# The LearningOnline Network with CAPA
# a pile of common routines
#
# $Id: loncommon.pm,v 1.38 2002/06/24 19:06:05 albertel 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/
#
# YEAR=2001
# 2/13-12/7 Guy Albertelli
# 12/11,12/12,12/17 Scott Harrison
# 12/21 Gerd Kortemeyer
# 12/21 Scott Harrison
# 12/25,12/28 Gerd Kortemeyer
# YEAR=2002
# 1/4 Gerd Kortemeyer

# Makes a table out of the previous attempts
# Inputs result_from_symbread, user, domain, course_id
# Reads in non-network-related .tab files

# POD header:

=head1 NAME

Apache::loncommon - pile of common routines

=head1 SYNOPSIS

Referenced by other mod_perl Apache modules.

Invocation:
 &Apache::loncommon::SUBROUTINENAME(ARGUMENTS);

=head1 INTRODUCTION

Common collection of used subroutines.  This collection helps remove
redundancy from other modules and increase efficiency of memory usage.

Current things done:

 Makes a table out of the previous homework attempts
 Inputs result_from_symbread, user, domain, course_id
 Reads in non-network-related .tab files

This is part of the LearningOnline Network with CAPA project
described at http://www.lon-capa.org.

=head2 General Subroutines

=over 4

=cut 

# End of POD header
package Apache::loncommon;

use strict;
use Apache::lonnet();
use POSIX qw(strftime);
use Apache::Constants qw(:common);
use Apache::lonmsg();
my $readit;

# ----------------------------------------------- Filetypes/Languages/Copyright
my %language;
my %cprtag;
my %fe; my %fd;
my %fc;

# -------------------------------------------------------------- Thesaurus data
my @therelated;
my @theword;
my @thecount;
my %theindex;
my $thetotalcount;
my $thefuzzy=2;
my $thethreshold=0.1/$thefuzzy;
my $theavecount;

# ----------------------------------------------------------------------- BEGIN

=pod

=item BEGIN() 

Initialize values from language.tab, copyright.tab, filetypes.tab,
and filecategories.tab.

=cut
# ----------------------------------------------------------------------- BEGIN

BEGIN {

    unless ($readit) {
# ------------------------------------------------------------------- languages
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
				 '/language.tab');
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($key,$val)=(split(/\s+/,$_,2));
		$language{$key}=$val;
	    }
	}
    }
# ------------------------------------------------------------------ copyrights
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonIncludes'}.
				  '/copyright.tab');
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($key,$val)=(split(/\s+/,$_,2));
		$cprtag{$key}=$val;
	    }
	}
    }
# ------------------------------------------------------------- file categories
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
				  '/filecategories.tab');
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($key,$val)=(split(/\s+/,$_,2));
		push @{$fc{$key}},$val;
	    }
	}
    }
# ------------------------------------------------------------------ file types
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
	       '/filetypes.tab');
	if ($fh) {
            while (<$fh>) {
		next if (/^\#/);
		chomp;
		my ($ending,$emb,$descr)=split(/\s+/,$_,3);
		if ($descr ne '') { 
		    $fe{$ending}=lc($emb);
		    $fd{$ending}=$descr;
		}
	    }
	}
    }
# -------------------------------------------------------------- Thesaurus data
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
	       '/thesaurus.dat');
	if ($fh) {
            while (<$fh>) {
               my ($tword,$tindex,$tcount,$trelated)=split(/\@/,$_);
               $theindex{$tword}=$tindex;
               $theword[$tindex]=$tword;
               $thecount[$tindex]=$tcount;
               $thetotalcount+=$tcount;
               $therelated[$tindex]=$trelated;
	   }
        }
        $theavecount=$thetotalcount/$#thecount;
    }
    &Apache::lonnet::logthis(
              "<font color=yellow>INFO: Read file types and thesaurus</font>");
    $readit=1;
}
    
}
# ============================================================= END BEGIN BLOCK

=item linked_select_forms(...)

linked_select_forms returns a string containing a <script></script> block
and html for two <select> menus.  The select menus will be linked in that
changing the value of the first menu will result in new values being placed
in the second menu.  The values in the select menu will appear in alphabetical
order.

linked_select_forms takes the following ordered inputs:

=over 4

=item $formname, the name of the <form> tag

=item $middletext, the text which appears between the <select> tags

=item $firstdefault, the default value for the first menu

=item $firstselectname, the name of the first <select> tag

=item $secondselectname, the name of the second <select> tag

=item $hashref, a reference to a hash containing the data for the menus.

