# The LearningOnline Network with CAPA
# (Publication Handler
#
# $Id: lonstatistics.pm,v 1.28 2002/07/19 18:17:34 minaeibi 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/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
# (Navigate problems for statistical reports
# YEAR=2001
# 5/5,7/9,7/25/1,8/11,9/13,9/26,10/5,10/9,10/22,10/26 Behrouz Minaei
# 11/1,11/4,11/16,12/14,12/16,12/18,12/20,12/31 Behrouz Minaei
# YEAR=2002
# 1/22,2/1,2/6,2/25,3/2,3/6,3/17,3/21,3/22,3/26,4/7,5/6 Behrouz Minaei
# 5/12,5/14,5/15,5/19,5/26,7/16  Behrouz Minaei
#
###

package Apache::lonstatistics; 

use strict; 
use Apache::Constants qw(:common :http);
use Apache::lonnet();
use Apache::lonhomework;
use Apache::loncommon;
use HTML::TokeParser;
use GDBM_File;

# -------------------------------------------------------------- Module Globals
my %hash;
my %CachData;
my %GraphDat;
my $r;
my $GData;
my %color;
my %foil_to_concept;
my @Concepts;
my %ConceptData;
my %Answer=();
my %mapsort;

my %Activity=();
my %Grade=();
my %DoDiff=();
my %Discuss=();
my $TotalDiscuss=0;
my $TotalDiscuss_=0;


sub LoadDiscussion {
#    my $symb=shift;
#    $r->print('<br>$cid ... '.$symb);
#    my %contrib=&Apache::lonnet::dump('msu_2964385f9033c63msul1','msu','2964385f9033c63msul1');
    my $cid=$ENV{'request.course.id'};
    my %contrib=&Apache::lonnet::dump(
                $ENV{'request.course.id'},
                $ENV{'course.'.$ENV{'request.course.id'}.'.domain'},
                $ENV{'course.'.$ENV{'request.course.id'}.'.num'});
				                            
    foreach my $temp(keys %contrib) {
	if ($temp=~/^version/) {
	    my $ver=$contrib{$temp};
	    my ($dummy,$prb)=split(':',$temp);
	    for (my $idx=1; $idx<=$ver; $idx++ ) {
		my $name=$contrib{"$idx:$prb:sendername"};
		$Discuss{"$name:$prb"}=$idx;	
	    }
	}
    }       
#   $r->print('<br>cid='.$cid);
#    my %contrib=&Apache::lonnet::restore($symb,$cid,
#					 $ENV{$cid.'.domain'},
#					 $ENV{'course.'.$cid.'.num'});

#    $Apache::lonxml::debug=1;
#    &Apache::lonhomework::showhash(%Discuss);
#    $Apache::lonxml::debug=0;
}

sub LoadDoDiffFile {
    my $file="/home/minaeibi/183d.txt";
    open(FILEID, "<$file");
    my $line=<FILEID>;
    %DoDiff=();
    my @Act=split('&',$line);
    
#    $r->print('<br>'.$#Act);
    for(my $n=0;$n<=$#Act;$n++){
       my ($res,$Degree)=split('@',$Act[$n]);
      $DoDiff{$res}=$Degree;
    }
}


sub LoadClassFile {
    my $file="/home/minaeibi/class.txt";
    open(FILEID, "<$file");
    my $line;
    %Grade=();
    while ($line=<FILEID>) {
        my ($id,$ex1,$ex2,$ex3,$ex4,$hw,$final,$grade)=split(' ',$line);
        $Grade{$id}=$grade;
    }
}


#------- Classification  
sub Classify {
    my ($DiscFac, $students)=@_;
    &LoadClassFile();
    my $Count=0;
    my @List=();
    my @LS=();
    my @LF=();
    my @LM=();
    my $cf=0;
    my $cs=0;
    my $cm=0;
    foreach (keys(%$DiscFac)){  
	my @l=split(/\:/,$_);
	if (!($students->{$l[1]})) {next;}
	my $Grade=$Grade{$students->{$l[1]}};
	if( $Grade > 3 ) {
	    $cs++;
	    push(@LS,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Successful"));
	} elsif ( $Grade > 2 ) {
	    $cm++;
	    push(@LM,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Average"));
	} else {
	    $cf++;
	    push(@LF,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Failed"));
	}
    }    
    for(my $n=0;$n<$cs;$n++){$r->print('<br>'.$LS[$n]);}
    for(my $n=0;$n<$cm;$n++){$r->print('<br>'.$LM[$n]);}  
    for(my $n=0;$n<$cf;$n++){$r->print('<br>'.$LF[$n]);}
} 


sub ProcAct {
    # return;
    my ($Act,$Submit)=@_;
    my @Act=split(/\@/,$Act);
    @Act = sort(@Act);

    ##$r->print('<br>'.$#Act);
    ##for(my $n=0;$n<=$#Act;$n++){
##	$r->print('<br>n='.$n.')'.$Act[$n]);
##    }

#    my $Beg=$Act[0];
    my $Dif=$Submit-$Act[0];
    $Dif = ($Dif>0) ? ($Dif/3600) : 0; 

#    $r->print('<br>Access Number = '.$#Act.'<br>Submit Time='.$Submit.'<br>First Access='.$Act[0].'<br>Last Access='.$Act[$#Act].'<br> Submit - First = <b>'.$Dif.'</b>');


#time spent for solving the problem           
#    $r->print('<br>Def'.($Act[$#Act-1]-$Act[0]));

    return $Dif;
}



sub LoadActivityLog {
#    my $CacheDB = "/home/minaeibi/act183.log.cache";
    my $CacheDB = "/home/httpd/perl/tmp/act183.log.cache";
    
    if (-e "$CacheDB") {
	if (tie(%Activity,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
	    return;
        }
        else {
	    $r->print("Unable to tie log Cache hash to db file");
        }
    }
    else {
	if (tie(%Activity,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
	    foreach (keys %Activity) {delete $Activity{$_};}
	    &Build_log(); 
	}
        else {
	    $r->print("Unable to tie log Build hash to db file");
        }
    }
}

sub Build_log {
    my $file="/home/minaeibi/act183.log";
    open(FILEID, "<$file");
    my $line;
    my $count=0;
    while ($line=<FILEID>) {
	my ($time,$machine,$what)=split(':',$line);
	$what=&Apache::lonnet::unescape($what);
	my @accesses=split('&',$what);
	           
	foreach my $access (@accesses) {

	    $count++;

	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
	    if (!$resource) { next; }
	    my $res=&Apache::lonnet::unescape($resource);
	    if (($res =~ /\.problem/)) {
		$Activity{$who.':'.$res}.=$date.'@';
                #$r->print('<br>'.$time.':'.$who.'---'.$res);
		&Update_PrgInit($count);

	    }
	}
    }

# my $c=1;
# foreach (sort keys %Activity) {
#     $r->print('<br>'.$c.')'.$_.' ... '.$Activity{$_});
#     $c++;
# }

}

sub Activity {
#    $rid=~/(\d+)\.(\d+)/;
#    my $MapId=$1;
#    my $PrbId=$2;
#    my $MapOrg = $hash{'map_id_'.$MapId};
#    my $Map = &Apache::lonnet::declutter($MapOrg);
#    my $URI = $hash{'src_'.$rid};
#    my $Symb = $Map.'___'.$PrbId.'___'.&Apache::lonnet::declutter($URI);
    my $file="/home/minaeibi/activity.log";
    my $userid='adamsde1';
    $r->print("<br>Using $file");
    $r->rflush();
    open(FILEID, "<$file");
    my $line;
    my @allaccess;
    my $Count=0;
    while ($line=<FILEID>) {
	my ($time,$machine,$what)=split(':',$line);
	$what=&Apache::lonnet::unescape($what);
	my @accesses=split('&',$what);
	foreach my $access (@accesses) {
	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
	    #if ($who ne $userid) { next; }
	    if (!$resource) { next; }
	    my $res=&Apache::lonnet::unescape($resource);
	    if (($res =~ /\.(sequence|problem|htm|html|page)/)) {
	    	$Count++;
		$r->print("<br>$Count) ".localtime($date).": $who --> $res");
#	        if ($post) { 
#		    $Count++;
#		    $r->print("<br><b>$Count) Sent data ".join(':',
#                              &Apache::lonnet::unescape(@posts)).'</b>');
#		}
		$r->rflush();
	    }
	    #push (@allaccess,unescape($access));
	    #print $machine;
	}
    }
#    @allaccess=sort(@allaccess);
#    $Count=0;
#    foreach my $access (@allaccess) {
#	my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
#	$Count++;
#	$r->print("<br>$Count) $date: $who --> $resource");
#	$r->rflush();
#	if ($post) { 
#	    $r->print("<br><b>Sent data ".join(':',unescape(@posts)).'</b>');
#	}
#    }
}


sub InitAnalysis {
    my ($uri,$part,$problem,$student,$courseID)=@_;
    my ($uname,$udom)=split(/\:/,$student);


