# The LearningOnline Network with CAPA
# a pile of common routines
#
# $Id: loncommon.pm,v 1.133 2003/10/23 21:01:54 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
# 12/21 Gerd Kortemeyer
# 12/25,12/28 Gerd Kortemeyer
# YEAR=2002
# 1/4 Gerd Kortemeyer
# 6/24,7/2 H. K. Ng

# 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:

=pod

=head1 NAME

Apache::loncommon - pile of common routines

=head1 SYNOPSIS

Common routines for manipulating connections, student answers,
    domains, common Javascript fragments, etc.

=head1 OVERVIEW

A collection of commonly used subroutines that don't have a natural
home anywhere else. This collection helps remove
redundancy from other modules and increase efficiency of memory usage.

=cut 

# End of POD header
package Apache::loncommon;

use strict;
use Apache::lonnet();
use GDBM_File;
use POSIX qw(strftime mktime);
use Apache::Constants qw(:common :http :methods);
use Apache::lonmsg();
use Apache::lonmenu();
use Apache::lonlocal;

my $readit;

=pod 

=head1 Global Variables

=cut

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

# ---------------------------------------------- Designs

my %designhash;

# ---------------------------------------------- Thesaurus variables

# FIXME: I don't think it's necessary to document these things;
# they're privately used - Jeremy

=pod

=over 4

=item * %Keywords  

A hash used by &keyword to determine if a word is considered a keyword.

=item * $thesaurus_db_file

Scalar containing the full path to the thesaurus database.                 

=back

=cut

my %Keywords;
my $thesaurus_db_file;

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

# FIXME: I don't think this needs to be documented, it prepares
# private data structures - Jeremy
=pod

=head1 General Subroutines

=over 4

=item * BEGIN() 

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

=back

=cut

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

BEGIN {
    # Variable initialization
    $thesaurus_db_file = $Apache::lonnet::perlvar{'lonTabDir'}."/thesaurus.db";
    #
    unless ($readit) {
# ------------------------------------------------------------------- languages
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
				 '/language.tab');
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($key,$two,$country,$three,$enc,$val,$sup)=(split(/\t/,$_));
		$language{$key}=$val.' - '.$enc;
		if ($sup) {
		    $supported_language{$key}=$sup;
		}
	    }
	}
    }
# ------------------------------------------------------------------ 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;
	    }
	}
    }

# -------------------------------------------------------------- domain designs

    my $filename;
    my $designdir=$Apache::lonnet::perlvar{'lonTabDir'}.'/lonDomColors';
    opendir(DIR,$designdir);
    while ($filename=readdir(DIR)) {
	my ($domain)=($filename=~/^(\w+)\./);
    {
	my $fh=Apache::File->new($designdir.'/'.$filename);
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($key,$val)=(split(/\=/,$_));
		if ($val) { $designhash{$domain.'.'.$key}=$val; }
	    }
	}
    }

    }
    closedir(DIR);


# ------------------------------------------------------------- file categories
    {
	my $fh=Apache::File->new($Apache::lonnet::perlvar{'lonTabDir'}.
				  '/filecategories.tab');
	if ($fh) {
	    while (<$fh>) {
		next if /^\#/;
		chomp;
		my ($extension,$category)=(split(/\s+/,$_,2));
		push @{$category_extensions{lc($category)}},$extension;
	    }
	}
    }
# ------------------------------------------------------------------ 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;
		}
	    }
	}
    }
    &Apache::lonnet::logthis(
              "<font color=yellow>INFO: Read file types</font>");
    $readit=1;
    }  # end of unless($readit) 
    
}

###############################################################
##           HTML and Javascript Helper Functions            ##
###############################################################

=pod 

=head1 HTML and Javascript Functions

=over 4

=item * browser_and_searcher_javascript ()

X<browsing, javascript>X<searching, javascript>Returns a string
containing javascript with two functions, C<openbrowser> and
C<opensearcher>. Returned string does not contain E<lt>scriptE<gt>
tags.

=over 4

=item * openbrowser(formname,elementname,only,omit) [javascript]

inputs: formname, elementname, only, omit

formname and elementname indicate the name of the html form and name of
the element that the results of the browsing selection are to be placed in. 

Specifying 'only' will restrict the browser to displaying only files
with the given extension.  Can be a comma seperated list.

Specifying 'omit' will restrict the browser to NOT displaying files
with the given extension.  Can be a comma seperated list.

=item * opensearcher(formname, elementname) [javascript]

Inputs: formname, elementname

formname and elementname specify the name of the html form and the name
of the element the selection from the search results will be placed in.

=back

=cut

sub browser_and_searcher_javascript {
    return <<END;
    var editbrowser = null;
    function openbrowser(formname,elementname,only,omit) {
        var url = '/res/?';
        if (editbrowser == null) {
            url += 'launch=1&';
        }
        url += 'catalogmode=interactive&';
        url += 'mode=edit&';
        url += 'form=' + formname + '&';
        if (only != null) {
            url += 'only=' + only + '&';
        } 
        if (omit != null) {
            url += 'omit=' + omit + '&';
        }
        url += 'element=' + elementname + '';
        var title = 'Browser';
        var options = 'scrollbars=1,resizable=1,menubar=0';
        options += ',width=700,height=600';
        editbrowser = open(url,title,options,'1');
        editbrowser.focus();
    }
    var editsearcher;
    function opensearcher(formname,elementname) {
        var url = '/adm/searchcat?';
        if (editsearcher == null) {
            url += 'launch=1&';
        }
        url += 'catalogmode=interactive&';
        url += 'mode=edit&';
        url += 'form=' + formname + '&';
        url += 'element=' + elementname + '';
        var title = 'Search';
        var options = 'scrollbars=1,resizable=1,menubar=0';
        options += ',width=700,height=600';
        editsearcher = open(url,title,options,'1');
        editsearcher.focus();
    }
END
}

sub studentbrowser_javascript {
   unless (
            (($ENV{'request.course.id'}) && 
             (&Apache::lonnet::allowed('srm',$ENV{'request.course.id'})))
         || ($ENV{'request.role'}=~/^(au|dc|su)/)
          ) { return ''; }  
   return (<<'ENDSTDBRW');
<script type="text/javascript" language="Javascript" >
    var stdeditbrowser;
    function openstdbrowser(formname,uname,udom,roleflag) {
        var url = '/adm/pickstudent?';
        var filter;
        eval('filter=document.'+formname+'.'+uname+'.value;');
        if (filter != null) {
           if (filter != '') {
               url += 'filter='+filter+'&';
	   }
        }
        url += 'form=' + formname + '&unameelement='+uname+
                                    '&udomelement='+udom;
	if (roleflag) { url+="&roles=1"; }
        var title = 'Student_Browser';
        var options = 'scrollbars=1,resizable=1,menubar=0';
        options += ',width=700,height=600';
        stdeditbrowser = open(url,title,options,'1');
        stdeditbrowser.focus();
    }
</script>
ENDSTDBRW
}

