<?php
/**
 * iweibo2.0
 * 
 * oauth相关类
 *
 * @author gionouyang 
 * @link http://open.t.qq.com/iweibo
 * @copyright Copyright © 1998-2011. All Rights Reserved 
 * @license http://open.t.qq.com/iweibo/license
 * @version $Id: Core_Open_OAuth.php 2011-05-23 15:42:00Z gionouyang $
 * @package Core
 * @since 2.0
 */
class Core_Open_OAuth
{
    public $key;
    public $secret;

    function __construct($key, $secret)
    {
        $this->key = $key;
        $this->secret = $secret;
    }

    function __toString()
    {
        return "Open_OAuth[key=$this->key,secret=$this->secret]";
    }
}

class Core_Open_OAuthToken
{
    public $key;
    public $secret;

    function __construct($key, $secret)
    {
        $this->key = $key;
        $this->secret = $secret;
    }

    /** 
     * 
     * generates the basic string serialization of a token that a server 
     * would respond to request_token and access_token calls with 
     */
    function to_string()
    {
        return "oauth_token=" . Core_Open_OAuthUtil::urlencode_rfc3986($this->key) . "&oauth_token_secret=" .
         Core_Open_OAuthUtil::urlencode_rfc3986($this->secret);
    }

    function __toString()
    {
        return $this->to_string();
    }
}

//oauth签名方法
class Core_Open_OAuthSignatureMethod
{

    public function check_signature(&$request, $consumer, $token, $signature)
    {
        $built = $this->build_signature($request, $consumer, $token);
        return $built == $signature;
    }
}
class Core_Open_OAuthSignatureMethodHmacSha1 extends Core_Open_OAuthSignatureMethod
{

    function get_name()
    {
        return "HMAC-SHA1";
    }

    public function build_signature($request, $consumer, $token)
    {
        $base_string = $request->get_signature_base_string();
        //echo $base_string."<hr>";
        

        $request->base_string = $base_string;
        
        //echo "<hr/>";
        $key_parts = array($consumer->secret, ($token) ? $token->secret : "");
        
        $key_parts = Core_Open_OAuthUtil::urlencode_rfc3986($key_parts);
        
        $key = implode('&', $key_parts);
        //echo "<hr/>";
        return base64_encode(hash_hmac('sha1', $base_string, $key, true));
    }
}

class Core_Open_OAuthSignatureMethodPlaintext extends Core_Open_OAuthSignatureMethod
{

    public function get_name()
    {
        return "PLAINTEXT";
    }

    public function build_signature($request, $consumer, $token)
    {
        $sig = array(Core_Open_OAuthUtil::urlencode_rfc3986($consumer->secret));
        
        if($token)
        {
            array_push($sig, Core_Open_OAuthUtil::urlencode_rfc3986($token->secret));
        }
        else
        {
            array_push($sig, '');
        }
        
        $raw = implode("&", $sig);
        // for debug purposes 
        $request->base_string = $raw;
        
        return Core_Open_OAuthUtil::urlencode_rfc3986($raw);
    }
}

/** 
 * @ignore 
 */
class Core_Open_OAuthSignatureMethodRsaSha1 extends Core_Open_OAuthSignatureMethod
{

    public function get_name()
    {
        return "RSA-SHA1";
    }

    protected function fetch_public_cert(&$request)
    {
        // not implemented yet, ideas are: 
        // (1) do a lookup in a table of trusted certs keyed off of consumer 
        // (2) fetch via http using a url provided by the requester 
        // (3) some sort of specific discovery code based on request 
        // 
        // either way should return a string representation of the certificate 
        throw Core_Api_Exception("fetch_public_cert not implemented");
    }

    protected function fetch_private_cert(&$request)
    {
        // not implemented yet, ideas are: 
        // (1) do a lookup in a table of trusted certs keyed off of consumer 
        // 
        // either way should return a string representation of the certificate 
        throw Core_Api_Exception("fetch_private_cert not implemented");
    }

    public function build_signature(&$request, $consumer, $token)
    {
        $base_string = $request->get_signature_base_string();
        $request->base_string = $base_string;
        
        // Fetch the private key cert based on the request 
        $cert = $this->fetch_private_cert($request);
        
        // Pull the private key ID from the certificate 
        $privatekeyid = openssl_get_privatekey($cert);
        
        // Sign using the key 
        $ok = openssl_sign($base_string, $signature, $privatekeyid);
        
