# The LearningOnline Network with CAPA
# (Publication Handler
#
# $Id: lonstatistics.pm,v 1.20 2002/05/19 15:44:40 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 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 %OpResp;
my %maps;
my %mapsort;
my %section;
my %StuBox;
my %DiscFac;
my %DisUp;
my %DisLow;
my $UpCnt;
my $CurMap;
my $CurSec;
my $CurStu;
my @cols;
my @list;
my @students;
my $p_count;
my $Pos;
my $r;
my $OpSel1;
my $OpSel2;
my $OpSel3;
my $OpSel4;
my $GData;
my $cid;
my $firstres;
my $lastres;
my $DiscFlag;
my $HWN;
my $P_Order;
my %foil_to_concept;
my @Concepts;
my %ConceptData;
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");
my %Answer = ();

sub InitAnalysis {
    my ($rid, $student)=@_;
    my ($uname,$udom)=split(/\:/,$student);
    $rid=~/(\d+)\.(\d+)/;
    my $symb=&Apache::lonnet::declutter($hash{'map_id_'.$1}).'___'.$2.'___'.
	     &Apache::lonnet::declutter($hash{'src_'.$rid});
    my $URI = $hash{'src_'.$rid};
    my $Answ=&Apache::lonnet::ssi($URI,('grade_target' => 'analyze',
                                  'grade_username' => $uname,
                                  'grade_domain' => $udom,
                                  'grade_courseid' => $cid,
                                  'grade_symb' => $symb));
#    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 $symb;
}


sub Interval {
    my ($rid,$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 ($InpStr, $Int_No)=@_;
    my ($rid,$part)=split(/\:/,substr($InpStr,8));
    $ConceptData{"Interval"}=$Int_No;
    #Initialize the option response true answers
    my $symb=&InitAnalysis($rid,$students[0]);
    #compute the intervals
    &Interval($rid,$part,$symb);
    my $URI = $hash{'src_'.$rid};
    my $Src = $hash{'title_'.$rid};
    $Src =~ 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<=$#students;$index++) {
	&Update_PrgWin($index);
	&OpStatus($rid,$students[$index]);
    }
    &Close_PrgWin();

    $r->print('<br>');
    for (my $k=0; $k<$Int_No; $k++ ) {
	&DrawGraph($k,$Src);
    }
    for (my $k=0; $k<$Int_No; $k++ ) {
	&DrawTable($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=#FFFFDD> ".$Concepts[$n]." </td>".
                "\n"."<td bgcolor=#DDFFDD> ".$data1[$n]." </td>".
                "\n"."<td bgcolor=#FFDDDD> ".$data2[$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 AnalyzeProblem {
    # selecting the number of intervals
    my $OpSel='';
    my $CurInt = $ENV{'form.interval'};
    if ($CurInt eq '') {$CurMap = '1';}
    my $Ptr = '<b>Select number of intervals</b>'."\n".
       	      '<select name="interval">'."\n";                     	     	     
    for (my $n=1;$n<=7;$n++) {	          
	$Ptr .= '<option';
        if ($CurInt eq $n) {$Ptr .= ' selected';}     
	$Ptr .= '>'.$n."</option>"."\n";	     
    }
    $Ptr .= '</select>'."\n";
    $r->print( $Ptr );

    #the table of option response problems
    $r->print('<br><b> Option Response Problems in this course:</b><br><br>');
    my $Str = "\n".'<table border=2>'.
              "\n".'<tr>'.
              "\n".'<th> # </th>'.
	      "\n".'<th> Problem Title </th>'.
	      "\n".'<th> Resouse </th>'.
	      "\n".'<th> Address </th>'.
	      "\n".'</tr>';

     my $P_No=1;
     foreach (sort keys %OpResp) {
	 my ($rid,$part)=split(/\:/,$OpResp{$_});
	 my $Temp = '<a href="'.$hash{'src_'.$rid}.
                    '" target="_blank">'.$hash{'title_'.$rid}.'</a>';
	 $Str .= "\n"."<tr>".
	         "\n"."<td> $P_No </td>".
                 "\n"."<td bgcolor=#DDFFDD> ".$Temp." </td>".
                 "\n"."<td bgcolor=#EEFFCC> ".$hash{'src_'.$rid}." </td>".
	         "\n"."<td> ".'<input type="submit" name="sort" value="'.'Analyze_'.$rid.'" />'.'</td>'.
                 "\n"."</tr>";
	 $P_No++;
     }
     $Str .= "\n".'</table>';
     $Str .= "\n".'</form>';
     $r->print($Str);
     $r->rflush();	
}


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 ($rid,$student)=@_;
    my ($uname,$udom)=split(/\:/,$student);
    my $code='U';
    $rid=~/(\d+)\.(\d+)/;
    my $symb=&Apache::lonnet::declutter($hash{'map_id_'.$1}).'___'.$2.'___'.
	     &Apache::lonnet::declutter($hash{'src_'.$rid});
    my %reshash=&Apache::lonnet::restore($symb,$cid,$udom,$uname);
    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 );}
			}
		    }
	        }	  
	    }
        }
    }
}