sub selectstudent_link {
   my ($form,$unameele,$udomele)=@_;
   if ($ENV{'request.course.id'}) {  
       unless (&Apache::lonnet::allowed('srm',$ENV{'request.course.id'})) {
	   return '';
       }
       return "<a href='".'javascript:openstdbrowser("'.$form.'","'.$unameele.
        '","'.$udomele.'");'."'>".&mt('Select User')."</a>";
   }
   if ($ENV{'request.role'}=~/^(au|dc|su)/) {
       return "<a href='".'javascript:openstdbrowser("'.$form.'","'.$unameele.
        '","'.$udomele.'",1);'."'>".&mt('Select User')."</a>";
   }
   return '';
}

sub coursebrowser_javascript {
    my ($domainfilter)=@_;
   return (<<ENDSTDBRW);
<script type="text/javascript" language="Javascript" >
    var stdeditbrowser;
    function opencrsbrowser(formname,uname,udom) {
        var url = '/adm/pickcourse?';
        var filter;
        if (filter != null) {
           if (filter != '') {
               url += 'filter='+filter+'&';
	   }
        }
        var domainfilter='$domainfilter';
        if (domainfilter != null) {
           if (domainfilter != '') {
               url += 'domainfilter='+domainfilter+'&';
	   }
        }
        url += 'form=' + formname + '&cnumelement='+uname+
                                    '&cdomelement='+udom;
        var title = 'Course_Browser';
        var options = 'scrollbars=1,resizable=1,menubar=0';
        options += ',width=700,height=600';
        stdeditbrowser = open(url,title,options,'1');
        stdeditbrowser.focus();
    }
</script>
ENDSTDBRW
}

sub selectcourse_link {
   my ($form,$unameele,$udomele)=@_;
    return "<a href='".'javascript:opencrsbrowser("'.$form.'","'.$unameele.
        '","'.$udomele.'");'."'>".&mt('Select Course')."</a>";
}

=pod

=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.

=back 

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 value 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"
                           }
                   }
               );

=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);
        $result.=">".&mt($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);
        $result.=">".&mt($select2{$value})."</option>\n";
    }
    $result .= "</select>\n";
    #    return $debug;
    return $result;
}   #  end of sub linked_select_forms {

=pod

=item * help_open_topic($topic, $text, $stayOnPage, $width, $height)

Returns a string corresponding to an HTML link to the given help
$topic, where $topic corresponds to the name of a .tex file in
/home/httpd/html/adm/help/tex, with underscores replaced by
spaces. 

$text will optionally be linked to the same topic, allowing you to
link text in addition to the graphic. If you do not want to link
text, but wish to specify one of the later parameters, pass an
empty string. 

$stayOnPage is a value that will be interpreted as a boolean. If true,
the link will not open a new window. If false, the link will open
a new window using Javascript. (Default is false.) 

$width and $height are optional numerical parameters that will
override the width and height of the popped up window, which may
be useful for certain help topics with big pictures included. 

=cut

sub help_open_topic {
    my ($topic, $text, $stayOnPage, $width, $height) = @_;
    $text = "" if (not defined $text);
    $stayOnPage = 0 if (not defined $stayOnPage);
    if ($ENV{'browser.interface'} eq 'textual' ||
	$ENV{'environment.remote'} eq 'off' ) {
	$stayOnPage=1;
    }
    $width = 350 if (not defined $width);
    $height = 400 if (not defined $height);
    my $filename = $topic;
    $filename =~ s/ /_/g;

    my $template = "";
    my $link;

    if (!$stayOnPage)
    {
	$link = "javascript:void(open('/adm/help/${filename}.hlp', 'Help_for_$topic', 'menubar=0,toolbar=1,scrollbars=1,width=$width,height=$height,resizable=yes'))";
    }
    else
    {
	$link = "/adm/help/${filename}.hlp";
    }

    # Add the text
    if ($text ne "")
    {
	$template .= 
  "<table bgcolor='#3333AA' cellspacing='1' cellpadding='1' border='0'><tr>".
  "<td bgcolor='#5555FF'><a href=\"$link\"><font color='#FFFFFF' size='2'>$text</font></a>";
    }

    # Add the graphic
    $template .= <<"ENDTEMPLATE";
 <a href="$link"><image src="/adm/help/gif/smallHelp.gif" border="0" alt="(Help: $topic)" /></a>
ENDTEMPLATE
    if ($text ne '') { $template.='</td></tr></table>' };
    return $template;

}

# This is a quicky function for Latex cheatsheet editing, since it 
# appears in at least four places
sub helpLatexCheatsheet {
    my $other = shift;
    my $addOther = '';
    if ($other) {
	$addOther = Apache::loncommon::help_open_topic($other, shift,
						       undef, undef, 600) .
							   '</td><td>';
    }
    return '<table><tr><td>'.
	$addOther .
	&Apache::loncommon::help_open_topic("Greek_Symbols",'Greek Symbols',
					    undef,undef,600)
	.'</td><td>'.
	&Apache::loncommon::help_open_topic("Other_Symbols",'Other Symbols',
					    undef,undef,600)
	.'</td></tr></table>';
}

=pod

=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;
}

=pod

=item * change_content_javascript():

This and the next function allow you to create small sections of an
otherwise static HTML page that you can update on the fly with
Javascript, even in Netscape 4.

The Javascript fragment returned by this function (no E<lt>scriptE<gt> tag)
must be written to the HTML page once. It will prove the Javascript
function "change(name, content)". Calling the change function with the
name of the section 
you want to update, matching the name passed to C<changable_area>, and
the new content you want to put in there, will put the content into
that area.

B<Note>: Netscape 4 only reserves enough space for the changable area
to contain room for the original contents. You need to "make space"
for whatever changes you wish to make, and be B<sure> to check your
code in Netscape 4. This feature in Netscape 4 is B<not> powerful;
it's adequate for updating a one-line status display, but little more.
This script will set the space to 100% width, so you only need to
worry about height in Netscape 4.

Modern browsers are much less limiting, and if you can commit to the
user not using Netscape 4, this feature may be used freely with
pretty much any HTML.

