Builds an HTML index of all Spotify playlists belonging to a particular user

spotify-playlist-indexer.php

#!/usr/bin/php -q
<?php
/**
 * Builds an HTML index of all Spotify playlists belonging to a particular user; 
 * unfortunately, the API does not return folder information, so you can't
 * structure the index according to folders.
 *
 * How to use:
 *  1. go to https://developer.spotify.com/, log in, and create an app; you
 *     will need the Client ID and Client Secret
 *
 *  2. get your user ID: in the Spotify desktop application, click your name,  
 *     and click the ellipses beneath your name on the user screen; select
 *     "Share" from the popup menu, and copy the URL to the clipboard.
 *     The numeric portion at the end is your user id.
 * 
 *  3. download this script and save it on a system with PHP 5.5 or up
 *     (you will also need composer on this system: https://getcomposer.org/)
 *
 *  4. use composer to install spotify-web-api-php:
 *
 *     composer require jwilsson/spotify-web-api-php
 *   
 *  5. edit this script to put in the CLIENT_ID, CLIENT_SECRET, and USER_ID
 */

require 'vendor/autoload.php';

$user_id       = USER_ID;
$client_id     = 'CLIENT_ID';
$client_secret = 'CLIENT_SECRET';

$session = new SpotifyWebAPI\Session(
    $client_id,
    $client_secret
);

$api = new SpotifyWebAPI\SpotifyWebAPI();

$session->requestCredentialsToken();
$accessToken = $session->getAccessToken();

// Set the code on the API wrapper
$api->setAccessToken($accessToken);

retrieve_all_playlists ($api, $user_id);

function retrieve_all_playlists ($api, $user_id)
{
    $offset = 0;

    while (true)
    {
        $playlists = $api->getUserPlaylists($user_id, [
            'limit' => 50,
            'offset' => $offset,
        ]);

        $playlists = $playlists->items;

        $num_returned = count ($playlists);

        if ($num_returned == 0)
        {
            break;
        }
        $offset += $num_returned;

        foreach ($playlists as $p)
        {
            print <<<__TEXT__
<li><a href="{$p->external_urls->spotify}">{$p->name}</a></li>

__TEXT__;
        }
    }
}