<?php
/**
 * Defines and renders a nested menu list. Accepts arbitary absolute URLs into arbitary recursive levels, and optionally caches the structure. When renders, checks current URL (ignoring querystring) to expand menu to show current file. Renders in XHTML, use CSS to style of course.
 * If you use caching, you have to manually check and display.
 * Written in PHP 5, should work in PHP 4 :P
 @todo if load from cache, don't actaully  instance the structure until we check that HTML isn't already cached
 * Sample usage: 
 * $p = new NavSystem('cache_loc');
* if ($p->cached) {
*     echo $p->toHTML();
 *    return;
* } 
* // add absolute URLs
* $p->setroot('/', 'Home', 'Back to Home');
* $p->add('/cv/', 'CV', 'Curriculum Vitae');
* // create child
* $q = new NavSystem();
* $q->setroot('/submenu/', 'Grouping Folder', '');
* $q->add('/1/', 'Thing 1', '');
* $q->add('/2/about.php', 'Thing 2', '');
* $q->add('http://www.google.com/', 'BBC', 'asd');
*$p->add($q);
* $p->add('/bottom/', 'Thing at Bottom', 'bottom');
* echo $p->toHTML();

* @version 0.1
* @Copyright Vodex (vodex.net) 2005 
* ABSOLUTELY NO WARRANTY: license at http://www.opensource.org/licenses/lgpl-license.php
* Version 0.1: Initial release
  */

class NavSystem {
    /**
     * Holds menu data
     */
    var $data = array();
    /**
     * Holds current URL
     */var $current_url = null;
    /**
     * States if menu data was loaded from cache
     */
    var $cached = false;
    /*
* Holds cache data	
*/
    var $cache_file = null;
    /**
     * Adds a menu item or menu folder to the menu. Optionally accepts a local file name which will cache both menu structure and per-URL HTML
     * 
     * @param string $cache_file 
     */
    function NavSystem($cache_file = null)
    {
        if ($cache_file) {
            $this->cache_file = $cache_file; 
            // see if we have the menu structure living in cache
            $cache = @file($this->cache_file);
            if ($cache) {
                $this->data = unserialize($cache[0]);
                $this->cached = true;
            } 
        } 
        // get current location
        $this->setCurrentURL();
    } 