    # Render the student's view of the problem.  $Answ is the problem 
    # Stringafied
    my $Answ=&Apache::lonnet::ssi($uri,('grade_target' => 'analyze',
                                  'grade_username' => $uname,
                                  'grade_domain' => $udom,
                                  'grade_courseid' => $courseID,
                                  'grade_symb' => $problem));
#    my $Answ=&Apache::lonnet::ssi($URI,('grade_target' => 'analyze'));

#    (my $garbage,$Answ)=split(/_HASH_REF__/,$Answ,2);
    %Answer=();
    %Answer=&Apache::lonnet::str2hash($Answ);

    my $parts='';
    foreach my $elm (@{$Answer{"parts"}}) {
	$parts.="$elm,";
    }
    chop($parts);
    my $conc='';
    foreach my $elm (@{$Answer{"$parts.concepts"}}) {
	$conc.="$elm@";
    }
    chop($conc);

    @Concepts=split(/\@/,$conc);
    foreach my $concept (@{$Answer{"$parts.concepts"}}) {
	foreach my $foil (@{$Answer{"$parts.concept.$concept"}}) {
	    $foil_to_concept{$foil} = $concept;
	    #$ConceptData{$foil} = $Answer{"$parts.foil.value.$foil"};
	}
    }

    return;
}


sub Interval {
    my ($part,$symb)=@_;
    my $Int=$ConceptData{"Interval"};
    my $due = &Apache::lonnet::EXT('resource.$part.duedate',$symb)+1;
    my $opn = &Apache::lonnet::EXT('resource.$part.opendate',$symb);
    my $add=int(($due-$opn)/$Int);
    $ConceptData{"Int.0"}=$opn;
    for (my $i=1;$i<$Int;$i++) {
	$ConceptData{"Int.$i"}=$opn+$i*$add;
    }
    $ConceptData{"Int.$Int"}=$due;     
    for (my $i=0;$i<$Int;$i++) {
	for (my $n=0; $n<=$#Concepts; $n++ ) {
	    my $tmp=$Concepts[$n];
	    $ConceptData{"$tmp.$i.true"}=0;
	    $ConceptData{"$tmp.$i.false"}=0;
	}
    }
}


sub ShowOpGraph {
    my ($cache, $students, $courseID)=@_;
    my $uri      = $cache->{'AnalyzeURI'};
    my $part     = $cache->{'AnalyzePart'};
    my $problem  = $cache->{'AnalyzeProblem'};
    my $title    = $cache->{'AnalyzeTitle'};
    my $interval = $cache->{'Interval'};
    $ConceptData{"Interval"} = $interval;

    #Initialize the option response true answers
    &InitAnalysis($uri, $part, $problem, $students->[0],$courseID);

    #compute the intervals
    &Interval($part,$problem);

    $title =~ s/\ /"_"/eg;
    $r->print('<br><b>'.$uri.'</b>');
    $r->rflush();
         
    #Java script Progress window
    &Create_PrgWin();
    &Update_PrgWin("Starting-to-analyze-problem");
    for (my $index=0;$index<(scalar @$students);$index++) {
	&Update_PrgWin($index);
	&OpStatus($problem,$students->[$index],$courseID);
    }
    &Close_PrgWin();

    $r->print('<br>');
    for (my $k=0; $k<$interval; $k++ ) {
	&DrawGraph($k,$title);
    }
    for (my $k=0; $k<$interval; $k++ ) {
	&DrawTable($k);
    }
#$Apache::lonxml::debug=1;
#&Apache::lonhomework::showhash(%ConceptData);
#$Apache::lonxml::debug=0;
    my $Answ=&Apache::lonnet::ssi($uri);
    $r->print("<br><b>Here you can see the Problem:</b><br>$Answ");
}


sub DrawTable {
    my $k=shift;
    my $Max=0;
    my @data1;
    my @data2;
    my $Correct=0;
    my $Wrong=0;
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	my $tmp=$Concepts[$n];
	$data1[$n]=$ConceptData{"$tmp.$k.true"};
	$Correct+=$data1[$n];
	$data2[$n]=$ConceptData{"$tmp.$k.false"};
	$Wrong+=$data2[$n];
	my $Sum=$data1[$n]+$data2[$n];
	if ( $Max<$Sum ) {$Max=$Sum;}
    }
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	if ($data1[$n]+$data2[$n]<$Max) {
	    $data2[$n]+=$Max-($data1[$n]+$data2[$n]);
	}
    }
    my $P_No = $#data1+1;
#    $r->print('<br><b>From: ['.localtime($ConceptData{'Int.'.($k-1)}).
#              '] To: ['.localtime($ConceptData{"Int.$k"}).']</b>'); 
    my $Str = "\n".'<table border=2>'.
              "\n".'<tr>'.
              "\n".'<th> # </th>'.
	      "\n".'<th> Concept </th>'.
	      "\n".'<th> Correct </th>'.
	      "\n".'<th> Wrong </th>'.
	      "\n".'</tr>';

    for (my $n=0; $n<=$#Concepts; $n++ ) {
	$Str .= "\n"."<tr>".
	        "\n"."<td>".($n+1)."</td>".
                "\n".'<td bgcolor='.$color{"yellow"}.'> '.$Concepts[$n]." </td>".
                "\n".'<td bgcolor='.$color{"green"}.'> '.$data1[$n]." </td>".
                "\n".'<td bgcolor='.$color{"red"}.'> '.$data2[$n]." </td>".
                "\n"."</tr>";
    }
    $Str.='<td></td><td><b>From:['.localtime($ConceptData{'Int.'.$k}).
          '] To: ['.localtime($ConceptData{'Int.'.($k+1)}-1).
          "]</b></td><td>$Correct</td><td>$Wrong</td>";

    $Str .= "\n".'</table>';

    $r->print($Str);
#$Apache::lonxml::debug=1;
#&Apache::lonhomework::showhash(%ConceptData);
#$Apache::lonxml::debug=0;
}


sub DrawGraph {
    my ($k,$Src)=@_;
    my $Max=0;
    my @data1;
    my @data2;

    # Adjust Data and find the Max 
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	my $tmp=$Concepts[$n];
	$data1[$n]=$ConceptData{"$tmp.$k.true"};
	$data2[$n]=$ConceptData{"$tmp.$k.false"};
	my $Sum=$data1[$n]+$data2[$n];
	if ( $Max<$Sum ) {$Max=$Sum;}
    }
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	if ($data1[$n]+$data2[$n]<$Max) {
	    $data2[$n]+=$Max-($data1[$n]+$data2[$n]);
	}
    }
    my $P_No = $#data1+1;

    if ( $Max > 1 ) { 
	$Max += (10 - $Max % 10);
	$Max = int($Max);
    } else { $Max = 1; }

    my $Titr=($ConceptData{'Interval'}>1) ? $Src.'_interval_'.($k+1) : $Src;
#    $GData=$Titr.'&Concepts'.'&'.'Answers'.'&'.$Max.'&'.$P_No.'&'.$data1.'&'.$data2;
    $GData="$Titr&Concepts&Answers&$Max&$P_No&".
           (join(',',@data1)).'&'.(join(',',@data2));

    $r->print('<IMG src="/cgi-bin/graph.gif?'.$GData.'" border=1/>');
}


sub Decide {
    #deciding the true or false answer belongs to each interval
    my ($type,$foil,$time)=@_; 
    my $k=0;
    while ($time>$ConceptData{'Int.'.($k+1)} && 
           $k<$ConceptData{'Interval'}) {$k++;}
    $ConceptData{"$foil_to_concept{$foil}.$k.$type"}++;
}

#restore the student submissions and finding the result
sub OpStatus {
    my ($problem, $student, $courseID)=@_;
    my ($username,$userdomain)=split(/':'/,$student);
    my $code='U';
    my %reshash=&Apache::lonnet::restore($problem, $courseID, $userdomain, 
                                         $username);
    my @True = ();
    my @False = ();
    my $flag=0;
    if ($reshash{'version'}) {
        my $tries=0;
	&Apache::lonhomework::showhash(%Answer);
	for (my $version=1;$version<=$reshash{'version'};$version++) {
	    my $time=$reshash{"$version:timestamp"};
	   
	    foreach my $key (sort(split(/\:/,$reshash{$version.':keys'}))) {
		if (($key=~/\.(\w+)\.(\w+)\.submission$/)) {
		    my $Id1 = $1; my $Id2 = $2;
		    #check if this is a repeat submission, if so skip it
          	    if ($reshash{"$version:resource.$Id1.previous"}) { next; }
		    #if no solved this wasn't a real submission, ignore it
		    if (!defined($reshash{"$version:resource.$Id1.solved"})) {
			&Apache::lonxml::debug("skipping ");
			next;
		    }
		    my $Resp = $reshash{"$version:$key"};
		    my %submission=&Apache::lonnet::str2hash($Resp);
		    foreach (keys %submission) {
			my $Ansr = $Answer{"$Id1.$Id2.foil.value.$_"};
			if ($submission{$_}) {
			    if ($submission{$_} eq $Ansr) {
				&Decide("true",$_,$time );
			    }
			    else {&Decide("false",$_,$time );}
			}
		    }
	        }	  
	    }
        }
    }
}


