Expand an associative array N-times and get all key combinations - php

Question

I am trying to expand/multiply an associative array N times and get all possible key combinations.
To do it manually for two times, I would do this:
$copy = $array;
foreach ($array as $key1=>$tmp1) {
foreach ($copy as $key2=>$tmp2) {
$combos[] = array($key1,$key2);
}
}
for expanding three times:
$copy = $copy2 = $arr1;
foreach ($arr1 as $key1=>$qd1) {
foreach ($copy as $key2=>$qd2) {
foreach ($copy2 as $key3=>$qd3) {
$combos[] = array($key1,$key2,$key3);
}
}
}
how would one do this for n-times? $combos should have n-elements for each element as shown.
I looked at the other questions, but it is not quite the same here.

Answer 1

Finally got it:
$array = ['1' => [3, 4], '2' => [5, 6]];
$depth = 2;
function florg ($n, $elems) {
if ($n > 0) {
$tmp_set = array();
$res = florg($n-1, $elems);
foreach ($res as $ce) {
foreach ($elems as $e) {
array_push($tmp_set, $ce . $e);
}
}
return $tmp_set;
}
else {
return array('');
}
}
$output = florg($depth, array_keys($array));
What I did is basically extract the first level keys with array_keys and then created all possibles combinations thanks to https://stackoverflow.com/a/19067650/4585634.
Here's a working demo: http://sandbox.onlinephpfunctions.com/code/94c74e7e275118cf7c7f2b7fa018635773482fd5
Edit: didn't see David Winder comment, but that's basically the idea.