<?php
/**
 * @author  Philip Sturgeon
 * @created 09/02/2009
 */

class OutputBuffer
{
    private static $replace_from = array();
    private static $replace_to = array();

    public static $title_separator = ' | ';

    /**
     * Override the title at any point
     *
     * @param string $new_title The new title to output
     */
    public static function set_title($title_parts = array())
    {
        if(!is_array($title_parts))
        {
        	$title_parts =& func_get_args();
        }

        $title = htmlspecialchars(trim(implode(self::$title_separator, $title_parts)));

        self::set_regex('#<title>(.+)</title>#', '<title>'.$title.'</title>');
    }


    /**
     * Override head tag (or add it if missing)
     *
     * @param string $new_title The new title to output
     */
    public static function set_head($content = '')
    {
    	self::set_regex('#</head>#', "\t".$content."\n</head>");
    }


    /**
     * Override meta data (or add it if missing)
     *
     * @param string $new_title The new title to output
     */
    public static function set_metadata($name = '')
    {
        // Accepts unlimited arguments (2nd+)
        $args =& func_get_args();
        unset($args[0]);

        // Remove HTML and join the arguments
        $content = strip_tags( implode(' ', $args) );

        // Keyword specific replacing
        if($name == 'keywords')
        {
            $content = str_replace(array('_', '-', '(', ')', '!', '?', ':', '"', ',', '.'), '', $content);
        	$content = str_replace(array(' ', ',of,', ',and,', ',in,'), ',', $content);
        }

        // If this meta data exists, replace it
        if(strpos(ob_get_contents(), '<meta name="'.$name.'"'))
        {
            self::set_regex('#<meta name="'.$name.'" content="([^"]+)?"#', '<meta name="'.$name.'" content="'.trim($content).'"');
        }

        // Otherwise, add it after the </title> tag
        else
        {
            self::set_regex('#</title>#', '</title>'."\n\t".'<meta name="'.$name.'" content="'.trim($content).'"/>');
        }
    }

    /**
     * Override meta data (or add it if missing)
     *
     * @param string $new_title The new title to output
     */
    public static function set_canonical($link = '')
    {
        global $smarty;

        $url = smarty_outputfilter_linkparser($link, $smarty);

        // If canonical tag exists, replace it
        if(strpos(ob_get_contents(), '<link rel="canonical"'))
        {
            self::set_regex('#<link rel="canonical" href="([^"]+)?"#', '<link rel="canonical" href="'.trim($url).'"');
        }

        // Otherwise, add it after the </title> tag
        else
        {
            self::set_regex('#</title>#', '</title>'."\n\t".'<link rel="canonical" href="'.trim($url).'"/>');
        }
    }

    /**
     * Override the title at any point
     *
     * @param string $new_title The new title to output
     */
    public static function set_regex($from, $to)
    {
        self::$replace_from[] = $from;

        self::$replace_to[]   = str_replace('$', '\$', $to);
    }


    /**
     * Override the title at any point
     *
     * @param string $new_title The new title to output
     */
    public static function replace()
    {
        // Get, clean and end the current buffer
        $current_buffer = ob_get_clean();

        // Start a new one
        ob_start();

        // Output the old buffer with the changes as the new buffer
        echo preg_replace(
            self::$replace_from,
            self::$replace_to,
        $current_buffer);

        // Reset the replace pieces in case this is randomly called again
        self::$replace_from = array();
        self::$replace_to = array();

    }

}
?>