how to set PHP cookie value via a url link

<?php
/* Example snippet	: [!langGet? &outputKer=`text here` &outputEng=`text here` &outputBilingual=`text here`!]
 * &outputKer 		: output for Cornish titles
 * &outputEng 		: output for English titles
 * &outputBilingual 	: output for bilingual titles 
 *
 * Example snippet	: [!langGet? &titleKer=`pagetitle` &titleEng=`description !]
 * &titleKer 			: MODx document varible for Cornish, use MODx varible names
 * &titleEng 			: MODx document varible for English, use MODx varible names
 *
 * Example snippet	: [!langGet? &chunkKerTpl=`chunk-name` &chunkEngTpl=`chunk-name` !]
 * &chunkKerTpl		: chunk used to show Cornish
 * &chunkEngTpl		: chunk used to show English
 */
 
$language = (isset($_GET['lang'])) ? $_GET['lang'] : (isset($_COOKIE['lang']) ? $_COOKIE['lang'] : 'eng');
$output='';

switch ($language){
	case 'ker':
		if(isset($chunkKerTpl)){
			$output=$modx->getChunk($chunkKerTpl); // Show only chunk if set 
		} elseif (isset($titleKer)) {
			$output=$modx->documentObject[$titleKer]; // Show title if set
		} else {
			$output=(isset($outputKer) ? $outputKer : ''); // Show output if if exists
		};
		setcookie ('lang', 'ker');
		break;
	case 'eng':
		if(isset($chunkEngTpl)){
			$output=$modx->getChunk($chunkEngTpl); // Show chunk if set
		} elseif (isset($titleEng)) {
			$output=$modx->documentObject[$titleEng]; // Show title if set
		} else {
			$output=(isset($outputEng) ? $outputEng : '');  // Show output if it exists
		};
		setcookie ('lang', 'eng');
		break;
	default:
			if(isset($outputBilingual)) {
				$output=$outputBilingual;
			} elseif ((isset($chunkKerTpl)) && (isset($chunkEngTpl))) {
				$output=$modx->getChunk($chunkEngTpl) . $modx->getChunk($chunkKerTpl); // Show only chunks if they are set 
			} elseif ($_COOKIE['lang'] == "ker") {
				(isset($chunkKerTpl)) ? $output=$modx->getChunk($chunkKerTpl) : (isset($titleKer)) ? $output=$modx->documentObject[$titleKer] : (isset($outputKer)) ? $output=$outputKer : '';  // Show values for Cornish if set 
			} else {
				(isset($chunkEngTpl)) ? $output=$modx->getChunk($chunkEngTpl) : (isset($titleEng)) ? $output=$modx->documentObject[$titleEng] : (isset($outputEng)) ? $output=$outputEng : '';  // Show values for English if set 
			};
	};
return $output;
?>