#---- END Analyze Web Page ----------------------------------------------

#---- Problem Statistics Web Page ---------------------------------------

#------- Processing upperlist and lowerlist according to each problem
sub ProcessDiscriminant {
    my ($List) = @_;
    my @sortedList = sort (@$List);
    my $Count = scalar @sortedList;
    my $Problem;
    my @Dis;
    my $Slvd=0;
    my $tmp;
    my $Sum1=0;
    my $Sum2=0;
    my $nIndex=0;
    my $nStudent=0;
    my %Proc=undef;
    while ($nIndex<$Count) {
	($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
	@Dis=split(/\+/,$tmp);
	my $Temp = $Problem;
	do {
	    $nIndex++;
	    $nStudent++;
	    $Sum1 += $Dis[0];
	    $Sum2 += $Dis[1];
	    ($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
	    @Dis=split(/\+/,$tmp);
	} while ( $Problem eq $Temp && $nIndex < $Count );
#	$Proc{$Temp}=($Sum1/$nStudent).':'.$nStudent;
	$Proc{$Temp}=($Sum1/$nStudent).':'.($Sum2/$nStudent);
#       $r->print("$nIndex) $Temp --> ($nStudent) $Proc{$Temp} <br>");
	$Sum1=0;
	$Sum2=0;
	$nStudent=0;
    }

    return %Proc;
}



#------- Creating Discimination factor   
sub Discriminant {
    my ($discriminantFactor)=@_;
    my @discriminantKeys=keys(%$discriminantFactor);
    my $Count = scalar @discriminantKeys;

    my $UpCnt = int(0.27*$Count);
    my $low=0;
    my $up=$Count-$UpCnt;
    my @UpList=();
    my @LowList=();

    $Count=0;
    foreach my $key (sort(@discriminantKeys)) { 
	$Count++;    
	if($low < $UpCnt || $Count > $up) {
            $low++;
            my $str=$discriminantFactor->{$key};
            foreach(split(/\:/,$str)){
                if($_) {
                    if($low<$UpCnt) { push(@LowList,$_); }
                    else            { push(@UpList,$_);  }
                }
            }
        }
    }
    my %DisUp =  &ProcessDiscriminant(\@UpList);
    my %DisLow = &ProcessDiscriminant(\@LowList);

    return (\%DisUp, \%DisLow);
}

   
sub NumericSort {          
    $a <=> $b;
}


sub CreateProblemStatisticsTableHeading {
    my ($displayFormat,$sequenceSource,$sequenceTitle,$headings)=@_;
    if($displayFormat eq 'Display CSV Format') {
        $r->print('<br>"'.$sequenceTitle.'","');
        $r->print($sequenceSource.'"');
	return;
    }

    $r->print('<br><a href="'.$sequenceSource.
              '" target="_blank">'.$sequenceTitle.'</a>');

    my $Result = "\n".'<table border=2><tr><th>P#</th>'."\n";
    for(my $nIndex=0; $nIndex < (scalar (keys %$headings)); $nIndex++) { 
	$Result .= '<th>'.'<input type="submit" name="';
        $Result .= 'ProblemStatisticsHeading" value="';
        $Result .= $headings->{$nIndex}.'" />'.'</th>'."\n";
    }
    $Result .= "\n".'</tr>'."\n";    
    $r->print($Result);
    $r->rflush();
}

sub CloseTable {
    my ($cache)=@_;
    if($cache->{'DisplayFormat'} eq 'Display CSV Format') {
	return;
    }    
    $r->print("\n".'</table>'."\n");
    $r->rflush();
}


 
# ------ Dump the Student's DB file and handling the data for statistics table 
sub ExtractStudentData {
    my ($cache,$name,$list)=@_;
    my %discriminantFactor;

    my $totalTries = 0;
    my $totalAwarded = 0;
    my $tempProblemOrder=0;
    my $spent=0;
    my $spent_yes=0;
    my $TotDiscuss=0;
    my $TotalOpend = 0;
    my $ProbSolved = 0;
    my $ProbTot = 0;
    my $TotFirst = 0;
    my $TimeTot = 0;
    my $Discussed=0;

    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

        my $Dis = '';
        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
            my $problem = $cache->{$problemID.':problem'};
            my $LatestVersion = $cache->{$name.':version:'.$problem};

            # Output dashes for all the parts of this problem if there
            # is no version information about the current problem.
            #if(!$LatestVersion) {
            #    foreach my $part (split(/\:/,$cache->{$sequence.':'.
            #                                          $problemID.
            #                                          ':parts'})) {
            #        $codes    .= "-,";
            #        $attempts .= "0,"; 
            #    }
            #    next;
            #}

            my %partData=undef;
            # Initialize part data, display skips correctly
            # Skip refers to when a student made no submissions on that
            # part/problem.
            foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                  $problemID.
                                                  ':parts'})) {
                $partData{$part.':tries'}=0;
                $partData{$part.':code'}='-';
            }

            # Looping through all the versions of each part, starting with the
            # oldest version.  Basically, it gets the most recent 
            # set of grade data for each part.
	    for(my $Version=1; $Version<=$LatestVersion; $Version++) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {

                    if(!defined($cache->{$name.":$Version:$problem".
                                               ":resource.$part.solved"})) {
                        # No grade for this submission, so skip
                        next;
                    }

                    my $tries=0;
                    my $time=0;
                    my $awarded=0;
		    $Discussed=0;
                    my $code='U';

                    $awarded = $cache->{$name.
                                        "$Version:$problem:resource.".
                                        "$part.awarded"};
                    $partData{$part.':awarded'} = ($awarded) ? $awarded : 0;
                    $totalAwarded += $awarded;

                    $tries = $cache->{$name.":$Version:$problem".
                                      ":resource.$part.tries"};
                    $partData{$part.':tries'} = ($tries) ? $tries : 0;
                    $partData{$part.':wrong'} = $partData{$part.':tries'};
                    $totalTries += $tries;

                    my $val = $cache->{$name.":$Version:$problem".
                                       ":resource.$part.solved"};
                    if    ($val eq 'correct_by_student')   {$code = 'C';} 
                    elsif ($val eq 'correct_by_override')  {$code = 'O';}
                    elsif ($val eq 'incorrect_attempted')  {$code = 'I';} 
                    elsif ($val eq 'incorrect_by_override'){$code = 'I';}
                    elsif ($val eq 'excused')              {$code = 'x';}
                    $partData{$part.':code'}=$code;

                    if($partData{$part.':wrong'} ne 0 && 
                       ($code eq 'C' || $code eq 'O')) {
                        $partData{$part.':wrong'}--;
                    }
                }
            }

            # Loop through all the parts for the current problem in the 
            # correct order and prepare the output
            foreach (split(/\:/,$cache->{$sequence.':'.$problemID.
                                         ':parts'})) {
                my $Yes = 0;
                if($partData{$_.':code'} eq 'C' || 
                   $partData{$_.':code'} eq 'O') {
                    $Yes=1;
                }
                #my $ptr = "$hash{'title_'.$ResId}";
                my $ptr = $tempProblemOrder.'&'.$problemID;

                if($_ > 1) {
                    $ptr .= "*(part $_)";
                    $Dis .= '&';
                }

		my ($pr_no,$dod)=split('&',$ptr);
		my $DoDiff=$DoDiff{$dod};
#               $r->print('<br>'.$name.'---'.$ptr.'==='.$DoDiff);

                my $Fac = ($partData{$_.':Tries'}) ? 
                    ($partData{$_.':awarded'}/$partData{$_.':tries'}) : 0;
                my $DisF;
                if($Fac > 0 &&  $Fac < 1) { 
                    $DisF = sprintf( "%.4f", $Fac );
                } else {
                    $DisF = $Fac;
                }

                if ($Discuss{"$name:$problem"}) {
		    $TotDiscuss++;
                    $Discussed=1;
                }
                my $time = $cache->{"$name:$LatestVersion:$problem:timestamp"};
                $Dis .= $tempProblemOrder.'='.$DisF.'+'.$Yes;
                $ptr .= '&'.$partData{$_.'.Tries'}.
                        '&'.$partData{$_.'.Wrongs'}.
                        '&'.$partData{$_.'.Code'};
                push (@$list, $ptr."&$Discussed");

####		if ($DoDiff>0.85) {

                $TimeTot += $time;

                if ($Yes==1 && $partData{$_.'.Tries'}==1) {
		    $TotFirst++;
                }
		my $Acts= $Activity{$name.':'.$problem};
		if ($Acts) {
		    my $Pt=&ProcAct( $Acts, $time );
		    #my ($spe,$beg) = split(/\+/,$Pt);
                    my $spe= $Pt;
		    if ($Yes==1) {$spent_yes += $spe;}
		    $spent += $spe;
		    #$Beg += $beg;
#                   $r->print('<br>'.$name.'---'.$problem.'---'.$spe);
		}
		$TotalOpend++;
		$ProbTot++;

