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version 1.20, 2001/11/28 18:18:17 version 1.59, 2002/07/09 15:43:49
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 # The LearningOnline Network with CAPA  # The LearningOnline Network with CAPA
   # (Publication Handler
   #
   # $Id$
   #
   # 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/
   #
 # Homework Performance Chart  # Homework Performance Chart
 #  #
 # (Navigate Maps Handler  # (Navigate Maps Handler
Line 6 Line 32
 # (Page Handler  # (Page Handler
 #  #
 # (TeX Content Handler  # (TeX Content Handler
 #  # YEAR=2000
 # 05/29/00,05/30 Gerd Kortemeyer)  # 05/29/00,05/30 Gerd Kortemeyer)
 # 08/30,08/31,09/06,09/14,09/15,09/16,09/19,09/20,09/21,09/23,  # 08/30,08/31,09/06,09/14,09/15,09/16,09/19,09/20,09/21,09/23,
 # 10/02,10/10,10/14,10/16,10/18,10/19,10/31,11/6,11/14,11/16 Gerd Kortemeyer)  # 10/02,10/10,10/14,10/16,10/18,10/19,10/31,11/6,11/14,11/16 Gerd Kortemeyer)
 #  # YEAR=2001
 # 3/1/1,6/1,17/1,29/1,30/1,31/1 Gerd Kortemeyer)  # 3/1/1,6/1,17/1,29/1,30/1,31/1 Gerd Kortemeyer)
 # 7/10/01 Behrouz Minaei  # 7/10/01 Behrouz Minaei
 # 9/8 Gerd Kortemeyer  # 9/8 Gerd Kortemeyer
 # 10/18/01, 10/19/01 Behrouz Minaei  # 10/1, 10/19, 11/17, 11/22, 11/24, 11/28 12/18 Behrouz Minaei
 # 11/17/01, 11/22/01, 11/24/01 Behrouz Minaei  # YEAR=2002
   # 2/1, 2/6, 2/19, 2/28 Behrouz Minaei
   #
   ###
   
   =pod
   
   =head1 NAME
   
   lonchart
   
   =head1 SYNOPSIS
   
   Quick display of students grades for a course in a compressed table format.
   
   =head1 DESCRIPTION
   
   This module process all student grades for a course and turns them into a 
   table like structure.
   
   This is part of the LearningOnline Network with CAPA project
   described at http://www.lon-capa.org
   
   lonchart presents the user with a condensed view all a course's data.  The
   class title, the number of students, and the date for the last update of the
   displayed data.  There is also a legend that describes the chart values.  
   
   For each valid grade for a student is linked with a submission record for that
   problem.  The ability to add and remove columns of data from the chart was
   added for reducing the burden of having to scroll through large quantities
   of data.  The interface also allows for sorting of students by username,
   last name, and section number of class.  Active and expired students are
   also available.
   
   The interface is controlled by three primary buttons: Recalculate Chart, 
   Refresh Chart, and Reset Selections.  Recalculate Chart will update 
   the chart to the most recent data and keep the display settings for the chart
   the same.  Refresh Chart is used to redisplay the chart after selecting
   different output formatting.  Reset Selections is used to set the chart
   display options back to default values.
   
   =head1 CODE LAYOUT DESCRIPTION
   
   The code is broken down into three components: formatting data for printing,
   helper functions, and the central processing functions.  The module is broken 
   into chunks for each component.
   
   =head1 PACKAGES USED
   
    Apache::Constants qw(:common :http)
    Apache::lonnet()
    Apache::loncommon()
    HTML::TokeParser
    GDBM_File
   
   =cut
   
 package Apache::lonchart;  package Apache::lonchart;
   
 use strict;  use strict;
 use Apache::Constants qw(:common :http);  use Apache::Constants qw(:common :http);
 use Apache::lonnet();  use Apache::lonnet();
   use Apache::loncommon();
   use Apache::loncoursedata();
 use HTML::TokeParser;  use HTML::TokeParser;
 use GDBM_File;  use GDBM_File;
   
 # -------------------------------------------------------------- Module Globals  #my $jr; 
 my %hash;  
 my @cols;  =pod
 my @rowlabels;  
 my @students;  =head1 FORMAT DATA FOR PRINTING
 my $r;  
   =cut
 # ------------------------------------------------------------- Find out status  
   # ----- FORMAT PRINT DATA ----------------------------------------------
 sub ExtractStudentData {  
     my ($index,$coid)=@_;  =pod
     my ($sname,$sdom) = split( /\:/, $students[$index] );  
     my $shome=&Apache::lonnet::homeserver( $sname,$sdom );            =item &FormatStudentInformation()
     my $reply=&Apache::lonnet::reply('dump:'.$sdom.':'.$sname.':'.$coid,$shome );  
     my %result=();  This function produces a formatted string of the student's information:
     my $ResId;  username, domain, section, full name, and PID.
     my $Code;  
     my $Tries;  =over 4
     my $Wrongs;  
     my %TempHash;  Input: $cache, $name, $studentInformation, $spacePadding
   
   $cache: This is a pointer to a hash that is tied to the cached data
   
   $name:  The name and domain of the current student in name:domain format
   
   $studentInformation: A pointer to an array holding the names used to
   
   remove data from the hash.  They represent the name of the data to be removed.
   
   $spacePadding: Extra spaces that represent the space between columns
   
   Output: $Str
   
   $Str: Formatted string.
   
   =back
   
   =cut
   
   sub FormatStudentInformation {
       my ($cache,$name,$studentInformation,$spacePadding)=@_;
       my $Str='';
   
       for(my $index=0; $index<(scalar @$studentInformation); $index++) {
           if(!&ShouldShowColumn($cache, 'ChartHeading'.$index)) {
               next;
           }
    my $data=$cache->{$name.':'.$studentInformation->[$index]};
    $Str .= $data;
   
    my @dataLength=split(//,$data);
    my $length=scalar @dataLength;
    $Str .= (' 'x($cache->{$studentInformation->[$index].'Length'}-
                         $length));
    $Str .= $spacePadding;
       }
   
       return $Str;
   }
   
   =pod
   
   =item &FormatStudentData()
   
   First, FormatStudentInformation is called and prefixes the course information.
   This function produces a formatted string of the student's course information.
   Each column of data represents all the problems for a given sequence.  For
   valid grade data, a link is created for that problem to a submission record
   for that problem.
   