=cut

sub change_content_javascript {
    # If we're on Netscape 4, we need to use Layer-based code
    if ($ENV{'browser.type'} eq 'netscape' &&
	$ENV{'browser.version'} =~ /^4\./) {
	return (<<NETSCAPE4);
	function change(name, content) {
	    doc = document.layers[name+"___escape"].layers[0].document;
	    doc.open();
	    doc.write(content);
	    doc.close();
	}
NETSCAPE4
    } else {
	# Otherwise, we need to use semi-standards-compliant code
	# (technically, "innerHTML" isn't standard but the equivalent
	# is really scary, and every useful browser supports it
	return (<<DOMBASED);
	function change(name, content) {
	    element = document.getElementById(name);
	    element.innerHTML = content;
	}
DOMBASED
    }
}

=pod

=item * changable_area($name, $origContent):

This provides a "changable area" that can be modified on the fly via
the Javascript code provided in C<change_content_javascript>. $name is
the name you will use to reference the area later; do not repeat the
same name on a given HTML page more then once. $origContent is what
the area will originally contain, which can be left blank.

=cut

sub changable_area {
    my ($name, $origContent) = @_;

    if ($ENV{'browser.type'} eq 'netscape' &&
	$ENV{'browser.version'} =~ /^4\./) {
	# If this is netscape 4, we need to use the Layer tag
	return "<ilayer width='100%' id='${name}___escape' overflow='none'><layer width='100%' id='$name' overflow='none'>$origContent</layer></ilayer>";
    } else {
	return "<span id='$name'>$origContent</span>";
    }
}

=pod

=back

=cut

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

=pod

=head1 Home Server option list generating code

=over 4

=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;
}

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

=pod

=item * select_form($defdom,$name,%hash)

Returns a string containing a <select name='$name' size='1'> form to 
allow a user to select options from a hash option_name => displayed text.  
See lonrights.pm for an example invocation and use.

=cut

#-------------------------------------------
sub select_form {
    my ($def,$name,%hash) = @_;
    my $selectform = "<select name=\"$name\" size=\"1\">\n";
    my @keys;
    if (exists($hash{'select_form_order'})) {
	@keys=@{$hash{'select_form_order'}};
    } else {
	@keys=sort(keys(%hash));
    }
    foreach (@keys) {
        $selectform.="<option value=\"$_\" ".
            ($_ eq $def ? 'selected' : '').
                ">".&mt($hash{$_})."</option>\n";
    }
    $selectform.="</select>";
    return $selectform;
}


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

=pod

=item * select_dom_form($defdom,$name,$includeempty)

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.

If the $includeempty flag is set, it also includes an empty choice ("no domain
selected");

=cut

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

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

=pod

=item * get_library_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_library_servers {
    my $domain = shift;
    my %library_servers;
    foreach (keys(%Apache::lonnet::libserv)) {
        if ($Apache::lonnet::hostdom{$_} eq $domain) {
            $library_servers{$_} = $Apache::lonnet::hostname{$_};
        }
    }
    return %library_servers;
}

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

=pod

=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 $domain = shift;
    my %servers = &get_library_servers($domain);
    my $result = '';
    foreach (sort keys(%servers)) {
        $result.=
            '<option value="'.$_.'">'.$_.' '.$servers{$_}."</option>\n";
    }
    return $result;
}

=pod

=back

=cut

###############################################################
##                  Decoding User Agent                      ##
###############################################################

=pod

=head1 Decoding the User Agent

=over 4

=item * &decode_user_agent()

Inputs: $r

Outputs:

=over 4

=item * $httpbrowser

=item * $clientbrowser

=item * $clientversion

=item * $clientmathml

=item * $clientunicode

=item * $clientos

=back

=cut

###############################################################
###############################################################
sub decode_user_agent {
    my @browsertype=split(/\&/,$Apache::lonnet::perlvar{"lonBrowsDet"});
    my %mathcap=split(/\&/,$$Apache::lonnet::perlvar{"lonMathML"});
    my $httpbrowser=$ENV{"HTTP_USER_AGENT"};
    my $clientbrowser='unknown';
    my $clientversion='0';
    my $clientmathml='';
    my $clientunicode='0';
    for (my $i=0;$i<=$#browsertype;$i++) {
        my ($bname,$match,$notmatch,$vreg,$minv,$univ)=split(/\:/,$browsertype[$i]);
	if (($httpbrowser=~/$match/i)  && ($httpbrowser!~/$notmatch/i)) {
	    $clientbrowser=$bname;
            $httpbrowser=~/$vreg/i;
	    $clientversion=$1;
            $clientmathml=($clientversion>=$minv);
            $clientunicode=($clientversion>=$univ);
	}
    }
    my $clientos='unknown';
    if (($httpbrowser=~/linux/i) ||
        ($httpbrowser=~/unix/i) ||
        ($httpbrowser=~/ux/i) ||
        ($httpbrowser=~/solaris/i)) { $clientos='unix'; }
    if (($httpbrowser=~/vax/i) ||
        ($httpbrowser=~/vms/i)) { $clientos='vms'; }
    if ($httpbrowser=~/next/i) { $clientos='next'; }
    if (($httpbrowser=~/mac/i) ||
        ($httpbrowser=~/powerpc/i)) { $clientos='mac'; }
    if ($httpbrowser=~/win/i) { $clientos='win'; }
    if ($httpbrowser=~/embed/i) { $clientos='pda'; }
    return ($httpbrowser,$clientbrowser,$clientversion,$clientmathml,
            $clientunicode,$clientos,);
}

=pod

=back

=cut

###############################################################
##    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.
#-------------------------------------------

=pod

=head1 Authentication Routines

=over 4

=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 => '',
        @_,
    );
    $in{'formname'} = 'document.' . $in{'formname'};
    my $result='';

#---------------------------------------------- Code for upper case translation
    my $Javascript_toUpperCase;
    unless ($in{kerb_def_dom}) {
        $Javascript_toUpperCase =<<"END";
        switch (choice) {
           case 'krb': currentform.elements[choicearg].value =
               currentform.elements[choicearg].value.toUpperCase();
               break;
           default:
        }
END
    } else {
        $Javascript_toUpperCase = "";
    }

    $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 !='') {
        $Javascript_toUpperCase
        // 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',
              kerb_def_auth => 'krb4',
              @_,
              );
    my $result='';
    my $check4;
    my $check5;
    if ($in{'kerb_def_auth'} eq 'krb5') {
       $check5 = " checked=\"on\"";
    } else {
       $check4 = " checked=\"on\"";
    }
    $result.=<<"END";
<input type="radio" name="login" value="krb" 
       onclick="javascript:changed_radio('krb',$in{'formname'});"
       onchange="javascript:changed_radio('krb',$in{'formname'});" />
Kerberos authenticated with domain
<input type="text" size="10" name="krbarg" value="$in{'kerb_def_dom'}"
       onchange="javascript:changed_text('krb',$in{'formname'});" />
<input type="radio" name="krbver" value="4" $check4 />Version 4
<input type="radio" name="krbver" value="5" $check5 />Version 5
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;
}

=pod

=back

=cut

###############################################################
##    Get Authentication Defaults for Domain                 ##
###############################################################

=pod

=head1 Domains and Authentication

Returns default authentication type and an associated argument as
listed in file 'domain.tab'.

