// create some custom exceptions to be able to catch them
// specifically if needed

// general lyrics finder exception
class LyricsFinderException extends CException {}

// used when there is a connection problem
class LyricsFinderHTTPException extends LyricsFinderException{}


class LyricsFinder
{
   private $apiUrl = 'http://example.com/lyricsapi&songtitle=%s';

   function getText($songTitle)
   {
      $url = $this->getUrl($songTitle);
      $curl = curl_init();       
      curl_setopt($curl, CURLOPT_URL, $url); 
      curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
      $result = curl_exec($curl);

      // if there is an HTTP error, we'll throw an exception if($result===false)
      {
         $errorText = curl_error($curl);
         curl_close($url);
         throw new LyricsFinderHTTPException($errorText);
      }

      curl_close($curl);
      return $result;
   }
   
   private function getRequestUrl($songTitle)
   {
      return sprintf($this->apiUrl, urlencode($songTitle));
   }
}

class TestController extends CController
{
  public function actionIndex($song)
  {
    $lyric = 'Nothing was found.';
    
    // importing api class
    Yii::import('application.apis.lyrics.LyricsFinder');

    $finder = new LyricsFinder();

    if(!empty($song))
    {
       // We don't want to show user an error.
       // Instead we want to apologize and
       // invite him to try again later.
       try {
          $lyric = $finder->getText($song);
       }
       // we are looking for specific exception here
       catch (LyricsFinderHTTPException $e)
       {
          echo 'Sorry, we cannot process your request. Try again later.';
       }
    }         

    echo $lyric;
  }
}

class PostController extends CController
{
  function actionView()
  {
    if(!isset($_GET['id']))
      // If there is no post ID supplied, request is definitely wrong.
      // According to HTTP specification its code is 400.
      throw new ChttpException(400);
      
      // Finding a post by its ID
      $post = Post::model()->findByPk($_GET['id']);
      
      if(!$post)
         // If there is no post with ID specified we'll generate
         // HTTP response with code 404 Not Found.
         throw new CHttpException(404);

         //  If everything is OK, render a post
         $this->render('post', array('model' => $post));
  }
}