   =over 4
   
   Input: $name, $studentInformation, $spacePadding, $ChartDB
   
   $name: The name and domain of the current student in name:domain format
   
   $studentInformation: A pointer to an array holding the names used to 
   remove data from the hash.  They represent 
   the name of the data to be removed.
   
   $spacePadding: Extra spaces that represent the space between columns
   
   $ChartDB: The name of the cached data database which will be tied to that 
   database.
   
   Output: $Str
   
   $Str: Formatted string that is an entire row of the chart.  It is a 
   concatenation of student information and student course information.
   
   =back
   
   =cut
   
   sub FormatStudentData {
       my ($name,$studentInformation,$spacePadding,$ChartDB)=@_;
       my ($sname,$sdom) = split(/\:/,$name);
       my $Str;
       my %CacheData;
   
       unless(tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_READER,0640)) {
           return '';
       }
       # Handle Student information ------------------------------------------
       # Handle user data
       $Str=&FormatStudentInformation(\%CacheData, $name, $studentInformation, 
                                      $spacePadding);
   
       # Handle errors
       if($CacheData{$name.':error'} =~ /environment/) {
           $Str .= '<br>';
           untie(%CacheData);
           return $Str;
       }
   
       if($CacheData{$name.':error'} =~ /course/) {
           $Str .= '<br>';
           untie(%CacheData);
           return $Str;
       }
   
       # Handle problem data ------------------------------------------------
     my $Version;      my $Version;
     my $ProbNo;      my $problemsCorrect = 0;
     my $PrTotal;      my $totalProblems   = 0;
     my $LatestVersion;                  my $problemsSolved  = 0;
       my $numberOfParts   = 0;
     my $test = $ENV{'request.course.fn'};      foreach my $sequence (split(/\:/,$CacheData{'orderedSequences'})) {
     my $comp = '/home/httpd/perl/tmp/minaeibi_msu_12679c3ed543a25msul1';           if(!&ShouldShowColumn(\%CacheData, 'ChartSequence'.$sequence)) {
                              next;
     my $Str=substr($students[$index].          }
             '                                                        ',0,14).' ! '.  
             substr($rowlabels[$index].   my $characterCount=0;
             '                                                        ',0,45).' ! ';   foreach my $problemID (split(/\:/,$CacheData{$sequence.':problems'})) {
     unless ($reply=~/^error\:/) {      my $problem = $CacheData{$problemID.':problem'};
         map {      my $LatestVersion = $CacheData{$name.":version:$problem"};
             my ($name,$value)=split(/\=/,&Apache::lonnet::unescape($_));  
             $result{$name}=$value;              # Output blanks for all the parts of this problem if there
         } split(/\&/,$reply);              # is no version information about the current problem.
  $ProbNo = 0;              if(!$LatestVersion) {
  $PrTotal = 0;                  foreach my $part (split(/\:/,$CacheData{$sequence.':'.
  my $IterationNo = 0;                                                          $problemID.
         foreach $ResId (@cols) {                                                          ':parts'})) {
     if ($IterationNo == 0) {$IterationNo++; next;}                      $Str .= ' ';
     if (!$ResId) {                       $totalProblems++;
  my $PrNo = sprintf( "%3d", $ProbNo );                      $characterCount++;
  $Str .= ' '.'<font color="#007700">'.$PrNo.'</font> ';                  }
  $PrTotal += $ProbNo;                  next;
  $ProbNo=0;              }
  next;   
     }              my %partData=undef;
             $ResId=~/(\d+)\.(\d+)/;              # Initialize part data, display skips correctly
     my $meta=$hash{'src_'.$ResId};              # Skip refers to when a student made no submissions on that
     my $PartNo = 0;              # part/problem.
     undef %TempHash;              foreach my $part (split(/\:/,$CacheData{$sequence.':'.
     map {                                                      $problemID.
  if ($_=~/^stores\_(\d+)\_tries$/) {                                                      ':parts'})) {
                     my $Part=&Apache::lonnet::metadata($meta,$_.'.part');                  $partData{$part.':tries'}=0;
     if ( $TempHash{"$Part"} eq '' ) {                   $partData{$part.':code'}=' ';
  $TempHash{"$Part"} = $Part;              }
  $TempHash{$PartNo}=$Part;  
  $TempHash{"$Part.Code"} = ' ';                # Looping through all the versions of each part, starting with the
  $PartNo++;              # oldest version.  Basically, it gets the most recent 
     }              # set of grade data for each part.
  }      for(my $Version=1; $Version<=$LatestVersion; $Version++) {
             } split(/\,/,&Apache::lonnet::metadata($meta,'keys'));                  foreach my $part (split(/\:/,$CacheData{$sequence.':'.
                                                           $problemID.
             my $Prob = &Apache::lonnet::declutter( $hash{'map_id_'.$1} ).                                                          ':parts'})) {
                        '___'.$2.'___'.  
                        &Apache::lonnet::declutter( $hash{'src_'.$ResId} );                      if(!defined($CacheData{$name.":$Version:$problem".
             $Code=' ';                                                 ":resource.$part.solved"})) {
             $Tries = 0;                          # No grade for this submission, so skip
      $LatestVersion = $result{"version:$Prob"};                          next;
                       }
             if ( $LatestVersion ) {  
  for ( my $Version=1; $Version<=$LatestVersion; $Version++ ) {                      my $tries=0;
     my $vkeys = $result{"$Version:keys:$Prob"};                      my $code=' ';
     my @keys = split(/\:/,$vkeys);    
                       $tries = $CacheData{$name.":$Version:$problem".
     foreach my $Key (@keys) {                                            ":resource.$part.tries"};
  if (($Key=~/\.(\w+)\.solved$/) && ($Key!~/^\d+\:/)) {                      $partData{$part.':tries'}=($tries) ? $tries : 0;
     my $Part = $1;  
     $Tries = $result{"$Version:$Prob:resource.$Part.tries"};                      my $val = $CacheData{$name.":$Version:$problem".
     $TempHash{"$Part.Tries"}=($Tries) ? $Tries : 0;                                           ":resource.$part.solved"};
     my $Val = $result{"$Version:$Prob:resource.$Part.solved"};                      if    ($val eq 'correct_by_student')   {$code = '*';} 
     if ($Val eq 'correct_by_student'){$Code='*';}                       elsif ($val eq 'correct_by_override')  {$code = '+';}
     elsif ($Val eq 'correct_by_override'){$Code = '+';}                                              elsif ($val eq 'incorrect_attempted')  {$code = '.';} 
     elsif ($Val eq 'incorrect_attempted'){$Code = '.';}                       elsif ($val eq 'incorrect_by_override'){$code = '-';}
     elsif ($Val eq 'incorrect_by_override'){$Code = '-';}                      elsif ($val eq 'excused')              {$code = 'x';}
     elsif ($Val eq 'excused'){$Code = 'x';}                      elsif ($val eq 'ungraded_attempted')   {$code = '#';}
     else {$Code = ' ';}                      else                                   {$code = ' ';}
     $TempHash{"$Part.Code"} = $Code;                      $partData{$part.':code'}=$code;
 #            if ($test=~/*minaeibi*/) {                  }
  $r->print($Key."  PartNo =$PartNo "." Tries=$Tries!<br>$Version:$Prob:resource.$Part.tries".' = '.$result{"$Version:$Prob:resource.$Part.tries"}."  $Val "."($Code)".'<br>');              }
 #    }  
  }              # All grades (except for versionless parts) are displayed as links
          }              # to their submission record.  Loop through all the parts for the
                 }               # current problem in the correct order and prepare the output links
               $Str.='<a href="/adm/grades?symb='.
  for ( my $n = 0; $n < $PartNo; $n++ ) {                    &Apache::lonnet::escape($problem).
     my $part = $TempHash{$n};                  '&student='.$sname.'&domain='.$sdom.'&command=submission">'; 
                     if ($TempHash{"$part.Code"} eq '*') {              foreach(split(/\:/,$CacheData{$sequence.':'.$problemID.
  $ProbNo++;                                            ':parts'})) {
                         if (($TempHash{"$part.Tries"}<10) ||                  if($partData{$_.':code'} eq '*') {
                             ($TempHash{"$part.Tries"} eq '')) {                      $problemsCorrect++;
     $TempHash{"$part.Code"}=$TempHash{"$part.Tries"};                      if (($partData{$_.':tries'}<10) &&
  }                          ($partData{$_.':tries'} ne '')) {
                           $partData{$_.':code'}=$partData{$_.':tries'};
                     }                      }
     $Str .= $TempHash{"$part.Code"};                  } elsif($partData{$_.':code'} eq '+') {
     $r->print($n.") Part=".$part."  code=$TempHash{$part.'.Code'}<br>");                      $problemsCorrect++;
  }                  }
             }     
     else {for(my $n=0; $n<$PartNo; $n++) {$Str.=' ';}}                  $Str .= $partData{$_.':code'};
         }                   $characterCount++;
     }  
     my $PrTot = sprintf( "%5d", $PrTotal );                  if($partData{$_.':code'} ne 'x') {
     $Str .= ' '.'<font color="#000088">'.$PrTot.'</font> ';                      $totalProblems++;
                   }
     return $Str ;              }
               $Str.='</a>';
           }
   
