Create Tree Structure from Array in PHP

I have an array like this:

array(
      array(id => 7, parent_id => 0, name => Current Assets)
      array(id => 8, parent_id => 0, name => Fixed Assets)
      array(id => 18, parent_id => 7, name => Assets)
      array(id => 38, parent_id => 18, name => Receivable)
      array(id => 38, parent_id => 18, name => Inventory)
      array(id => 39, parent_id => 0, name => Landed Cost Of Inventory)
      array(id => 40, parent_id => 38, name => Jazz Cash)
      array(id => 41, parent_id => 39, name => Advance to Vendors)
)

Now I need some efficient way to convert this into tree structure like this.

array(
      array(id => 7, parent_id => 0, name => Current Assets, level=>0)
      array(id => 8, parent_id => 0, name => Fixed Asset, level => )
      array(id => 18, parent_id => 7, name => Assets, level => 1)
      array(id => 38, parent_id => 18, name => Inventory, level => 2)
      array(id => 39, parent_id => 0, name => Landed Cost Of Inventory, level => 0)
      array(id => 40, parent_id => 38, name => Jazz Cash, level => 3)
      array(id => 41, parent_id => 39, name => Advance to Vendors, level => 1)
)

I no need to add them left or right, I just need the simple levels that I will pass to jQgrid.

Answer

Collect all ids in the order of parent -> child in an array where parent_id is the key and it has an array of all child IDs. Second step is to just traverse the tree and assign the ranks.

<?php

function assignLevels(&$data){
    $kids = [];

    foreach($data as $d){
        $kids[ $d['parent_id'] ] = $kids[ $d['parent_id'] ] ?? [];
        $kids[ $d['parent_id'] ][] = $d['id'];
    }
    
    $data = array_column($data, null, 'id');
    traverseTree($kids, 0, $data);
    $data = array_values($data);
}


function traverseTree($kids, $id, &$data, $level = 0){
    foreach($kids[ $id ] as $sub_id){
        $data[ $sub_id ]['level'] = $level;
        if(isset($kids[ $sub_id ] )) traverseTree($kids, $sub_id, $data, $level + 1);
    }
}

assignLevels($data);

print_r($data);

Online Demo