How to get data from json to php

<?php
$USER_NAME ="abc";
$PASSWORD = "abc";
$sessionResponse = null;
$sessionId       = null;
$secretKey       = null;
 
  
$subContext = "/files/report?domain=PKE1513&entityReturnFormat=RJSON";
//$subContext = "/report";
//$subContext = "/files/reports";
 
while (true) {
  try {
    if ($sessionId == null) {
      $encodedUserAndPassword = base64_encode($USER_NAME . ":" . $PASSWORD);
      $authParameters[]       = "Authorization: Basic " . $encodedUserAndPassword;
      $sessionResponse        = requestHTTP("GET", "http://www.xx.com", "/core/session/", $authParameters);
 
      if ($sessionResponse["http_code"] == 401) {
        exit("Incorrect username or password");
      }
      echo "\n/core/session/ body: \n$sessionResponse[body]\n";
 
      $decode    = json_decode($sessionResponse["body"], TRUE);
      $sessionId = $decode["sessionId"];
      $secretKey = $decode["secretKey"];
    }
 
    $timestamp = time();
    $signature = base64_encode(hash("MD5", $sessionId . $secretKey . $timestamp, true));
 
    $authParameters   = array();
    $authParameters[] = "Authorization: StkAuth session=\"$sessionId\",signature=\"$signature\",timestamp=\"$timestamp\"";
 

    $response     = requestHTTP("GET", "externalappgw.br.xx.com", $subContext, $authParameters);
    $responseCode = $response["http_code"];

    //var_dump($response);
    //exit();
 
    if ($responseCode == "200") {
      // Aquí poner el código correspondiente al parseo del contenido.
      echo "\nResponseBody:\n$response[body]";
    
      
 
    } else if ($responseCode == "401") {
      $decodedResponse = json_decode($response["body"], TRUE);
      $errorCode       = $decodedResponse["errorCode"];
 
      if ($errorCode == "111") {
        $sessionId = null;
        $secretKey = null;
 
        try {
          //Espera 30 segundos antes de renovar sesión.
          sleep(30);
        } catch (InterruptedException $iex) {}
 
        continue;
      }
    } else {
      echo "Unknown error";
    }
  } catch (Exception $ex) {}
 
  try {
  
    sleep(30);
  } catch (InterruptedException $iex) {}
}
 
function requestHTTP($method, $server, $serviceContext, $authParameters) {
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
  curl_setopt($ch, CURLOPT_URL, $server.$serviceContext);
  curl_setopt($ch, CURLOPT_HEADER, 0);
  curl_setopt($ch, CURLOPT_HTTPHEADER, $authParameters);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  $body = curl_exec($ch);
 
  $response         = curl_getinfo($ch);
  $response["body"] = $body;
 
  curl_close($ch);
  return $response;
}