           # Output the number of correct answers for the current sequence.
           # This part takes up 6 character slots, but is formated right 
           # justified.
           my $spacesNeeded=$CacheData{$sequence.':columnWidth'}-$characterCount;
           $spacesNeeded -= 3;
           $Str .= (' 'x$spacesNeeded);
   
    my $outputProblemsCorrect = sprintf( "%3d", $problemsCorrect );
    $Str .= '<font color="#007700">'.$outputProblemsCorrect.'</font>';
    $problemsSolved += $problemsCorrect;
    $problemsCorrect=0;
   
           $Str .= $spacePadding;
       }
   
       # Output the total correct problems over the total number of problems.
       # I don't like this type of formatting, but it is a solution.  Need
       # a way to dynamically determine the space requirements.
       my $outputProblemsSolved = sprintf( "%4d", $problemsSolved );
       my $outputTotalProblems  = sprintf( "%4d", $totalProblems );
       $Str .= '<font color="#000088">'.$outputProblemsSolved.
       ' / '.$outputTotalProblems.'</font><br>';
   
       untie(%CacheData);
       return $Str;
 }  }
   
   =pod
   
   =item &CreateTableHeadings()
   
   This function generates the column headings for the chart.
   
 # ------------------------------------------------------------ Build page table  =over 4
   
 sub tracetable {  Inputs: $CacheData, $studentInformation, $headings, $spacePadding
     my ($rid,$beenhere)=@_;  
     unless ($beenhere=~/\&$rid\&/) {  $CacheData: pointer to a hash tied to the cached data database
        $beenhere.=$rid.'&';    
 # new ... updating the map according to sequence and page  $studentInformation: a pointer to an array containing the names of the data 
        if (defined($hash{'is_map_'.$rid})) {  held in a column and is used as part of a key into $CacheData
    my $cmap=$hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$rid}}};  
            if ( $cmap eq 'sequence' || $cmap eq 'page' ) {   $headings: The names of the headings for the student information
                $cols[$#cols+1]=0;   
            }  $spacePadding: The spaces to go between columns
            if ((defined($hash{'map_start_'.$hash{'src_'.$rid}})) &&  
                (defined($hash{'map_finish_'.$hash{'src_'.$rid}}))) {  Output: $Str
               my $frid=$hash{'map_finish_'.$hash{'src_'.$rid}};  
   $Str: A formatted string of the table column headings.
                 &tracetable($hash{'map_start_'.$hash{'src_'.$rid}},  
                 '&'.$frid.'&');  =back
   
