MyCurrencyGrabber

MyCurrencyGrabber.php

<?php
namespace Megagroup;

interface CurrencyGrabberInterface 
{
  /**
   * @brief Downloads currency rates from the remote server
   * and saves in database.
   *
   * @return boolean
   */
  public function download();
  /**
   * @brief Converts rate
   *
   * @param string $from Source currency symbol
   * @param string $to Destination Currency symbol
   *
   * @return double
   */
  public function convert($from, $to);
  /**
   * @brief Retrieves currency from DB
   *
   * @param string $symbol
   *
   * @return array
   */
  public function get($symbol);
}

class MyCurrencyGrabber implements CurrencyGrabberInterface, \Iterator
{
	private $db;
	private $position = 0;
	private $arrayCurrency;

	function __construct(Db $db=null) 
	{
		$this->db = $db;
	}

	public function current() {
		return $this->arrayCurrency[$this->position];
	}

	public function next() {
		++$this->position;
	}

	public function valid() {
		return isset($this->arrayCurrency[$this->position]);
	}

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

	public function rewind() {
		if($this->initArray()) $this->position = 0;
			else trigger_error("No data!", E_USER_ERROR);
		//var_dump($this->arrayCurrency);
	}
	
	public function download()
	{
		if(!$this->db) return false;
		//prepare and clear buffer	
		$this->db->query('truncate table currency_rates');

		$xml = new \DOMDocument();
		$url = 'http://www.cbr.ru/scripts/XML_daily.asp?date_req=' . date('d.m.Y');

 		//download data from server
		if (@$xml->load($url))
		{
			$root = $xml->documentElement;
			$items = $root->getElementsByTagName('Valute');

 			//save the data to database
			foreach ($items as $item)
			{
				$numcode = $this->esc($item->getElementsByTagName('NumCode')->item(0)->nodeValue);
				$charcode = $this->esc($item->getElementsByTagName('CharCode')->item(0)->nodeValue);
				$nominal = $this->esc($item->getElementsByTagName('Nominal')->item(0)->nodeValue);
				$name = $this->esc($item->getElementsByTagName('Name')->item(0)->nodeValue);
				$value = $this->esc($item->getElementsByTagName('Value')->item(0)->nodeValue);
				$value = floatval(str_replace(',', '.', $value));
				$query="INSERT INTO `cbr`.`currency_rates` (`num_code`, `char_code`, `nominal`, `name`, `value`)"
				." VALUES ($numcode, '$charcode', $nominal, '$name', $value)";
				$this->db->query($query);
			}

			return true;
		} 
		else
			return false;
	}

	public function convert($from=null, $to=null)
	{
		$rate_from = null; 
		$rate_to = null; 
		//var_dump($from);var_dump($to);
		if(!$from or !$to or !$this->db){
			return 0;	
		} 
		$from=$this->esc($from);
		$to=$this->esc($to);
  		// get data from db
		$query=
			"select * from currency_rates where char_code = '$from' or char_code = '$to'";
			
		if ($result = $this->db->query($query) and $result->num_rows==2) {
			//die('The query passed!'.$result->num_rows);
			$rate_from=$result->fetch_object();
			$rate_to=$result->fetch_object();
			$result->close();
		}
  		else   		// if no data 
			return 0;

  		// calculate rate
    	// the formula to calculate exchange rate is
    	// nominalFrom*nominalTo*valueFrom/valueTo
		$result = $rate_from->nominal*$rate_to->nominal*$rate_from->value/$rate_to->value;
		return round($result,4);
	}

	public function get($symbol)
	{
		$result = null;
		if(!$symbol or !$this->db){
			return $result;	
		}
		$symbol=$this->esc($symbol); 
  		// get data from db 
		$query="select * from currency_rates where char_code = '$symbol'";
		if ($res = $this->db->query($query)) {
			$result=$res->fetch_assoc();
			$res->close();
		}

		return $result;
	}

	private function esc($value='')
	{
		return $this->db->real_escape_string($value);
	}

	private function initArray()
	{
		$xml = new \DOMDocument();
		$url = 'http://www.cbr.ru/scripts/XML_daily.asp?date_req=' . date('d.m.Y');

 		//download data from server
		if (@$xml->load($url))
		{
			$root = $xml->documentElement;
			$items = $root->getElementsByTagName('Valute');

 			//save the data to database
			foreach ($items as $item)
			{
				$numcode = htmlspecialchars($item->getElementsByTagName('NumCode')->item(0)->nodeValue);
				$charcode = htmlspecialchars($item->getElementsByTagName('CharCode')->item(0)->nodeValue);
				$nominal = htmlspecialchars($item->getElementsByTagName('Nominal')->item(0)->nodeValue);
				$name = htmlspecialchars($item->getElementsByTagName('Name')->item(0)->nodeValue);
				$value = htmlspecialchars($item->getElementsByTagName('Value')->item(0)->nodeValue);
				$value = floatval(str_replace(',', '.', $value));
				//fill array
				$this->arrayCurrency[]=[
					"numcode"=> $numcode,
					"charcode"=> $charcode,
					"nominal"=> $nominal,
					"name"=> $name,
					"value"=> $value,
					"value"=> $value
				];
			}

			return true;
		}
		else 
			return false; 
		
	}

}

 ?>