Power BI embedded - switch to premium in php application

Hi there - I'm currently making the switch from Power BI workspace collections to the new model. Previously I used embedded in a PHP application (I'm not a professional PHP developer, though I work with Power BI + BI architecture every day).

Unfortunately, all of the documentation is in c# for ASP.net development. 

Obviously, I dont wan't to reinvent the wheel, and would need for this to work in PHP which is where our development Minimum Viable Product currently is.

This is the code that I used before, which is from an old embedded Microsoft tutorial (which was great!) 

Will it be possible to amend the code below for the new model, or do I need to start from scratch?

<!--?php 
// 1. power bi access key 
$accesskey = "HIDDEN"; 
// 2. construct input value 
$token1 = "{" . "\"typ\":\"JWT\"," . "\"alg\":\"HS256\"" . "}"; 
$token2 = "{" . "\"wid\":\"HIDDEN\"," . 
// workspace id 
"\"rid\":\"HIDDEN\"," . 
// report id 
"\"wcn\":\"HIDDEN\"," . 
// workspace collection name "\"iss\":\"HIDDEN\"," . "\"ver\":\"0.2.0\"," . "\"aud\":\"https://analysis.windows.net/powerbi/api\"," . "\"nbf\":" . 
date("U") . "," . "\"exp\":" . date("U" , strtotime("+1 hour")) . "}"; 
$inputval = rfc4648_base64_encode($token1) . "." . rfc4648_base64_encode($token2); 
// 3. get encoded signature value 
$hash = hash_hmac("sha256", $inputval, $accesskey, true); 
$sig = rfc4648_base64_encode($hash); 
// 4. get apptoken 
$apptoken = $inputval . "." . $sig; 
// helper functions 
function rfc4648_base64_encode($arg) { $res = $arg; 
$res = base64_encode($res); 
$res = str_replace("/", "_", $res); 
$res = str_replace("+", "-", $res); 
$res = rtrim($res, "="); return $res; } ?--><button id="btnView" class="et_pb_contact_submit et_pb_button">Open Report</button><div id="divView"><iframe id="ifrTile" width="100%" height="700"></iframe></div><script>
        (function () {
          document.getElementById('btnView').onclick = function() {
            var iframe = document.getElementById('ifrTile');
            iframe.src="https://app.powerbi.com/appTokenReportEmbed?reportId=HIDDEN";
            iframe.onload = function() {
              var msgJson = {
                action: "loadReport",
                accessToken: "<?=$apptoken?>",
                height: 500,
                width: 722
              };
              var msgTxt = JSON.stringify(msgJson);
              iframe.contentWindow.postMessage(msgTxt, "*");
            };
          };
        }());</script>