<?php
 
$json = '{
    "foo.bar.test.thing": 1
}';
 
$decoded = json_decode($json, true);
 
 
$data = array();
foreach ($decoded as $key => $value) {
	$keys = explode('.', $key);	
	$data[] = buildNestedArray($keys, $value);
}
 
print_r($data);
 
function buildNestedArray($keys, $value) {
	$new = array();
	foreach ($keys as $key) {
		if (empty($new)) {
			$new[$key] = $value;
		} else {
			array_walk_recursive($new, function(&$item) use ($key, $value) {
				if ($item === $value) {
					$item = array($key => $value);
				}
			});
		}	
	}
 
	return $new;
}

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