use 5.010;

my @lines
  = ('some text FOO | some text BAR | oh , no , commas | some text BAZ | some text QUX');

for my $line (@lines) {
    chomp $line;
    if ($line =~ /,/) {
        my @items  = split /,/, $line;
        my $prefix = substr $items[0],  0, rindex $items[0],  '|';
        my $suffix = substr $items[-1], index  $items[-1], '|';
        #say $prefix;
        #say $suffix;
        foreach my $item (@items) {
            say "$prefix | $item $suffix";
        }
    }
    else {
        say $line;
    }
}