Below is an example of such a hash.  Only the 'text', 'default', and 
'select2' keys must appear as stated.  keys(%menu) are the possible 
values for the first select menu.  The text that coincides with the 
first menu values is given in $menu{$choice1}->{'text'}.  The values 
and text for the second menu are given in the hash pointed to by 
$menu{$choice1}->{'select2'}.  

 my %menu = ( A1 => { text =>"Choice A1" ,
                      default => "B3",
                      select2 => { 
                          B1 => "Choice B1",
                          B2 => "Choice B2",
                          B3 => "Choice B3",
                          B4 => "Choice B4"
                          }
                  },
              A2 => { text =>"Choice A2" ,
                      default => "C2",
                      select2 => { 
                          C1 => "Choice C1",
                          C2 => "Choice C2",
                          C3 => "Choice C3"
                          }
                  },
              A3 => { text =>"Choice A3" ,
                      default => "D6",
                      select2 => { 
                          D1 => "Choice D1",
                          D2 => "Choice D2",
                          D3 => "Choice D3",
                          D4 => "Choice D4",
                          D5 => "Choice D5",
                          D6 => "Choice D6",
                          D7 => "Choice D7"
                          }
                  }
              );

=back

=cut

# ------------------------------------------------

sub linked_select_forms {
    my ($formname,
        $middletext,
        $firstdefault,
        $firstselectname,
        $secondselectname, 
        $hashref
        ) = @_;
    my $second = "document.$formname.$secondselectname";
    my $first = "document.$formname.$firstselectname";
    # output the javascript to do the changing
    my $result = '';
    $result.="<script>\n";
    $result.="var select2data = new Object();\n";
    $" = '","';
    my $debug = '';
    foreach my $s1 (sort(keys(%$hashref))) {
        $result.="select2data.d_$s1 = new Object();\n";        
        $result.="select2data.d_$s1.def = new String('".
            $hashref->{$s1}->{'default'}."');\n";
        $result.="select2data.d_$s1.values = new Array(";        
        my @s2values = sort(keys( %{ $hashref->{$s1}->{'select2'} } ));
        $result.="\"@s2values\");\n";
        $result.="select2data.d_$s1.texts = new Array(";        
        my @s2texts;
        foreach my $value (@s2values) {
            push @s2texts, $hashref->{$s1}->{'select2'}->{$value};
        }
        $result.="\"@s2texts\");\n";
    }
    $"=' ';
    $result.= <<"END";

function select1_changed() {
    // Determine new choice
    var newvalue = "d_" + $first.value;
    // update select2
    var values     = select2data[newvalue].values;
    var texts      = select2data[newvalue].texts;
    var select2def = select2data[newvalue].def;
    var i;
    // out with the old
    for (i = 0; i < $second.options.length; i++) {
        $second.options[i] = null;
    }
    // in with the nuclear
    for (i=0;i<values.length; i++) {
        $second.options[i] = new Option(values[i]);
        $second.options[i].text = texts[i];
        if (values[i] == select2def) {
            $second.options[i].selected = true;
        }
    }
}
</script>
END
    # output the initial values for the selection lists
    $result .= "<select size=\"1\" name=\"$firstselectname\" onchange=\"select1_changed()\">\n";
    foreach my $value (sort(keys(%$hashref))) {
        $result.="    <option value=\"$value\" ";
        $result.=" selected=\"true\" " if ($value eq $firstdefault);
        $result.=">$hashref->{$value}->{'text'}</option>\n";
    }
    $result .= "</select>\n";
    my %select2 = %{$hashref->{$firstdefault}->{'select2'}};
    $result .= $middletext;
    $result .= "<select size=\"1\" name=\"$secondselectname\">\n";
    my $seconddefault = $hashref->{$firstdefault}->{'default'};
    foreach my $value (sort(keys(%select2))) {
        $result.="    <option value=\"$value\" ";        
        $result.=" selected=\"true\" " if ($value eq $seconddefault);
        $result.=">$select2{$value}</option>\n";
    }
    $result .= "</select>\n";
    #    return $debug;
    return $result;
}   #  end of sub linked_select_forms {

###############################################################

=item csv_translate($text) 

Translate $text to allow it to be output as a 'comma seperated values' 
format.