               if ($hash{'src_'.$frid}) {  =cut
                  if ($hash{'src_'.$frid}=~  
                                  /\.(problem|exam|quiz|assess|survey|form)$/) {  sub CreateTableHeadings {
      $cols[$#cols+1]=$frid;      my ($CacheData,$studentInformation,$headings,$spacePadding)=@_;
                  }      my $Str='<tr>';
       }  
       for(my $index=0; $index<(scalar @$headings); $index++) {
    }          if(!&ShouldShowColumn($CacheData, 'ChartHeading'.$index)) {
        } else {              next;
           if ($hash{'src_'.$rid}) {          }
              if ($hash{'src_'.$rid}=~  
                                  /\.(problem|exam|quiz|assess|survey|form)$/) {          $Str .= '<td align="left"><pre>';
          $cols[$#cols+1]=$rid;   my $data=$$headings[$index];
              }   $Str .= $data;
           }  
        }   my @dataLength=split(//,$data);
        if (defined($hash{'to_'.$rid})) {   my $length=scalar @dataLength;
           map {   $Str .= (' 'x($CacheData->{$$studentInformation[$index].'Length'}-
               &tracetable($hash{'goesto_'.$_},$beenhere);                        $length));
           } split(/\,/,$hash{'to_'.$rid});   $Str .= $spacePadding;
        }          $Str .= '</pre></td>';
       }
   
       foreach my $sequence (split(/\:/,$CacheData->{'orderedSequences'})) {
           if(!&ShouldShowColumn($CacheData, 'ChartSequence'.$sequence)) {
               next;
           }
   
           $Str .= '<td align="left"><pre>';
           my $name = $CacheData->{$sequence.':title'};
    $Str .= $name;
    my @titleLength=split(//,$CacheData->{$sequence.':title'});
    my $leftover=$CacheData->{$sequence.':columnWidth'}-
                        (scalar @titleLength);
    $Str .= (' 'x$leftover);
    $Str .= $spacePadding;
           $Str .= '</pre></td>';
     }      }
   
       $Str .= '<td><pre>Total Solved/Total Problems</pre></td>';
       $Str .= '</tr>';
   
       return $Str;
 }  }
   
 # ================================================================ Main Handler  =pod
   
 sub handler {  =item &CreateColumnSelectionBox()
   $r=shift;  
   If there are columns not being displayed then this selection box is created
   with a list of those columns.  When selections are made and the page 
   refreshed, the columns will be removed from this box and the column is
   put back in the chart.  If there is no columns to select, no row is added
   to the interface table.
   
   =over 4
   Input: $CacheData, $headings
   
   
   $CacheData: A pointer to a hash tied to the cached data
   
   $headings:  An array of the names of the columns for the student information.  
   They are used for displaying which columns are missing.
   
   Output: $notThere
   
   $notThere: The string contains one row of a table.  The first column has the 
   name of the selection box.  The second contains the selection box 
   which has a size of four.
   
   =back
   
   =cut
   
   sub CreateColumnSelectionBox {
       my ($CacheData,$headings)=@_;
   
       my $missing=0;
       my $notThere='<tr><td align="right"><b>Select column to view:</b>';
       my $name;
       $notThere .= '<td align="left">';
       $notThere .= '<select name="ChartReselect" size="4" multiple="true">'."\n";
   
       for(my $index=0; $index<(scalar @$headings); $index++) {
           if(&ShouldShowColumn($CacheData, 'ChartHeading'.$index)) {
               next;
           }
           $name = $headings->[$index];
           $notThere .= '<option value="ChartHeading'.$index.'">';
           $notThere .= $name.'</option>'."\n";
           $missing++;
       }
   
       foreach my $sequence (split(/\:/,$CacheData->{'orderedSequences'})) {
           if(&ShouldShowColumn($CacheData, 'ChartSequence'.$sequence)) {
               next;
           }
           $name = $CacheData->{$sequence.':title'};
           $notThere .= '<option value="ChartSequence'.$sequence.'">';
           $notThere .= $name.'</option>'."\n";
           $missing++;
       }
   
       if($missing) {
           $notThere .= '</select>';
       } else {
           $notThere='<tr><td>';
       }
   
       return $notThere.'</td></tr>';
   }
   
   =pod
   
   =item &CreateColumnSelectors()
   
   This function generates the checkboxes above the column headings.  The 
   column will be removed if the checkbox is unchecked.
   
   =over 4
   
   Input: $CacheData, $headings
   
   $CacheData: A pointer to a hash tied to the cached data
   
   $headings:  An array of the names of the columns for the student 
   information.  They are used to know what are the student information columns
   
   Output: $present
   
   $present: The string contains the first row of a table.  Each column contains
   a checkbox which is left justified.  Currently left justification is used
   for consistency of location over the column in which it presides.
   
   =back
   
   =cut
   
   sub CreateColumnSelectors {
       my ($CacheData,$headings)=@_;
   
       my $found=0;
       my ($name, $length, $position);
   
       my $present = '<tr>';
       for(my $index=0; $index<(scalar @$headings); $index++) {
           if(!&ShouldShowColumn($CacheData, 'ChartHeading'.$index)) {
               next;
           }
           $present .= '<td align="left">';
           $present .= '<input type="checkbox" checked="on" ';
           $present .= 'name="ChartHeading'.$index.'" />';
           $present .= '</td>';
           $found++;
       }
   
       foreach my $sequence (split(/\:/,$CacheData->{'orderedSequences'})) {
           if(!&ShouldShowColumn($CacheData, 'ChartSequence'.$sequence)) {
               next;
           }
           $present .= '<td align="left">';
           $present .= '<input type="checkbox" checked="on" ';
           $present .= 'name="ChartSequence'.$sequence.'" />';
           $present .= '</td>';
           $found++;
       }
   
   if (&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {      if(!$found) {
 # ------------------------------------------- Set document type for header only          $present = '';
       }
   
       return $present.'<td></td></tr></form>'."\n";;
   }
   
   =pod
   
   =item &CreateForm()
   
   The interface for this module consists primarily of the controls in this
   function.  The student status selection (active, expired, any) is set here.
   The sort buttons: username, last name, and section are set here.  The
   other buttons are Recalculate Chart, Refresh Chart, and Reset Selections.
   These controls are in a table to clean up the interface.
   