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


#------- Creating Discimination factor   
sub Discriminant {
    my $Count=0;
    foreach (keys(%DiscFac)){ 
	$Count++;
    }
    $UpCnt = int(0.27*$Count);
    my $low=0;
    my $up=$Count-$UpCnt;
    my @UpList=();
    my @LowList=();
    $Count=0;
    foreach my $key (sort(keys(%DiscFac))){ 
	$Count++;    
        #$r->print("<br>$Count) $key = $DiscFac{$key}");
	if ($low < $UpCnt || $Count > $up) {
	    $low++;
	    my $str=$DiscFac{$key};
	    foreach(split(/\:/,$str)){
		if ($_) {
		    if ($low<$UpCnt){push(@LowList,$_);}
		    else {push(@UpList,$_);}
		}
	    }
	}
    }
    %DisUp=&ProcessDisc(@UpList);
    %DisLow=&ProcessDisc(@LowList);
}

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

# ------ Create different Student Report 
sub StudentReport {
    my ($sname,$sdom)=@_;
    if ( $sname eq 'All Students' ) {
	$r->print( '<h3><font color=blue>WARNING: 
                    Please select a student</font></h3>' );
	return;
    }
    my %result = &Apache::lonnet::dump($cid,$sdom,$sname);
    my $ResId;
    my $PrOrd;
    my $Code;
    my $Tries;
    my $TotalTries = 0;
    my $ParCr = 0;
    my $Wrongs;
    my %TempHash;
    my $Version;
    my $LatestVersion;
    my $PtrTry='';
    my $PtrCod='';
    my $SetNo=0;
    my $Str = "\n".'<table border=2>'.
              "\n".'<tr>'.
              "\n".'<th> # </th>'.
	      "\n".'<th> Set Title </th>'.
	      "\n".'<th> Results </th>'.
	      "\n".'<th> Tries </th>'.
	      "\n".'</tr>';
    my ($temp)=keys(%result);
    unless ($temp=~/^error\:/) {
        foreach my $CurCol (@cols) {
	    if (!$CurCol){
		my $Set=&Apache::lonnet::declutter($hash{'map_id_'.$1});
		if ( $Set ) {
		    $SetNo++;
		    $Str .= "\n"."<tr>".
			    "\n"."<td> $SetNo </td>".
                            "\n"."<td> $Set </td>".
                            "\n"."<td> $PtrCod </td>".
                            "\n"."<td> $PtrTry</td>".
                            "\n"."</tr>";
		}
		$PtrTry='';
		$PtrCod='';
		next; 
	    }
	    ($PrOrd,$ResId)=split(/\:/,$CurCol);
            $ResId=~/(\d+)\.(\d+)/;
            my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
            if ( $CurMap ne 'All Maps' ) {
		my ( $ResMap, $NameMap ) = split(/\=/,$CurMap);
		if ( $Map ne $ResMap ) { next; }
	    }
	    my $meta=$hash{'src_'.$ResId};
	    my $PartNo = 0;
	    undef %TempHash;
	    foreach (split(/\,/,&Apache::lonnet::metadata($meta,'keys'))){
		if ($_=~/^stores\_(\w+)\_tries$/) {
                    my $Part=&Apache::lonnet::metadata($meta,$_.'.part');
		    if ( $TempHash{"$Part"} eq '' ) { 
			$TempHash{"$Part"} = $Part;
			$TempHash{$PartNo}=$Part;
			$TempHash{"$Part.Code"} = '-';  
			$TempHash{"$Part.PrOrd"} = $PrOrd+$PartNo;  
			$PartNo++;
		    }
		}
            }

            my $Prob = $Map.'___'.$2.'___'.
                       &Apache::lonnet::declutter( $hash{'src_'.$ResId} );
            $Code='U';
            $Tries = 0;
            $Wrongs = 0;
  	    $LatestVersion = $result{"version:$Prob"};
	    if ( $LatestVersion ) {
		for ( my $Version=1; $Version<=$LatestVersion; $Version++ ) {
		    my $vkeys = $result{"$Version:keys:$Prob"};
		    my @keys = split(/\:/,$vkeys);		
  
		    foreach my $Key (@keys) {		  
			if (($Key=~/\.(\w+)\.solved$/) && ($Key!~/^\d+\:/)) {
			    my $Part = $1;
			    $Tries = $result{"$Version:$Prob:resource.$Part.tries"};
			    $TempHash{"$Part.Tries"} = ($Tries) ? $Tries : 0; 
			    $TotalTries += $Tries;
			    my $Val = $result{"$Version:$Prob:resource.$Part.solved"};
			    if ( $Val eq 'correct_by_student' )
                                { $Wrongs = $Tries - 1; $Code = 'Y'; } 
			    elsif ( $Val eq 'correct_by_override' )
                                { $Wrongs = $Tries - 1; $Code = 'y'; }                        
			    elsif ( $Val eq 'incorrect_attempted' || 
                                $Val eq 'incorrect_by_override' )
		                { $Wrongs = $Tries; $Code = 'N'; }
			    $TempHash{"$Part.Code"} = $Code;
			    $TempHash{"$Part.Wrongs"} = $Wrongs;
			}
     		    }
                }
		for ( my $n = 0; $n < $PartNo; $n++ ) {		  
		    my $part = $TempHash{$n};
		    if ($PtrTry ne '') {$PtrTry .= ',';}
		    $PtrTry .= "$TempHash{$part.'.Tries'}";
                    $PtrCod .= "$TempHash{$part.'.Code'}";    
		}
            }
	    else { 
		for(my $n=0; $n<$PartNo; $n++) { 
		    if ($PtrTry ne '') {$PtrTry .= ',';}
		    $PtrTry .= "0";
                    $PtrCod .= "-"; 
		}
	    }
        }
    }
    $Str .= "\n".'</table>';
    $r->print($Str);
    $r->rflush();
}