=cut

sub csv_translate {
    my $text = shift;
    $text =~ s/\"/\"\"/g;
    $text =~ s/\n//g;
    return $text;
}

###############################################################

###############################################################
##        Home server <option> list generating code          ##
###############################################################
#-------------------------------------------

=item get_domains()

Returns an array containing each of the domains listed in the hosts.tab
file.

=cut

#-------------------------------------------
sub get_domains {
    # The code below was stolen from "The Perl Cookbook", p 102, 1st ed.
    my @domains;
    my %seen;
    foreach (sort values(%Apache::lonnet::hostdom)) {
        push (@domains,$_) unless $seen{$_}++;
    }
    return @domains;
}

#-------------------------------------------

=item select_dom_form($defdom,$name)

Returns a string containing a <select name='$name' size='1'> form to 
allow a user to select the domain to preform an operation in.  
See loncreateuser.pm for an example invocation and use.

=cut

#-------------------------------------------
sub select_dom_form {
    my ($defdom,$name) = @_;
    my @domains = get_domains();
    my $selectdomain = "<select name=\"$name\" size=\"1\">\n";
    foreach (@domains) {
        $selectdomain.="<option value=\"$_\" ".
            ($_ eq $defdom ? 'selected' : '').
                ">$_</option>\n";
    }
    $selectdomain.="</select>";
    return $selectdomain;
}

#-------------------------------------------

=item get_home_servers($domain)

Returns a hash which contains keys like '103l3' and values like 
'kirk.lite.msu.edu'.  All of the keys will be for machines in the
given $domain.

=cut

#-------------------------------------------
sub get_home_servers {
    my $domain = shift;
    my %home_servers;
    foreach (keys(%Apache::lonnet::libserv)) {
        if ($Apache::lonnet::hostdom{$_} eq $domain) {
            $home_servers{$_} = $Apache::lonnet::hostname{$_};
        }
    }
    return %home_servers;
}

#-------------------------------------------

=item home_server_option_list($domain)

returns a string which contains an <option> list to be used in a 
<select> form input.  See loncreateuser.pm for an example.

=cut

#-------------------------------------------
sub home_server_option_list {
    my $domain = shift;
    my %servers = &get_home_servers($domain);
    my $result = '';
    foreach (sort keys(%servers)) {
        $result.=
            '<option value="'.$_.'">'.$_.' '.$servers{$_}."</option>\n";
    }
    return $result;
}
###############################################################
##    End of home server <option> list generating code       ##
###############################################################

###############################################################
##    Authentication changing form generation subroutines    ##
###############################################################
##
## All of the authform_xxxxxxx subroutines take their inputs in a
## hash, and have reasonable default values.
##
##    formname = the name given in the <form> tag.
#-------------------------------------------

=item authform_xxxxxx

The authform_xxxxxx subroutines provide javascript and html forms which 
handle some of the conveniences required for authentication forms.  
This is not an optimal method, but it works.  

See loncreateuser.pm for invocation and use examples.

=over 4

=item authform_header

=item authform_authorwarning

=item authform_nochange

=item authform_kerberos

=item authform_internal

=item authform_filesystem

=back

=cut

#-------------------------------------------
sub authform_header{  
    my %in = (
        formname => 'cu',
        kerb_def_dom => 'MSU.EDU',
        @_,
    );
    $in{'formname'} = 'document.' . $in{'formname'};
    my $result='';
    $result.=<<"END";
var current = new Object();
current.radiovalue = 'nochange';
current.argfield = null;

function changed_radio(choice,currentform) {
    var choicearg = choice + 'arg';
    // If a radio button in changed, we need to change the argfield
    if (current.radiovalue != choice) {
        current.radiovalue = choice;
        if (current.argfield != null) {
            currentform.elements[current.argfield].value = '';
        }
        if (choice == 'nochange') {
            current.argfield = null;
        } else {
            current.argfield = choicearg;
            switch(choice) {
                case 'krb': 
                    currentform.elements[current.argfield].value = 
                        "$in{'kerb_def_dom'}";
                break;
              default:
                break;
            }
        }
    }
    return;
}

