FeedWriter.php

<?php
// RSS 0.90  Officially obsoleted by 1.0
// RSS 0.91, 0.92, 0.93 and 0.94  Officially obsoleted by 2.0
// So, define constants for RSS 1.0, RSS 2.0 and ATOM

	define('RSS1', 'RSS 1.0', true);
	define('RSS2', 'RSS 2.0', true);
	define('ATOM', 'ATOM', true);

/**
 * Univarsel Feed Writer class
 *
 * generate RSS 1.0, RSS2.0 and ATOM Feed
 *
 * @package     UnivarselFeedWriter
 * @author      Anis uddin Ahmad <anisniit@gmail.com>
 * @link        http://www.ajaxray.com/projects/rss
 */
class FeedWriter {
	private $channels       = array();  // Collection of channel elements
	private $items          = array();  // Collection of items as object of FeedItem class.
	private $data           = array();  // Store some other version wise data
	private $CDATAEncoding  = array();  // The tag names which have to encoded as CDATA

	private $version        = null;

/**
 * Constructor
 *
 * @param    constant    the version constant (RSS1/RSS2/ATOM).
 */
	function __construct($version = RSS2) {
		$this->version = $version;

	// Setting default value for assential channel elements
		$this->channels['title']    = $version . ' Feed';
		$this->channels['link']     = 'http://www.ajaxray.com/blog';

	//Tag names to encode in CDATA
		$this->CDATAEncoding = array('description', 'content:encoded', 'summary');
	}

/**
 * Set a channel element
 * @access   public
 * @param    string  name of the channel tag
 * @param    string  content of the channel tag
 * @return   void
 */
	public function setChannelElement($elementName, $content) {
		$this->channels[$elementName] = $content ;
	}

/**
 * Set multiple channel elements from an array. Array elements
 * should be 'channelName' => 'channelContent' format.
 *
 * @access   public
 * @param    array   array of channels
 * @return   void
 */
	public function setChannelElementsFromArray($elementArray) {
		if (!is_array($elementArray))
            return;
		foreach ($elementArray as $elementName => $content)
			$this->setChannelElement($elementName, $content);
	}

/**
 * generate the actual RSS/ATOM file
 *
 * @access   public
 * @return   void
 */
	public function generateFeed() {
        header("Content-type: text/xml");

		$this->printHead();
		$this->printChannels();
		$this->printItems();
		$this->printTale();
	}

/**
 * Create a new FeedItem.
 *
 * @access   public
 * @return   object  instance of FeedItem class
 */
	public function createNewItem() {
		$Item = new FeedItem($this->version);
		return $Item;
	}

/**
 * Add a FeedItem to the main class
 *
 * @access   public
 * @param    object  instance of FeedItem class
 * @return   void
 */
	public function addItem($feedItem) {
		$this->items[] = $feedItem;
	}

/**
 * Set the 'title' channel element
 *
 * @access   public
 * @param    string  value of 'title' channel tag
 * @return   void
 */
	public function setTitle($title) {
		$this->setChannelElement('title', $title);
	}

/**
 * Set the 'description' channel element
 *
 * @access   public
 * @param    string  value of 'description' channel tag
 * @return   void
 */
	public function setDescription($desciption) {
		$this->setChannelElement('description', $desciption);
	}

/**
 * Set the 'link' channel element
 *
 * @access   public
 * @param    string  value of 'link' channel tag
 * @return   void
 */
	public function setLink($link) {
		$this->setChannelElement('link', $link);
	}

/**
 * Set the 'image' channel element
 *
 * @access   public
 * @param    string  title of image
 * @param    string  link url of the imahe
 * @param    string  path url of the image
 * @return   void
 */
	public function setImage($title, $link, $url) {
		$this->setChannelElement('image', array('title'=>$title, 'link'=>$link, 'url'=>$url));
	}

/**
 * Set the 'about' channel element. Only for RSS 1.0
 *
 * @access   public
 * @param    string  value of 'about' channel tag
 * @return   void
 */
	public function setChannelAbout($url) {
		$this->data['ChannelAbout'] = $url;
	}

 /**
  * generates an UUID
  * @author     Anis uddin Ahmad <admin@ajaxray.com>
  * @param      string  an optional prefix
  * @return     string  the formated uuid
  */
    public function uuid($key = null, $prefix = '') {
        $key   = ($key == null)? uniqid(rand()) : $key;
        $chars = md5($key);
        $uuid  = substr($chars,0,8) . '-';
        $uuid .= substr($chars,8,4) . '-';
        $uuid .= substr($chars,12,4) . '-';
        $uuid .= substr($chars,16,4) . '-';
        $uuid .= substr($chars,20,12);

        return $prefix . $uuid;
    }

/**
 * Prints the xml and rss namespace
 *
 * @access   private
 * @return   void
 */
	private function printHead() {
		$out  = '<?xml version="1.0" encoding="utf-8"?>' . "\n";