sub CreateTable {
    my ($Hd, $Hid)=@_;
    if ($ENV{'form.showcsv'}) { 
	if ( $Hd == 1 ) {
	    $r->print('<br>"'.$hash{'title_'.$Hid}.'","'.$hash{'src_'.$Hid}.'"');
	}
	return;
    }
    my $ColNo=0;
    foreach (keys(%Header)){ 
	$ColNo++;
    } 
    if ( $Hd == 1 ) {
	$r->print('<br><a href="'.$hash{'src_'.$Hid}.
                  '" target="_blank">'.$hash{'title_'.$Hid}.'</a>');
    }
    my $Result = "\n".'<table border=2>';
    $Result .= '<tr><th>P#</th>'."\n";
    for ( my $nIdx=0; $nIdx < $ColNo; $nIdx++ ) { 
	$Result .= '<th>'.'<input type="submit" name="sort" value="'.
                   $Header{$nIdx}.'" />'.'</th>'."\n";
    }
    $Result .= "\n".'</tr>'."\n";    
    $r->print( $Result );
    $r->rflush();
}

sub CloseTable {
    if ($ENV{'form.showcsv'}) {
	return;
    }    
    $r->print("\n".'</table>'."\n");
    $r->rflush();
}
 
# ------------------------------------------- Prepare Statistics Table
sub PreStatTable {

    my $CacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$cid\_statistics.db";
    my $GraphDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$cid\_graph.db";
    my $OpSel11='';
    my $OpSel12='';
    my $OpSel13='';
    my $Status = $ENV{'form.status'};
    if ( $Status eq 'Any' ) { $OpSel13='selected'; }
    elsif ($Status eq 'Expired' ) { $OpSel12 = 'selected'; }
    else { $OpSel11 = 'selected'; }

    my $Ptr = '';
    $Ptr .= '<br><b> Student Status: &nbsp; </b>'."\n".
            '<select name="status">'. 
            '<option '.$OpSel11.' >Active</option>'."\n".
            '<option '.$OpSel12.' >Expired</option>'."\n".
	    '<option '.$OpSel13.' >Any</option> </select> '."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type=submit name=sort value="Recalculate Statistics"/>'."\n";

    $Ptr .= '<br><b> Sorting Type: &nbsp; </b>'."\n".
            '<select name="order"> <option '.$OpSel1.' >Ascending</option>'."\n".
	    '<option '.$OpSel2.'>Descending</option> </select> '."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="sort" value="DoDiff Graph" />'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="sort" value="%Wrong Graph" />'."\n";

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

    $r->print($Ptr);
    
    $r->print('Output CSV format: <input type=checkbox name=showcsv onClick="submit()"');
    if ($ENV{'form.showcsv'}) { $r->print(' checked'); }
    $r->print('>');

    $r->rflush();	

    if ((-e "$CacheDB")&&($ENV{'form.sort'} ne 'Recalculate Statistics')) {
	if (tie(%CachData,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
	    tie(%GraphDat,'GDBM_File',$GraphDB,&GDBM_WRCREAT,0640);
	    &Cache_Statistics();
        }
        else {
	    $r->print("Unable to tie hash to db file");
        }
    }
    else {
	if (tie(%CachData,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
	    tie(%GraphDat,'GDBM_File',$GraphDB,&GDBM_WRCREAT,0640);
	    foreach (keys %DiscFac) {delete $CachData{$_};}
	    foreach (keys %CachData) {delete $CachData{$_};}
	    $DiscFlag=0;
	    &Build_Statistics();
	}
        else {
	    $r->print("Unable to tie hash to db file");
        }
    }

#    $r->print('Total instances of the problems : '.($p_count*($#students+1)));
    untie(%CachData);
    untie(%GraphDat);
}


# ------------------------------------- Find the section of student in a course

sub usection {
    my ($udom,$unam,$courseid,$ActiveFlag)=@_;
    $courseid=~s/\_/\//g;
    $courseid=~s/^(\w)/\/$1/;
    foreach (split(/\&/,&Apache::lonnet::reply('dump:'.
             $udom.':'.$unam.':roles',
             &Apache::lonnet::homeserver($unam,$udom)))){
        my ($key,$value)=split(/\=/,$_);
        $key=&Apache::lonnet::unescape($key);
        if ($key=~/^$courseid(?:\/)*(\w+)*\_st$/) {
            my $section=$1;
            if ($key eq $courseid.'_st') { $section=''; }
	    my ($dummy,$end,$start)=split(/\_/,&Apache::lonnet::unescape($value));
	    if ( $ActiveFlag ne 'Any' ) {
		my $now=time;
		my $notactive=0;
		if ($start) {
		    if ($now<$start) { $notactive=1; }
		}
		if ($end) {
		    if ($now>$end) { $notactive=1; }
		}
		if ((($ActiveFlag eq 'Expired') && $notactive == 1) || 
                    (($ActiveFlag eq 'Active') && $notactive == 0 ) ) {
		    return $section;
		}
		else { return '-1'; } 
	    }
	    return $section;
        }
    }
    return '-1';
}