function changed_text(choice,currentform) {
    var choicearg = choice + 'arg';
    if (currentform.elements[choicearg].value !='') {
        switch (choice) {
            case 'krb': currentform.elements[choicearg].value =
                currentform.elements[choicearg].value.toUpperCase();
                break;
            default:
        }
        // clear old field
        if ((current.argfield != choicearg) && (current.argfield != null)) {
            currentform.elements[current.argfield].value = '';
        }
        current.argfield = choicearg;
    }
    set_auth_radio_buttons(choice,currentform);
    return;
}

function set_auth_radio_buttons(newvalue,currentform) {
    var i=0;
    while (i < currentform.login.length) {
        if (currentform.login[i].value == newvalue) { break; }
        i++;
    }
    if (i == currentform.login.length) {
        return;
    }
    current.radiovalue = newvalue;
    currentform.login[i].checked = true;
    return;
}
END
    return $result;
}

sub authform_authorwarning{
    my $result='';
    $result=<<"END";
<i>As a general rule, only authors or co-authors should be filesystem
authenticated (which allows access to the server filesystem).</i>
END
    return $result;
}

sub authform_nochange{  
    my %in = (
              formname => 'document.cu',
              kerb_def_dom => 'MSU.EDU',
              @_,
          );
    my $result='';
    $result.=<<"END";
<input type="radio" name="login" value="nochange" checked="checked"
       onclick="javascript:changed_radio('nochange',$in{'formname'});">
Do not change login data
END
    return $result;
}

sub authform_kerberos{  
    my %in = (
              formname => 'document.cu',
              kerb_def_dom => 'MSU.EDU',
              @_,
              );
    my $result='';
    $result.=<<"END";
<input type="radio" name="login" value="krb" 
       onclick="javascript:changed_radio('krb',$in{'formname'});"
       onchange="javascript:changed_radio('krb',$in{'formname'});">
Kerberos authenticated with domain
<input type="text" size="10" name="krbarg" value=""
       onchange="javascript:changed_text('krb',$in{'formname'});">
END
    return $result;
}

sub authform_internal{  
    my %args = (
                formname => 'document.cu',
                kerb_def_dom => 'MSU.EDU',
                @_,
                );
    my $result='';
    $result.=<<"END";
<input type="radio" name="login" value="int"
       onchange="javascript:changed_radio('int',$args{'formname'});"
       onclick="javascript:changed_radio('int',$args{'formname'});">
Internally authenticated (with initial password 
<input type="text" size="10" name="intarg" value=""
       onchange="javascript:changed_text('int',$args{'formname'});">
END
    return $result;
}

sub authform_local{  
    my %in = (
              formname => 'document.cu',
              kerb_def_dom => 'MSU.EDU',
              @_,
              );
    my $result='';
    $result.=<<"END";
<input type="radio" name="login" value="loc"
       onchange="javascript:changed_radio('loc',$in{'formname'});"
       onclick="javascript:changed_radio('loc',$in{'formname'});"> 
Local Authentication with argument
<input type="text" size="10" name="locarg" value=""
       onchange="javascript:changed_text('loc',$in{'formname'});">
END
    return $result;
}

sub authform_filesystem{  
    my %in = (
              formname => 'document.cu',
              kerb_def_dom => 'MSU.EDU',
              @_,
              );
    my $result='';
    $result.=<<"END";
<input type="radio" name="login" value="fsys" 
       onchange="javascript:changed_radio('fsys',$in{'formname'});"
       onclick="javascript:changed_radio('fsys',$in{'formname'});"> 
Filesystem authenticated (with initial password 
<input type="text" size="10" name="fsysarg" value=""
       onchange="javascript:changed_text('fsys',$in{'formname'});">
END
    return $result;
}

###############################################################
##   End Authentication changing form generation functions   ##
###############################################################



# ---------------------------------------------------------- Is this a keyword?

sub keyword {
    my $newword=shift;
    $newword=~s/\W//g;
    $newword=~tr/A-Z/a-z/;
    my $tindex=$theindex{$newword};
    if ($tindex) {
        if ($thecount[$tindex]>$theavecount) {
           return 1;
        }
    }
    return 0;
}
# -------------------------------------------------------- Return related words