                $tempProblemOrder++;
            }
        }
	my $pstr;
        if($totalTries) {
	    my $DisFac = ($totalAwarded/$totalTries);
	    my $DisFactor = sprintf( "%.4f", $DisFac );
            my $TS = sprintf( "%.2f", $spent );
            my $TS_yes = sprintf( "%.2f", $spent_yes );
	   # $DiscFac{$DisFactor}=$Dis;
	    $pstr=$DisFactor.':'.$name.':'.$ProbTot.':'.$TotalOpend.':'.
                  $totalTries.':'.$ProbSolved.':'.$TotFirst.':'.
                  $TS_yes.':'.$TS.':'.$TotDiscuss;
	    $discriminantFactor{$pstr}=$Dis;
	}
    }

    return (\%discriminantFactor);
}


=pod
sub MySort {          
    if ( $Pos > 0 ) {
	if ($ENV{'form.order'} eq 'Descending') {$b <=> $a;}
	else { $a <=> $b; }
    }
    else {
	if ($ENV{'form.order'} eq 'Descending') {$b cmp $a;}
	else { $a cmp $b; }
    }
}
=cut

sub BuildStatisticsTable {
    my ($cache,$discriminantFactor,$list,$headings,$students)=@_;

#6666666
#    my $file="/home/httpd/perl/tmp/183d.txt";
#    open(OUT, ">$file");
#6666666
    &Create_PrgWin();
##777777
##    &LoadActivityLog();
##    $r->print('<script>popwin.document.popremain.remaining.value="'.
##              'Loading Discussion...";</script>');
##    &LoadDoDiffFile();
    &LoadDiscussion();

    my $p_count = 0;
    my $nIndex = 0;
    my $dummy;
    my $p_val;
    my $ResId;
    my $NoElements = scalar @$list;

    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

	&CreateProblemStatisticsTableHeading($cache->{'DisplayFormat'},
                                             $cache->{$sequence.':source'}, 
                                             $cache->{$sequence.':title'},
                                             $headings);

##777777
##    &Classify($discriminantFactor, $students);


	my ($Hid,$pr)=split(/\:/,$mapsort{$_});
	my @lpr=split(/\&/,$pr);
	for (my $i=1; $i<=$#lpr; $i++) {
	    my %storestats=();
	    my ($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
	    my $Temp = $Prob;
	    my $MxTries = 0;
	    my $TotalTries = 0;
	    my $YES = 0;
	    my $Incorrect = 0;
	    my $Override = 0;
	    my $StdNo = 0;
	    my $DiscNo=0;
	    my @StdLst;
	    while ( $PrOrd == $lpr[$i] ) 
	    {
		$nIndex++;
		$StdNo++;
		$StdLst[ $StdNo ] = $Tries;
		$TotalTries += $Tries;
		if ( $MxTries < $Tries ) { $MxTries = $Tries; } 
		if ( $Code eq 'C' ){ $YES++; }
		elsif( $Code eq 'I' ) { $Incorrect++; }
		elsif( $Code eq 'O' ) { $Override++; }
		elsif( $Code eq 'U' ) { $StdNo--; }
		($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
	    }	

	    $p_count++;
	    my $Dummy;
	    ($ResId,$Dummy)=split(/\*/,$Temp);

	    $Temp = '<a href="'.$hash{'src_'.$ResId}.
                '" target="_blank">'.$hash{'title_'.$ResId}.$Dummy.'</a>';

	    my $res = &Apache::lonnet::declutter($hash{'src_'.$ResId});
	    my $urlres=$res;

	    $ResId=~/(\d+)\.(\d+)/;
	    my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
	    $urlres=$Map;
 
	    $res = '<a href="'.$hash{'src_'.$ResId}.'">'.$res.'</a>';
	    #$Map = '<a href="'.$Map.'">'.$res.'</a>';

#------------------------ Compute the Average of Tries about one problem
	    my $Average = ($StdNo) ? $TotalTries/$StdNo : 0;

	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___timestamp'}=time;       
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___stdno'}=$StdNo;
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___avetries'}=$Average;
   
#-------------------------------- Compute percentage of Wrong tries
	    my $Wrong = ( $StdNo ) ? 100 * ( $Incorrect / $StdNo ) : 0;

#-------------------------------- Compute Standard Deviation
	    my $StdDev = 0; 
	    if ( $StdNo > 1 ) {
		for ( my $n = 0; $n < $StdNo; $n++ ) {
		    my $Dif = $StdLst[ $n ]-$Average;
		    $StdDev += $Dif*$Dif;
		} 
		$StdDev /= ( $StdNo - 1 );
		$StdDev = sqrt( $StdDev );
	    }

#-------------------------------- Compute Degree of Difficulty
	    my $DoDiff = 0;
	    if( $TotalTries > 0 ) {
		$DoDiff = 1 - ( ( $YES + $Override ) / $TotalTries );
#	    $DoDiff =  ($TotalTries)/($YES + $Override+ 0.1);	    
	    }
       
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___difficulty'}=$DoDiff;

#-------------------------------- Compute the Skewness
	    my $Skewness = 0;
	    my $Sum = 0; 
	    if ( $StdNo > 0 && $StdDev > 0 ) {
		for ( my $n = 0; $n < $StdNo; $n++ ) {
		    my $Dif = $StdLst[ $n ]-$Average;
		    $Skewness += $Dif*$Dif*$Dif;
		} 
		$Skewness /= $StdNo;
		$Skewness /= $StdDev*$StdDev*$StdDev;
	    }

#--------------------- Compute the Discrimination Factors
            my ($Up1,$Up2)=split(/\:/,':');#jason$DisUp->{$lpr[$i]});
	    my ($Lw1,$Lw2)=split(/\:/,':');#jason$DisLow->{$lpr[$i]});
	    my $Dis1 = $Up1 - $Lw1;
	    my $Dis2 = $Up2 - $Lw2;
	    my $_D1 = sprintf("%.2f", $Dis1);
	    my $_D2 = sprintf("%.2f", $Dis2);

#-----------------  Some restition in presenting the float numbers
	    my $Avg = sprintf( "%.2f", $Average );
	    my $Wrng = sprintf( "%.1f", $Wrong );
	    my $SD = sprintf( "%.1f", $StdDev );
	    my $DoD = sprintf( "%.2f", $DoDiff );
	    my $Sk = sprintf( "%.1f", $Skewness );
	    my $join = $lpr[$i].'&'.$Temp.'&'.$StdNo.'&'.
                       $TotalTries.'&'.$MxTries.'&'.$Avg.'&'.
                       $YES.'&'.$Override.'&'.$Wrng.'&'.$DoD.'&'.
		       $SD.'&'.$Sk.'&'.$_D1.'&'.$_D2.'&'.
                       $DiscNo.'&'.$Prob;
	    $CachData{($p_count-1)}=$join;

#6666666
#	    $r->print('<br>'.$out.'&'.$DoD);
#            print (OUT $out.'@'.$DoD.'&');
#6666666

	    $urlres=~/^(\w+)\/(\w+)/;
	    if ($StdNo) { 
		&Apache::lonnet::put('resevaldata',\%storestats,$1,$2); 
	    }
#-------------------------------- Row of statistical table
            &TableRow($cache,$join,$i,($p_count-1));
	}
	&CloseTable($cache);
    }
    &Close_PrgWin();
#666666
#    close( OUT );
#666666
}

=pod
sub Cache_Statistics {
    my ($cache)=@_;
    my @list = ();
    my $Useful;
    my $UnUseful;
#    $r->print('<input type="hidden" name="show" value="excel" />'."\n"); 
    my %myHeader = reverse( %Header );
    $Pos = $myHeader{$ENV{'form.sort'}};
    if ($Pos > 0) {$Pos++;}
    my $p_count = 0;
    foreach my $key( keys %CachData) { 
	my @Temp=split(/\&/,$CachData{$key});
	if ( $Pos == 0 ) {
	    ($UnUseful,$Useful)=split(/\>/,$Temp[$Pos]);
	}
	else {
	    $Useful = $Temp[$Pos];
	}   
	$list[$p_count]=$Useful.'@'.$CachData{$key};
        $p_count++;
    }