# ------ Dump the Student's DB file and handling the data for statistics table 
sub ExtractStudentData {
    my $student=shift;
    my ($sname,$sdom) = split( /\:/, $student );
    my %result = &Apache::lonnet::dump($cid,$sdom,$sname);
    my $ResId;
    my $PrOrd;
    my $Dis = '';
    my $Code;
    my $Tries;
    my $ParCr;
    my $TotalTries = 0;
    my $TotalOpend = 0;
    my $ProbSolved = 0;
    my $ProbTot = 0;
    my $TimeTot = 0;
    my $TotParCr = 0;
    my $Wrongs;
    my %TempHash;
    my $Version; 
    my $LatestVersion;
    my $SecLimit;
    my $MapLimit;
    my ($temp)=keys(%result);
    unless ($temp=~/^error\:/) {
        foreach my $CurCol(@cols) {
	    ($PrOrd,$ResId)=split(/\:/,$CurCol);
	    if ( !$CurCol ) { next; }
            $ResId=~/(\d+)\.(\d+)/;
	    my $MapId=$1;
	    my $PrbId=$2;
            my $MapOrg = $hash{'map_id_'.$MapId};
            my $Map = &Apache::lonnet::declutter($MapOrg);
            if ( $CurMap ne 'All Maps' ) {
		my ( $ResMap, $NameMap ) = split(/\=/,$CurMap);
		if ( $Map ne $ResMap ) { next; }
	    }
	    my $meta=$hash{'src_'.$ResId};
	    my $PartNo = 0;
	    $Dis .= ':';
	    undef %TempHash;

	    foreach (split(/\,/,&Apache::lonnet::metadata($meta,'keys'))) { 
		if ($_=~/^stores\_(\w+)\_tries$/) {
                    my $Part=&Apache::lonnet::metadata($meta,$_.'.part');
		    if ( $TempHash{"$Part"} eq '' ) { 
			$TempHash{"$Part"} = $Part;
			$TempHash{$PartNo}=$Part;
			$TempHash{"$Part.Code"} = 'U';  
			$TempHash{"$Part.PrOrd"} = $PrOrd+$PartNo;
			$PartNo++;
		    }
                    #my $Part=&Apache::lonnet::metadata($meta,$_.'.part');
		}
            }
            &Apache::lonnet::declutter( $hash{'src_'.$ResId} );
	    my $URI = $hash{'src_'.$ResId};
            my $Prob = $Map.'___'.$PrbId.'___'.
                       &Apache::lonnet::declutter($URI);
            $Code='U';
            $Tries = 0;
	    $ParCr = 0;
            $Wrongs = 0;
  	    $LatestVersion = $result{"version:$Prob"};        
	    if ( $LatestVersion ) {
		for ( my $Version=1; $Version<=$LatestVersion; $Version++ ) {
		    my $vkeys = $result{"$Version:keys:$Prob"};
		    my @keys = split(/\:/,$vkeys);		
		    foreach my $Key (@keys) {		  
			if (($Key=~/\.(\w+)\.solved$/) && ($Key!~/^\d+\:/)) {
			    my $Part = $1;
			    $Tries = $result{"$Version:$Prob:resource.$Part.tries"};
			    $ParCr = $result{"$Version:$Prob:resource.$Part.awarded"};
			    my $Time = $result{"$Version:$Prob:timestamp"};
			    $TempHash{"$Part.Time"} = ($Time) ? $Time : 0;
			    $TempHash{"$Part.Tries"} = ($Tries) ? $Tries : 0;
			    $TempHash{"$Part.ParCr"} = ($ParCr) ? $ParCr : 0;        
			    $TotalTries += $TempHash{"$Part.Tries"};
			    $TotParCr += $TempHash{"$Part.ParCr"};
			    my $Val = $result{"$Version:$Prob:resource.$Part.solved"};
			    if ( $Val eq 'correct_by_student' )
                               { $Wrongs = $Tries - 1; $Code = 'C'; } 
			    elsif ( $Val eq 'correct_by_override' )
                               { $Wrongs = $Tries - 1; $Code = 'O'; }                        
			    elsif ( $Val eq 'incorrect_attempted' || 
                                $Val eq 'incorrect_by_override' )
		               { $Wrongs = $Tries; $Code = 'I'; }
			    $TempHash{"$Part.Code"} = $Code;
			    $TempHash{"$Part.Wrongs"} = $Wrongs;
			}
     		    }
                } 
		for ( my $n = 0; $n < $PartNo; $n++ ) {		  
		    my $part = $TempHash{$n};
		    my $Yes = 0;
                    if ( $TempHash{$part.'.Code'} eq 'C' ||
                         $TempHash{$part.'.Code'} eq 'O'  ) 
		       {$ProbSolved++;$Yes=1;}		