sub related {
    my $newword=shift;
    $newword=~s/\W//g;
    $newword=~tr/A-Z/a-z/;
    my $tindex=$theindex{$newword};
    if ($tindex) {
        my %found=();
        foreach (split(/\,/,$therelated[$tindex])) {
# - Related word found
            my ($ridx,$rcount)=split(/\:/,$_);
# - Direct relation index
            my $directrel=$rcount/$thecount[$tindex];
            if ($directrel>$thethreshold) {
               foreach (split(/\,/,$therelated[$ridx])) {
                  my ($rridx,$rrcount)=split(/\:/,$_);
                  if ($rridx==$tindex) {
# - Determine reverse relation index
                     my $revrel=$rrcount/$thecount[$ridx];
# - Calculate full index
                     $found{$ridx}=$directrel*$revrel;
                     if ($found{$ridx}>$thethreshold) {
                        foreach (split(/\,/,$therelated[$ridx])) {
                            my ($rrridx,$rrrcount)=split(/\:/,$_);
                            unless ($found{$rrridx}) {
                               my $revrevrel=$rrrcount/$thecount[$ridx];
                               if (
                          $directrel*$revrel*$revrevrel>$thethreshold
                               ) {
                                  $found{$rrridx}=
                                       $directrel*$revrel*$revrevrel;
                               }
                            }
                        }
                     }
                  }
               }
            }
        }
    }
    return ();
}

# ---------------------------------------------------------------- Language IDs
sub languageids {
    return sort(keys(%language));
}

# -------------------------------------------------------- Language Description
sub languagedescription {
    return $language{shift(@_)};
}

# --------------------------------------------------------------- Copyright IDs
sub copyrightids {
    return sort(keys(%cprtag));
}

# ------------------------------------------------------- Copyright Description
sub copyrightdescription {
    return $cprtag{shift(@_)};
}

# ------------------------------------------------------------- File Categories
sub filecategories {
    return sort(keys(%fc));
}

# -------------------------------------- File Types within a specified category
sub filecategorytypes {
    return @{$fc{lc(shift(@_))}};
}

# ------------------------------------------------------------------ File Types
sub fileextensions {
    return sort(keys(%fe));
}

# ------------------------------------------------------------- Embedding Style
sub fileembstyle {
    return $fe{lc(shift(@_))};
}

# ------------------------------------------------------------ Description Text
sub filedescription {
    return $fd{lc(shift(@_))};
}

# ------------------------------------------------------------ Description Text
sub filedescriptionex {
    my $ex=shift;
    return '.'.$ex.' '.$fd{lc($ex)};
}

sub get_previous_attempt {
  my ($symb,$username,$domain,$course)=@_;
  my $prevattempts='';
  if ($symb) {
    my (%returnhash)=
      &Apache::lonnet::restore($symb,$course,$domain,$username);
    if ($returnhash{'version'}) {
      my %lasthash=();
      my $version;
      for ($version=1;$version<=$returnhash{'version'};$version++) {
        foreach (sort(split(/\:/,$returnhash{$version.':keys'}))) {
	  $lasthash{$_}=$returnhash{$version.':'.$_};
        }
      }
      $prevattempts='<table border=2></tr><th>History</th>';
      foreach (sort(keys %lasthash)) {
	my ($ign,@parts) = split(/\./,$_);
	if ($#parts > 0) {
	  my $data=$parts[-1];
	  pop(@parts);
	  $prevattempts.='<th>Part '.join('.',@parts).'<br />'.$data.'</th>';
	} else {
	  if ($#parts == 0) {
	    $prevattempts.='<th>'.$parts[0].'</th>';
	  } else {
	    $prevattempts.='<th>'.$ign.'</th>';
	  }
	}
      }
      for ($version=1;$version<=$returnhash{'version'};$version++) {
        $prevattempts.='</tr><tr><th>Attempt '.$version.'</th>';
        foreach (sort(keys %lasthash)) {
	  my $value;
	  if ($_ =~ /timestamp/) {
	    $value=scalar(localtime($returnhash{$version.':'.$_}));
	  } else {
	    $value=$returnhash{$version.':'.$_};
	  }
	  $prevattempts.='<td>'.$value.'</td>';   
        }
      }
      $prevattempts.='</tr><tr><th>Current</th>';
      foreach (sort(keys %lasthash)) {
	my $value;
	if ($_ =~ /timestamp/) {
	  $value=scalar(localtime($lasthash{$_}));
	} else {
	  $value=$lasthash{$_};
	}
	$prevattempts.='<td>'.$value.'</td>';
      }
      $prevattempts.='</tr></table>';
    } else {
      $prevattempts='Nothing submitted - no attempts.';
    }
  } else {
    $prevattempts='No data.';
  }
}

