<?php
class TwitterAPIExchange
{
    private $oauth_access_token;
    private $oauth_access_token_secret;
    private $consumer_key;
    private $consumer_secret;
    private $postfields;
    private $getfield;
    protected $oauth;
    public $url;  
	
	/**  
	* @param array $settings
	*/
    public function __construct(array $settings)
    {
        if (!in_array('curl', get_loaded_extensions())){
            throw new Exception('You need to install cURL, see: http://curl.haxx.se/docs/install.html');
        }        
        if (!isset($settings['oauth_access_token'])
            || !isset($settings['oauth_access_token_secret'])
            || !isset($settings['consumer_key'])
            || !isset($settings['consumer_secret'])){
            throw new Exception('Make sure you are passing in the correct parameters');
        }
        $this->oauth_access_token = $settings['oauth_access_token'];
        $this->oauth_access_token_secret = $settings['oauth_access_token_secret'];
        $this->consumer_key = $settings['consumer_key'];
        $this->consumer_secret = $settings['consumer_secret'];
    }    
	/**
	* Set postfields array, example: array('screen_name' => 'J7mbo')
	* @param array $array Array of parameters to send to API
	* @return TwitterAPIExchange Instance of self for method chaining
	*/
    public function setPostfields(array $array){
		
        if (!is_null($this->getGetfield())){
            throw new Exception('You can only choose get OR post fields.');
        }        
        if (isset($array['status']) && substr($array['status'], 0, 1) === '@'){
            $array['status'] = sprintf("\0%s", $array['status']);
        }        
        $this->postfields = $array;        
        return $this;
    }    
	/**
	* Set getfield string, example: '?screen_name=J7mbo'
	* @param string $string Get key and value pairs as string
	* @return \TwitterAPIExchange Instance of self for method chaining
	*/
    public function setGetfield($string){
		
        if (!is_null($this->getPostfields())){
            throw new Exception('You can only choose get OR post fields.');
        }        
        $search = array('#', ',', '+', ':');
        $replace = array('%23', '%2C', '%2B', '%3A');
        $string = str_replace($search, $replace, $string);        
        $this->getfield = $string;        
        return $this;
    }    
	/**
	* Get getfield string (simple getter)
	* @return string $this->getfields
	*/
    public function getGetfield(){
        return $this->getfield;
    }    
	/**
	* Get postfields array (simple getter)
	* @return array $this->postfields
	*/
    public function getPostfields(){
        return $this->postfields;
    }    
	/**
	* @param string $url The API url to use. Example: https://api.twitter.com/1.1/search/tweets.json
	* @param string $requestMethod Either POST or GET
	* @return \TwitterAPIExchange Instance of self for method chaining
	*/
    public function buildOauth($url, $requestMethod){
        if (!in_array(strtolower($requestMethod), array('post', 'get'))){
            throw new Exception('Request method must be either POST or GET');
        }        
        $consumer_key = $this->consumer_key;
        $consumer_secret = $this->consumer_secret;
        $oauth_access_token = $this->oauth_access_token;
        $oauth_access_token_secret = $this->oauth_access_token_secret;
        
        $oauth = array(
            'oauth_consumer_key' => $consumer_key,
            'oauth_nonce' => time(),
            'oauth_signature_method' => 'HMAC-SHA1',
            'oauth_token' => $oauth_access_token,
            'oauth_timestamp' => time(),
            'oauth_version' => '1.0'
        );        
        $getfield = $this->getGetfield();        
        if (!is_null($getfield)){
            $getfields = str_replace('?', '', explode('&', $getfield));
            foreach ($getfields as $g){
                $split = explode('=', $g);
                $oauth[$split[0]] = $split[1];
            }
        }        
        $base_info = $this->buildBaseString($url, $requestMethod, $oauth);
        $composite_key = rawurlencode($consumer_secret) . '&' . rawurlencode($oauth_access_token_secret);
        $oauth_signature = base64_encode(hash_hmac('sha1', $base_info, $composite_key, true));
        $oauth['oauth_signature'] = $oauth_signature;
        
        $this->url = $url;
        $this->oauth = $oauth;
        
        return $this;
    }
    
	/**
	* Perform the acual data retrieval from the API
	*/
    public function performRequest($return = true){
		
        if (!is_bool($return)){
            throw new Exception('performRequest parameter must be true or false');
        }        
        $header = array($this->buildAuthorizationHeader($this->oauth), 'Expect:');        
        $getfield = $this->getGetfield();
        $postfields = $this->getPostfields();
        $options = array(
            CURLOPT_HTTPHEADER => $header,
            CURLOPT_HEADER => false,
            CURLOPT_URL => $this->url,
            CURLOPT_RETURNTRANSFER => true
        );
        if (!is_null($postfields)){
            $options[CURLOPT_POSTFIELDS] = $postfields;
        }else{
            if ($getfield !== ''){
                $options[CURLOPT_URL] .= $getfield;
            }
        }
        $feed = curl_init();
        curl_setopt_array($feed, $options);
        $json = curl_exec($feed);
        curl_close($feed);
        if ($return) { 
			return $json; 
		}
    }
		
	/**
	* Private method to generate the base string used by cURL
	* @return string Built base string
	*/
    private function buildBaseString($baseURI, $method, $params){
        $return = array();
        ksort($params);        
        foreach($params as $key=>$value){
            $return[] = "$key=" . $value;
        }        
        return $method . "&" . rawurlencode($baseURI) . '&' . rawurlencode(implode('&', $return));
    }
    
	/**
	* Private method to generate authorization header used by cURL
	*/
    private function buildAuthorizationHeader($oauth){
        $return = 'Authorization: OAuth ';
        $values = array();        
        foreach($oauth as $key => $value){
            $values[] = "$key=\"" . rawurlencode($value) . "\"";
        }        
        $return .= implode(', ', $values);
        return $return;
    }
} 


/**
* Set the user credentials 
*/
$settings = array(
	'oauth_access_token' => trim(get_option('netgo_access_token')),
	'oauth_access_token_secret' => trim(get_option('netgo_access_token_secret')),
	'consumer_key' => trim(get_option('netgo_consumer_key')),
	'consumer_secret' => trim(get_option('netgo_consumer_secret'))
);

$url = 'https://api.twitter.com/1.1/statuses/user_timeline.json';
$getfield = '?screen_name='.trim(get_option('netgo_screen_name'));
$requestMethod = 'GET';
$twitter = new TwitterAPIExchange($settings);
$response = $twitter->setGetfield($getfield)->buildOauth($url, $requestMethod)->performRequest();

 
?>