 #		    my $ptr = "$hash{'title_'.$ResId}";
		    my $ptr = $TempHash{$part.'.PrOrd'}.'&'.$ResId;

		    if ( $PartNo > 1 ) {                
			$ptr .= "*(part $part)";
			$Dis .= '&';
		    }
		    my $Fac = ($TempHash{"$part.Tries"}) ? 
                              ($TempHash{"$part.ParCr"}/$TempHash{"$part.Tries"}) : 0;
		    my $DisF;
		    if ( $Fac > 0 &&  $Fac < 1 ) { 
			$DisF = sprintf( "%.4f", $Fac );
		    }
		    else {$DisF = $Fac;}
#		    $DisF .= '+'.$TempHash{"$part.Time"};33333333
		    $TimeTot += $TempHash{"$part.Time"};
		    $Dis .= $TempHash{$part.'.PrOrd'}.'='.$DisF.'+'.$Yes;
		    $ptr .= "&$TempHash{$part.'.Tries'}".
		            "&$TempHash{$part.'.Wrongs'}".
                            "&$TempHash{$part.'.Code'}";
		    push (@list, $ptr);
		    $TotalOpend++;
		    $ProbTot++;
		}
            }
	    #else { 
		#for(my $n=0; $n<$PartNo; $n++) {
		#    push (@list, "$TempHash{'0'.'.PrOrd'}.':'.$ResId:0:0:U");
		#    $ProbTot++; 
		#}
	    #}
        }
	if ( $TotalTries ) {
	    my $DisFac = ( $TotalTries ) ? ($TotParCr/$TotalTries) : 0;
	    my $DisFactor = sprintf( "%.4f", $DisFac );
	    $DiscFac{$DisFactor}=$Dis;
	    #my $time;
	    #if ($ProbSolved){
		#$time = int(($TimeTot/$ProbSolved)-10000000);
	    #}
	    #$DiscFac{($DisFactor.':'.$sname.':'.$ProbTot.':'.$TotalOpend.':'.
            #          $TotalTries.':'.$ProbSolved.':'.$time)}=$Dis;
	}
    }
    #$r->print($sname.' PrCr= '.$TotParCr.' Slvd= '.$ProbSolved.' Tries='.$TotalTries.'<br>');
}


# ------------------------------------------------------------ Build page table
sub tracetable {
    my ($rid,$beenhere)=@_;
    my $IsMap=0;
    $rid=~/(\d+)\.(\d+)/;
    $maps{&Apache::lonnet::declutter($hash{'map_id_'.$1})}='';#$hash{'title_'.$rid}; 
    #$maps{$HWN}=$hash{'title_'.$rid}; 
    unless ($beenhere=~/\&$rid\&/) {
       $beenhere.=$rid.'&'; 
       if (defined($hash{'is_map_'.$rid})) {
	   my $cmap=$hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$rid}}};
           if ( $cmap eq 'sequence' || $cmap eq 'page' ) { 
               $cols[$#cols+1]=0;
	       $P_Order++;
	       $HWN=$P_Order;
               $mapsort{$HWN} = $rid.':';
	       $IsMap=1;
 
               #$maps{&Apache::lonnet::declutter($hash{'src_'.$rid})}= 
               #      $hash{'title_'.$rid}; 
           }
           if ((defined($hash{'map_start_'.$hash{'src_'.$rid}})) &&
               (defined($hash{'map_finish_'.$hash{'src_'.$rid}}))) {
	       my $frid=$hash{'map_finish_'.$hash{'src_'.$rid}};

               &tracetable($hash{'map_start_'.$hash{'src_'.$rid}},
			   '&'.$frid.'&');

	       $cols[$#cols+1]=($P_Order+1).':'.$frid;
      
	       my $meta=$hash{'src_'.$frid};
	       my $PartNo = 0;
	       my $Part;
	#       if ($IsMap==0){
               if ($meta) {
		   if ($meta=~/\.(problem|exam|quiz|assess|survey|form)$/) {
		       foreach (split(/\,/,&Apache::lonnet::metadata($meta,'keys'))) {
			   if ($_=~/^stores\_(\w+)\_tries$/) {
			       $Part=&Apache::lonnet::metadata($meta,$_.'.part');
			       $P_Order++;
			       $mapsort{$HWN} .= '&'.$P_Order;
			       $PartNo++;
			       #$r->print('<br>'.$PartNo.'---'.$P_Order);
			   }
			   foreach my $K(split(/\,/,&Apache::lonnet::metadata($meta,'packages'))) {
			       if ($K=~/^optionresponse\_($Part)\_(\w+)$/) {
				   #$r->print('<br>'.$_.'...'.$P_Order.'---'.$Part);
				   $OpResp{$P_Order}="$frid:$Part";
			       } 
			   }
		       }
		   }
               }
	   }
	 #  }
       } else {
	   $cols[$#cols+1]=($P_Order+1).':'.$rid;
	   my $meta=$hash{'src_'.$rid};
	   my $PartNo = 0;
	   if ($meta) {
	       if ($meta=~/\.(problem|exam|quiz|assess|survey|form)$/) {
		   foreach my $Key(split(/\,/,&Apache::lonnet::metadata($meta,'keys'))) {
		       if ($Key=~/^stores\_(\w+)\_tries$/) {
			   my $Part=&Apache::lonnet::metadata($meta,$Key.'.part');
			   $P_Order++;
			   $mapsort{$HWN} .= '&'.$P_Order;
			   $PartNo++;
			   foreach (split(/\,/,&Apache::lonnet::metadata($meta,'packages'))) {
			       if ($_=~/^optionresponse\_($Part)\_(\w+)$/) {
				   #$r->print('<br>'.$_.'...'.$P_Order.'---'.$Part);
				   $OpResp{$P_Order}="$rid:$Part";;
			       } 
		   