   =over 4
   
   Input: $CacheData
   
   $CacheData is a hash pointer to tied database for cached data.
   
   Output: $Ptr
   
   $Ptr is a string containing all the html for the above mentioned buttons.
   
   =back
   
   =cut
   
   sub CreateForm {
       my ($CacheData)=@_;
       my $OpSel1='';
       my $OpSel2='';
       my $OpSel3='';
       my $Status = $CacheData->{'form.ChartStatus'};
       if ( $Status eq 'Any' ) { $OpSel3='selected'; }
       elsif ($Status eq 'Expired' ) { $OpSel2 = 'selected'; }
       else { $OpSel1 = 'selected'; }
   
       my $Ptr .= '<form name="ChartStat" method="post" action="/adm/chart" >';
       $Ptr .= "\n";
       $Ptr .= '<tr><td align="right">';
       $Ptr .= '</td><td align="left">';
       $Ptr .= '<input type="submit" name="ChartRecalculate" ';
       $Ptr .= 'value="Recalculate Chart"/>'."\n";
       $Ptr .= '&nbsp;&nbsp;&nbsp;';
       $Ptr .= '<input type="submit" name="ChartRefresh" ';
       $Ptr .= 'value="Refresh Chart"/>'."\n";
       $Ptr .= '&nbsp;&nbsp;&nbsp;';
       $Ptr .= '<input type="submit" name="ChartReset" ';
       $Ptr .= 'value="Reset Selections"/></td>'."\n";
       $Ptr .= '</tr><tr><td align="right">';
       $Ptr .= '<b> Sort by: </b>'."\n";
       $Ptr .= '</td><td align="left">';
       $Ptr .= '<input type="submit" name="ChartSort" value="User Name" />'."\n";
       $Ptr .= '&nbsp;&nbsp;&nbsp;';
       $Ptr .= '<input type="submit" name="ChartSort" value="Last Name" />'."\n";
       $Ptr .= '&nbsp;&nbsp;&nbsp;';
       $Ptr .= '<input type="submit" name="ChartSort" value="Section"/>'."\n";
       $Ptr .= '</td></tr><tr><td align="right">';
       $Ptr .= '<b> Student Status: &nbsp; </b>'."\n".
               '</td><td align="left">'.
               '<select name="ChartStatus">'. 
               '<option '.$OpSel1.' >Active</option>'."\n".
               '<option '.$OpSel2.' >Expired</option>'."\n".
       '<option '.$OpSel3.' >Any</option> </select> '."\n";
       $Ptr .= '</td></tr>';
   
       return $Ptr;
   }
   
   =pod
   
   =item &CreateLegend()
   
   This function returns a formatted string containing the legend for the
   chart.  The legend describes the symbols used to represent grades for
   problems.
   
   =cut
   
   sub CreateLegend {
       my $Str = "<p><pre>".
                 "1..9: correct by student in 1..9 tries\n".
                 "   *: correct by student in more than 9 tries\n".
         "   +: correct by override\n".
                 "   -: incorrect by override\n".
         "   .: incorrect attempted\n".
         "   #: ungraded attempted\n".
                 "    : not attempted\n".
         "   x: excused".
                 "</pre><p>"; 
       return $Str;
   }
   
   =pod
   
   =item &StartDocument()
   
   Returns a string containing the header information for the chart: title,
   logo, and course title.
   
   =cut
   
   sub StartDocument {
       my ($title, $header)=@_;
       my $Str = '';
       $Str .= '<html>';
       $Str .= '<head><title>';
       $Str .= $title.'</title></head>';
       $Str .= '<body bgcolor="#FFFFFF">';
       $Str .= '<script>window.focus();</script>';
       $Str .= '<img align=right src=/adm/lonIcons/lonlogos.gif>';
       $Str .= '<h1>'.$header.'</h1>';
       $Str .= '<h1>'.$ENV{'course.'.$ENV{'request.course.id'}.'.description'};
       $Str .= '</h1>';
   
       return $Str;
   }
   
   # ----- END FORMAT PRINT DATA ------------------------------------------
   
   =pod
   
   =head1 HELPER FUNCTIONS
   
   These are just a couple of functions do various odd and end 
   jobs.
   
   =cut
   
   # ----- HELPER FUNCTIONS -----------------------------------------------
   
   =pod
   
   =item &ProcessFormData()
   
   Cache form data and set default form data (sort, status, heading.$number,
   sequence.$number, reselect, reset, recalculate, and refresh)
   
   =over 4
   
   Input: $ChartDB, $isCached
   
   $ChartDB: The name of the database for cached data
   
   $isCached: Is there already data for this course cached.  This is used in 
   conjunction with the absence of all form data to know to display all selection 
   types.
   