        // Release the key resource 
        openssl_free_key($privatekeyid);
        
        return base64_encode($signature);
    }

    public function check_signature(&$request, $consumer, $token, $signature)
    {
        $decoded_sig = base64_decode($signature);
        
        $base_string = $request->get_signature_base_string();
        
        // Fetch the public key cert based on the request 
        $cert = $this->fetch_public_cert($request);
        
        // Pull the public key ID from the certificate 
        $publickeyid = openssl_get_publickey($cert);
        
        // Check the computed signature against the one passed in the query 
        $ok = openssl_verify($base_string, $decoded_sig, $publickeyid);
        
        // Release the key resource 
        openssl_free_key($publickeyid);
        
        return $ok == 1;
    }
}

/** 
 * @ignore 
 */
class Core_Open_OAuthRequest
{
    public $parameters;
    private $http_method;
    private $http_url;
    // for debug purposes 
    public $base_string;
    public static $version = '1.0';
    public static $POST_INPUT = 'php://input';

    function __construct($http_method, $http_url, $parameters = NULL)
    {
        @$parameters or $parameters = array();
        $this->parameters = $parameters;
        $this->http_method = $http_method;
        $this->http_url = $http_url;
    }

    /** 
     * attempt to build up a request from what was passed to the server 
     */
    public static function from_request($http_method = NULL, $http_url = NULL, $parameters = NULL)
    {
        $scheme = (! isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on") ? 'http' : 'https';
        @$http_url or $http_url = $scheme . '://' . $_SERVER['HTTP_HOST'] . ':' . $_SERVER['SERVER_PORT'] .
         $_SERVER['REQUEST_URI'];
        @$http_method or $http_method = $_SERVER['REQUEST_METHOD'];
        
        // We weren't handed any parameters, so let's find the ones relevant to 
        // this request. 
        // If you run XML-RPC or similar you should use this to provide your own 
        // parsed parameter-list 
        if(! $parameters)
        {
            // Find request headers 
            $request_headers = Core_Open_OAuthUtil::get_headers();
            
            // Parse the query-string to find GET parameters 
            $parameters = Core_Open_OAuthUtil::parse_parameters($_SERVER['QUERY_STRING']);
            
            // It's a POST request of the proper content-type, so parse POST 
            // parameters and add those overriding any duplicates from GET 
            if($http_method == "POST" && @strstr($request_headers["Content-Type"], 
            "application/x-www-form-urlencoded"))
            {
                $post_data = Core_Open_OAuthUtil::parse_parameters(file_get_contents(self::$POST_INPUT));
                $parameters = array_merge($parameters, $post_data);
            }
            
            // We have a Authorization-header with OAuth data. Parse the header 
            // and add those overriding any duplicates from GET or POST 
            if(@substr($request_headers['Authorization'], 0, 6) == "OAuth ")
            {
                $header_parameters = Core_Open_OAuthUtil::split_header($request_headers['Authorization']);
                $parameters = array_merge($parameters, $header_parameters);
            }
        
        }
        return new Core_Open_OAuthRequest($http_method, $http_url, $parameters);
    }

    /** 
     * pretty much a helper function to set up the request 
     */
    public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters = NULL)
    {
        @$parameters or $parameters = array();
        $defaults = array("oauth_version" => Core_Open_OAuthRequest::$version, 
        "oauth_nonce" => Core_Open_OAuthRequest::generate_nonce(), 
        "oauth_timestamp" => Core_Open_OAuthRequest::generate_timestamp(), "oauth_consumer_key" => $consumer->key);
        if($token)
            $defaults['oauth_token'] = $token->key;
        
        $parameters = array_merge($defaults, $parameters);
        //unset($parameters['pic']);
        return new Core_Open_OAuthRequest($http_method, $http_url, $parameters);
    }

    public function set_parameter($name, $value, $allow_duplicates = true)
    {
        if($allow_duplicates && isset($this->parameters[$name]))
        {
            // We have already added parameter(s) with this name, so add to the list 
            if(is_scalar($this->parameters[$name]))
            {
                // This is the first duplicate, so transform scalar (string) 
                // into an array so we can add the duplicates 
                $this->parameters[$name] = array($this->parameters[$name]);
            }
            
            $this->parameters[$name][] = $value;
        }
        else
        {
            $this->parameters[$name] = $value;
        }
    }

    public function get_parameter($name)
    {
        return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
    }

