#!/usr/bin/perl  
         
use 5.010;
            
use strict;
use warnings;
 
my %data;
my %seen;

while (<DATA>) {
    chomp;
    my ($id, $name, $type, $pid, $qty, $gross) = split /\s*,\s*/;
    given ($type) {
        when ('Item') {
            $data{$id,$name}{$type}{$pid}{qty} += $qty;
            $data{$id,$name}{$type}{$pid}{gross} += $gross;   
            $seen{$pid} = 1;
            next;
        }
        when ('Cart') {
            $data{$id,$name}{$type}{qty} = $qty;
            $data{$id,$name}{$type}{gross} = $gross;
        }
    }
}

my @pids = sort keys %seen;

print "Txn ID, Name, Qty, Gross";
print ", $_ Qty, $_ Gross" for @pids;
print "\n";

foreach my $ckey (sort keys %data) {
    my ($id, $name) = split $;, $ckey;
    print "$id, $name, ", $data{$ckey}{Cart}{qty} // "", ", ",
                          $data{$ckey}{Cart}{gross} // "";
    foreach my $pid (@pids) {
        print ", ", $data{$ckey}{Item}{$pid}{qty} // "", ", ",
                    $data{$ckey}{Item}{$pid}{gross} // "";
    }
    print "\n";
}
    
    
__DATA__
Txn ID,  Name ,  Type , Product ID, Qty, Gross
010   ,  Moe  ,  Cart ,           ,  1 ,   15
010   ,  Moe  ,  Item ,  widget-1 ,  1 ,   15
020   ,  Larry,  Cart ,           ,  3 ,   35
020   ,  Larry,  Item ,  widget-1 ,  1 ,   15
020   ,  Larry,  Item ,  widget-2 ,  2 ,   20

##</code><code>##

Txn ID, Name, Qty, Gross, widget-1 Qty, widget-1 Gross, widget-2 Qty, widget-2 Gross
010, Moe, 1, 15, 1, 15, , 
020, Larry, 3, 35, 1, 15, 2, 20