=over 4

=item * get_auth_defaults

get_auth_defaults($target_domain) returns the default authentication
type and an associated argument (initial password or a kerberos domain).
These values are stored in lonTabs/domain.tab

($def_auth, $def_arg) = &get_auth_defaults($target_domain);

If target_domain is not found in domain.tab, returns nothing ('').

=cut

#-------------------------------------------
sub get_auth_defaults {
    my $domain=shift;
    return ($Apache::lonnet::domain_auth_def{$domain},$Apache::lonnet::domain_auth_arg_def{$domain});
}
###############################################################
##   End Get Authentication Defaults for Domain              ##
###############################################################

###############################################################
##    Get Kerberos Defaults for Domain                 ##
###############################################################
##
## Returns default kerberos version and an associated argument
## as listed in file domain.tab. If not listed, provides
## appropriate default domain and kerberos version.
##
#-------------------------------------------

=pod

=item * get_kerberos_defaults

get_kerberos_defaults($target_domain) returns the default kerberos
version and domain. If not found in domain.tabs, it defaults to
version 4 and the domain of the server.

($def_version, $def_krb_domain) = &get_kerberos_defaults($target_domain);

=cut

#-------------------------------------------
sub get_kerberos_defaults {
    my $domain=shift;
    my ($krbdef,$krbdefdom) =
        &Apache::loncommon::get_auth_defaults($domain);
    unless ($krbdef =~/^krb/ && $krbdefdom) {
        $ENV{'SERVER_NAME'}=~/(\w+\.\w+)$/;
        my $krbdefdom=$1;
        $krbdefdom=~tr/a-z/A-Z/;
        $krbdef = "krb4";
    }
    return ($krbdef,$krbdefdom);
}

=pod

=back

=cut

###############################################################
##                Thesaurus Functions                        ##
###############################################################

=pod

=head1 Thesaurus Functions

=over 4

=item * initialize_keywords

Initializes the package variable %Keywords if it is empty.  Uses the
package variable $thesaurus_db_file.

=cut

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

sub initialize_keywords {
    return 1 if (scalar keys(%Keywords));
    # If we are here, %Keywords is empty, so fill it up
    #   Make sure the file we need exists...
    if (! -e $thesaurus_db_file) {
        &Apache::lonnet::logthis("Attempt to access $thesaurus_db_file".
                                 " failed because it does not exist");
        return 0;
    }
    #   Set up the hash as a database
    my %thesaurus_db;
    if (! tie(%thesaurus_db,'GDBM_File',
              $thesaurus_db_file,&GDBM_READER(),0640)){
        &Apache::lonnet::logthis("Could not tie \%thesaurus_db to ".
                                 $thesaurus_db_file);
        return 0;
    } 
    #  Get the average number of appearances of a word.
    my $avecount = $thesaurus_db{'average.count'};
    #  Put keywords (those that appear > average) into %Keywords
    while (my ($word,$data)=each (%thesaurus_db)) {
        my ($count,undef) = split /:/,$data;
        $Keywords{$word}++ if ($count > $avecount);
    }
    untie %thesaurus_db;
    # Remove special values from %Keywords.
    foreach ('total.count','average.count') {
        delete($Keywords{$_}) if (exists($Keywords{$_}));
    }
    return 1;
}

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

=pod

=item * keyword($word)

Returns true if $word is a keyword.  A keyword is a word that appears more 
than the average number of times in the thesaurus database.  Calls 
&initialize_keywords

=cut

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

sub keyword {
    return if (!&initialize_keywords());
    my $word=lc(shift());
    $word=~s/\W//g;
    return exists($Keywords{$word});
}

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

=pod 

=item * get_related_words

Look up a word in the thesaurus.  Takes a scalar arguement and returns
an array of words.  If the keyword is not in the thesaurus, an empty array
will be returned.  The order of the words returned is determined by the
database which holds them.

Uses global $thesaurus_db_file.

=cut

###############################################################
sub get_related_words {
    my $keyword = shift;
    my %thesaurus_db;
    if (! -e $thesaurus_db_file) {
        &Apache::lonnet::logthis("Attempt to access $thesaurus_db_file ".
                                 "failed because the file does not exist");
        return ();
    }
    if (! tie(%thesaurus_db,'GDBM_File',
              $thesaurus_db_file,&GDBM_READER(),0640)){
        return ();
    } 
    my @Words=();
    if (exists($thesaurus_db{$keyword})) {
        $_ = $thesaurus_db{$keyword};
        (undef,@Words) = split/:/;  # The first element is the number of times
                                    # the word appears.  We do not need it now.
        for (my $i=0;$i<=$#Words;$i++) {
            ($Words[$i],undef)= split/\,/,$Words[$i];
        }
    }
    untie %thesaurus_db;
    return @Words;
}

=pod

=back

=cut

# -------------------------------------------------------------- Plaintext name
=pod

=head1 User Name Functions

=over 4

=item * plainname($uname,$udom)

Takes a users logon name and returns it as a string in
"first middle last generation" form

=cut

###############################################################
sub plainname {
    my ($uname,$udom)=@_;
    my %names=&Apache::lonnet::get('environment',
                    ['firstname','middlename','lastname','generation'],
					 $udom,$uname);
    my $name=$names{'firstname'}.' '.$names{'middlename'}.' '.
	$names{'lastname'}.' '.$names{'generation'};
    $name=~s/\s+$//;
    $name=~s/\s+/ /g;
    return $name;
}

# -------------------------------------------------------------------- Nickname
=pod

=item * nickname($uname,$udom)

Gets a users name and returns it as a string as

"&quot;nickname&quot;"

if the user has a nickname or

"first middle last generation"

if the user does not

=cut

sub nickname {
    my ($uname,$udom)=@_;
    my %names=&Apache::lonnet::get('environment',
  ['nickname','firstname','middlename','lastname','generation'],$udom,$uname);
    my $name=$names{'nickname'};
    if ($name) {
       $name='&quot;'.$name.'&quot;'; 
    } else {
       $name=$names{'firstname'}.' '.$names{'middlename'}.' '.
	     $names{'lastname'}.' '.$names{'generation'};
       $name=~s/\s+$//;
       $name=~s/\s+/ /g;
    }
    return $name;
}