sub get_student_view {
  my ($symb,$username,$domain,$courseid) = @_;
  my ($map,$id,$feedurl) = split(/___/,$symb);
  my (%old,%moreenv);
  my @elements=('symb','courseid','domain','username');
  foreach my $element (@elements) {
    $old{$element}=$ENV{'form.grade_'.$element};
    $moreenv{'form.grade_'.$element}=eval '$'.$element #'
  }
  &Apache::lonnet::appenv(%moreenv);
  my $userview=&Apache::lonnet::ssi('/res/'.$feedurl);
  &Apache::lonnet::delenv('form.grade_');
  foreach my $element (@elements) {
    $ENV{'form.grade_'.$element}=$old{$element};
  }
  $userview=~s/\<body[^\>]*\>//gi;
  $userview=~s/\<\/body\>//gi;
  $userview=~s/\<html\>//gi;
  $userview=~s/\<\/html\>//gi;
  $userview=~s/\<head\>//gi;
  $userview=~s/\<\/head\>//gi;
  $userview=~s/action\s*\=/would_be_action\=/gi;
  return $userview;
}

sub get_student_answers {
  my ($symb,$username,$domain,$courseid) = @_;
  my ($map,$id,$feedurl) = split(/___/,$symb);
  my (%old,%moreenv);
  my @elements=('symb','courseid','domain','username');
  foreach my $element (@elements) {
    $old{$element}=$ENV{'form.grade_'.$element};
    $moreenv{'form.grade_'.$element}=eval '$'.$element #'
  }
  $moreenv{'form.grade_target'}='answer';
  &Apache::lonnet::appenv(%moreenv);
  my $userview=&Apache::lonnet::ssi('/res/'.$feedurl);
  &Apache::lonnet::delenv('form.grade_');
  foreach my $element (@elements) {
    $ENV{'form.grade_'.$element}=$old{$element};
  }
  return $userview;
}

###############################################

###############################################

sub get_unprocessed_cgi {
  my ($query,$possible_names)= @_;
  # $Apache::lonxml::debug=1;
  foreach (split(/&/,$query)) {
    my ($name, $value) = split(/=/,$_);
    $name = &Apache::lonnet::unescape($name);
    if (!defined($possible_names) || (grep {$_ eq $name} @$possible_names)) {
      $value =~ tr/+/ /;
      $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
      &Apache::lonxml::debug("Seting :$name: to :$value:");
      unless (defined($ENV{'form.'.$name})) { &add_to_env('form.'.$name,$value) };
    }
  }
}

sub cacheheader {
  unless ($ENV{'request.method'} eq 'GET') { return ''; }
  my $date=strftime("%a, %d %b %Y %H:%M:%S GMT",gmtime);
  my $output .='<meta HTTP-EQUIV="Expires" CONTENT="'.$date.'" />
                <meta HTTP-EQUIV="Cache-control" CONTENT="no-cache" />
                <meta HTTP-EQUIV="Pragma" CONTENT="no-cache" />';
  return $output;
}

sub no_cache {
  my ($r) = @_;
  unless ($ENV{'request.method'} eq 'GET') { return ''; }
  #my $date=strftime("%a, %d %b %Y %H:%M:%S GMT",gmtime);
  $r->no_cache(1);
  $r->header_out("Pragma" => "no-cache");
  #$r->header_out("Expires" => $date);
}

sub add_to_env {
  my ($name,$value)=@_;
  if (defined($ENV{$name})) {
    if (ref($ENV{$name})) {
      #already have multiple values
      push(@{ $ENV{$name} },$value);
    } else {
      #first time seeing multiple values, convert hash entry to an arrayref
      my $first=$ENV{$name};
      undef($ENV{$name});
      push(@{ $ENV{$name} },$first,$value);
    }
  } else {
    $ENV{$name}=$value;
  }
}

=pod

=back

=head2 CSV Upload/Handling functions

=over 4

=item  upfile_store($r)

Store uploaded file, $r should be the HTTP Request object,
needs $ENV{'form.upfile'}
returns $datatoken to be put into hidden field