		if ($this->version == RSS2) {
			$out .= '<rss version="2.0"
					xmlns:content="http://purl.org/rss/1.0/modules/content/"
					xmlns:wfw="http://wellformedweb.org/CommentAPI/"
				  >' . PHP_EOL;
		}
		elseif ($this->version == RSS1) {
			$out .= '<rdf:RDF
					 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
					 xmlns="http://purl.org/rss/1.0/"
					 xmlns:dc="http://purl.org/dc/elements/1.1/"
					>' . PHP_EOL;;
		}
		else if ($this->version == ATOM) {
			$out .= '<feed xmlns="http://www.w3.org/2005/Atom">' . PHP_EOL;;
		}
		echo $out;
	}

/**
 * Closes the open tags at the end of file
 *
 * @access   private
 * @return   void
 */
	private function printTale() {
		if ($this->version == RSS2)
			echo '</channel>'.PHP_EOL.'</rss>';
		elseif ($this->version == RSS1)
			echo '</rdf:RDF>';
		elseif ($this->version == ATOM)
			echo '</feed>';
	}

/**
 * Creates a single node as xml format
 *
 * @access   private
 * @param    string  name of the tag
 * @param    mixed   tag value as string or array of nested tags in 'tagName' => 'tagValue' format
 * @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
 * @return   string  formatted xml tag
 */
	private function makeNode($tagName, $tagContent, $attributes = null) {
		$nodeText = '';
		$attrText = '';

		if (is_array($attributes))
			foreach ($attributes as $key => $value)
				$attrText .= " $key=\"$value\" ";

		if (is_array($tagContent) && $this->version == RSS1)
			$attrText = ' rdf:parseType="Resource"';

		$attrText .= (in_array($tagName, $this->CDATAEncoding) && $this->version == ATOM)? ' type="html" ' : '';
		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "<{$tagName}{$attrText}><![CDATA[" : "<{$tagName}{$attrText}>";

		if (is_array($tagContent)) {
			foreach ($tagContent as $key => $value)
				$nodeText .= $this->makeNode($key, $value);
		}
		else
			$nodeText .= $tagContent;

		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "]]></$tagName>" : "</$tagName>";

		return $nodeText . PHP_EOL;
	}

/**
 * @desc     Print channels
 * @access   private
 * @return   void
 */
	private function printChannels() {
	//Start channel tag
		switch ($this->version) {
		   case RSS2:
				echo '<channel>' . PHP_EOL;
				break;
		   case RSS1:
				echo (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']}\">";
				break;
		}

	//Print Items of channel
		foreach ($this->channels as $key => $value) {
			if ($this->version == ATOM && $key == 'link') {
			// ATOM prints link element as href attribute
				echo $this->makeNode($key,'',array('href'=>$value));
			//Add the id for ATOM
				echo $this->makeNode('id',$this->uuid($value,'urn:uuid:'));
			}
			else
				echo $this->makeNode($key, $value);

		}

	//RSS 1.0 have special tag <rdf:Seq> with channel
		if ($this->version == RSS1) {
			echo "<items>" . PHP_EOL . "<rdf:Seq>" . PHP_EOL;
			foreach ($this->items as $item) {
				$thisItems = $item->getElements();
				echo "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . PHP_EOL;
			}
			echo "</rdf:Seq>" . PHP_EOL . "</items>" . PHP_EOL . "</channel>" . PHP_EOL;
		}
	}

/**
 * Prints formatted feed items
 *
 * @access   private
 * @return   void
 */
	private function printItems() {
		foreach ($this->items as $item) {
			$thisItems = $item->getElements();

		//the argument is printed as rdf:about attribute of item in rss 1.0
			echo $this->startItem($thisItems['link']['content']);

			foreach ($thisItems as $feedItem )
				echo $this->makeNode($feedItem['name'], $feedItem['content'], $feedItem['attributes']);
			echo $this->endItem();
		}
	}

/**
 * Make the starting tag of channels
 *
 * @access   private
 * @param    string  The vale of about tag which is used for only RSS 1.0
 * @return   void
 */
	private function startItem($about = false) {
		if ($this->version == RSS2)
			echo '<item>' . PHP_EOL;
		elseif ($this->version == RSS1) {
			if ($about)
				echo "<item rdf:about=\"$about\">" . PHP_EOL;
			else
				die('link element is not set .\n It\'s required for RSS 1.0 to be used as about attribute of item');
		}
		else if ($this->version == ATOM)
			echo "<entry>" . PHP_EOL;
	}

/**
 * Closes feed item tag
 *
 * @access   private
 * @return   void
 */
	private function endItem() {
		if ($this->version == RSS2 || $this->version == RSS1)
			echo '</item>' . PHP_EOL;
		else if ($this->version == ATOM)
			echo "</entry>" . PHP_EOL;
	}

}