    @list = sort MySort (@list);

    my $nIndex=0;

    if ( $Pos == 0 ) {
	foreach (sort keys %mapsort) {
	    my ($Hid,$pr)=split(/\:/,$mapsort{$_});
	    &CreateProblemStatisticsTableHeading($cache,1,$Hid);
	    my @lpr=split(/\&/,$pr);
	    for (my $i=1; $i<=$#lpr; $i++) {
		my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
		#$r->print('<br>'.$Pre.'---'.$Post);
		&TableRow($cache,$Post,$i,$nIndex);
		$nIndex++;
	    }
	    &CloseTable($cache);
	}
    }
    else {
	&CreateProblemStatisticsTableHeading($cache,0);
	for ( my $nIndex = 0; $nIndex < $p_count; $nIndex++ ) {
	    my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
	    &TableRow($cache,$Post,$nIndex,$nIndex);
	} 
	&CloseTable($cache);
    }
}
=cut 



sub TableRow {
    my ($Str,$Idx,$RealIdx)=@_;
    my($PrOrd,$Temp,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2,$DiscNo,$Prob)=split(/\&/,$Str);	
    if ($ENV{'form.showcsv'}) {
        my ($ResId,$Dummy)=split(/\*/,$Prob);
        my $Ptr =  "\n".'<br>'.
               "\n".'"'.($RealIdx+1).'",'.
               "\n".'"'.$hash{'title_'.$ResId}.$Dummy.'",'.
               "\n".'"'.$hash{'src_'.$ResId}.'",'.
               "\n".'"'.$StdNo.'",'.
               "\n".'"'.$TotalTries.'",'.
               "\n".'"'.$MxTries.'",'.
               "\n".'"'.$Avg.'",'.
               "\n".'"'.$YES.'",'.
               "\n".'"'.$Override.'",'.
               "\n".'"'.$Wrng.'",'.
               "\n".'"'.$DoD.'",'.
               "\n".'"'.$SD.'",'.
               "\n".'"'.$Sk.'",'.
               "\n".'"'.$_D1.'",'.
	       "\n".'"'.$_D2.'"'.
	       "\n".'"'.$DiscNo.'"';

        $r->print("\n".$Ptr);
    }
    else{
        my $Ptr =  "\n".'<tr>'.
               "\n".'<td>'.($RealIdx+1).'</td>'.
          #     "\n".'<td>'.$PrOrd.$Temp.'</td>'.
               "\n".'<td>'.$Temp.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'> '.$StdNo.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'>'.$TotalTries.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'>'.$MxTries.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'>'.$Avg.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'> '.$YES.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'> '.$Override.'</td>'.
               "\n".'<td bgcolor='.$color{"red"}.'> '.$Wrng.'</td>'.
               "\n".'<td bgcolor='.$color{"red"}.'> '.$DoD.'</td>'.
               "\n".'<td bgcolor='.$color{"green"}.'> '.$SD.'</td>'.
               "\n".'<td bgcolor='.$color{"green"}.'> '.$Sk.'</td>'.
               "\n".'<td bgcolor='.$color{"purple"}.'> '.$_D1.'</td>'.
	       "\n".'<td bgcolor='.$color{"purple"}.'> '.$_D2.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'> '.$DiscNo.'</td>';
        $r->print("\n".$Ptr.'</tr>' );
    }
    $GraphDat{$RealIdx}=$DoD.':'.$Wrng;
}
sub StatusOptions {
    my ($cache)=@_;

    my $Status = $cache->{'Status'};
    my $OpSel1 = '';
    my $OpSel2 = '';
    my $OpSel3 = '';

    if($Status eq 'Any')         { $OpSel3 = ' selected'; }
    elsif($Status eq 'Expired' ) { $OpSel2 = ' selected'; }
    else                         { $OpSel1 = ' selected'; }

    my $Ptr = '';
    $Ptr .= '<tr><td align="right"><b>Student Status:</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Status">';
    $Ptr .= '<option'.$OpSel1.'>Active</option>'."\n";
    $Ptr .= '<option'.$OpSel2.'>Expired</option>'."\n";
    $Ptr .= '<option'.$OpSel3.'>Any</option>'."\n";
    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

sub AscendOrderOptions {
    my ($cache)=@_;

    my $order = $cache->{'Ascend'};
    my $OpSel1 = '';
    my $OpSel2 = '';

    if($order eq 'Ascending') {
        $OpSel1 = ' selected';
    } else {
        $OpSel2 = ' selected';
    }

    my $Ptr = '';
    $Ptr .= '<tr><td align="right"><b>Sorting Type:</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Ascend">'."\n";
    $Ptr .= '<option'.$OpSel1.'>Ascending</option>'."\n".
	    '<option'.$OpSel2.'>Descending</option>'."\n";
    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

sub ProblemStatisticsButtons {
    my ($cache)=@_;

    my $Ptr = '<tr><td></td><td align="left">';
    $Ptr .= '<input type=submit name="ProblemStatisticsRecalculate" ';
    $Ptr .= 'value="Recalculate Statistics"/>'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="DoDiffGraph" ';
    $Ptr .= 'value="DoDiff Graph" />'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="PercentWrongGraph" ';
    $Ptr .= 'value="%Wrong Graph" />'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="DisplayCSVFormat" ';
    if($cache->{'DisplayFormat'} eq 'Display CSV Format') {
        $Ptr .= 'value="Display CSV Format" />'."\n";
    } else {
        $Ptr .= 'value="Display Table Format" />'."\n";
    }
    $Ptr .= '</td></tr>';

    return $Ptr;
}

sub ProblemStatisticsLegend {
    my $Ptr = '';
    $Ptr = '<table border="0">';
    $Ptr .= '<tr><td>';
    $Ptr .= '<b>#Stdnts</b>:</td>';
    $Ptr .= '<td>Total Number of Students opened the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Tries</b>:</td>';
    $Ptr .= '<td>Total Number of Tries for solving the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Mod</b>:</td>';
    $Ptr .= '<td>Maximunm Number of Tries for solving the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Mean</b>:</td>';
    $Ptr .= '<td>Average Number of the tries. [ Tries / #Stdnts ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>#YES</b>:</td>';
    $Ptr .= '<td>Number of students solved the problem correctly.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>#yes</b>:</td>';
    $Ptr .= '<td>Number of students solved the problem by override.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>%Wrng</b>:</td>';
    $Ptr .= '<td>Percentage of students tried to solve the problem ';
    $Ptr .= 'but still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]';
    $Ptr .= '</td></tr><tr><td>';
#    Kashy formula
#    '<b>  DoDiff </b>: Degree of Difficulty of the problem.<br>'.
#    '[ Tries/(#YES+#yes+0.1) ]<br>'.
    #Gerd formula
    $Ptr .= '<b>DoDiff</b>:</td>';
    $Ptr .= '<td>Degree of Difficulty of the problem.  ';
    $Ptr .= '[ 1 - ((#YES+#yes) / Tries) ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>S.D.</b>:</td>';
    $Ptr .= '<td>Standard Deviation of the tries.  ';
    $Ptr .= '[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) ';
    $Ptr .= 'where Xi denotes every student\'s tries ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Skew.</b>:</td>';
    $Ptr .= '<td>Skewness of the students tries.';
    $Ptr .= '[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Dis.F.</b>:</td>';
    $Ptr .= '<td>Discrimination Factor: A Standard for evaluating the ';
    $Ptr .= 'problem according to a Criterion<br>';
    $Ptr .= '<b>[Applied Criterion in %27 Upper Students - ';
    $Ptr .= 'Applied the same Criterion in %27 Lower Students]</b><br>';
    $Ptr .= '<b>1st Criterion</b> for Sorting the Students: ';
    $Ptr .= '<b>Sum of Partial Credit Awarded / Total Number of Tries</b><br>';
    $Ptr .= '<b>2nd Criterion</b> for Sorting the Students: ';
    $Ptr .= '<b>Total number of Correct Answers / Total Number of Tries</b>';
    $Ptr .= '</td>';
    $Ptr .= '<td><b>Disc.</b></td>';
    $Ptr .= '<td>Number of Students had at least one discussion.';
    $Ptr .= '</td></tr></table>';

    return $Ptr;
}

#---- END Problem Statistics Web Page ----------------------------------------

#---- Problem Statistics Graph Web Page --------------------------------------

# ------------------------------------------- Prepare data for Graphical chart

sub GetGraphData {
    my $ylab = shift;
    my $Col;
    my $data='';
    my $count = 0;
    my $Max = 0;
    my $cid=$ENV{'request.course.id'};
    my $GraphDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$cid\_graph.db";
    foreach (keys %GraphDat) {delete $GraphDat{$_};}
    if (-e "$GraphDB") {
	if (tie(%GraphDat,'GDBM_File',"$GraphDB",&GDBM_READER,0640)) {
	    if ( $ylab eq 'DoDiff Graph' ) {
		$ylab = 'Degree-of-Difficulty';
		$Col = 0;
	    }
	    else {
		$ylab = 'Wrong-Percentage';
		$Col = 1;
	    }
	    foreach (sort NumericSort keys %GraphDat) { 
		my @Temp=split(/\:/,$GraphDat{$_});
                my $inf = $Temp[$Col]; 
		if ( $Max < $inf ) {$Max = $inf;}
		$data .= $inf.',';
		$count++;
	    }
	    if ( $Max > 1 ) { 
		$Max += (10 - $Max % 10);
		$Max = int($Max);
	    }
	    else { $Max = 1; }
            untie(%GraphDat);
	    my $Course = $ENV{'course.'.$cid.'.description'};
	    $Course =~ s/\ /"_"/eg;
	    $GData=$Course.'&'.'Problems'.'&'.$ylab.'&'.$Max.'&'.$count.'&'.$data;
	}
	else {
	    $r->print("Unable to tie hash to db file");
	}
    }
}
#---- Problem Analysis Web Page ----------------------------------------------