# ------------------------------------------------------------------ Screenname

=pod

=item * screenname($uname,$udom)

Gets a users screenname and returns it as a string

=cut

sub screenname {
    my ($uname,$udom)=@_;
    my %names=
 &Apache::lonnet::get('environment',['screenname'],$udom,$uname);
    return $names{'screenname'};
}

# ------------------------------------------------------------- Message Wrapper

sub messagewrapper {
    my ($link,$un,$do)=@_;
    return 
"<a href='/adm/email?compose=individual&recname=$un&recdom=$do'>$link</a>";
}
# --------------------------------------------------------------- Notes Wrapper

sub noteswrapper {
    my ($link,$un,$do)=@_;
    return 
"<a href='/adm/email?recordftf=retrieve&recname=$un&recdom=$do'>$link</a>";
}
# ------------------------------------------------------------- Aboutme Wrapper

sub aboutmewrapper {
    my ($link,$username,$domain)=@_;
    return "<a href='/adm/$domain/$username/aboutme'>$link</a>";
}

# ------------------------------------------------------------ Syllabus Wrapper


sub syllabuswrapper {
    my ($linktext,$coursedir,$domain,$fontcolor)=@_;
    if ($fontcolor) { 
        $linktext='<font color="'.$fontcolor.'">'.$linktext.'</font>'; 
    }
    return "<a href='/public/$domain/$coursedir/syllabus'>$linktext</a>";
}

=pod

=back

=head1 Access .tab File Data

=over 4

=item * languageids() 

returns list of all language ids

=cut

sub languageids {
    return sort(keys(%language));
}

=pod

=item * languagedescription() 

returns description of a specified language id

=cut

sub languagedescription {
    my $code=shift;
    return  ($supported_language{$code}?'* ':'').
            $language{$code}.
	    ($supported_language{$code}?' ('.&mt('interface available').')':'');
}

=pod

=item * copyrightids() 

returns list of all copyrights

=cut

sub copyrightids {
    return sort(keys(%cprtag));
}

=pod

=item * copyrightdescription() 

returns description of a specified copyright id

=cut

sub copyrightdescription {
    return $cprtag{shift(@_)};
}

=pod

=item * filecategories() 

returns list of all file categories

=cut

sub filecategories {
    return sort(keys(%category_extensions));
}

=pod

=item * filecategorytypes() 

returns list of file types belonging to a given file
category

=cut

sub filecategorytypes {
    return @{$category_extensions{lc($_[0])}};
}

=pod

=item * fileembstyle() 

returns embedding style for a specified file type

=cut

sub fileembstyle {
    return $fe{lc(shift(@_))};
}

=pod

=item * filedescription() 

returns description for a specified file type

=cut

sub filedescription {
    return $fd{lc(shift(@_))};
}

=pod

=item * filedescriptionex() 

returns description for a specified file type with
extra formatting

=cut

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

# End of .tab access
=pod

=back

=cut

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

# ----------------------------------------------------------- Display Languages
# returns a hash with all desired display languages
#

sub display_languages {
    my %languages=();
    foreach (&preferred_languages()) {
	$languages{$_}=1;
    }
    &get_unprocessed_cgi($ENV{'QUERY_STRING'},['displaylanguage']);
    if ($ENV{'form.displaylanguage'}) {
	foreach (split(/\s*(\,|\;|\:)\s*/,$ENV{'form.displaylanguage'})) {
	    $languages{$_}=1;
        }
    }
    return %languages;
}

sub preferred_languages {
    my @languages=();
    if ($ENV{'environment.languages'}) {
	@languages=split(/\s*(\,|\;|\:)\s*/,$ENV{'environment.languages'});
    }
    if ($ENV{'course.'.$ENV{'request.course.id'}.'.languages'}) {
	@languages=(@languages,split(/\s*(\,|\;|\:)\s*/,
	         $ENV{'course.'.$ENV{'request.course.id'}.'.languages'}));
    }
    my $browser=(split(/\;/,$ENV{'HTTP_ACCEPT_LANGUAGE'}))[0];
    if ($browser) {
	@languages=(@languages,split(/\s*(\,|\;|\:)\s*/,$browser));
    }
    if ($Apache::lonnet::domain_lang_def{$ENV{'user.domain'}}) {
	@languages=(@languages,
		$Apache::lonnet::domain_lang_def{$ENV{'user.domain'}});
    }
    if ($Apache::lonnet::domain_lang_def{$ENV{'request.role.domain'}}) {
	@languages=(@languages,
		$Apache::lonnet::domain_lang_def{$ENV{'request.role.domain'}});
    }
    if ($Apache::lonnet::domain_lang_def{
	                          $Apache::lonnet::perlvar{'lonDefDomain'}}) {
	@languages=(@languages,
		$Apache::lonnet::domain_lang_def{
                                  $Apache::lonnet::perlvar{'lonDefDomain'}});
    }
# turn "en-ca" into "en-ca,en"
    my @genlanguages;
    foreach (@languages) {
	unless ($_=~/\w/) { next; }
	push (@genlanguages,$_);
	if ($_=~/(\-|\_)/) {
	    push (@genlanguages,(split(/(\-|\_)/,$_))[0]);
	}
    }
    return @genlanguages;
}

###############################################################
##               Student Answer Attempts                     ##
###############################################################

=pod

=head1 Alternate Problem Views

=over 4

=item * get_previous_attempt($symb, $username, $domain, $course,
    $getattempt, $regexp, $gradesub)

Return string with previous attempt on problem. Arguments:

=over 4

=item * $symb: Problem, including path

=item * $username: username of the desired student

=item * $domain: domain of the desired student

=item * $course: Course ID

=item * $getattempt: Leave blank for all attempts, otherwise put
    something

=item * $regexp: if string matches this regexp, the string will be
    sent to $gradesub

=item * $gradesub: routine that processes the string if it matches $regexp

=back

The output string is a table containing all desired attempts, if any.