   Output: None
   
   =back
   
   =cut
   
   # For all data, if ENV data doesn't exist for it, default values is used.
   sub ProcessFormData {
       my ($ChartDB, $isCached)=@_;
       my %CacheData;
   
       if(tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_WRCREAT,0640)) {
           # Ignore $ENV{'form.ChartRefresh'}
           # Ignore $ENV{'form.ChartRecalculate'}
   
           if(defined($ENV{'form.ChartSort'})) {
               $CacheData{'form.ChartSort'}=$ENV{'form.ChartSort'};
           } elsif(!defined($CacheData{'form.ChartSort'})) {
               $CacheData{'form.ChartSort'}='username';
           }
   
   if ($r->header_only) {          if(defined($ENV{'form.ChartStatus'})) {
        if ($ENV{'browser.mathml'}) {              $CacheData{'form.ChartStatus'}=$ENV{'form.ChartStatus'};
            $r->content_type('text/xml');          } elsif(!defined($CacheData{'form.ChartStatus'})) {
        } else {              $CacheData{'form.ChartStatus'}='Active';
            $r->content_type('text/html');          }
        }  
        $r->send_http_header;  
        return OK;  
    }  
   
   my $requrl=$r->uri;  
 # ----------------------------------------------------------------- Tie db file  
   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  
   
   
 # ------------------------------------------------------------------ Build page  
   
 # ---------------------------------------------------------------- Send headers  
   
              $r->content_type('text/html');  
              $r->send_http_header;  
              $r->print(  
   '<html><head><title>LON-CAPA Assessment Chart</title></head>');  
   
      $r->print('<body bgcolor="#FFFFFF">'.  
                                     '<script>window.focus();</script>'.  
                            '<img align=right src=/adm/lonIcons/lonlogos.gif>'.  
                                     '<h1>Assessment Chart</h1>');  
   
 # ---------------------------------------------------------------- Course title  
   
     $r->print('<h1>'.  
     $ENV{'course.'.$ENV{'request.course.id'}.'.description'}.'</h1><h3>'.  
     localtime()."</h3><p><pre>1..9: correct by student in 1..9 tries\n".  
                             "   *: correct by student in more than 9 tries\n".  
                     "   +: correct by override\n".  
                             "   -: incorrect by override\n".  
                     "   .: incorrect attempted\n".  
                             "    : not attempted\n".  
                     "   x: excused</pre><p>");  
     
 # ------------------------------- This is going to take a while, produce output  
   
              $r->rflush();  
   
 # ----------------------- Get first and last resource, see if there is anything  
   
   
               my $firstres=$hash{'map_start_/res/'.$ENV{'request.course.uri'}};  
               my $lastres=$hash{'map_finish_/res/'.$ENV{'request.course.uri'}};  
               if (($firstres) && ($lastres)) {  
 # ----------------------------------------------------------------- Render page  
   
                  my $cid=$ENV{'request.course.id'};  
                  my $chome=$ENV{'course.'.$cid.'.home'};  
                  my ($cdom,$cnum)=split(/\_/,$cid);  
   
 # ---------------------------------------------- Read class list and row labels  
   
     undef @rowlabels;  
     undef @students;  
   
     my $classlst=&Apache::lonnet::reply  
                                  ('dump:'.$cdom.':'.$cnum.':classlist',$chome);  
     my $now=time;  
     unless ($classlst=~/^error\:/) {  
         map {  
             my ($name,$value)=split(/\=/,$_);  
             my ($end,$start)=split(/\:/,&Apache::lonnet::unescape($value));  
             my $active=1;  
             if (($end) && ($now>$end)) { $active=0; }  
             if ($active) {  
                 my $thisindex=$#students+1;  
                 $name=&Apache::lonnet::unescape($name);  
                 $students[$thisindex]=$name;  
                 my ($sname,$sdom)=split(/\:/,$name);  
                 my $ssec=&Apache::lonnet::usection($sdom,$sname,$cid);  
                 if ($ssec==-1) {  
                     $rowlabels[$thisindex]=  
                       'Data not available: '.$name;  
                 } else {  
                     my %reply=&Apache::lonnet::idrget($sdom,$sname);  
     my $reply=&Apache::lonnet::reply('get:'.$sdom.':'.$sname.  
                                                      ':environment:lastname&generation&firstname&middlename',  
                                                      &Apache::lonnet::homeserver($sname,$sdom));  
                     $rowlabels[$thisindex]=  
                       sprintf('%3s',$ssec).' '.$reply{$sname}.' ';  
                     my $i=0;  
                     map {  
                       $i++;  
                       if ( $_ ne '') {  
                         $rowlabels[$thisindex].=&Apache::lonnet::unescape($_).' ';  
                       }  
                       if ($i == 2) {  
                         chop($rowlabels[$thisindex]);  
                         $rowlabels[$thisindex].=', ';  
                       }  
                     } split(/\&/,$reply);  
   
           # $found checks for any instances of form data in the ENV.  If it is
           # missing I assume the chrt button on the remote has been pressed.
           my @headings=();
           my @sequences=();
           my $found=0;
           foreach (keys(%ENV)) {
               if(/form\.ChartHeading/) {
                   $found++;
                   push(@headings, $_);
               } elsif(/form\.ChartSequence/) {
                   $found++;
                   push(@sequences, $_);
               } elsif(/form\./) {
                   $found++;
               }
           }
   
           if($found) {
               $CacheData{'form.ChartHeadings'}=join(":::",@headings);
               $CacheData{'form.ChartSequences'}=join(":::",@sequences);
           }
   
           if(defined($ENV{'form.ChartReselect'})) {
               my @reselected = (ref($ENV{'form.ChartReselect'}) ? 
                                 @{$ENV{'form.ChartReselect'}}
                                 : ($ENV{'form.ChartReselect'}));
               foreach (@reselected) {
                   if(/ChartHeading/) {
                       $CacheData{'form.ChartHeadings'}.=":::".$_;
                   } elsif(/ChartSequence/) {
                       $CacheData{'form.ChartSequences'}.=":::".$_;
                 }                  }
             }              }
         } sort split(/\&/,$classlst);          }
   
     } else {          # !$found and !$isCached are how I determine if the chrt button
         $r->print('<h1>Could not access course data</h1>');          # on the remote was pressed and needs to reset all the selections
           if(defined($ENV{'form.ChartReset'}) || (!$found && !$isCached)) {
               $CacheData{'form.ChartReset'}='true';
               $CacheData{'form.ChartStatus'}='Active';
               $CacheData{'form.ChartSort'}='username';
               $CacheData{'form.ChartHeadings'}='ALLHEADINGS';
               $CacheData{'form.ChartSequences'}='ALLSEQUENCES';
           } else {
               $CacheData{'form.ChartReset'}='false';
           }
   
           untie(%CacheData);
     }      }
   
     my $allstudents=$#students+1;      return;
     $r->print('<h3>'.$allstudents.' students</h3>');  }
     $r->rflush();  
   =pod
   
   =item &SpaceColumns()
   
   Determines the width of all the columns in the chart.  It is based on
   the max of the data for that column and its header.
   