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

    public function unset_parameter($name)
    {
        unset($this->parameters[$name]);
    }

    /** 
     * The request parameters, sorted and concatenated into a normalized string. 
     * @return string 
     */
    public function get_signable_parameters()
    {
        // Grab all parameters 
        $params = $this->parameters;
        
        // remove pic 
        if(isset($params['pic']))
        {
            unset($params['pic']);
        }
        
        if(isset($params['image']))
        {
            unset($params['image']);
        }
        
        // Remove oauth_signature if present 
        // Ref: Spec: 9.1.1 ("The oauth_signature parameter MUST be excluded.") 
        if(isset($params['oauth_signature']))
        {
            unset($params['oauth_signature']);
        }
        
        return Core_Open_OAuthUtil::build_http_query($params);
    }

    /** 
     * Returns the base string of this request 
     * 
     * The base string defined as the method, the url 
     * and the parameters (normalized), each urlencoded 
     * and the concated with &. 
     */
    public function get_signature_base_string()
    {
        $parts = array($this->get_normalized_http_method(), $this->get_normalized_http_url(), 
        $this->get_signable_parameters());
        
        //print_r( $parts );
        

        $parts = Core_Open_OAuthUtil::urlencode_rfc3986($parts);
        return implode('&', $parts);
    }

    /** 
     * just uppercases the http method 
     */
    public function get_normalized_http_method()
    {
        return strtoupper($this->http_method);
    }

    /** 
     * parses the url and rebuilds it to be 
     * scheme://host/path 
     */
    public function get_normalized_http_url()
    {
        $parts = parse_url($this->http_url);
        
        $port = @$parts['port'];
        $scheme = $parts['scheme'];
        $host = $parts['host'];
        $path = @$parts['path'];
        
        $port or $port = ($scheme == 'https') ? '443' : '80';
        
        if(($scheme == 'https' && $port != '443') || ($scheme == 'http' && $port != '80'))
        {
            $host = "$host:$port";
        }
        return "$scheme://$host$path";
    }

    /** 
     * builds a url usable for a GET request 
     */
    public function to_url()
    {
        $post_data = $this->to_postdata();
        $out = $this->get_normalized_http_url();
        if($post_data)
        {
            $out .= '?' . $post_data;
        }
        return $out;
    }

    /** 
     * builds the data one would send in a POST request 
     */
    public function to_postdata($multi = false)
    {
        //echo "multi=" . $multi . '`';
        if($multi)
            return Core_Open_OAuthUtil::build_http_query_multi($this->parameters);
        else
            return Core_Open_OAuthUtil::build_http_query($this->parameters);
    }

    /** 
     * builds the Authorization: header 
     */
    public function to_header()
    {
        $out = 'Authorization: OAuth realm=""';
        $total = array();
        foreach($this->parameters as $k => $v)
        {
            if(substr($k, 0, 5) != "oauth")
                continue;
            if(is_array($v))
            {
                throw new Core_Exception('Arrays not supported in headers');
            }
            $out .= ',' . Core_Open_OAuthUtil::urlencode_rfc3986($k) . '="' . Core_Open_OAuthUtil::urlencode_rfc3986($v) .
             '"';
        }
        return $out;
    }

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

    public function sign_request($signature_method, $consumer, $token)
    {
        $this->set_parameter("oauth_signature_method", $signature_method->get_name(), false);
        //var_dump($consumer); 
        //var_dump($token); 
        $signature = $this->build_signature($signature_method, $consumer, $token);
        //echo "sign=" . $signature;
        $this->set_parameter("oauth_signature", $signature, false);
    }

    public function build_signature($signature_method, $consumer, $token)
    {
        $signature = $signature_method->build_signature($this, $consumer, $token);
        return $signature;
    }

    /** 
     * util function: current timestamp 
     */
    private static function generate_timestamp()
    {
        //return 1273566716;
        //echo date("y-m-d H:i:s");
        return Core_Fun::time();
    }

    /** 
     * util function: current nonce 
     */
    private static function generate_nonce()
    {
        //return '462d316f6f40c40a9e0eef1b009f37fa';
        $mt = microtime();
        $rand = mt_rand();
        
        return md5($mt . $rand); // md5s look nicer than numbers 
    }
}

/** 
 * @ignore 
 */
class Core_Open_OAuthServer
{
    protected $timestamp_threshold = 300; // in seconds, five minutes 
    protected $version = 1.0; // hi blaine 
    protected $signature_methods = array();
    
    protected $data_store;

    function __construct($data_store)
    {
        $this->data_store = $data_store;
    }

    public function add_signature_method($signature_method)
    {
        $this->signature_methods[$signature_method->get_name()] = $signature_method;
    }

