<?php

class NewsItem
{	
  var $rssItem = null;
  var $keywords = null;
  var $photos = null;

  // Flickr only allows 20 tags in a tag search
  var $maxKeywords = 20;

  // Some common words to ignore
  var $commonWords = array(
    'a', 'an', 'the', 'it', 'is', 'for', 'to', 'he', 'she', 'in', 
    'why', 'which', 'where', 'who', 'about', 'this', 'that', 'as',
    'his', 'her', 'as', 'i', 'me', 'my'
  );

  function NewsItem($rssItem)
  {
    $this->rssItem = $rssItem;
    $this->photos = array();
  }

  function addPhoto($url, $link)
  {
    array_push($this->photos, array('url' => $url, 'link' => $link));
  }

  function getPhotos()
  {
    return $this->photos;
  }

  function getTitle()
  {
    return $this->rssItem['title'];
  }

  function getDescription()
  {
    return $this->rssItem['description'];
  }

  function getLink()
  {
    return $this->rssItem['link'];
  }

  function getKeywords()
  {
    if ($this->keywords == null)
    {
      $s = $this->getTitle() . " " . $this->getDescription();
      $words = $this->splitIntoWords($s);
      $this->keywords = $this->extractKeywords($words);
    }

    return $this->keywords;
  }

  function splitIntoWords($data)
  {
    // Remove any possessive apostrophes
    $s = preg_replace('/\'s /', ' ', $data); 
    // remove all except alphanumeric characters and spaces
    $s = preg_replace('/[^ \w]/', '', $s); 

    return preg_split('/ +/', $s);
  }


  function extractKeywords($data)
  {
    $words = array();

    $names = $this->findFullNames($data);
    $words = array_merge($words, $names);

    foreach ($data as $word)
    {
      if (!in_array(strtolower($word), $words) && $this->isGoodKeyword($word))
      {
        array_push($words, strtolower($word));	
      }

      if (count($words) >= $this->maxKeywords)
      {
         break;
      }
    }

    return $words;
  }

  function isGoodKeyword($word)
  {
    // Discard immediately if it is a number
    if (preg_match('/^\d+$/', $word))
    {
      return false;
    }

    // Discard all common words
    if (in_array(strtolower($word), $this->commonWords))
    {
      return false;
    }
    
    // Does it contain any capital letters or numbers?
    if (preg_match('/[A-Z0-9]/', $word))
    {
      return true;
    }

    // If it is more than five characters, it must be a good word
    if (strlen($word) > 5)
    {
      return true;
    }

    return false;
  }
  
  function findFullNames($data)
  {
    $names = array();
    $currentName = "";
    $count = 0;
    foreach ($data as $word)
    {
      $firstLetter = substr($word, 0, 1);
      if ($firstLetter == strtoupper ($firstLetter))
      {
        // This word begins with an upper case letter
        $currentName .= $word . " ";
        $count++;
      }
      else
      {
        // This word does not begin with an upper case letter
        if ($count > 1)
        {
          // But we have already found a run of two or more capitalized words
          array_push($names, trim($currentName));
        }

        $currentName = "";
        $count = 0;
      }
    }

    return $names;
  }

}
?>