#!/usr/bin/perl

#!c:\Perl\bin\perl.exe

use strict;
use warnings;
use CGI::Carp qw(fatalsToBrowser);
use lib qw(/path/to/lib_dev);
use CGI::Simple;
use CGI::Session;   # v4.13 (was v3.11)
use HTML::Template;
use DBI;            # v1.32

my $q = CGI::Simple->new() 
  or die "can't create query object: $!";

my $dbh = DBI->connect('DBI:mysql:database=mydb;host=myhost', 'myuid', 'mypwd')
  or die "can't connect to db";

my $sid = $q->cookie("CGISESSID") or undef;
my $s = CGI::Session->new(undef, $sid, {Handle => $dbh}) 
  or die CGI::Session->errstr; # corrected

$_ = $q->param('a');
if    (/next/) { next_page()     }
elsif (/prev/) { previous_page() }
else           { first_page()    }

sub next_page {
  my $first = $s->param('f');
  $first += 20;
  $s->param('f', $first);
  print_output($first);
}

sub previous_page {
  my $first = $s->param('f');
  $first -= 20;
  $s->param('f' => $first);
  print_output($first);
}

sub first_page{
  $s->param('f', 0);
  print_output(0);
}

sub print_output {
  my ($first) = @_;
  my $file = 'tmpl/session.html';
  my $t = HTML::Template->new(
    filename => $file
  ) or die "can't find $file: $!";
  $t->param({first => $first});
  print $s->header;
  print $t->output;
}