    // high level functions 
    

    /** 
     * process a request_token request 
     * returns the request token on success 
     */
    public function fetch_request_token(&$request)
    {
        $this->get_version($request);
        
        $consumer = $this->get_consumer($request);
        
        // no token required for the initial token request 
        $token = NULL;
        
        $this->check_signature($request, $consumer, $token);
        
        $new_token = $this->data_store->new_request_token($consumer);
        
        return $new_token;
    }

    /** 
     * process an access_token request 
     * returns the access token on success 
     */
    public function fetch_access_token(&$request)
    {
        $this->get_version($request);
        
        $consumer = $this->get_consumer($request);
        
        // requires authorized request token 
        $token = $this->get_token($request, $consumer, "request");
        
        $this->check_signature($request, $consumer, $token);
        
        $new_token = $this->data_store->new_access_token($token, $consumer);
        
        return $new_token;
    }

    /** 
     * verify an api call, checks all the parameters 
     */
    public function verify_request(&$request)
    {
        $this->get_version($request);
        $consumer = $this->get_consumer($request);
        $token = $this->get_token($request, $consumer, "access");
        $this->check_signature($request, $consumer, $token);
        return array($consumer, $token);
    }

    // Internals from here 
    /** 
     * version 1 
     */
    private function get_version(&$request)
    {
        $version = $request->get_parameter("oauth_version");
        if(! $version)
        {
            $version = 1.0;
        }
        if($version && $version != $this->version)
        {
            throw new Core_Exception("OAuth version '$version' not supported");
        }
        return $version;
    }

    /** 
     * figure out the signature with some defaults 
     */
    private function get_signature_method(&$request)
    {
        $signature_method = @$request->get_parameter("oauth_signature_method");
        if(! $signature_method)
        {
            $signature_method = "PLAINTEXT";
        }
        
        if(! in_array($signature_method, array_keys($this->signature_methods)))
        {
            throw new Core_Exception(
            "Signature method '$signature_method' not supported " . "try one of the following: " .
             implode(", ", array_keys($this->signature_methods)));
        }
        return $this->signature_methods[$signature_method];
    }

    /** 
     * try to find the consumer for the provided request's consumer key 
     */
    private function get_consumer(&$request)
    {
        $consumer_key = @$request->get_parameter("oauth_consumer_key");
        if(! $consumer_key)
        {
            throw new Core_Exception("Invalid consumer key");
        }
        
        $consumer = $this->data_store->lookup_consumer($consumer_key);
        if(! $consumer)
        {
            throw new Core_Exception("Invalid consumer");
        }
        
        return $consumer;
    }

    /** 
     * try to find the token for the provided request's token key 
     */
    private function get_token(&$request, $consumer, $token_type = "access")
    {
        $token_field = @$request->get_parameter('oauth_token');
        $token = $this->data_store->lookup_token($consumer, $token_type, $token_field);
        if(! $token)
        {
            throw new Core_Exception("Invalid $token_type token: $token_field");
        }
        return $token;
    }

    /** 
     * all-in-one function to check the signature on a request 
     * should guess the signature method appropriately 
     */
    private function check_signature(&$request, $consumer, $token)
    {
        // this should probably be in a different method 
        $timestamp = @$request->get_parameter('oauth_timestamp');
        $nonce = @$request->get_parameter('oauth_nonce');
        
        $this->check_timestamp($timestamp);
        $this->check_nonce($consumer, $token, $nonce, $timestamp);
        
        $signature_method = $this->get_signature_method($request);
        
        $signature = $request->get_parameter('oauth_signature');
        $valid_sig = $signature_method->check_signature($request, $consumer, $token, $signature);
        
        if(! $valid_sig)
        {
            throw new Core_Exception("Invalid signature");
        }
    }

    /** 
     * check that the timestamp is new enough 
     */
    private function check_timestamp($timestamp)
    {
        // verify that timestamp is recentish 
        $now = Core_Fun::time();
        if($now - $timestamp > $this->timestamp_threshold)
        {
            throw new Core_Exception("Expired timestamp, yours $timestamp, ours $now");
        }
    }

