Spotify Token Authorization in PHP

spotify_auth.php

<?php

$client_id = "your client id";
$client_secret = "your client secret";
$redirect_uri = "redirect URI, should be the URL to this PHP file after placed on a web server (e.g. http://localhost:9000/spotify_auth.php)";

if(isset($_GET["code"])) { // return the auth details
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://accounts.spotify.com/api/token");
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
    curl_setopt($ch, CURLOPT_POSTFIELDS, "grant_type=authorization_code&redirect_uri=" . $redirect_uri . "&code=" . $_GET["code"]); 
    curl_setopt($ch, CURLOPT_HTTPHEADER, array("Authorization: Basic " . base64_encode($client_id . ":" . $client_secret))); 

    // for local developement, do not use elsewhere.
    // curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

    $result = curl_exec($ch);
    curl_close($ch);
    
    
    header('Content-Type: application/json; charset=utf-8');
    echo $result;
} else { // redirect to spotify auth page
    $auth_headers = (object) [
        "client_id" => $client_id,
        "response_type" => "code",
        "redirect_uri" => $redirect_uri,
        "scope" => "user-library-read user-read-email"
    ];

    header("Location: https://accounts.spotify.com/authorize?" . http_build_query($auth_headers));
}

?>