			   }

		       }
		   }
	       }
	   }       
       }
       if (defined($hash{'to_'.$rid})) {
          foreach (split(/\,/,$hash{'to_'.$rid})){
              &tracetable($hash{'goesto_'.$_},$beenhere);
          }
       }
    }
}

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; }
    }
}

sub Create_PrgWin {
#----------- Create progress
    $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();
}


sub Update_PrgWin {
#----------- update progress
    my $index = shift;
    $r->print('<script>popwin.document.popremain.remaining.value="'.
              'Computing '.($index+1).'/'.($#students+1).': '.
              $students[$index].'";</script>');
    $r->rflush();
}

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

sub Build_Statistics {
    &Create_PrgWin();
# ---------------------------- Gathering the Data of students' tries
    for (my $index=0;$index<=$#students;$index++) {
	&Update_PrgWin($index);
        &ExtractStudentData($students[$index]);
    }

# -------------------- sorting the Data
    $r->print('<script>popwin.document.popremain.remaining.value="'.
              'Calculating Discrimination Factors...";</script>');

    @list = sort (@list);

    &Discriminant();

    $OpSel2='';
    $OpSel1='selected';
 		   
    $p_count = 0; 
    my $nIdx = 0;
    my $dummy; 
    my $p_val;
    my $ResId;
    my $NoElements = $#list + 1;
#-------------------------------- loop for data representation
    foreach (sort keys %mapsort) {
	my ($Hid,$pr)=split(/\:/,$mapsort{$_});
	my @lpr=split(/\&/,$pr);
	&CreateTable(1,$Hid);
	for (my $i=1; $i<=$#lpr; $i++) {
	    my %storestats=();
	    my ($PrOrd,$Prob,$Tries,$Wrongs,$Code)=split(/\&/,$list[$nIdx]);
	    my $Temp = $Prob;
	    my $MxTries = 0;
	    my $TotalTries = 0;
	    my $YES = 0;
	    my $Incorrect = 0;
	    my $Override = 0;
	    my $StdNo = 0;
	    my @StdLst;
	    while ( $PrOrd == $lpr[$i] ) 
	    {
		$nIdx++;
		$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)=split(/\&/,$list[$nIdx]);
	    }	

	    $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(/\:/,$DisUp{$lpr[$i]});
	    my ($Lw1,$Lw2)=split(/\:/,$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.'&'.
                       $Prob;
	    $CachData{($p_count-1)}=$join;

	    $urlres=~/^(\w+)\/(\w+)/;
	    if ($StdNo) { 
		&Apache::lonnet::put('resevaldata',\%storestats,$1,$2); 
	    }
#-------------------------------- Row of statistical table
	    if ( $DiscFlag == 0 ) {
		&TableRow($join,$i,($p_count-1));
	    } 
	}
	&CloseTable();
    }
    &Close_PrgWin();
}

sub Cache_Statistics {
    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++;}
    $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 $nIdx=0;

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

sub TableRow {
    my ($Str,$Idx,$RealIdx)=@_;
    my($PrOrd,$Temp,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2,$Prob)=split(/\&/,$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.'"';
        $r->print("\n".$Ptr);
    }
    else{
        my $Ptr =  "\n".'<tr>'.
               "\n".'<td>'.($RealIdx+1).'</td>'.
          #     "\n".'<td>'.$PrOrd.$Temp.'</td>'.
               "\n".'<td>'.$Temp.'</td>'.
               "\n".'<td bgcolor="#EEFFCC"> '.$StdNo.'</td>'.
               "\n".'<td bgcolor="#EEFFCC">'.$TotalTries.'</td>'.
               "\n".'<td bgcolor="#EEFFCC">'.$MxTries.'</td>'.
               "\n".'<td bgcolor="#DDFFFF">'.$Avg.'</td>'.
               "\n".'<td bgcolor="#DDFFFF"> '.$YES.'</td>'.
               "\n".'<td bgcolor="#DDFFFF"> '.$Override.'</td>'.
               "\n".'<td bgcolor="#FFDDDD"> '.$Wrng.'</td>'.
               "\n".'<td bgcolor="#FFDDDD">'.$DoD.'</td>'.
               "\n".'<td bgcolor="#DDFFDD"> '.$SD.'</td>'.
               "\n".'<td bgcolor="#DDFFDD"> '.$Sk.'</td>'.
               "\n".'<td bgcolor="#FFDDFF"> '.$_D1.'</td>'.
	       "\n".'<td bgcolor="#FFDDFF"> '.$_D2.'</td>';
        $r->print("\n".$Ptr.'</tr>' );
    }
    $GraphDat{$RealIdx}=$DoD.':'.$Wrng;
}

# ------------------------------------------- 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");
	}
    }
}


sub initial {
# --------------------------------- Initialize the global varaibles
  undef @students;
  undef @cols;
  undef %maps;
  undef %section;
  undef %StuBox;
  undef @list;
  undef %CachData;
  undef %GraphDat;
  undef %DiscFac;
  undef %OpResp;
  undef %ConceptData;
  undef $CurMap;
  undef $CurSec;
  undef $CurStu;
  undef $p_count;
  undef $Pos;
  undef $GData;
  $DiscFlag=0; 
  $P_Order=100000;
  $HWN=$P_Order;
}

