Extract "path" from array - php

Question

I'm working on documenting an API, so I am parsing example XML/JSOn output and need to find all the named keys to add definitions. So, I have an array like this:
$array = [
"user" => [
"name" => "John",
"email" => "email#email.com",
"products" => [
0 => "product A",
1 => "product B"
],
"files" => [
"logo" => "/path/logo.jpg",
"profile" => "/path/profile.jpg"
]
],
"offer" => [
0 => "My offer"
]
];
And I want to extract all the keys from the array, no matter its depth, and get an output akin to:
$keys = [
0 => ["user"],
1 => ["user", "name"],
2 => ["user", "email"],
3 => ["user", "products"],
4 => ["user", "files"],
5 => ["user", "files", "logo"],
6 => ["user", "files", "profile"],
7 => ["offer"]
];
Note that keys that are numeric are ignored, only named keys are included in the hierarchy. I have googled and tried to find something that does this, but I've come up blank. I have tried some function chaining but I just can't wrap my head around the loops and returns correctly. Any help is appreciated!

Answer 1

Ok, with help of #0stone0 I was directed to a Stackoverflow answer that led me right, this is the end function:
function definitionTree(array $array): array{
$tree = function($siblings, $path) use (&$tree) {
$result = [];
foreach ($siblings as $key => $val) {
$currentPath = is_numeric($key) ? $path : array_merge($path, [$key]);
if (is_array($val)) {
if (!is_numeric($key)) $result[] = join(' / ', $currentPath);
$result = array_merge($result, $tree($val, $currentPath));
} else {
$result[] = join(' / ', $currentPath);
}
}
return $result;
};
$paths = $tree($array, []);
return array_unique($paths);
}
Which returns the following:
Array
(
[0] => user
[1] => user / name
[2] => user / email
[3] => user / products
[6] => user / files
[7] => user / files / logo
[8] => user / files / profile
[9] => offer
)