=cut

sub upfile_store {
    my $r=shift;
    $ENV{'form.upfile'}=~s/\r/\n/gs;
    $ENV{'form.upfile'}=~s/\f/\n/gs;
    $ENV{'form.upfile'}=~s/\n+/\n/gs;
    $ENV{'form.upfile'}=~s/\n+$//gs;

    my $datatoken=$ENV{'user.name'}.'_'.$ENV{'user.domain'}.
	'_enroll_'.$ENV{'request.course.id'}.'_'.time.'_'.$$;
    {
	my $fh=Apache::File->new('>'.$r->dir_config('lonDaemons').
				 '/tmp/'.$datatoken.'.tmp');
	print $fh $ENV{'form.upfile'};
    }
    return $datatoken;
}

=item load_tmp_file($r)

Load uploaded file from tmp, $r should be the HTTP Request object,
needs $ENV{'form.datatoken'},
sets $ENV{'form.upfile'} to the contents of the file

=cut

sub load_tmp_file {
    my $r=shift;
    my @studentdata=();
    {
	my $fh;
	if ($fh=Apache::File->new($r->dir_config('lonDaemons').
				  '/tmp/'.$ENV{'form.datatoken'}.'.tmp')) {
	    @studentdata=<$fh>;
	}
    }
    $ENV{'form.upfile'}=join('',@studentdata);
}

=item upfile_record_sep()

Separate uploaded file into records
returns array of records,
needs $ENV{'form.upfile'} and $ENV{'form.upfiletype'}

=cut

sub upfile_record_sep {
    if ($ENV{'form.upfiletype'} eq 'xml') {
    } else {
	return split(/\n/,$ENV{'form.upfile'});
    }
}

=item record_sep($record)

Separate a record into fields $record should be an item from the upfile_record_sep(), needs $ENV{'form.upfiletype'}

=cut

sub record_sep {
    my $record=shift;
    my %components=();
    if ($ENV{'form.upfiletype'} eq 'xml') {
    } elsif ($ENV{'form.upfiletype'} eq 'space') {
        my $i=0;
        foreach (split(/\s+/,$record)) {
            my $field=$_;
            $field=~s/^(\"|\')//;
            $field=~s/(\"|\')$//;
            $components{$i}=$field;
            $i++;
        }
    } elsif ($ENV{'form.upfiletype'} eq 'tab') {
        my $i=0;
        foreach (split(/\t+/,$record)) {
            my $field=$_;
            $field=~s/^(\"|\')//;
            $field=~s/(\"|\')$//;
            $components{$i}=$field;
            $i++;
        }
    } else {
        my @allfields=split(/\,/,$record);
        my $i=0;
        my $j;
        for ($j=0;$j<=$#allfields;$j++) {
            my $field=$allfields[$j];
            if ($field=~/^\s*(\"|\')/) {
		my $delimiter=$1;
                while (($field!~/$delimiter$/) && ($j<$#allfields)) {
		    $j++;
		    $field.=','.$allfields[$j];
		}
                $field=~s/^\s*$delimiter//;
                $field=~s/$delimiter\s*$//;
            }
            $components{$i}=$field;
	    $i++;
        }
    }
    return %components;
}

=item upfile_select_html()

return HTML code to select file and specify its type

=cut

sub upfile_select_html {
    return (<<'ENDUPFORM');
<input type="file" name="upfile" size="50">
<br />Type: <select name="upfiletype">
<option value="csv">CSV (comma separated values, spreadsheet)</option>
<option value="space">Space separated</option>
<option value="tab">Tabulator separated</option>
<option value="xml">HTML/XML</option>
</select>
ENDUPFORM
}

=item csv_print_samples($r,$records)

Prints a table of sample values from each column uploaded $r is an
Apache Request ref, $records is an arrayref from
&Apache::loncommon::upfile_record_sep

=cut

sub csv_print_samples {
    my ($r,$records) = @_;
    my (%sone,%stwo,%sthree);
    %sone=&record_sep($$records[0]);
    if (defined($$records[1])) {%stwo=&record_sep($$records[1]);}
    if (defined($$records[2])) {%sthree=&record_sep($$records[2]);}

    $r->print('Samples<br /><table border="2"><tr>');
    foreach (sort({$a <=> $b} keys(%sone))) { $r->print('<th>Column&nbsp;'.($_+1).'</th>'); }
    $r->print('</tr>');
    foreach my $hash (\%sone,\%stwo,\%sthree) {
	$r->print('<tr>');
	foreach (sort({$a <=> $b} keys(%sone))) {
	    $r->print('<td>');
	    if (defined($$hash{$_})) { $r->print($$hash{$_}); }
	    $r->print('</td>');
	}
	$r->print('</tr>');
    }
    $r->print('</tr></table><br />'."\n");
}

