST endpoints which is much simpler than site parsing. https://gist.github.com/nneul/6eda98fd87a58a623b857523247f3471

This is now once again working after PacktPub's major site changes

PacktPub have just implemented some changes again. The ability to buy/own books seems to be being phased out, in favour of a subscription model to access their whole library. Their API URLs seem to be changing slightly e.g. the prefix https://services.packtpub.com/entitlements-v1 is changing to https://subscription.packtpub.com/api/entitlements.
Ultimately I wouldn't expect to be able to download all of your books using this tool forever, and eventually to have to use their website to read the books.