Extract currency rates from moneypolo.cz

moneypolo.php

<?php
class MoneyPoloRates
{
    public $EUR;
    public $GBP;
    public $USD;

    private $reply;
    private $error = true;
    private $errorMessage;

    public function MoneyPoloRates()
    {
        $this->getAjaxContents();
        $this->extractRates();
    }

    public function error()
    {
        return $this->error;
    }

    public function errorMessage()
    {
        return $this->errorMessage == "" ? "Unknown error" : $this->errorMessage;
    }

    private function getAjaxContents()
    {
        // Maybe use some cache on disk?
        $url = "http://moneypolo.cz/wp-content/themes/moneypolo/ajax-handler.php";
        $data = "func=getCurrencyRates";

        try {
            $this->reply = $this->do_post_request($url, $data);
        }
        catch (Exception $e) {
            $this->error = true;
            $this->errorMessage = $e->getMessage();
        }
    }

    private function extractRates()
    {
        // $this->reply is in JSON format
        $decoded = json_decode($this->reply);

        if ($decoded === null) {
            $this->error = true;
            $this->errorMessage = "Cannot decode JSON!";
            return;
        }

        if ($decoded->{"success"} === false) {
            $this->error = true;
            $this->errorMessage = "Remote server returned success = fail.";
            return;
        }

        $data = $decoded->{"data"};

        $dataEUR = $data->{"EUR"};
        $this->EUR["buy"] = $dataEUR->{"MTCZKBUY"}->{"Rate"};
        $this->EUR["sell"] = $dataEUR->{"MTCZKSELL"}->{"Rate"};

        $dataGBP = $data->{"GBP"};
        $this->GBP["buy"] = $dataGBP->{"MTCZKBUY"}->{"Rate"};
        $this->GBP["sell"] = $dataGBP->{"MTCZKSELL"}->{"Rate"};

        $dataUSD = $data->{"USD"};
        $this->USD["buy"] = $dataUSD->{"MTCZKBUY"}->{"Rate"};
        $this->USD["sell"] = $dataUSD->{"MTCZKSELL"}->{"Rate"};

        $this->error = false;
        $this->errorMessage = "No error";
    }

    // http://wezfurlong.org/blog/2006/nov/http-post-from-php-without-curl/
    private function do_post_request($url, $data, $optional_headers = null)
    {
        $params = array('http' => array(
            'method' => 'POST',
            'content' => $data
        ));

        if ($optional_headers!== null) {
            $params['http']['header'] = $optional_headers;
        }

        $ctx = stream_context_create($params);
        $fp = @fopen($url, 'rb', false, $ctx);

        if (!$fp) {
            throw new Exception("Problem with $url, $php_errormsg");
        }

        $response = @stream_get_contents($fp);

        if ($response === false) {
            throw new Exception("Problem reading data from $url, $php_errormsg");
        }

        return $response;
    }
}

// Usage
$c = new MoneyPoloRates();
if ($c->error()) {
    echo "<b>Error:</b> " . $c->errorMessage() . "<br/>";
}
else {
    echo "Currency - Buy - Sell<br/>";
    echo "EUR: " . $c->EUR["buy"] . " / " . $c->EUR["sell"] . "<br/>";
    echo "GBP: " . $c->GBP["buy"] . " / " . $c->GBP["sell"] . "<br/>";
    echo "USD: " . $c->USD["buy"] . " / " . $c->USD["sell"] . "<br/>";
}
?>