   =over 4
   
 # --------------- Find all assessments and put them into some linear-like order  Input: $students, $studentInformation, $headings, $ChartDB
   
    &tracetable($firstres,'&'.$lastres.'&');  $students: An array pointer to a list of students (username:domain)
   
   $studentInformatin: The type of data for the student information.  It is
   used as part of the key in $CacheData.
   
   $headings: The name of the student information columns.
   
   $ChartDB: The name of the cache database which is opened for read/write.
   
   Output: None - All data stored in cache.
   
   =back
   
   =cut
   
   sub SpaceColumns {
       my ($students,$studentInformation,$headings,$cache)=@_;
   
       # Initialize Lengths
       for(my $index=0; $index<(scalar @$headings); $index++) {
           my @titleLength=split(//,$$headings[$index]);
           $cache->{$$studentInformation[$index].'Length'}=
               scalar @titleLength;
       }
   
 # ----------------------------------------------------------------- Start table      foreach my $name (@$students) {
           foreach (@$studentInformation) {
               my @dataLength=split(//,$cache->{$name.':'.$_});
               my $length=scalar @dataLength;
               if($length > $cache->{$_.'Length'}) {
                   $cache->{$_.'Length'}=$length;
               }
           }
       }
   
                           $r->print('<p><pre>');      return;
    my $index;  
                            for ($index=0;$index<=$#students;$index++) {  
                               $r->print(&ExtractStudentData($index,$cid).'<br>');  
                               $r->rflush();  
                           }  
                           $r->print('</pre>');  
   
      } else {  
                  $r->print('<h3>Undefined course sequence</h3>');  
              }  
   
                       $r->print('</body></html>');  
                                        
 # ------------------------------------------------------------- End render page  
               } 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;   
   
   =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 ($students,$CacheData)=@_;
   
       my @sorted1Students=();
       foreach (@$students) {
           my ($end,$start)=split(/\:/,$CacheData->{$_.':date'});
           my $active=1;
           my $now=time;
           my $Status=$CacheData->{'form.ChartStatus'};
           $Status = ($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 = $CacheData->{'form.ChartSort'};
       my %sortData;
       if($Pos eq 'Last Name') {
    for(my $index=0; $index<scalar @sorted1Students; $index++) {
       $sortData{$CacheData->{$sorted1Students[$index].':fullname'}}=
    $sorted1Students[$index];
    }
       } elsif($Pos eq 'Section') {
    for(my $index=0; $index<scalar @sorted1Students; $index++) {
       $sortData{$CacheData->{$sorted1Students[$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;
 }  }
   
   =pod
   
   =item &ShouldShowColumn()
   
   Determine if a specified column should be shown on the chart.
   
   =over 4
   
   Input: $cache, $test
   
   $cache: A pointer to the hash tied to the cached data
   
   $test: The form name of the column (heading.$headingIndex) or 
   (sequence.$sequenceIndex)
   
   Output: 0 (false), 1 (true)
   
   =back
   
   =cut
   
   sub ShouldShowColumn {
       my ($cache,$test)=@_;
   
       if($cache->{'form.ChartReset'} eq 'true') {
           return 1;
       }
   
       my $headings=$cache->{'form.ChartHeadings'};
       my $sequences=$cache->{'form.ChartSequences'};
       if($headings eq 'ALLHEADINGS' || $sequences eq 'ALLSEQUENCES' ||
          $headings=~/$test/ || $sequences=~/$test/) {
           return 1;
       }
   
       return 0;
 }  }
 1;  
 __END__  
   
   # ----- END HELPER FUNCTIONS --------------------------------------------
   
   =pod
   
   =head1 Handler and main function(BuildChart)
   
   The handler does some initial error checking and then passes the torch to
   BuildChart.  BuildChart calls all the appropriate functions to get the
   job done.  These are the only two functions that use print ($r).  All other
   functions return strings to BuildChart to be printed.
   
   =cut
   
   =pod
   
   =item &BuildChart()
   
    The following is the process that BuildChart goes through to 
     create the html document.
   
    -Start the lonchart document
    -Test for access to the CacheData
    -Download class list information if not using cached data 
    -Sort students and print out table desciptive data
    -Output student data
    -If recalculating, store a list of students, but only if all 
     their data was downloaded.  Leave off the others.
    -End document
   
   =over 4
   
   Input: $r
   
   $r:  Used to print html
   
   Output: None
   
   =back
   
   =cut
   
   sub BuildChart {
       my ($r)=@_;
       my $c = $r->connection;
   
       # Start the lonchart document
       $r->content_type('text/html');
       $r->send_http_header;
       $r->print(&StartDocument('LON-CAPA Assessment Chart', 'Assessment Chart'));
       $r->rflush();
   
       # Test for access to the CacheData
       my $isCached=0;
       my $cid=$ENV{'request.course.id'};
       my $ChartDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                     "_$ENV{'user.domain'}_$cid\_chart.db";
       my $isRecalculate=0;
       if(defined($ENV{'form.ChartRecalculate'})) {
           $isRecalculate=1;
       }
       $isCached=&Apache::loncoursedata::TestCacheData($ChartDB, $isRecalculate);
       if($isCached < 0) {
           $r->print("Unable to tie hash to db file</body></html>");
           $r->rflush();
           return;
       }
       &ProcessFormData($ChartDB, $isCached);
   