#	my $CacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
#                  "_$ENV{'user.domain'}_$cid\_classlist.db";
#	if (-e "$CacheDB") {
#	    if (tie(%students,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
#		&CachClassList();
#	    }
#            else {
#	        $r->print("Unable to tie hash to db file");
#            }
#        }
#        else {
#	    if (tie(%students,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
#	        &MakeClassList();
#	    }
#            else {
#	        $r->print("Unable to tie hash to db file");
#            }
#        }
#        untie(%students);


sub ClassList {

    &GetStatus();

    $cid=$ENV{'request.course.id'};
    my $chome=$ENV{'course.'.$cid.'.home'};
    my ($cdom,$cnum)=split(/\_/,$cid);
# ----------------------- Get first and last resource, see if there is anything
    $firstres=$hash{'map_start_/res/'.$ENV{'request.course.uri'}};
    $lastres=$hash{'map_finish_/res/'.$ENV{'request.course.uri'}};
    if (($firstres) && ($lastres)) {
#	my %students = &Apache::lonnet::dump('classlist',$cdom,$cnum);
#    $Apache::lonxml::debug=1;
#    &Apache::lonhomework::showhash(%students);
#    $Apache::lonxml::debug=0;
#	my $StudNo = 0;
#	my $now=time;
#	my ($temp)=keys(%students);
#	unless ($temp=~/^error\:/) {
#	    foreach my $KeyPoint(sort keys(%students)) {


	my $classlst=&Apache::lonnet::reply('dump:'.$cdom.':'.$cnum.':classlist',$chome);

	my $StudNo = 0;
	my $now=time;
	unless ($classlst=~/^error\:/) {
	    foreach my $KeyPoint(sort split(/\&/,$classlst)) {
		my ($name,$value)=split(/\=/,$KeyPoint);
		my ($end,$start)=split(/\:/,&Apache::lonnet::unescape($value));
		my $active=1;
		my $Status=$ENV{'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) {
		    my $thisindex=$#students+1;
		    $name=&Apache::lonnet::unescape($name);
		    $students[$thisindex]=$name;
		    my ($sname,$sdom)=split(/\:/,$name);
		    my $ssec=&usection($sdom,$sname,$cid,$Status);
		    if ($ssec==-1 || $ssec eq 'adm' ) {next;}
		    $ssec=($ssec) ? $ssec : '(none)';
		    #$ssec=(int($ssec)) ? int($ssec) : $ssec;
		    $section{$ssec}=$ssec;
		    if ($CurSec eq 'All Sections' || $ssec eq $CurSec) {
			$students[$StudNo]=$name;
			$StuBox{$sname}=$sdom;
		    }
		    $StudNo++;
	        }
	    }
	}
	else {
	    $r->print('<h1>Could not access course data</h1>');
	} 
        $r->print("Total number of students : ".($#students+1));
        $r->rflush();
# --------------- Find all assessments and put them into some linear-like order
	&tracetable($firstres,'&'.$lastres.'&');
#    my $c=0;
#    foreach (sort keys %mapsort) {
#	$r->print('<br>'.$c.')'.$_.' ... '.$mapsort{$_});
#	$c++;
#    }
#	my $c=1;
#	foreach (sort keys %OpResp) {
#	    $r->print('<br>'.$c.')'.$_.' ... '.$OpResp{$_}.' ... '.$hash{'src_'.$OpResp{$_}});
#	    $c++;
#	}

    }

# ------------------------------------------------------------- End render page 
    else {
	$r->print('<h3>Undefined course sequence</h3>');
    }
}


sub Title {
    $r->print('<html><head><title>LON-CAPA Statistics</title></head>');
    $r->print('<body bgcolor="#FFFFFF">'.
              '<script>window.focus(); window.width=500;window.height=500;</script>'.
              '<img align=right src=/adm/lonIcons/lonlogos.gif>');
# ---------------------------------------------------------------- Course title
    $r->print('<h1> Course : "'.
              $ENV{'course.'.$ENV{'request.course.id'}.
              '.description'}.'"</h1><h2>'.localtime().'</h2>');
# ------------------------------- This is going to take a while, produce output
    $r->rflush();	
}


sub CreateForm {
    $r->print("\n".'<form name=stat method=post action="/adm/statistics" >');
    my $content = $ENV{'form.sort'};
    if (!($ENV{'form.showcsv'}) && 
        ($content eq '' || $content eq 'Return to Menu')) {
	my $Ptr = '<h3>';
	$Ptr .= '<input type=submit name=sort value="Problem Stats"/>';
	$Ptr .= '<br><br>';
	$Ptr .= '<input type=submit name=sort value="Problem Analysis"/>';
	$Ptr .= '<br><br>';
	$Ptr .= '<input type=submit name=sort value="Student Assessment"/>';
	$Ptr .= '</h3>';
	$r->print( $Ptr );
    }
    else {
	&ClassList();
	if ( $content eq 'Student Assessment' || 
	     $content eq 'Create Student Report' ) {
	    &MapSecOptions();
	    &StudentOptions();
	    &StudentReport($CurStu,$StuBox{"$CurStu"});
	}
	elsif ( $content eq 'Problem Analysis' ) {
	    &AnalyzeProblem();
	}
	else {
	    &MapSecOptions();
	    &PreStatTable();
	}
    }
}


