<?php

function getToken(){
    $curl = curl_init();
    
    $params = array(
        CURLOPT_URL =>  ACCESS_TOKEN_URL."?"
                        ."code=".$code
                        ."&grant_type=authorization_code"
                        ."&client_id=". CLIENT_ID
                        ."&client_secret=". CLIENT_SECRET
                        ."&redirect_uri=". CALLBACK_URL,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_MAXREDIRS => 10,
        CURLOPT_TIMEOUT => 30,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
        CURLOPT_CUSTOMREQUEST => "POST",
        CURLOPT_NOBODY => false, 
        CURLOPT_HTTPHEADER => array(
        "cache-control: no-cache",
        "content-type: application/x-www-form-urlencoded",
        "accept: *",
        "accept-encoding: gzip, deflate",
        ),
    );
    
    curl_setopt_array($curl, $params);
    
    $response = curl_exec($curl);
    $err = curl_error($curl);
    
    curl_close($curl);
    
    if ($err) {
        echo "cURL Error #01: " . $err;
    } else {
        $response = json_decode($response, true);    
        if(array_key_exists("access_token", $response)) return $response;
        if(array_key_exists("error", $response)) echo $response["error_description"];
        echo "cURL Error #02: Something went wrong! Please contact admin.";
    }
}