<?php
/**
 
 * **************************
 * Snippet: prevtv V.1.0
 * By: sharkbait / @kunane
 * Date: Nov 2009
 * inspired & borrowed some parts of: PrevJumpNextXHTML Snippet
 * from the version modified by PMS
 * **************************
 
installation:
1. create a new snippet "prevtv" and copy this code into the  Snippet code-field
2 in your template call the snippet like this: [!prevtv? &direction=`1` &tvname=`yourtvname` !]

&direction=`1` will return the value of the TV from the previous ressource
&direction=`2` will return the value of the TV from the next ressource

enter the name of the TV you want to retrieve the value
&tvname=`yourtvname`

enter the text you want to be displayed if there's no image (ressource prev. to the first / next to the last) - leave it empty if you want no text to be displayed
&text=`no image`

currently a text will be displayed "no image available" for the previous ressource of the first item and for
the next ressource of the last item. If you don't want do display a value, just delete the string in line 72 & 89

the order of the TVs  currently reflects the defauld order of Wayfinder
 
 sorry for the ugly code - #itsmyfirstsnippet :)

*/

// default Wayfinder
if(!isset($sortBy)){
		$sortBy = 'menuindex'; 
	}
// default Wayfinder
if(!isset($sortHow)){
		$sortHow = 'ASC';
	}

// Get the value of the TV named in the Snippet call
$pntv = $tvname;

// Get the value of 
$pntext = $text;

// Get the parent ID
$parentid = $modx->documentObject['parent'];

// (re)set the $id variable to the one of this document.
$id = $modx->documentIdentifier;

// select the other members in this folder
$children = $modx->getActiveChildren($parentid, $sortBy, $sortHow);

// the number of selected documents
$limit = count($children);

// set $y to zero
$y = 1;

// sorting the documents, giving them a sequential and searchable index
foreach ($children as $child)
	{
		$my_array[$y] = $child;
		if ($my_array[$y]['id']==$id){
		$current=$y; // The current page has number $y in the array
		}
		$y++;
	}

$prev = $current-1;
$next = $current+1;

// if &direction is set to 1 do this
if ($direction == 1) {

		if ($prev == 0) {
			// in case a value previous to the first document
			return $pntext;
			} else {
			// get the id of the previous document
			$previd = $my_array[$prev]['id'];
			// return the output of the TV  named in the Snippet call -> tvname ($pntv)
			$document_tvs = $modx->getTemplateVarOutput(true, $previd);
			$templatevar_output = $document_tvs[$pntv];
			$output = $templatevar_output;
			return $output;
			}
		} 

// if &direction is set to 2 do this
elseif ($direction == 2) {

		if ($current == $limit) {
			// in case a value next to the last document
			return $pntext;
			} else {
			// get the id of the next document
			$nextid = $my_array[$next]['id'];
			// return the output of the TV  named in the Snippet call -> tvname ($pntv)
			$document_tvs = $modx->getTemplateVarOutput(true, $nextid);
			$templatevar_output = $document_tvs[$pntv];
			$output = $templatevar_output;
			return $output;
			}
		}
		else {
		$output = '';
		return $output;
		}
?>