    /** 
     * check that the nonce is not repeated 
     */
    private function check_nonce($consumer, $token, $nonce, $timestamp)
    {
        // verify that the nonce is uniqueish 
        $found = $this->data_store->lookup_nonce($consumer, $token, $nonce, $timestamp);
        if($found)
        {
            throw new Core_Exception("Nonce already used: $nonce");
        }
    }

}

/** 
 * @ignore 
 */
class Core_Open_OAuthDataStore
{

    function lookup_consumer($consumer_key)
    {
    
     // implement me 
    }

    function lookup_token($consumer, $token_type, $token)
    {
    
     // implement me 
    }

    function lookup_nonce($consumer, $token, $nonce, $timestamp)
    {
    
     // implement me 
    }

    function new_request_token($consumer)
    {
    
     // return a new token attached to this consumer 
    }

    function new_access_token($token, $consumer)
    {
    
     // return a new access token attached to this consumer 
    // for the user associated with this token if the request token 
    // is authorized 
    // should also invalidate the request token 
    }

}
class Core_Open_OAuthDataApi extends Core_Open_OAuthDataStore
{

}

/** 
 * @ignore 
 */
class Core_Open_OAuthUtil
{
    
    public static $boundary = '';

    public static function urlencode_rfc3986($input)
    {
        if(is_array($input))
        {
            return array_map(array('Core_Open_OAuthUtil', 'urlencode_rfc3986'), $input);
        }
        else 
            if(is_scalar($input))
            {
                return str_replace('+', ' ', str_replace('%7E', '~', rawurlencode($input)));
            }
            else
            {
                return '';
            }
    }

    // This decode function isn't taking into consideration the above 
    // modifications to the encoding process. However, this method doesn't 
    // seem to be used anywhere so leaving it as is. 
    public static function urldecode_rfc3986($string)
    {
        return urldecode($string);
    }

    // Utility function for turning the Authorization: header into 
    // parameters, has to do some unescaping 
    // Can filter out any non-oauth parameters if needed (default behaviour) 
    public static function split_header($header, $only_allow_oauth_parameters = true)
    {
        $pattern = '/(([-_a-z]*)=("([^"]*)"|([^,]*)),?)/';
        $offset = 0;
        $params = array();
        while(preg_match($pattern, $header, $matches, PREG_OFFSET_CAPTURE, $offset) > 0)
        {
            $match = $matches[0];
            $header_name = $matches[2][0];
            $header_content = (isset($matches[5])) ? $matches[5][0] : $matches[4][0];
            if(preg_match('/^oauth_/', $header_name) || ! $only_allow_oauth_parameters)
            {
                $params[$header_name] = Core_Open_OAuthUtil::urldecode_rfc3986($header_content);
            }
            $offset = $match[1] + strlen($match[0]);
        }
        
        if(isset($params['realm']))
        {
            unset($params['realm']);
        }
        
        return $params;
    }

    // helper to try to sort out headers for people who aren't running apache 
    public static function get_headers()
    {
        if(function_exists('apache_request_headers'))
        {
            // we need this to get the actual Authorization: header 
            // because apache tends to tell us it doesn't exist 
            return apache_request_headers();
        }
        // otherwise we don't have apache and are just going to have to hope 
        // that $_SERVER actually contains what we need 
        $out = array();
        foreach($_SERVER as $key => $value)
        {
            if(substr($key, 0, 5) == "HTTP_")
            {
                // this is chaos, basically it is just there to capitalize the first 
                // letter of every word that is not an initial HTTP and strip HTTP 
                // code from przemek 
                $key = str_replace(" ", "-", 
                ucwords(strtolower(str_replace("_", " ", substr($key, 5)))));
                $out[$key] = $value;
            }
        }
        return $out;
    }

    // This function takes a input like a=b&a=c&d=e and returns the parsed 
    // parameters like this 
    // array('a' => array('b','c'), 'd' => 'e') 
    public static function parse_parameters($input)
    {
        if(! isset($input) || ! $input)
            return array();
        
        $pairs = explode('&', $input);
        
