#!/usr/bin/perl

use warnings;
use strict;

use WWW::Mechanize;
use HTML::TokeParser;
use CGI;

my $id  = YOUR_ID_HERE;  #use quotes!
my $pin = YOUR_PIN_HERE; #use quotes!

my $semester = shift;
my $courses = shift;

my $cgi = CGI->new();
my $form = $cgi->Vars;

my $agent = WWW::Mechanize->new(cookie_jar=>{});
$agent->get('https://poseidon.cc.mcgill.ca/pls/mcgp/twbkwbis.P_WWWLogin');
$agent->form(2);
$agent->field('sid', $id);
$agent->field('PIN', $pin);
$agent->click();

$agent->get('https://poseidon.cc.mcgill.ca/pls/mcgp/bzsktran.P_Display_Form?user_type=S&tran_type=V');

if (!($agent->content =~ m/TERM GPA/)) {
    die("Error accessing transcript. Perhaps system is busy or bad login information?\n");
}

my @semmatch = ($agent->content =~ m@(?:(.*?<TR>.*?<B>.*?)(?:TERM GPA|START OF).*?){$semester}@si);

my @grades;
my @nogrades;
my $count;
my @matches;
for ($count=1; $count <= $courses; $count++) {
    @matches = ( $semmatch[0] =~ m@.*?(?:<TR>\s*<TD[^>]+>(?:<SPAN[^>]+>)?([^<]+)(?:</SPAN>)?</TD>\s*<TD[^>]+><SPAN[^>]+>([^<]+)(?:&nbsp;<SPAN[^>]+>[^<]+</SPAN>)?</SPAN></TD>\s*<TD[^>]+><SPAN[^>]+>([^<]+)</SPAN></TD>\s*<TD[^>]+><SPAN[^>]+>([^<]+)</SPAN></TD>\s*<TD[^>]+><SPAN[^>]+>([^<]+)</SPAN></TD>\s*<TD[^>]+>[^<]+</TD>\s*<TD[^>]+>(?:<SPAN[^>]+>)?([^<]+)(?:</SPAN>)?</TD>.*?</TR>.*?){$count}@si );

    if ($matches[5] ne "&nbsp;") {
	$grades[$#grades+1] = "   " . $matches[5] . " in " . $matches[1] . " (" . $matches[3] . ")";
    }
    else {
	$nogrades[$#nogrades+1] = $matches[1];
    }
}

$agent->get('https://poseidon.cc.mcgill.ca/pls/mcgp/twbkwbis.P_Logout');

if ($#grades >= 0) {
    print "Available grades:\n" . join("\n", @grades) . "\n";
}
if ($#nogrades >= 0) {
    print "Grades not available for " . join(", ", @nogrades) . ".\n";
}