    /**
     * Adds a menu item or menu folder to the menu
     * 
     * @param NavSystem or string $link
     * @param string $text 
     * @param string $desc 
     */
    function add($link, $text = null, $desc = null)
    { 
        // check if $link is a string or NavSystem object; is_a for non-PHP5 hosts
        if (is_a ($link , 'NavSystem')) {
            $this->data[] = $link;
            return;
        } 
        $link = (string) $link;
        $text = (string) $text;
        $desc = (string) $desc; 
        // only add if enough data provided
        if ($link > '' &$text > '') {
            $this->data[] = array('link' => $link, 'text' => $text, 'desc' => $desc);
        } 
    } 
    /**
     * Defines the root item (usually 'home' or root of folder)
     * 
     * @param string $link 
     * @param string $text 
     * @param string $desc 
     */
    function setroot($link, $text, $desc = null)
    { 
	    $link = (string) $link;
        $text = (string) $text;
        $desc = (string) $desc; 
        // if there's a root already defined, replace
        if ($this->data[0]['root']) {
            $this->data[0] = array('root' => 'true', 'link' => $link, 'text' => $text, 'desc' => $desc);
        } else {
            // create root
            array_unshift($this->data, array('root' => 'true', 'link' => $link, 'text' => $text, 'desc' => $desc));
        } 
    } 
    /**
     * Sets the URL of the invoking page
     */
    function setCurrentURL()
    {
        $url = $_SERVER['REQUEST_URI']; 
        // strip off querystring
        $q = strpos($url, '?');
        if ($q != false) {
            $url = substr($url, 0, $q);
        } 
        $this->current_url = $url;
        if ($this->cache_file) {
            // we are caching, also locate cache of menu HTML
            $this->url_cache_file = $this->cache_file . md5($url);
        } 
    } 
    /**
     * Determines if the current URL in in the menu structure
     */
    function hasCurrentURL()
    { 
        // find if a URL exists within the structure
        if (count($this->data) > 0) {
            $url = $this->current_url;
            foreach ($this->data as $k => $v) {
                // var_dump($v);
                if (is_a ($v , 'NavSystem')) {
                    // recurse to child
                    $return = $v->hasCurrentURL();
                    if ($return) {
                        // found
                        return true;
                    } 
                } else {
                    if ($v['link'] == $url) {
                        // found
                        return true;
                    } 
                } 
            } 
        } 
        return false;
    } 
    /**
     * Caches the menu structure, which is the only state we want to persist
     */
    function cache_data()
    { 
        // cache the structure, if not already loaded from cache
        if (!$this->cached) {
            // for PHP5+, we'd use file_put_contents
            $handle = fopen($this->cache_file, 'w');
            if ($handle) {
                fwrite($handle, serialize($this->data));
                fclose($handle);
            } 
        } 
    } 
    /**
     * Caches HTML for a given URL
     */
    function cache_html($html)
    { 
        // cache the structure if not already cached
        // for PHP5+, we'd use file_put_contents
        $handle = fopen($this->url_cache_file, 'w');
        if ($handle) {
            fwrite($handle, $html);
            fclose($handle);
        } 
    } 
    /**
     * Renders HTML of the menu. Does some initiailisation first, and then delegates to ::_ToHTML
     */
    function ToHTML()
    {
        if ($this->cache_file) {
            // we are caching; cache the data
            $this->cache_data(); 
            // and let's see if the menu HTML is cached
            $html = @file($this->url_cache_file);
            if ($html) {
                // file reads in a line at a time into array
                return join($html, "");
            } 
        } 
        // begin rendering the menu; we always expand the first level

$html=null;
$html.= "<div id=\"nav\">\n<ul>\n";
        $html.=  $this->_ToHTML(true);
$html.= "</ul>\n</div>\n";
        if ($this->url_cache_file) {
            // cache HTML
            $this->cache_html($html);
        } 

        return $html;
    } 
    /**
     * Iterates through the structure, expanding if current URL is within folder. If $top_level is true, then expand	anyway and don't next the next level, so that 'home' and first menu choices are on the same level
     */
    function _ToHTML($top_level = false)
    {
        if (count($this->data) > 0) {
            $html = null;

            $expand = ($top_level || $this->hasCurrentURL()); 
            // show root entry
            $html .= $this->do_li($this->data[0]);

            if ($expand) { // expand the menu, either by force or because current url is inside
                if (!$top_level) {
                    $html .= "<li>\n<ul>\n";
                } 
                foreach ($this->data as $k => $v) {
                    // check if $link is a string or object; is_a for non-PHP5 hosts
                    if (is_a ($v , 'NavSystem')) {
                        // recurse to child, passing in current url
                        $v->current_url = $this->current_url;
                        $html .= $v->_ToHTML();
                    } else if ($v['root'] <> 'true') {
                        // show non-root only
                        // var_dump($v);
                        $html .= $this->do_li($v);
                    } 
                } 
                if (!$top_level) {
                    $html .= "</ul>\n</li>\n";
                } 
            } 

            return $html;
        } 
    } 
    /**
     * Utility function to render the all important <li>
     */
    function do_li($data)
    {
        if ($data) {
            // if this entry is the current url, change
            if ($data['link'] == $this->current_url) {
                return "<li><span>{$data['text']}</span></li>\n";
            } else {
                return "<li><a href=\"{$data['link']}\"title=\"{$data['desc']}\">{$data['text']}</a></li>\n";
            } 
        } 
    } 
} 


?>