SimpleMenu for Beginner - a Snippet

<?php
/*
 * SimpleMenu Snippet
 *
 * - parameters: context, parent, bar, tpl, wrapper
 *
 * - example 1: [[SimpleMenu]]
 * - example 2: 
     [[SimpleMenu? 
       &context=`web` 
       &parent=`0` 
       &bar=` &nbps; ` 
       &tpl=`<a href="[[~[[+id]]]]">[[+menutitle:default=`[[+pagetitle]]`]]</a>` 
       &wrapper=`<div>[[+wrapper]]</div>`
     ]]
 * 
 * Features:
 * - learn how to create snippet
 * - learn how to use xPDO
 * - learn how to use modChunk (@INLINE mode)
 * - it's works and amazingly fast (compared to heavyweight addon menu)
 * - need different menu? duplicate this snippet and modify as you wish
*/

$output = '';
$current_context = $modx->context->get('key');

$context = isset($context) ? $context : $current_context;
$parent  = isset($parent) ? intval($parent) : 0;

$wrapper = isset($wrapper) ? $wrapper : "";
$bar = isset($bar) ? $bar : '  ';
$tpl = isset($tpl) ? $tpl : '<a href="[[+link]]" name="[[+alias]]" class="[[+class]]">[[+menutitle:default=`[[+pagetitle]]`]]</a>';
$tpl = str_replace('{~', '[[', $tpl);
$tpl = str_replace('~}', ']]', $tpl);


//xPDO stuff
$criteria = $modx->newQuery('modResource');
$criteria->where(array(
    'parent' => $parent,
    'context_key' => $context,
    'published' => 1,
    'hidemenu' => '0'
));
$criteria->sortby('menuindex','ASC');
$resources = $modx->getCollection('modResource', $criteria);

// get all resource ID from results
$resourcesIDs = array_keys($resources);

// get all parent ID from current resource
$parentIDs = $modx->getParentIds($modx->resourceIdentifier);
array_unshift($parentIDs, $modx->resourceIdentifier);

// selected menu
$selected_parent = array_keys(array_intersect($resourcesIDs, $parentIDs));
$selected_menu   = !empty($selected_parent) ? intval($selected_parent[0]) : 0;

//DEBUG?
//print_r(array('<pre>DEBUG ON:', $resourcesIDs, $parentIDs, $selected_parent, $selected_menu, 'OFF</pre>'));

$i = 0;
$n = sizeof($resources);
$_row = null;
foreach ($resources as $resourceID => $resource) {
  $_row = array();
  $_row['id'] = $resourceID;
  $_row['alias'] = $resource->get('alias');
  $_row['pagetitle'] = $resource->get('pagetitle');
  $_row['menutitle'] = $resource->get('menutitle');
  $_row['link'] = $modx->makeUrl($resourceID, '', '', 'full');

  //set css-class
  $_row['class'] = 'menu-'.$i . ' resource-' . $resourceID;
  if ($selected_menu == $i) {
    $_row['class'] .= ' selected';
  }
  if ($i < 1)     $_row['class'] .= ' first';
  if ($i+1 == $n) $_row['class'] .= ' last';
  
  //modChunk
  $chunk = $modx->newObject('modChunk');
  $chunk->setContent($tpl);
  $chunk->setProperties($_row);
  $chunk->setCacheable(false);
  $output .= $chunk->process();
  if ($n-1 > $i) {
      $output .= $bar;
  }
  $i++;
}

//add wrapper
if (!empty($wrapper)) {
  $chunk = $modx->newObject('modChunk');
  $chunk->setContent($wrapper);
  $chunk->setProperties(array('wrapper'=>$output));
  //$chunk->setCacheable(false);
  $output = $chunk->process();
}

unset($context);
unset($parent);
unset($wrapper);
unset($bar);
unset($tpl);
unset($criteria);
unset($resources);
unset($resourcesIDs);
unset($resourcesIDs);
unset($selected_parent);
unset($selected_menu);
unset($_row);
unset($chunk);

return $output;