sub IntervalOptions {
    my ($cache)=@_;

    my $interval = 1;
    for(my $n=1; $n<=7; $n++) {
        if($cache->{'Interval'} == $n) {
            $interval = $n;
        }
    }

    my $Ptr = '<br><b>Select number of intervals</b>'."\n".
       	      '<select name="Interval">'."\n";
    for(my $n=1; $n<=7;$ n++) {
	$Ptr .= '<option';
        if($interval == $n) {
            $Ptr .= ' selected';
        }
	$Ptr .= '>'.$n."</option>"."\n";
    }
    $Ptr .= '</select>'."\n";

    return $Ptr;
}

sub OptionResponseTable {
    my ($cache)=@_;
    my $Str = '';
    $Str .= '<br><b> Option Response Problems in this course:</b>'."\n";
    $Str .= '<br><br>'."\n";
    $Str .= "<table border=2><tr><th> \# </th><th> Problem Title </th>";
    $Str .= '<th> Resource </th><th> Analysis  </th></tr>'."\n";

    my $number=1;
    foreach (split(':::',$cache->{'OptionResponses'})) {
        my ($uri,$title,$part,$problem)=split('::',$_);
        my $Temp = '<a href="'.$uri.'" target="_blank">'.$title.'</a>';
        $Str .= '<tr>';
        $Str .= '<td> '.$number.' </td>';
        $Str .= '<td bgcolor="'.$color{"green"}.'"> '.$Temp.' </td>';
        $Str .= '<td bgcolor="'.$color{"yellow"}.'"> '.$uri.' </td>';
        $Str .= '<td><input type="submit" name="Analyze:::'.$uri.':::';
        $Str .= $title.':::'.$part.':::'.$problem.'" value="';
        $Str .= 'Analyze" /></td></tr>'."\n";
        $number++;
    }
    $Str .= '</table>'."\n";

    return $Str;
}

#---- END Problem Analysis Web Page ------------------------------------------

#---- Student Assessment Web Page --------------------------------------------

sub MapOptions {
    my ($cache, $page)=@_;
    my $Ptr = '<tr>';
    $Ptr .= '<td align="right"><b>Select Map</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Maps">'."\n";

    my $selected = 0;
    foreach my $sequence (split(':',$cache->{'orderedSequences'})) {
	$Ptr .= '<option';
        if($cache->{$page.'Map'} eq $cache->{$sequence.':title'}) {
            $Ptr .= ' selected';
            $selected = 1;
        }
	$Ptr .= '>'.$cache->{$sequence.':title'}.'</option>'."\n";	     
    }
    $Ptr .= '<option';
    if(!$selected) {
        $Ptr .= ' selected';
    }
    $Ptr .= '>All Maps</option>'."\n";

    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

sub StudentOptions {
    my ($students, $selectedName)=@_;

    my $Ptr ='<tr>';
    $Ptr .= '<td align="right"><b>Select Student</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Students">'."\n";

    my $selected=0;
    foreach (@$students) {
        my ($name) = split(':',$_);
	$Ptr .= '<option';
	if($selectedName eq $name) {
            $Ptr .= ' selected';
            $selected = 1;
        }
        $Ptr .= '>'.$name.'</option>'."\n";	     
    }

    $Ptr .= '<option';
    if(!$selected) {
        $Ptr .= ' selected';
    }
    $Ptr .= '>No Student Selected</option>'."\n";

    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

# ------ Create different Student Report 
sub StudentReport {
    my ($cache, $name)=@_;

    my $Str = '';
    if($cache->{$name.':error'} =~ /course/) {
        my ($username)=split(':',$name);
        $Str .= '<b><font color="blue">No course data for student </font>';
        $Str .= '<font color="red">'.$username.'.</font></b><br>';
        return $Str;
    }

    $Str .= "<table border=2><tr><th> \# </th><th> Set Title </th>";
    $Str .= '<th> Results </th><th> Tries </th></tr>'."\n";

    my $codes;
    my $attempts;
    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'StudentAssessmentMap'} ne 'All Maps'  &&
           $cache->{'StudentAssessmentMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

        $Str .= '<tr><td>'.$sequence.'</td>';
        $Str .= '<td>'.$cache->{$sequence.':title'}.'</td>';

        $codes = '';
        $attempts = '';
        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
            my $problem = $cache->{$problemID.':problem'};
            my $LatestVersion = $cache->{$name.':version:'.$problem};

            # Output dashes for all the parts of this problem if there
            # is no version information about the current problem.
            if(!$LatestVersion) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {
		    $codes    .= "-,";
                    $attempts .= "0,"; 
                }
                next;
            }

            my %partData=undef;
            # Initialize part data, display skips correctly
            # Skip refers to when a student made no submissions on that
            # part/problem.
            foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                  $problemID.
                                                  ':parts'})) {
                $partData{$part.':tries'}=0;
                $partData{$part.':code'}='-';
            }

            # Looping through all the versions of each part, starting with the
            # oldest version.  Basically, it gets the most recent 
            # set of grade data for each part.
	    for(my $Version=1; $Version<=$LatestVersion; $Version++) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {

                    if(!defined($cache->{$name.":$Version:$problem".
                                               ":resource.$part.solved"})) {
                        # No grade for this submission, so skip
                        next;
                    }

                    my $tries=0;
                    my $code='U';

                    $tries = $cache->{$name.":$Version:$problem".
                                      ":resource.$part.tries"};
                    $partData{$part.':tries'}=($tries) ? $tries : 0;

                    my $val = $cache->{$name.":$Version:$problem".
                                       ":resource.$part.solved"};
                    if    ($val eq 'correct_by_student')   {$code = 'Y';} 
                    elsif ($val eq 'correct_by_override')  {$code = 'y';}
                    elsif ($val eq 'incorrect_attempted')  {$code = 'N';} 
                    elsif ($val eq 'incorrect_by_override'){$code = 'N';}
                    elsif ($val eq 'excused')              {$code = 'x';}
                    $partData{$part.':code'}=$code;
                }
            }

            # Loop through all the parts for the current problem in the 
            # correct order and prepare the output
            foreach (split(/\:/,$cache->{$sequence.':'.$problemID.
                                         ':parts'})) {
                $codes    .= $partData{$_.':code'}.',';
                $attempts .= $partData{$_.':tries'}.','; 
            }
        }
        $codes    =~ s/,$//;
        $attempts =~ s/,$//;
        $Str .= '<td>'.$codes.'</td>';
        $Str .= '<td>'.$attempts.'</td>';
        $Str .= '</tr>'."\n";
    }

    $Str .= '</table>'."\n";

    return $Str;
}

#---- END Student Assessment Web Page ----------------------------------------

#---- Menu Web Page ----------------------------------------------------------

sub Title {
    my ($downloadTime)=@_;

    my $Ptr = '';

    $Ptr .= '<html><head><title>LON-CAPA Statistics</title></head>'."\n";
    $Ptr .= '<body bgcolor="#FFFFFF">'."\n";
    $Ptr .= '<script>window.focus(); window.width=500;window.height=500;';
    $Ptr .= '</script>'."\n";
    $Ptr .= '<img align=right src=/adm/lonIcons/lonlogos.gif>'."\n";
    $Ptr .= '<h1> Course : "';
    $Ptr .= $ENV{'course.'.$ENV{'request.course.id'}.'.description'};
    $Ptr .= '"</h1>'."\n";
    $Ptr .= '<h3>'.$downloadTime.'</h3>';

    return $Ptr;
}

sub CreateMenuForm {
    my ($cache)=@_;
    my $Ptr = '<table border="0">';
    $Ptr .= '<tr><td><input type="submit" name="ProblemStatistics" ';
    $Ptr .= 'value="Problem Stats"/>';
    $Ptr .= '</td></tr>'."\n";

    if(defined($cache->{'OptionResponses'})) {
        $Ptr .= '<tr><td><input type="submit" name="ProblemAnalysis" ';
        $Ptr .= 'value="Problem Analysis"/>';
        $Ptr .= '</td></tr>'."\n";
    }

    $Ptr .= '<tr><td><input type="submit" name="StudentAssessment" ';
    $Ptr .= 'value="Student Assessment"/>';
    $Ptr .= '</td></tr>'."\n";
    #$Ptr .= '<input type="submit" name="ActivityLog" value="Activity Log"/>';