        $parsed_parameters = array();
        foreach($pairs as $pair)
        {
            $split = explode('=', $pair, 2);
            $parameter = Core_Open_OAuthUtil::urldecode_rfc3986($split[0]);
            $value = isset($split[1]) ? Core_Open_OAuthUtil::urldecode_rfc3986($split[1]) : '';
            
            if(isset($parsed_parameters[$parameter]))
            {
                // We have already recieved parameter(s) with this name, so add to the list 
                // of parameters with this name 
                if(is_scalar($parsed_parameters[$parameter]))
                {
                    // This is the first duplicate, so transform scalar (string) into an array 
                    // so we can add the duplicates 
                    $parsed_parameters[$parameter] = array(
                    $parsed_parameters[$parameter]);
                }
                $parsed_parameters[$parameter][] = $value;
            }
            else
            {
                $parsed_parameters[$parameter] = $value;
            }
        }
        return $parsed_parameters;
    }

    public static function build_http_query_multi($params)
    {
        if(! $params)
            return '';
        
     //print_r( $params );
        //return null;
        

        // Urlencode both keys and values 
        $keys = array_keys($params);
        $values = array_values($params);
        //$keys = Core_Open_OAuthUtil::urlencode_rfc3986(array_keys($params)); 
        //$values = Core_Open_OAuthUtil::urlencode_rfc3986(array_values($params)); 
        $params = array_combine($keys, $values);
        
        // Parameters are sorted by name, using lexicographical byte value ordering. 
        // Ref: Spec: 9.1.1 (1) 
        uksort($params, 'strcmp');
        
        $pairs = array();
        
        self::$boundary = $boundary = uniqid('------------------');
        $MPboundary = '--' . $boundary;
        $endMPboundary = $MPboundary . '--';
        $multipartbody = '';
        
        foreach($params as $parameter => $value)
        {
            //if( $parameter == 'pic' && $value{0} == '@' )
            if(in_array($parameter, array("pic", "image")))
            {
                /*
				$tmp = 'E:\iweibo_proj\trunk\1.txt';
				$url = ltrim($tmp,'@');
				$content = file_get_contents( $url );
				$filename = reset( explode( '?' , basename( $url ) ));
				$mime = self::get_image_mime($url); 
				*/
                //$url = ltrim( $value , '@' );
                $content = $value[2]; //file_get_contents( $url );
                $filename = $value[1]; //reset( explode( '?' , basename( $url ) ));
                $mime = $value[0]; //self::get_image_mime($url); 
                

                $multipartbody .= $MPboundary . "\r\n";
                $multipartbody .= 'Content-Disposition: form-data; name="' . $parameter . '"; filename="' . $filename .
                 '"' . "\r\n";
                $multipartbody .= 'Content-Type: ' . $mime . "\r\n\r\n";
                $multipartbody .= $content . "\r\n";
            }
            else
            {
                $multipartbody .= $MPboundary . "\r\n";
                $multipartbody .= 'Content-Disposition: form-data; name="' . $parameter . "\"\r\n\r\n";
                $multipartbody .= $value . "\r\n";
            
            }
        }
        
        $multipartbody .= "$endMPboundary\r\n";
        // For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61) 
        // Each name-value pair is separated by an '&' character (ASCII code 38) 
        // echo $multipartbody;
        return $multipartbody;
    }

    public static function build_http_query($params)
    {
        if(! $params)
            return '';
        
     // Urlencode both keys and values 
        $keys = Core_Open_OAuthUtil::urlencode_rfc3986(array_keys($params));
        $values = Core_Open_OAuthUtil::urlencode_rfc3986(array_values($params));
        $params = array_combine($keys, $values);
        
        // Parameters are sorted by name, using lexicographical byte value ordering. 
        // Ref: Spec: 9.1.1 (1) 
        uksort($params, 'strcmp');
        
        $pairs = array();
        foreach($params as $parameter => $value)
        {
            if(is_array($value))
            {
                // If two or more parameters share the same name, they are sorted by their value 
                // Ref: Spec: 9.1.1 (1) 
                natsort($value);
                foreach($value as $duplicate_value)
                {
                    $pairs[] = $parameter . '=' . $duplicate_value;
                }
            }
            else
            {
                $pairs[] = $parameter . '=' . $value;
            }
        }
        // For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61) 
        // Each name-value pair is separated by an '&' character (ASCII code 38) 
        return implode('&', $pairs);
    }

    public static function get_image_mime($file)
    {
        $ext = strtolower(pathinfo($file, PATHINFO_EXTENSION));
        switch($ext)
        {
            case 'jpg':
            case 'jpeg':
                $mime = 'image/jpg';
                break;
            
            case 'png':
                $mime = 'image/png';
                break;
            
            case 'gif':
            default:
                $mime = 'image/gif';
                break;
        }
        return $mime;
    }
}
?>