=cut

sub get_previous_attempt {
  my ($symb,$username,$domain,$course,$getattempt,$regexp,$gradesub)=@_;
  my $prevattempts='';
  no strict 'refs';
  if ($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="0" width="100%"><tr><td bgcolor="#777777">';
      $prevattempts.='<table border="0" width="100%"><tr bgcolor="#e6ffff"><td>History</td>';
      foreach (sort(keys %lasthash)) {
	my ($ign,@parts) = split(/\./,$_);
	if ($#parts > 0) {
	  my $data=$parts[-1];
	  pop(@parts);
	  $prevattempts.='<td>Part '.join('.',@parts).'<br />'.$data.'&nbsp;</td>';
	} else {
	  if ($#parts == 0) {
	    $prevattempts.='<th>'.$parts[0].'</th>';
	  } else {
	    $prevattempts.='<th>'.$ign.'</th>';
	  }
	}
      }
      if ($getattempt eq '') {
	for ($version=1;$version<=$returnhash{'version'};$version++) {
	  $prevattempts.='</tr><tr bgcolor="#ffffe6"><td>Transaction '.$version.'</td>';
	    foreach (sort(keys %lasthash)) {
	       my $value;
	       if ($_ =~ /timestamp/) {
		  $value=scalar(localtime($returnhash{$version.':'.$_}));
	       } else {
		  $value=$returnhash{$version.':'.$_};
	       }
	       $prevattempts.='<td>'.$value.'&nbsp;</td>';   
	    }
	 }
      }
      $prevattempts.='</tr><tr bgcolor="#ffffe6"><td>Current</td>';
      foreach (sort(keys %lasthash)) {
	my $value;
	if ($_ =~ /timestamp/) {
	  $value=scalar(localtime($lasthash{$_}));
	} else {
	  $value=$lasthash{$_};
	}
	if ($_ =~/$regexp$/ && (defined &$gradesub)) {$value = &$gradesub($value)}
	$prevattempts.='<td>'.$value.'&nbsp;</td>';
      }
      $prevattempts.='</tr></table></td></tr></table>';
    } else {
      $prevattempts='Nothing submitted - no attempts.';
    }
  } else {
    $prevattempts='No data.';
  }
}

sub relative_to_absolute {
    my ($url,$output)=@_;
    my $parser=HTML::TokeParser->new(\$output);
    my $token;
    my $thisdir=$url;
    my @rlinks=();
    while ($token=$parser->get_token) {
	if ($token->[0] eq 'S') {
	    if ($token->[1] eq 'a') {
		if ($token->[2]->{'href'}) {
		    $rlinks[$#rlinks+1]=$token->[2]->{'href'};
		}
	    } elsif ($token->[1] eq 'img' || $token->[1] eq 'embed' ) {
		$rlinks[$#rlinks+1]=$token->[2]->{'src'};
	    } elsif ($token->[1] eq 'base') {
		$thisdir=$token->[2]->{'href'};
	    }
	}
    }
    $thisdir=~s-/[^/]*$--;
    foreach (@rlinks) {
	unless (($_=~/^http:\/\//i) ||
		($_=~/^\//) ||
		($_=~/^javascript:/i) ||
		($_=~/^mailto:/i) ||
		($_=~/^\#/)) {
	    my $newlocation=&Apache::lonnet::hreflocation($thisdir,$_);
	    $output=~s/(\"|\'|\=\s*)$_(\"|\'|\s|\>)/$1$newlocation$2/;
	}
    }
# -------------------------------------------------- Deal with Applet codebases
    $output=~s/(\<applet[^\>]+)(codebase\=[^\S\>]+)*([^\>]*)\>/$1.($2?$2:' codebase="'.$thisdir.'"').$3.'>'/gei;
    return $output;
}

=pod

=item * get_student_view

show a snapshot of what student was looking at

=cut

sub get_student_view {
  my ($symb,$username,$domain,$courseid,$target) = @_;
  my ($map,$id,$feedurl) = &Apache::lonnet::decode_symb($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 #'
  }
  if ($target eq 'tex') {$moreenv{'form.grade_target'} = 'tex';}
  &Apache::lonnet::appenv(%moreenv);
  $feedurl=&Apache::lonnet::clutter($feedurl);
  my $userview=&Apache::lonnet::ssi_body($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;
  $userview=&relative_to_absolute($feedurl,$userview);
  return $userview;
}

=pod

=item * get_student_answers() 

show a snapshot of how student was answering problem

=cut

sub get_student_answers {
  my ($symb,$username,$domain,$courseid,%form) = @_;
  my ($map,$id,$feedurl) = &Apache::lonnet::decode_symb($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,%form);
  &Apache::lonnet::delenv('form.grade_');
  foreach my $element (@elements) {
    $ENV{'form.grade_'.$element}=$old{$element};
  }
  return $userview;
}

=pod

=item * &submlink()

Inputs: $text $uname $udom $symb

Returns: A link to grades.pm such as to see the SUBM view of a student

=cut

###############################################
sub submlink {
    my ($text,$uname,$udom,$symb)=@_;
    if (!($uname && $udom)) {
	(my $cursymb, my $courseid,$udom,$uname)=
	    &Apache::lonxml::whichuser($symb);
	if (!$symb) { $symb=$cursymb; }
    }
    if (!$symb) { $symb=&symbread(); }
    return '<a href="/adm/grades?symb='.$symb.'&student='.$uname.
	'&userdom='.$udom.'&command=submission">'.$text.'</a>';
}
##############################################

=pod

=back

=cut

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


sub timehash {
    my @ltime=localtime(shift);
    return ( 'seconds' => $ltime[0],
             'minutes' => $ltime[1],
             'hours'   => $ltime[2],
             'day'     => $ltime[3],
             'month'   => $ltime[4]+1,
             'year'    => $ltime[5]+1900,
             'weekday' => $ltime[6],
             'dayyear' => $ltime[7]+1,
             'dlsav'   => $ltime[8] );
}

sub maketime {
    my %th=@_;
    return POSIX::mktime(
        ($th{'seconds'},$th{'minutes'},$th{'hours'},
         $th{'day'},$th{'month'}-1,$th{'year'}-1900,0,0,$th{'dlsav'}));
}


#########################################
#
# Retro-fixing of un-backward-compatible time format

sub unsqltime {
    my $timestamp=shift;
    if ($timestamp=~/^(\d+)\-(\d+)\-(\d+)\s+(\d+)\:(\d+)\:(\d+)$/) {
       $timestamp=&maketime(
	   'year'=>$1,'month'=>$2,'day'=>$3,
           'hours'=>$4,'minutes'=>$5,'seconds'=>$6);
    }
    return $timestamp;
}

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

sub findallcourses {
    my %courses=();
    my $now=time;
    foreach (keys %ENV) {
	if ($_=~/^user\.role\.\w+\.\/(\w+)\/(\w+)/) {
	    my ($starttime,$endtime)=$ENV{$_};
            my $active=1;
            if ($starttime) {
		if ($now<$starttime) { $active=0; }
            }
            if ($endtime) {
                if ($now>$endtime) { $active=0; }
            }
            if ($active) { $courses{$1.'_'.$2}=1; }
        }
    }
    return keys %courses;
}