    $Ptr .= '</table>'."\n";

    return $Ptr;
}

#---- END Menu Web Page ------------------------------------------------------

#---- HELPER FUNCTIONS -------------------------------------------------------

sub CheckFormElement {
    my ($cache, $ENVName, $cacheName, $default)=@_;

    if(defined($ENV{'form.'.$ENVName})) {
        $cache->{$cacheName} = $ENV{'form.'.$ENVName};
    } elsif(!defined($cache->{$cacheName})) {
        $cache->{$cacheName} = $default;
    }

    return;
}

sub ProcessFormData{
    my ($cacheDB, $isCached)=@_;
    my %cache;

    if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
        # Select page to display
        if(defined($ENV{'form.ProblemStatistics'}) ||
           defined($ENV{'form.ProblemStatisticsRecalculate'}) || 
           defined($ENV{'form.DisplayCSVFormat'})) {
            $cache{'GoToPage'} = 'ProblemStatistics';
            &CheckFormElement(\%cache, 'DisplayCSVFormat',
                              'DisplayFormat', 'Display Table Format');
            &CheckFormElement(\%cache, 'Ascend','ProblemStatisticsAscend',
                              'Ascending');
            &CheckFormElement(\%cache, 'Maps', 'ProblemStatisticsMap', 
                              'All Maps');
        } elsif(defined($ENV{'form.ProblemAnalysis'})) {
            $cache{'GoToPage'} = 'ProblemAnalysis';
            &CheckFormElement(\%cache, 'Interval', 'Interval', '1');
        } elsif(defined($ENV{'form.StudentAssessment'}) ||
                defined($ENV{'form.CreateStudentAssessment'}) ||
                defined($ENV{'form.NextStudent'}) ||
                defined($ENV{'form.PreviousStudent'})) {
            $cache{'GoToPage'} = 'StudentAssessment';
            if(defined($ENV{'form.NextStudent'})) {
                $cache{'StudentAssessmentMove'} = 'next';
            } elsif(defined($ENV{'form.PreviousStudent'})) {
                $cache{'StudentAssessmentMove'} = 'previous';
            } else {
                $cache{'StudentAssessmentMove'} = 'selected';
            }
            &CheckFormElement(\%cache, 'Maps', 'StudentAssessmentMap', 
                              'All Maps');

            &CheckFormElement(\%cache, 'Students', 'StudentAssessmentStudent', 
                              'No Student Selected');
        } elsif(defined($ENV{'form.DoDiffGraph'})) {
            $cache{'GoToPage'} = 'DoDiffGraph';
        } elsif(defined($ENV{'form.PercentWrongGraph'})) {
            $cache{'GoToPage'} = 'PercentWrongGraph';
        } elsif(defined($ENV{'form.ActivityLog'})) {
            $cache{'GoToPage'} = 'ActivityLog';
        } else {
            $cache{'GoToPage'} = 'Menu';
        }

        &CheckFormElement(\%cache, 'Status', 'Status', 'Active');

        foreach (keys(%ENV)) {
            if(/form\.Analyze:::/) {
                $cache{'GoToPage'} = 'Analyze';
                my ($uri, $title, $part, $problem);
                (undef, $uri, $title, $part, $problem)=split(':::', $_);
                $cache{'AnalyzeURI'}     = $uri;
                $cache{'AnalyzeTitle'}   = $title;
                $cache{'AnalyzePart'}    = $part;
                $cache{'AnalyzeProblem'} = $problem;

                &CheckFormElement(\%cache, 'Interval', 'Interval', '1');
            }
        }
    }

    return;
}

=pod

=item &SortStudents()

Determines which students to display and in which order.  Which are 
displayed are determined by their status(active/expired).  The order
is determined by the sort button pressed (default to username).  The
type of sorting is username, lastname, or section.

=over 4

Input: $students, $CacheData

$students: A array pointer to a list of students (username:domain)

$CacheData: A pointer to the hash tied to the cached data

Output: \@order

@order: An ordered list of students (username:domain)

=back

=cut

sub SortStudents {
    my ($students,$cache)=@_;

    my @sorted1Students=();
    foreach (@$students) {
        push(@sorted1Students, $_);
    }
#        my ($end,$start)=split(/\:/,$cache->{$_.':date'});
#        my $active=1;
#        my $now=time;
#        my $Status=$cache->{'form.Status'};
#        $Status = ($Status) ? $Status : 'Active';
#        if((($end) && $now > $end) && (($Status eq 'Active'))) { 
#            $active=0; 
#        }
#        if(($Status eq 'Expired') && ($end == 0 || $now < $end)) {
#            $active=0;
#        }
#        if($active) {
#            push(@sorted1Students, $_);
#        }
#    }

    my $Pos = $cache->{'form.ChartSort'};
    my %sortData;
    if($Pos eq 'Last Name') {
	for(my $index=0; $index<scalar @sorted1Students; $index++) {
	    $sortData{$cache->{$sorted1Students[$index].':fullname'}}=
		$sorted1Students[$index];
	}
    } elsif($Pos eq 'Section') {
	for(my $index=0; $index<scalar @sorted1Students; $index++) {
	    $sortData{$cache->{$sorted1Students[$index].':section'}.
		      $sorted1Students[$index]}=$sorted1Students[$index];
	}
    } else {
	# Sort by user name
	for(my $index=0; $index<scalar @sorted1Students; $index++) {
	    $sortData{$sorted1Students[$index]}=$sorted1Students[$index];
	}
    }

    my @order = ();
    foreach my $key (sort(keys(%sortData))) {
	push (@order,$sortData{$key});
    }

    return \@order;
}

sub PrepareData {
    my ($c, $cacheDB)=@_;

    # Test for access to the cache data
    my $isCached=0;
    my $courseID=$ENV{'request.course.id'};
    my $isRecalculate=0;
    if(defined($ENV{'form.ProblemStatisticsRecalculate'}) ||
       defined($ENV{'form.ChartRecalculate'})) {
        $isRecalculate=1;
    }

    $isRecalculate=1;

    $isCached=&Apache::loncoursedata::TestCacheData($cacheDB, $isRecalculate);
    if($isCached < 0) {
        return "Unable to tie hash to db file.";
    }
    &ProcessFormData($cacheDB, $isCached);

    # Download class list information if not using cached data
    my %cache;
    my @students=();
    if(!$isCached) {
        unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
            return "Unable to tie hash to db file.";
        }

        my $processTopResourceMapReturn=
            &Apache::loncoursedata::ProcessTopResourceMap(\%cache, $c);
        if($processTopResourceMapReturn ne 'OK') {
            untie(%cache);
            return $processTopResourceMapReturn;
        }

        if($c->aborted()) {
            untie(%cache);
            return 'aborted'; 
        }

        my $classlist=&Apache::loncoursedata::DownloadStudentNamePIDSection(
                                                                   $courseID, 
                                                                   $c);
        my ($checkForError)=keys(%$classlist);
        if($checkForError =~ /^(con_lost|error|no_such_host)/i ||
           defined($classlist->{'error'})) {
            untie(%cache);
            return "Error getting student data.";
        }

        if($c->aborted()) {
            untie(%cache);
            return 'aborted'; 
        }

        # Active is a temporary solution, remember to change
        @students=&Apache::loncoursedata::ProcessClassList(\%cache, 
                                                           $classlist, 
                                                           $courseID, 
                                                           'Active', $c);

        if($c->aborted()) {
            untie(%cache);
            return 'aborted'; 
        }

        untie(%cache);
    } else {
        if(!$c->aborted() && tie(%cache,'GDBM_File',$cacheDB,
                                 &GDBM_READER,0640)) {
            @students=split(/:::/,$cache{'NamesOfStudents'});
        } else {
            return 'aborted';
        }
    }

    return ('OK', $isCached, \@students);
}

# Create progress
sub Create_PrgWin {
    $r->print(<<ENDPOP);
    <script>
    popwin=open('','popwin','width=400,height=100');
    popwin.document.writeln('<html><body bgcolor="#88DDFF">'+
      '<title>LON-CAPA Statistics</title>'+
      '<h4>Computation Progress</h4>'+
      '<form name=popremain>'+
      '<input type=text size=35 name=remaining value=Starting></form>'+
      '</body></html>');
    popwin.document.close();
    </script>
ENDPOP

    $r->rflush();
}

# update progress
sub Update_PrgWin {
    my ($totalStudents,$index,$name)=@_;
    $r->print('<script>popwin.document.popremain.remaining.value="'.
              'Computing '.$index.'/'.$totalStudents.': '.
              $name.'";</script>');
    $r->rflush();
}

# close Progress Line
sub Close_PrgWin {
    $r->print('<script>popwin.close()</script>');
    $r->rflush(); 
}

# For loading the colored table for display or un-colored for print
sub setbgcolor {
    my $PrintTable=shift;
    undef %color;
    if ($PrintTable){
	$color{"gb"}="#FFFFFF";
	$color{"red"}="#FFFFFF";
	$color{"yellow"}="#FFFFFF";
	$color{"green"}="#FFFFFF";
	$color{"purple"}="#FFFFFF";
    } else {
	$color{"gb"}="#DDFFFF";
	$color{"red"}="#FFDDDD";
	$color{"yellow"}="#EEFFCC";
	$color{"green"}="#DDFFDD";
	$color{"purple"}="#FFDDFF";
    }

    return;
}

sub initial {
    undef %hash;
    undef %CachData;
    undef %GraphDat;
    undef %ConceptData;
    undef $GData;
}

