Recursive array parse with nested nodes

Question

I have blackhole in my mind. Im trying to parse array with multilevel nodes. Here's example array:

global $array;
$array = [
    '0' => [
        'id' => 1,
        'parent' => 0,
        'name' => 'root 0'
    ],
    '1' => [
        'id' => 2,
        'parent' => 1,
        'name' => 'root 1'
    ],
    '2' => [
        'id' => 3,
        'parent' => 2,
        'name' => 'root 2'
    ],
    '3' => [
        'id' => 4,
        'parent' => 3,
        'name' => 'root 3'
    ],
    '4' => [
        'id' => 5,
        'parent' => 3,
        'name' => 'root 4'
    ],
    '5' => [
        'id' => 6,
        'parent' => 2,
        'name' => 'root 2'
    ]
];

This should looks after parse like this. Element 3 with parent 3 should have parent 1, because element 2 has parent 2, and its first child.

I trying to get to this using foreach and function:

global $new_array;
$new_array = [];

foreach( $array as $item )
{
    if( $item['parent'] == 0 ) {
        $new_array[] = $item; // if parent 0 - clone into new array
        continue;
    }

    //echo $item['name'] . PHP_EOL;
    $new_array[] = check_parent( $item['parent'] ); 

}

print_r($new_array);

function check_parent( $parent )
{
    //echo '- check for parent of ' . $parent . PHP_EOL;
    global $array;
    foreach( $array as $item ) {
        if( $item['id'] == $parent && $item['parent'] == 0 ) {
            //echo '[OK] found root parent id: ' . $item['id'] . PHP_EOL;
            $item['parent'] = $item['id'];
            return $item;
        } else {
            return check_parent( $item['id'] );
        }
    }
}

I'm so confused, but I didn't see where I make a mistake. Maybe someone, can help me to see - where's problem. I working on it few hours and for now, I had blackhole in my mind.

Fiddle: https://implode.io/jHS8m1

Desired output:

$new_array = [
    '0' => [
        'id' => 1,
        'parent' => 0,
        'name' => 'root 0'
    ],
    '1' => [
        'id' => 2,
        'parent' => 1,
        'name' => 'root 1'
    ],
    '2' => [
        'id' => 3,
        'parent' => 2, // this should have after parse parent 1
        'name' => 'root 2'
    ],
    '3' => [
        'id' => 4,
        'parent' => 3, // this should have after parse parent 1
        'name' => 'root 3'
    ],
    '4' => [
        'id' => 5,
        'parent' => 3, // this should have after parse parent 1
        'name' => 'root 4'
    ],
    '5' => [
        'id' => 6,
        'parent' => 2, // this should have after parse parent 1
        'name' => 'root 2'
    ]
];

Thanks !

Answer 1

Replace the following line in your code

        $new_array[] = check_parent( $item['parent'] ); // get child

with below lines of code.

        $temp = check_parent( $item['parent'] ); // get child
        $item['parent'] = $temp['id'];
        $new_array[] = $item;

What is happening is that your check_parent is returning the $item, which happens to be the parent. However, we are only interested in the id of this. So we get the id and replace the parent it in the original $item.

Here is the working Demo