code.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
require_once 'vendor/Request.php';
require_once 'vendor/Session.php';
require_once 'vendor/SpotifyWebAPI.php';
require_once 'vendor/SpotifyWebAPIException.php';

class Spotify extends MY_Controller
{

    public function __construct()
    {
        parent::__construct();

        // To use site_url and redirect on this controller.
        $this->load->helper('url');
    }

    public function login()
    {
        require_once 'vendor/Request.php';
        require_once 'vendor/Session.php';
        require_once 'vendor/SpotifyWebAPI.php';
        require_once 'vendor/SpotifyWebAPIException.php';

        $session = new SpotifyWebAPI\Session(
            'placeholder',
            'placeholder',
            'placeholder'
        );

        $scopes = array(
            'user-read-email',
            'user-library-modify'
            );

        $api = new SpotifyWebAPI\SpotifyWebAPI();

        // Redirect to Spotify login screen if user is not logged in.
        if (isset($_GET['code'])) {
            $session->requestAccessToken($_GET['code']);
            $accessToken = $session->getAccessToken();

            // Set the access token on the API wrapper
            $api->setAccessToken($accessToken);
            // Request a access token using the code from Spotify
            print_r($api->me());
        } else {
            $authorizeUrl = $session->getAuthorizeUrl(array(
            'scope' => $scopes
            ));
            header('Location: ' . $authorizeUrl);
            die();
        }
    }
}