#---- END HELPER FUNCTIONS ---------------------------------------------------

sub BuildProblemStatisticsPage {
    my ($cacheDB, $students)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    my $Ptr = '';
    $Ptr .= '<form name="ProblemStatisticsPage" method="post" ';
    $Ptr .= 'action="/adm/statistics">'."\n";
    $Ptr .= '<table border="0"><tbody>';
    $Ptr .= '<tr><td></td><td align="left"><input type="submit" name="Menu" ';
    $Ptr .= 'value="Return to Menu" /></td></tr>'."\n";
    $r->print($Ptr);

    $r->print(&MapOptions(\%cache, 'ProblemStatistics'));
    $r->print(&StatusOptions());
    $r->print(&AscendOrderOptions());
    $r->print(&ProblemStatisticsButtons(\%cache));
    $r->print('</table>');

    $r->print(&ProblemStatisticsLegend());

#    my $discriminantFactor;
#    my @list=();
#    foreach (@$students) {
#        ($discriminantFactor, $list) = &ExtractStudentData(\%cache, $_,
#                                                           \@list);
#    }

#    my ($upper, $lower) = &Discriminant($discriminantFactor);
#    my %Header = (0,"Homework Sets Order",1,"#Stdnts",2,"Tries",3,"Mod",
#                  4,"Mean",5,"#YES",6,"#yes",7,"%Wrng",8,"DoDiff",
#                  9,"S.D.",10,"Skew.",11,"D.F.1st",12,"D.F.2nd", 13, "Disc.");
#    &BuildStatisticsTable(\%cache, $discriminantFactor, \@list, \%Header, 
#                           $students);

    $r->print('</form>');

    untie(%cache);

    return;
}

sub BuildDiffGraph {
    my ($courseID)=@_;

    my $graphData = &GetGraphData('DiffGraph', $courseID);
    $r->print('<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />');

    return;
}

sub BuildWrongGraph {
    my ($courseID)=@_;

    my $graphData = &GetGraphData('WrongGraph', $courseID);
    $r->print('<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />');

    return;
}

sub BuildAnalyzePage {
    my ($cacheDB, $students, $courseID)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    &ShowOpGraph(\%cache, $students, $courseID);

    untie(%cache);

    return;
}

sub BuildProblemAnalysisPage {
    my ($cacheDB)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    $r->print('<form name="ProblemAnalysisPage" method="post" ');
    $r->print('action="/adm/statistics">'."\n");
    $r->print('<tr><td></td><td align="left"><input type="submit" ');
    $r->print('name="Menu" value="Return to Menu" /></td></tr>'."\n");
    $r->print(&IntervalOptions());
    $r->print(&OptionResponseTable(\%cache));
    $r->print('</form>'."\n");

    untie(%cache);

    return;
}

sub BuildStudentAssessmentPage {
    my ($cacheDB, $students, $courseID)=@_;

    my %cache;

    my $Ptr = '';
    $Ptr .= '<form name="StudentAssessmentPage" method="post" ';
    $Ptr .= 'action="/adm/statistics">'."\n";
    $Ptr .= '<table border="0"><tbody>';
    $Ptr .= '<tr><td></td><td align="left"><input type="submit" name="Menu" ';
    $Ptr .= 'value="Return to Menu" /></td></tr>'."\n";
    $r->print($Ptr);

    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    my $selectedName = $cache{'StudentAssessmentStudent'};
    for(my $index=0; $index<(scalar @$students); $index++) {
        my ($username) = split(':', $students->[$index]);
        if($username eq $selectedName) {
            if($cache{'StudentAssessmentMove'} eq 'next') {
                if($index == ((scalar @$students) - 1)) {
                    ($selectedName) = split(':',$students->[0]);
                } else {
                    ($selectedName) = split(':',$students->[$index+1]);
                }
            } elsif($cache{'StudentAssessmentMove'} eq 'previous') {
                if($index == 0) {
                    ($selectedName) = split(':',
                                           $students->[(scalar @$students)-1]);
                } else {
                    ($selectedName)=split(':',$students->[$index-1]);
                }
            }
            last;
        }
    }

    $r->print(&MapOptions(\%cache, 'StudentAssessment'));
    $r->print(&StudentOptions($students, $selectedName));

    $Ptr  = '<tr><td></td><td align="left">';
    $Ptr .= '<input type="submit" name="CreateStudentAssessment" ';
    $Ptr .= 'value="Create Student Report" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '<input type="submit" name="PreviousStudent" ';
    $Ptr .= 'value="Previous Student" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '<input type="submit" name="NextStudent" ';
    $Ptr .= 'value="Next Student" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '</td></tr></tbody></table></form>'."\n";
    $r->print($Ptr);

    untie(%cache);

    if($selectedName eq 'No Student Selected') {
	$r->print('<h3><font color=blue>WARNING: ');
        $r->print('Please select a student</font></h3>');
        return;
    }

    my $name = '';
    foreach (@$students) {
        my ($currentName) = split(':',$_);
        if($currentName eq $selectedName) {
            $name = $_;
            last;
        }
    }
    if($name eq '') {
        $r->print('<h3><font color=blue>ERROR: Unknown student selected.');
        $r->print('</font></h3>');
        return;
    }

    my $courseData = 
        &Apache::loncoursedata::DownloadStudentCourseInformation($name, 
                                                                 $courseID);
    if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
        &Apache::loncoursedata::ProcessStudentData(\%cache, 
                                                   $courseData, $name);
        untie(%cache);
    }

    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $Ptr .= 'Could not tie database.';
        return $Ptr;
    }
    $r->print(&StudentReport(\%cache, $name));
    untie(%cache);

    return;
}

sub BuildMenu {
    my ($cacheDB)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    $r->print('<form name="Menu" method="post" action="/adm/statistics" >');
    $r->print(&CreateMenuForm(\%cache));
    $r->print('</form>'."\n");

    untie(%cache);

    return;
}

# ================================================================ Main Handler

sub handler {
    $r=shift;
    &initial();

    unless(&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {
        $ENV{'user.error.msg'}=
        $r->uri.":vgr:0:0:Cannot view grades for complete course";
        return HTTP_NOT_ACCEPTABLE; 
    }

    # Set document type for header only
    if($r->header_only) {
        if ($ENV{'browser.mathml'}) {
            $r->content_type('text/xml');
        } else {
            $r->content_type('text/html');
        }
        &Apache::loncommon::no_cache($r);
        $r->send_http_header;
        return OK;
    }

    unless($ENV{'request.course.fn'}) {
	my $requrl=$r->uri;
        $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
        return HTTP_NOT_ACCEPTABLE; 
    }

    $r->content_type('text/html');
    $r->send_http_header;

    my %cache;
    my $courseID=$ENV{'request.course.id'};
    my $cacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$courseID\_statistics.db";
    my $c = $r->connection;

    my ($returnValue, $isCached, $students) = &PrepareData($c, $cacheDB);
    if($returnValue ne 'OK') {
        $r->print('<html><body>'.$returnValue."\n".'</body></html>');
        return OK;
    }

    my $downloadTime=0;
    my $GoToPage;
    if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $students = &SortStudents($students, \%cache);
        if(defined($cache{'time'})) {
            $downloadTime=$cache{'time'};
        } else {
            $downloadTime=localtime();
        }
        if(!defined($cache{'GoToPage'})) {
            $GoToPage = 'Menu';
        } else {
            $GoToPage = $cache{'GoToPage'};
        }
        untie(%cache);
    } else {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return OK;
    }

    &setbgcolor(0);
    $r->print(&Title());

    if($GoToPage eq 'ActivityLog') {
        &Activity();
    } elsif($GoToPage eq 'ProblemStatistics') {
        &BuildProblemStatisticsPage($cacheDB, $students);
    } elsif($GoToPage eq 'ProblemAnalysis') {
        &BuildProblemAnalysisPage($cacheDB);
    } elsif($GoToPage eq 'StudentAssessment') {
        &BuildStudentAssessmentPage($cacheDB, $students, $courseID);
    } elsif($GoToPage eq 'Analyze') {
        &BuildAnalyzePage($cacheDB, $students, $courseID);
    } elsif($GoToPage eq 'DoDiffGraph') {
        &BuildDiffGraph($courseID);
    } elsif($GoToPage eq 'PercentWrongGraph') {
        &BuildWrongGraph($courseID);
    } else {
        &BuildMenu($cacheDB);
    }

    $r->print("\n".'</body>'."\n".'</html>');
    $r->rflush();

    return OK;
}
1;
__END__