DHL Express - Change currency conversion rate with live data

functions.php

add_filter( 'wf_dhl_conversion_rate', 'alter_conversion_rate',10,2);

function alter_conversion_rate($rate, $dhl_currency){
    if( !function_exists('get_woocommerce_currency')){
        return;
    }  
    $from_currency = urlencode($dhl_currency);
    $to_currency = urlencode(get_woocommerce_currency());

    try {
        $result = file_get_contents("https://www.alphavantage.co/query?function=CURRENCY_EXCHANGE_RATE&from_currency=$from_currency&to_currency=$to_currency&apikey=VY5GQQZFQ7WA3U6Q");// generate api key in the alphavantage website
        if ( $result === FALSE ) {
            throw new Exception("Unable to receive currency conversion response from Alpha Vantage API call ( https://www.alphavantage.co ). Skipping the shipping rates for the DHL as shop currency and the currency returned by Rates API differs.");
        }
    }
    catch(Exception $e) {
        //Please provide fopen permission in php.ini
        return 0;
    }

    $result = json_decode($result,true);

    if(!empty($result['Realtime Currency Exchange Rate']['5. Exchange Rate']))
    $converted_rate = $result['Realtime Currency Exchange Rate']['5. Exchange Rate'];

    if(!empty($converted_rate)){
        $rate = $converted_rate;
    }
    return $rate;
}