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

=pod

=head1 Domain Template Functions

=over 4

=item * &determinedomain()

Inputs: $domain (usually will be undef)

Returns: Determines which domain should be used for designs

=cut

###############################################
sub determinedomain {
    my $domain=shift;
   if (! $domain) {
        # Determine domain if we have not been given one
        $domain = $Apache::lonnet::perlvar{'lonDefDomain'};
        if ($ENV{'user.domain'}) { $domain=$ENV{'user.domain'}; }
        if ($ENV{'request.role.domain'}) { 
            $domain=$ENV{'request.role.domain'}; 
        }
    }
    return $domain;
}
###############################################
=pod

=item * &domainlogo()

Inputs: $domain (usually will be undef)

Returns: A link to a domain logo, if the domain logo exists.
If the domain logo does not exist, a description of the domain.

=cut

###############################################
sub domainlogo {
    my $domain = &determinedomain(shift);    
     # See if there is a logo
    if (-e '/home/httpd/html/adm/lonDomLogos/'.$domain.'.gif') {
	my $lonhttpdPort=$Apache::lonnet::perlvar{'lonhttpdPort'};
	if (!defined($lonhttpdPort)) { $lonhttpdPort='8080'; }
        return '<img src="http://'.$ENV{'HTTP_HOST'}.':'.$lonhttpdPort.
	    '/adm/lonDomLogos/'.$domain.'.gif" />';
    } elsif(exists($Apache::lonnet::domaindescription{$domain})) {
        return $Apache::lonnet::domaindescription{$domain};
    } else {
        return '';
    }
}
##############################################

=pod

=item * &designparm()

Inputs: $which parameter; $domain (usually will be undef)

Returns: value of designparamter $which

=cut

##############################################
sub designparm {
    my ($which,$domain)=@_;
    if ($ENV{'browser.blackwhite'} eq 'on') {
	if ($which=~/\.(font|alink|vlink|link)$/) {
	    return '#000000';
	}
	if ($which=~/\.(pgbg|sidebg)$/) {
	    return '#FFFFFF';
	}
	if ($which=~/\.tabbg$/) {
	    return '#CCCCCC';
	}
    }
    if ($ENV{'environment.color.'.$which}) {
	return $ENV{'environment.color.'.$which};
    }
    $domain=&determinedomain($domain);
    if ($designhash{$domain.'.'.$which}) {
	return $designhash{$domain.'.'.$which};
    } else {
        return $designhash{'default.'.$which};
    }
}

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

=pod

=back

=head1 HTTP Helpers

=over 4

=item * &bodytag()

Returns a uniform header for LON-CAPA web pages.

Inputs: 

=over 4

=item * $title, A title to be displayed on the page.

=item * $function, the current role (can be undef).

=item * $addentries, extra parameters for the <body> tag.

=item * $bodyonly, if defined, only return the <body> tag.

=item * $domain, if defined, force a given domain.

=item * $forcereg, if page should register as content page (relevant for 
            text interface only)

=back

Returns: A uniform header for LON-CAPA web pages.  
If $bodyonly is nonzero, a string containing a <body> tag will be returned.
If $bodyonly is undef or zero, an html string containing a <body> tag and 
other decorations will be returned.

=cut

sub bodytag {
    my ($title,$function,$addentries,$bodyonly,$domain,$forcereg)=@_;
    $title=&mt($title);
    unless ($function) {
	$function='student';
        if ($ENV{'request.role'}=~/^(cc|in|ta|ep)/) {
	    $function='coordinator';
        }
	if ($ENV{'request.role'}=~/^(su|dc|ad|li)/) {
            $function='admin';
        }
        if (($ENV{'request.role'}=~/^(au|ca)/) ||
            ($ENV{'REQUEST_URI'}=~/^(\/priv|\~)/)) {
            $function='author';
        }
    }
    my $img=&designparm($function.'.img',$domain);
    my $pgbg=&designparm($function.'.pgbg',$domain);
    my $tabbg=&designparm($function.'.tabbg',$domain);
    my $font=&designparm($function.'.font',$domain);
    my $link=&designparm($function.'.link',$domain);
    my $alink=&designparm($function.'.alink',$domain);
    my $vlink=&designparm($function.'.vlink',$domain);
    my $sidebg=&designparm($function.'.sidebg',$domain);
# Accessibility font enhance
    unless ($addentries) { $addentries=''; }
    if ($ENV{'browser.fontenhance'} eq 'on') {
	$addentries.=' style="font-size: x-large"';
    }
 # role and realm
    my ($role,$realm)
       =&Apache::lonnet::plaintext((split(/\./,$ENV{'request.role'}))[0]);
# realm
    if ($ENV{'request.course.id'}) {
	$realm=
         $ENV{'course.'.$ENV{'request.course.id'}.'.description'};
    }
    unless ($realm) { $realm='&nbsp;'; }
# Set messages
    my $messages=&domainlogo($domain);
# Port for miniserver
    my $lonhttpdPort=$Apache::lonnet::perlvar{'lonhttpdPort'};
    if (!defined($lonhttpdPort)) { $lonhttpdPort='8080'; }
# construct main body tag
    my $bodytag = <<END;
<body bgcolor="$pgbg" text="$font" alink="$alink" vlink="$vlink" link="$link"
$addentries>
END
    my $upperleft='<img src="http://'.$ENV{'HTTP_HOST'}.':'.
                   $lonhttpdPort.$img.'" />';
    if ($bodyonly) {
        return $bodytag;
    } elsif ($ENV{'browser.interface'} eq 'textual') {
# Accessibility
        return $bodytag.&Apache::lonmenu::menubuttons($forcereg,'web',
                                                      $forcereg).
               '<h1>LON-CAPA: '.$title.'</h1>';
    } elsif ($ENV{'environment.remote'} eq 'off') {
# No Remote
        return $bodytag.&Apache::lonmenu::menubuttons($forcereg,'web',
                                                      $forcereg).
               '<table bgcolor="'.$pgbg.'" width="100%" border="0" cellspacing="3" cellpadding="3"><tr><td bgcolor="'.$tabbg.'"><font size="+3" color="'.$font.'"><b>'.$title.
'</b></font></td></tr></table>';
    }

