Facebook Marketing API : How to get Leads for each AdSet and each AD every day

I am using FB Marketing API for my first time. I want to fetch :

1) The Leads value for each AdSet and each Ad for every day.

2) The cost for each Lead.

Day (14/11/2018) :: Ad_1_Lead :: Ad_1_Cost_Per_Lead :: Ad_2_Lead :: Ad_2_Cost_Per_Lead

Day (15/11/2018) :: Ad_1_Lead :: Ad_1_Cost_Per_Lead :: Ad_2_Lead :: Ad_2_Cost_Per_Lead

what i have done so far is only listing the Campaigns && Adsets && Ads

for example this is my code to list the Adset:

$fields_adset = array(

$adsets = $account->getAdSets($fields_adset);

foreach ($adsets as $adset) {
    $adset_id = $adset->{AdSetFields::ID};
    echo  " Name " .PHP_EOL. $adset->{AdSetFields::NAME}.PHP_EOL."<br>";

The leads doesn't exist in fields of the Campaign && Adset && Ads.. so after doing some research i have found that.

Any leads associated with with a Lead Ad. Since these leads belong to a business' Page, not the ad itself, you need to be a Page Admin to access these. Alternately you can have permissions granted to you by the Page Admin.

So to list the leads i need to be admin of the page, and i am admin. i use this code

$ad = new Ad('<AD_ID>');
$leads = $ad->getLeads($fields_adset);
foreach ($leads as $lead) {
echo $lead->{LeadFields::ID}.PHP_EOL;

result : null.

i can't display LeadId i want to display (1) LeadId, (2) Leads count per Ad, (3) Leads cost per Ad

Any help would be appreciated.