<?php
/**
 * Converts currency using Google's Currency Converter
 *
 * @author Rochak Chauhan
 * 
 * @see Currency Conversion Disclaimer
 * Google cannot guarantee the accuracy of the exchange rates used by the calculator. 
 * You should confirm current rates before making any transactions that could be affected by changes in the exchange rates. 
 * Foreign currency rates provided by Citibank N.A. and displayed under license. 
 * Rates are for information purposes only and are subject to change without notice. 
 * Rates for actual transactions may vary, and Citibank is not offering to enter into any transaction at any rate displayed. 
 * NOT FOR COMMERTIAL USE
 */
class GoogleCurrencyConvertor{
    private $rate="";
    private $reverseRate="";

    /**
     * Contructor function
     *
     * @param int $amount
     * @param string $currFrom
     * @param string $currInto
     * 
     * @return resource
     */
    public function __construct($amount, $currFrom, $currInto){
        if (trim($amount)=="" ||!is_numeric($amount)) {
            trigger_error("Please enter a valid amount",E_USER_ERROR);         	
        }
        $return=array();
        $gurl="http://www.google.com/search?&q=$amount+$currFrom+in+$currInto";
        $html=$this->getHtmlCodeViaFopen($gurl);
        $pattern='/<h2 class=r(.*)\<\/h2\>/Uis';
        preg_match_all($pattern,$html,$return,PREG_PATTERN_ORDER);
        if (isset($return[0][0])) {
            $rate=strip_tags($return[0][0]);
            $tmp=explode("=",$rate);
            $rate=$tmp[1];
            $this->rate=$this->getIntegers($rate);            
            $this->reverseRate=1/$this->rate;
        }
        else {
            $this->rate=$this->reverseRate="Google could not convert your request. Please try again.";
        }
    }
    
    /**
     * Function to get only integers from a string
     *
     * @param string $str
     * @return int
     */
    private function getIntegers($str){
        $ret="";
        $str=trim($str);       
        for ($i=0;$i<strlen($str);$i++){
            $code=ord($str[$i]);
            if( ($code>47 && $code<58) || $code==46) {
               $ret.=$str[$i];        	
            }
        }
        return $ret;
    }
    
    /**
     * Fucntion to get HTML code of a URL
     *
     * @param string $url
     * @return string
     */
    function getHtmlCodeViaFopen($url){
        $returnStr="";
        $fp=fopen($url, "r") or die("ERROR: Failed to open $url for reading via this script.");
        while (!feof($fp)) {
            $returnStr.=fgetc($fp);
        }
        fclose($fp);
        return $returnStr;
    }

    /**
     * Function get the converter Rate
     *
     * @access public
     * 
     * @return int
     */
    function getRate(){
        return $this->rate;
    }

    /**
     * Function get the reverse of converter Rate
     * 
     * @access public
     * @return int
     *
     */
    function getReverseRate(){
        return $this->reverseRate;
    }
}
?>