#
# Top frame rendering, Remote is up
#
    return(<<ENDBODY);
$bodytag
<table width="100%" cellspacing="0" border="0" cellpadding="0">
<tr><td bgcolor="$sidebg">
$upperleft</td>
<td bgcolor="$sidebg" align="right">$messages&nbsp;</td>
</tr>
<tr>
<td rowspan="3" bgcolor="$tabbg">
&nbsp;<font size="5"><b>$title</b></font>
<td bgcolor="$tabbg"  align="right">
<font size="2">
    $ENV{'environment.firstname'}
    $ENV{'environment.middlename'}
    $ENV{'environment.lastname'}
    $ENV{'environment.generation'}
    </font>&nbsp;
</td>
</tr>
<tr><td bgcolor="$tabbg" align="right">
<font size="2">$role</font>&nbsp;
</td></tr>
<tr>
<td bgcolor="$tabbg" align="right"><font size="2">$realm</font>&nbsp;</td></tr>
</table><br>
ENDBODY
}

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

sub get_posted_cgi {
    my $r=shift;

    my $buffer;
    
    $r->read($buffer,$r->header_in('Content-length'),0);
    unless ($buffer=~/^(\-+\w+)\s+Content\-Disposition\:\s*form\-data/si) {
	my @pairs=split(/&/,$buffer);
	my $pair;
	foreach $pair (@pairs) {
	    my ($name,$value) = split(/=/,$pair);
	    $value =~ tr/+/ /;
	    $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
	    $name  =~ tr/+/ /;
	    $name  =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
	    &add_to_env("form.$name",$value);
	}
    } else {
	my $contentsep=$1;
	my @lines = split (/\n/,$buffer);
	my $name='';
	my $value='';
	my $fname='';
	my $fmime='';
	my $i;
	for ($i=0;$i<=$#lines;$i++) {
	    if ($lines[$i]=~/^$contentsep/) {
		if ($name) {
		    chomp($value);
		    if ($fname) {
			$ENV{"form.$name.filename"}=$fname;
			$ENV{"form.$name.mimetype"}=$fmime;
		    } else {
			$value=~s/\s+$//s;
		    }
		    &add_to_env("form.$name",$value);
		}
		if ($i<$#lines) {
		    $i++;
		    $lines[$i]=~
		/Content\-Disposition\:\s*form\-data\;\s*name\=\"([^\"]+)\"/i;
		    $name=$1;
		    $value='';
		    if ($lines[$i]=~/filename\=\"([^\"]+)\"/i) {
			$fname=$1;
			if 
                            ($lines[$i+1]=~/Content\-Type\:\s*([\w\-\/]+)/i) {
				$fmime=$1;
				$i++;
			    } else {
				$fmime='';
			    }
		    } else {
			$fname='';
			$fmime='';
		    }
		    $i++;
		}
	    } else {
		$value.=$lines[$i]."\n";
	    }
	}
    }
    $ENV{'request.method'}=$ENV{'REQUEST_METHOD'};
    $r->method_number(M_GET);
    $r->method('GET');
    $r->headers_in->unset('Content-length');
}

=pod

=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.

=cut

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) };
    }
  }
}

=pod

=item * cacheheader() 

returns cache-controlling header code

=cut

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;
}

=pod

=item * no_cache($r) 

specifies header code to not have cache

=cut

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 content_type {
  my ($r,$type,$charset) = @_;
  unless ($charset) {
      $charset=&Apache::lonlocal::current_encoding;
  }
  $r->content_type($type.($charset?'; charset='.$charset:''));
}

=pod

=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.

=cut

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 

=head1 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;
}

=pod

=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);
}

=pod

=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'});
    }
}

=pod

=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;
}

=pod

=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
}

=pod

=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");
}

=pod

=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;
}

=pod

=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);
}

=pod

=item clean_excel_name($name)

Returns a replacement for $name which does not contain any illegal characters.

=cut

sub clean_excel_name {
    my ($name) = @_;
    $name =~ s/[:\*\?\/\\]//g;
    if (length($name) > 31) {
        $name = substr($name,0,31);
    }
    return $name;
}

=pod

=item * check_if_partid_hidden($id,$symb,$udom,$uname)

Returns either 1 or undef

1 if the part is to be hidden, undef if it is to be shown

Arguments are:

$id the id of the part to be checked
$symb, optional the symb of the resource to check
$udom, optional the domain of the user to check for
$uname, optional the username of the user to check for

=cut

sub check_if_partid_hidden {
    my ($id,$symb,$udom,$uname) = @_;
    my $hiddenparts=&Apache::lonnet::EXT('resource.0.hiddenparts',
					 $symb,$udom,$uname);
    my @hiddenlist=split(/,/,$hiddenparts);
    foreach my $checkid (@hiddenlist) {
	if ($checkid =~ /^\s*\Q$id\E\s*$/) { return 1; }
    }
    return undef;
}

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

=pod

=item DrawGraph

Returns a link to cgi-bin/graph

=cut

############################################################
############################################################
sub DrawGraph {
    my ($Title,$xlabel,$ylabel,$Max,$colors,@Values)=@_;
    #
    my $identifier = time.'_'.int(rand(1000));
    if (! @Values || ref($Values[0]) ne 'ARRAY') {
        return '';
    }
    my $NumBars = scalar(@{$Values[0]});
    my %ValuesHash;
    my $NumSets=1;
    foreach my $array (@Values) {
        next if (! ref($array));
        $ValuesHash{'cgi.'.$identifier.'.data.'.$NumSets++} = 
            join(',',@$array);
    }
    #
    $Title  = '' if (! defined($Title));
    $xlabel = '' if (! defined($xlabel));
    $ylabel = '' if (! defined($ylabel));
    $Title  = &Apache::lonnet::escape($Title);
    $xlabel = &Apache::lonnet::escape($xlabel);
    $ylabel = &Apache::lonnet::escape($ylabel);
    #
    $Max = 1 if ($Max < 1);
    if ( int($Max) < $Max ) {
        $Max++;
        $Max = int($Max);
    }
    #
    &Apache::lonnet::appenv('cgi.'.$identifier.'.title'   => $Title,
                            'cgi.'.$identifier.'.xlabel'  => $xlabel,
                            'cgi.'.$identifier.'.ylabel'  => $ylabel,
                            'cgi.'.$identifier.'.Max'     => $Max,
                            'cgi.'.$identifier.'.NumBars' => $NumBars,
                            'cgi.'.$identifier.'.NumSets' => $NumSets,
                            'cgi.'.$identifier.'.Colors'  => join(',',@{$colors}),
                            %ValuesHash);
    return '<img src="/cgi-bin/graph.png?'.$identifier.'" border="1" />';
}

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

=pod

=back

=cut

1;
__END__;