=item csv_print_select_table($r,$records,$d)

Prints a table to create associations between values and table columns.
$r is an Apache Request ref,
$records is an arrayref from &Apache::loncommon::upfile_record_sep,
$d is an array of 2 element arrays (internal name, displayed name)

=cut

sub csv_print_select_table {
    my ($r,$records,$d) = @_;
    my $i=0;my %sone;
    %sone=&record_sep($$records[0]);
    $r->print('Associate columns with student attributes.'."\n".
	     '<table border="2"><tr><th>Attribute</th><th>Column</th></tr>'."\n");
    foreach (@$d) {
	my ($value,$display)=@{ $_ };
	$r->print('<tr><td>'.$display.'</td>');

	$r->print('<td><select name=f'.$i.
		  ' onchange="javascript:flip(this.form,'.$i.');">');
	$r->print('<option value="none"></option>');
	foreach (sort({$a <=> $b} keys(%sone))) {
	    $r->print('<option value="'.$_.'">Column '.($_+1).'</option>');
	}
	$r->print('</select></td></tr>'."\n");
	$i++;
    }
    $i--;
    return $i;
}

=item csv_samples_select_table($r,$records,$d)

Prints a table of sample values from the upload and can make associate samples to internal names.

$r is an Apache Request ref,
$records is an arrayref from &Apache::loncommon::upfile_record_sep,
$d is an array of 2 element arrays (internal name, displayed name)

=cut

sub csv_samples_select_table {
    my ($r,$records,$d) = @_;
    my %sone; my %stwo; my %sthree;
    my $i=0;

    $r->print('<table border=2><tr><th>Field</th><th>Samples</th></tr>');
    %sone=&record_sep($$records[0]);
    if (defined($$records[1])) {%stwo=&record_sep($$records[1]);}
    if (defined($$records[2])) {%sthree=&record_sep($$records[2]);}

    foreach (sort keys %sone) {
	$r->print('<tr><td><select name=f'.$i.
		  ' onchange="javascript:flip(this.form,'.$i.');">');
	foreach (@$d) {
	    my ($value,$display)=@{ $_ };
	    $r->print('<option value='.$value.'>'.$display.'</option>');
	}
	$r->print('</select></td><td>');
	if (defined($sone{$_})) { $r->print($sone{$_}."</br>\n"); }
	if (defined($stwo{$_})) { $r->print($stwo{$_}."</br>\n"); }
	if (defined($sthree{$_})) { $r->print($sthree{$_}."</br>\n"); }
	$r->print('</td></tr>');
	$i++;
    }
    $i--;
    return($i);
}
1;
__END__;

=pod

=back

=head2 Access .tab File Data

=over 4

=item languageids() 

returns list of all language ids

=item languagedescription() 

returns description of a specified language id

=item copyrightids() 

returns list of all copyrights

=item copyrightdescription() 

returns description of a specified copyright id

=item filecategories() 

returns list of all file categories

=item filecategorytypes() 

returns list of file types belonging to a given file
category

=item fileembstyle() 

returns embedding style for a specified file type

=item filedescription() 

returns description for a specified file type

=item filedescriptionex() 

returns description for a specified file type with
extra formatting

=back

=head2 Alternate Problem Views

=over 4

=item get_previous_attempt() 

return string with previous attempt on problem

=item get_student_view() 

show a snapshot of what student was looking at

=item get_student_answers() 

show a snapshot of how student was answering problem

=back

=head2 HTTP Helper

=over 4

=item get_unprocessed_cgi($query,$possible_names)

Modify the %ENV hash to contain unprocessed CGI form parameters held in
$query.  The parameters listed in $possible_names (an array reference),
will be set in $ENV{'form.name'} if they do not already exist.

Typically called with $ENV{'QUERY_STRING'} as the first parameter.  
$possible_names is an ref to an array of form element names.  As an example:
get_unprocessed_cgi($ENV{'QUERY_STRING'},['uname','udom']);
will result in $ENV{'form.uname'} and $ENV{'form.udom'} being set.

=item cacheheader() 

returns cache-controlling header code

=item nocache() 

specifies header code to not have cache

=item add_to_env($name,$value) 

adds $name to the %ENV hash with value
$value, if $name already exists, the entry is converted to an array
reference and $value is added to the array.

=back

=cut