sub Menu {
    &initial();
#    $Apache::lonxml::debug=1;
#    &Apache::lonhomework::showhash(%ENV);
#    $Apache::lonxml::debug=0;
    &Title();
    my $InpStr = $ENV{'form.sort'};
    if ($InpStr=~/^Analyze\_/) {
	&ClassList();
	&ShowOpGraph($InpStr,$ENV{'form.interval'});
    }
    elsif ( $InpStr eq 'DoDiff Graph' || $InpStr eq '%Wrong Graph' ) {      
	&GetGraphData($InpStr);
    	$r->print('<IMG src="/cgi-bin/graph.gif?'.$GData.'" />');
    }
    else {
	&CreateForm();
	$r->print("\n".'</form>');
    }
    $r->print("\n".'</body>'.
	      "\n".'</html>');
    $r->rflush();
}

sub StudentOptions {
    my $OpSel5='';
    $CurStu = $ENV{'form.student'};
    if ( $CurStu eq '' ) { 
        $CurStu = 'All Students';
        $OpSel5 = 'selected';
    }
    my $Ptr ='';
# ----------------------------------- Loading the Students Combobox
    $Ptr .= '<br><b>Select Student</b>'."\n".
       	    '<select name="student">'."\n". 
	    '<option '.$OpSel5.'>All Students</option>';                     	     	     
    foreach my $key ( sort keys %StuBox ) {	          
	$Ptr .= '<option';
	if ($CurStu eq $key) {$Ptr .= ' selected';}     
        $Ptr .= '>'.$key."</option>\n";	     
    }
    $Ptr .= '</select>';
    $Ptr .= '<br><input type="submit" name="sort" value="Create Student Report" />';
    $r->print( $Ptr );
    $r->rflush();	
}


sub GetStatus {
    $OpSel1='';
    $OpSel2='';
    $OpSel3='';
    $OpSel4='';

    if ( $ENV{'form.order'} eq 'Descending' ) { $OpSel2='selected'; }
    else { $OpSel1 = 'selected'; }

    my %myHeader = reverse( %Header );
    $Pos = $myHeader{$ENV{'form.sort'}};
    if ($Pos == 0) {
	$OpSel1 = 'selected';
	$ENV{'form.order'}='Ascendig';
    }

    $CurMap = $ENV{'form.maps'};
    if ( $CurMap eq '' ) { 
	$CurMap = 'All Maps';
	$OpSel3 = 'selected';
    }
    $CurSec = $ENV{'form.section'};
    if ( $CurSec eq '' ) { 
	$CurSec = 'All Sections';
        $OpSel4 = 'selected';
    }
}


sub MapSecOptions {
# ----------------------------------- Loading the Maps Combobox
    my $Ptr = '<br>';
    $Ptr .= '<input type="submit" name="sort" value="Return to Menu" />';
    $Ptr .= '<br><b> Select &nbsp; Map &nbsp; &nbsp; </b>'."\n".
       	    '<select name="maps">'."\n". 
	    '<option '.$OpSel3.'>All Maps</option>';                     	     	     
    foreach my $key ( sort keys %maps ) {	          
	$Ptr .= '<option';
        if ($CurMap eq $key) {$Ptr .= ' selected';}	     
	$Ptr .= '>'.$key."</option>\n";	     
    }
    $Ptr .= '</select>';
    $Ptr .= '&nbsp;&nbsp;&nbsp;';

# ----------------------------------- Loading the Sections Combobox
    $Ptr .= '<br><b>Select Section</b>'."\n".
       	    '<select name="section">'."\n". 
	    '<option '.$OpSel4.'>All Sections</option>';                     	     	     
    foreach my $key ( sort keys %section ) {	          
	$Ptr .= '<option';
        if ($CurSec eq $key) {$Ptr .= ' selected';}     
	$Ptr .= '>'.$key."</option>"."\n";	     
    }
    $Ptr .= '</select>'."\n";

    $r->print( $Ptr );
    $r->rflush();
}


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

sub handler {
    $r=shift;

    if (&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {
# ------------------------------------------- Set document type for header only
	if ($r->header_only) {
	    if ($ENV{'browser.mathml'}) {
		$r->content_type('text/xml');
	    } 
	    else {
		$r->content_type('text/html');
	    }
	    $r->send_http_header;
	    return OK;
	}    
	my $requrl=$r->uri;
# ----------------------------------------------------------------- Tie db file

	undef %hash;

	if ($ENV{'request.course.fn'}) {
	    my $fn=$ENV{'request.course.fn'};
	    if (-e "$fn.db") {
		if (tie(%hash,'GDBM_File',"$fn.db",&GDBM_READER,0640)) {
# ------------------------------------------------------------------- Hash tied
		    $r->content_type('text/html');
		    $r->send_http_header;
		    &Menu();
		}
		else {
		    $r->content_type('text/html');
		    $r->send_http_header;
		    $r->print('<html><body>Coursemap undefined.</body></html>');
		}
# ------------------------------------------------------------------ Untie hash
		unless (untie(%hash)) {
		    &Apache::lonnet::logthis("<font color=blue>WARNING: ".
                            "Could not untie coursemap $fn (browse).</font>"); 
		}

# -------------------------------------------------------------------- All done
		return OK;
# ----------------------------------------------- Errors, hash could no be tied
	    }
	} 
	else {
	    $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
	    return HTTP_NOT_ACCEPTABLE; 
	}
    }
    else {
        $ENV{'user.error.msg'}=
        $r->uri.":vgr:0:0:Cannot view grades for complete course";

        return HTTP_NOT_ACCEPTABLE; 
    }
}
1;
__END__