In PHP, hierarchical structure array based on randomised relational data? - php

Question

My questions is very very similar to the following, but I have a couple of differences, including writing it in PHP.
https://softwareengineering.stackexchange.com/questions/261074/process-to-generate-hierarchical-structure-based-on-relational-data
I have the following data in a CSV:
firstname,surname,position,manager
John,D,Clerk,Jane D
Bob,B,Clerk,Jane D
Harry,S,Supervisor,Jack W
Jack,W,CEO,
David,B,Cook,Jack W
Jane,D,CTO,
Amy,L,CBO,
Mike,M,Singer,John D
Using PHP, I need to create an array of this data in a heirarchical structure in which records sit under the correct manager record. A top level record is indicated by a blank 'manager' field. Notice how there can be more than one top level record. Furthermore, notice how the data is completely random.
I tried to convert the above buildtree() function in PHP, but it doesn't seem correct. Here is my attempt, can someone explain where I might be going wrong? The trouble I seem to get is that when I pass the array to buildtree(), its ending because it starts with the 'blank' key and thus it doesn't continue with the recursion:
function buildtree($parents,$tree = array(),$parent_id = ''){
$parent = $parents[$parent_id];
if($parent == ''){
return $tree;
}
foreach($parent as $child){
$report = array($child[0].' '.$child[1]);
if(empty($tree)){
$tree = $report;
}
else{
$reports = $tree['reports'];
$reports = array_merge($reports,$report);
}
buildtree($parents,$report,$child[0].' '.$child[1]);
}
return $tree;
}
# something not right about this.
# first, build an array of managers
foreach($_SESSION['csv_data'] as $k=>$val){
if($k > 0){
$manager = $val[3];
$heir[$manager]['reports'][$val[0].' '.$val[1]] = '';
}
}
$final = buildtree($heir);
echo '<pre>';
print_r($final);
echo '</pre>';
For reference, here is the original python buildtree() function:
def buildtree(t=None, parent_eid=''):
"""
Given a parents lookup structure, construct
a data hierarchy.
"""
parent = parents.get(parent_eid, None)
if parent is None:
return t
for eid, name, mid in parent:
report = { 'name': name }
if t is None:
t = report
else:
reports = t.setdefault('reports', [])
reports.append(report)
buildtree(report, eid)
return t
data = buildtree()