#! perl -slw
use strict;
use Data::Dump qw[ pp ];

our $i //= 'tutorial-data.txt';
our $debug //= 0;

open my $in, '<', $i or die "failed to open '$i':$!";

my %users;
my $userid;
while( <$in> ) {
    chomp;
    warn "DEBUG: $_\n" if $debug;
    s[#.*$][] if /#/;
    next unless /\S/;
    my( $lead, $key, $val ) = m[^(\s+)?(\S+)\s*:\s*(.+?)\s*$] or die "Invalid line format at line $.";
    $key = lc $key;
    if( defined $lead and length $lead ) {
        die "Missing userid at $." unless $userid;
        $val = [ split '\s*,\s*', $val ] if $key eq 'hobbies'; ## modified to trim
        $users{ $userid }{ $key } = $val;
    }
    else {
        die "Missing userid at line $." unless $val;
        die "Userid '$val' not a positive integer at line $." unless $val =~ /^\d+$/;
        die "Userid '$val' not unique at line $." if exists $users{ $val };
        $userid = $val;
    }
}

warn "DEBUG: Dumping user hash\n" and pp \%users if $debug;