       # Download class list information if not using cached data
       my %CacheData;
       my @students=();
       my @studentInformation=('username','domain','section','id','fullname');
       my @headings=('User Name','Domain','Section','PID','Full Name');
       my $spacePadding='   ';
       if(!$isCached) {
           unless(tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_WRCREAT,0640)) {
               $r->print("Unable to tie hash to db file</body></html>");
               $r->rflush();
               return;
           }
   
           my $processTopResourceMapReturn=
               &Apache::loncoursedata::ProcessTopResourceMap(\%CacheData,$c);
           if($processTopResourceMapReturn ne 'OK') {
               $r->print($processTopResourceMapReturn.'</body></html>');
               untie(%CacheData);
               return;
           }
   
           if($c->aborted()) {
               untie(%CacheData);
               $r->print('</body></html>'); 
               return;
           }
   
           my $classlist=&Apache::loncoursedata::DownloadStudentNamePIDSection(
                                                                      $cid, $c);
           my ($checkForError)=keys(%$classlist);
           if($checkForError =~ /^(con_lost|error|no_such_host)/i ||
              defined($classlist->{'error'})) {
               $r->print("Error getting student data.</body></html>");
               $r->rflush();
               untie(%CacheData);
               return;
           }
   
           if($c->aborted()) {
               untie(%CacheData);
               $r->print('</body></html>'); 
               return;
           }
   
   
           @students=&Apache::loncoursedata::ProcessClassList(\%CacheData, 
                                                 $classlist, $cid, 
                                                 $CacheData{'form.ChartStatus'},
                                                 $c);
   
           if($c->aborted()) {
               untie(%CacheData);
               $r->print('</body></html>'); 
               return;
           }
   
           &SpaceColumns(\@students,\@studentInformation,\@headings,
                         \%CacheData);
   
           if($c->aborted()) {
               untie(%CacheData);
               $r->print('</body></html>'); 
               return;
           }
   
           untie(%CacheData);
       } else {
           if(!$c->aborted() && tie(%CacheData,'GDBM_File',$ChartDB,
                                    &GDBM_READER,0640)) {
               @students=split(/:::/,$CacheData{'NamesOfStudents'});
           }
       }
   
       # Sort students and print out table desciptive data
       my $downloadTime=0;
       if(tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_READER,0640)) {
           if(!$c->aborted()) { @students=&SortStudents(\@students,\%CacheData); }
           if(defined($CacheData{'time'})) { $downloadTime=$CacheData{'time'}; }
           else { $downloadTime=localtime(); }
           if(!$c->aborted()) { $r->print('<h3>'.$downloadTime.'</h3>'); }
           if(!$c->aborted()) { $r->print('<h1>'.(scalar @students).
                                          ' students</h1>'); }
    if(!$c->aborted()) { $r->rflush(); }
    if(!$c->aborted()) { $r->print(&CreateLegend()); }
           if(!$c->aborted()) { $r->print('<table border="0"><tbody>'); }
    if(!$c->aborted()) { $r->print(&CreateForm(\%CacheData)); }
    if(!$c->aborted()) { $r->print(&CreateColumnSelectionBox(
                                                          \%CacheData,
                                                          \@headings)); }
           if(!$c->aborted()) { $r->print('</tbody></table>'); }
           if(!$c->aborted()) { $r->print('<b>Note: Uncheck the boxes above a'); }
           if(!$c->aborted()) { $r->print(' column to remove that column from'); }
           if(!$c->aborted()) { $r->print(' the display.</b></pre>'); }
           if(!$c->aborted()) { $r->print('<table border="0" cellpadding="0" '); }
           if(!$c->aborted()) { $r->print('cellspacing="0"><tbody>'); }
    if(!$c->aborted()) { $r->print(&CreateColumnSelectors(
                                                          \%CacheData,
                                                          \@headings)); }
    if(!$c->aborted()) { $r->print(&CreateTableHeadings(
                                                            \%CacheData,
                                                            \@studentInformation, 
    \@headings, 
    $spacePadding)); }
           if(!$c->aborted()) { $r->print('</tbody></table>'); }
    if(!$c->aborted()) { $r->rflush(); }
    untie(%CacheData);
       } else {
    $r->print("Init2: Unable to tie hash to db file");
    return;
       }
   
       # Output student data
       my @updateStudentList = ();
       my $courseData;
       $r->print('<pre>');
       foreach (@students) {
           if($c->aborted()) {
               last;
           }
   
           if(!$isCached) {
               $courseData=
                   &Apache::loncoursedata::DownloadStudentCourseInformation($_, 
                                                                            $cid);
               if($c->aborted()) { last; }
               if(tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_WRCREAT,0640)) {
                   &Apache::loncoursedata::ProcessStudentData(\%CacheData, 
                                                              $courseData, $_);
                   push(@updateStudentList, $_);
                   untie(%CacheData);
               } else {
                   next;
               }
           }
           $r->print(&FormatStudentData($_, \@studentInformation,
                                        $spacePadding, $ChartDB));
           $r->rflush();
       }
   
       # If recalculating, store a list of students, but only if all their 
       # data was downloaded.  Leave off the others.
       if(!$isCached && tie(%CacheData,'GDBM_File',$ChartDB,&GDBM_WRCREAT,0640)) {
           $CacheData{'NamesOfStudents'}=join(":::", @updateStudentList);
   #    $CacheData{'NamesOfStudents'}=
   #            &Apache::lonnet::arrayref2str(\@updateStudentList);
           untie(%CacheData);
       }
   
       # End document
       $r->print('</pre></body></html>');
       $r->rflush();
   
       return;
   }
   
   # ================================================================ Main Handler
   
   =pod
   
   =item &handler()
   
   The handler checks for permission to access the course data and for 
   initial header problem.  Then it passes the torch to the work horse
   function BuildChart.
   
   =over 4
   
   Input: $r
   
   $r: This is the object that is used to print.
   
   Output: A Value (OK or HTTP_NOT_ACCEPTABLE)
   
   =back
   
   =cut
   
   sub handler {
       my $r=shift;
   #    $jr=$r;
       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; 
       }
   
       &BuildChart($r);
   
       return OK;
   }
   1;
   __END__
Removed from v.1.20  
changed lines
  Added in v.1.59

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