package MyWebApp;
use base 'CGI::Application';

use strict;
use CGI;
use CGI::Ajax;
use CGI::Carp qw(fatalsToBrowser);
use CGI::Application::Plugin::DBH qw(dbh_config dbh);
use DBI qw(:sql_types);
use DBIx::Chart;

sub setup{
  my $self = shift;
  $self->start_mode('mode1');
  $self->mode_param('rm');
  $self->run_modes(
    'mode1' => 'runMode1',
    'mode2' => 'runMode2'
  );

  $self->dbh_config('dbh1', ['DBI:DB2:DS1', 'usr', 'pwd', {RaiseError => 0, PrintError => 0}]);
}

sub runMode1 {
  my $q = new CGI;
  my $pjx = new CGI::Ajax('GET_CHART' => \&BUILD_CHART, 'skip_header' => 1);
  open(SRC, "pageSrc.htm") or die $!;
  my $src = <SRC>;
  close(SRC);

  my $output = $q->start_html;
  $output .= $src;
  $output .= $q->end_html;

  return $pjx->build_html($q, $output);
}

sub BUILD_CHART {
  my ($chartSelection, $screenWidth) = @_;
  my $chartWidth = $screenWidth / 2;

  #this is where I want to take advantage of CGI::Application::Plugin::DBH -- so that I don't have to build this connection every time an ajax call is made to this subroutine
  my $dbh = DBIx::Chart->connect('DBI:DB2:DS1', 'usr', 'pwd', {RaiseError => 0, PrintError => 0}) or die $DBI::errstr;
  my $qryStatement = "SELECT SOMETHING FROM SOMEWHERE";
  my $chartStatement = "RETURNING BARCHART(*), IMAGEMAP  WHERE ...";
  my $sth = $dbh->prepare("$qryStatement $chartStatement");
  unless(eval{$sth->execute();}){
    die "Failed to execute!";
  }

  my $tempChartRef = $sth->fetchrow_arrayref or die "Failed to fetch!";
  $sth->finish;

  my $imageData = $$tempChartRef[0];
  my $imageMap  = $$tempChartRef[1];
  my $imageName = &WRITE_IMAGE_TO_DISK($imageData, 'PNG', 'barchart');

  my $html = "<IMG SRC=\"/$imageName\" USEMAP=\"#barMap\">";
  $html .= $imageMap;

  return $html;
}