use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);
use Text::CSV_XS;

# So original data look something like:

my @d = split /\n/, <<'END';
1,6064.86,85391.25,593.75,13.25
2,6072.17,85392.95,593.79,13.29
3,6078.94,85393.05,593.76,13.26
4,6085.51,85392.22,593.77,13.27
END

# I need to insert two lines at the top, two lines at the
# bottom, switch columns 2 and 3 around and replace column 5 with column
# 1.I'm using Text::CSV for parsing and also Lava GUI package. So part of
# the code that does parsing looks like this:D

my ($t, @t) = (Text::CSV_XS->new);

$t->parse($_) && push(@t, [($t->fields())[4,2,1,3,0]]) or die "Could not parse: $_" for @d; # Parse and rearrange

unshift @t, ["Top line 1"], ["Top line 2"]; # Top lines
push    @t, ["Bot line 1"], ["Bot line 2"]; # Bottom lines

$t->combine(@$_) && ($_ = $t->string)  or die "Cannot combine: ".dump($_) for @t; # Combine

pp(\@t); # Print result


##</code><code>##

[
  "\"Top line 1\"",
  "\"Top line 2\"",
  "13.25,85391.25,6064.86,593.75,1",
  "13.29,85392.95,6072.17,593.79,2",
  "13.26,85393.05,6078.94,593.76,3",
  "13.27,85392.22,6085.51,593.77,4",
  "\"Bot line 1\"",
  "\"Bot line 2\"",
]