#!/usr/bin/perl
#
# $Id: graph.png,v 1.23 2003/10/09 15:56:41 matthew Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/cgi-bin/graph.gif
#
# http://www.lon-capa.org/
#
# The LearningOnline Network with CAPA
#
# A CGI script that dynamically outputs a graphical chart for lonstatistics.
# 
#### 

=pod

=head1 NAME

graph.png

=head1 SYNOPSIS

produces plots based on input

=head1 DESCRIPTION

graph.png is a cgi-bin script which produces plots based on input data.

The query string is expected to be as follows (without whitespace):

escape(Plot title) & escape(X label)& escape(Y label) & Maximum Y value &
Number of bars & $data1 & $data2

$data1 and $data2 are expected to be comma seperated lists of numbers.
escape( value ) means the values must be run through lonnet::escape.

=cut

use strict;
use GD::Graph::bars;
use GD::Graph::colour;
use GD::Graph::Data;

sub unescape {
    my $str=shift;
    $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
    return $str;
}

$|=1;   # Autoflush after each print/write
my ($Titr,$xlab,$ylab,$Max,$NumBars,$data1,$data2)=split(/&/,$ENV{'QUERY_STRING'});
$Titr = &unescape($Titr);
$xlab = &unescape($xlab);
$ylab = &unescape($ylab);

my @data11=split(/\,/,$data1);
my @data12=split(/\,/,$data2);
my $skip_x = 1;
#my $bar_space=1;
my $bar_width=10;

my @xlabels;

for (my $nIdx=0; $nIdx<$NumBars; $nIdx++ ) {
    $xlabels[$nIdx]=$nIdx+1;
}

#if ($Titr =~ /^Percentage$/){
#    for (my $nIdx=0; $nIdx<$NumBars; $nIdx++ ) {
#        $xlabels[$nIdx]=$nIdx;
#    }
#    @data11=();
#    @data11=split(/\,/,$data2);
#    @data12=();
#    $Titr = '';
#} else {
#} 

my @data =(\@xlabels,\@data11,\@data12);

my $width;
my $height = 200;

if ($NumBars < 10) {
    $width = 120+$NumBars*15;
    $skip_x = 1;
    $bar_width = 15;
} elsif ($NumBars <= 25) {
    $width = 120+$NumBars*11;
    $skip_x = 5;
    $bar_width = 8;
} elsif ($NumBars <= 50) {
    $width = 120+$NumBars*8;
    $skip_x = 5;
    $bar_width = 4;
} else {
    $width = 120+$NumBars*8;
    $skip_x = 5;
    $bar_width = 4;
}

my $x_tick_offset = 0;
if ($skip_x > 1) {
    $x_tick_offset = $skip_x - 1;
}

my $MyGraph = GD::Graph::bars->new($width,$height);

$MyGraph->set( 
    x_label         => $xlab,
    y_label         => $ylab,
    x_label_position => 0.5,
    long_ticks      => 1,
    tick_length     => 0,
    x_ticks         => 0,
    title           => $Titr,
    y_max_value     => $Max,
#    y_tick_number   => $ytic,
#    y_label_skip    => 5,
    x_label_skip    => $skip_x,   
    x_tick_offset   => $x_tick_offset,

    dclrs           => [ qw( lgreen dgreen lyellow lpurple cyan lorange)],
    bar_width       => $bar_width,
#    bar_spacing     => $bar_space,
    cumulate        => 2,
    zero_axis        => 1,

#    legend_placement    => 'RT',

    fgclr               => 'black',
    boxclr              => 'white',
    accentclr           => 'dblue',
    valuesclr           => '#ffff77',
    l_margin            => 10,
    b_margin            => 10,
    r_margin            => 10,
    t_margin            => 10,

    transparent     => 0,
) or warn $MyGraph->error; 


# Tell the server we are sending a png graphic
print <<END;
Content-type: image/png

END

my $BinaryData=$MyGraph->plot(\@data)->png;
undef $MyGraph;
binmode(STDOUT);
#open IMG,"|pngtopnm|ppmtogif 2>/dev/null"; # convert into a gif image
#print IMG $BinaryData; # output image
#$|=1; # be sure to flush before closing
#close IMG;
print $BinaryData;