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File:  [LON-CAPA] / loncom / auth / lonroles.pm
Revision 1.84: download - view: text, annotated - select for diffs
Thu Jan 29 00:44:06 2004 UTC (20 years, 9 months ago) by www
Branches: MAIN
CVS tags: HEAD
If there is only one choice, immediately select it. Also, better message
for users who currently have no roles.

# The LearningOnline Network with CAPA
# User Roles Screen
#
# $Id: lonroles.pm,v 1.84 2004/01/29 00:44:06 www 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/
#
# (Directory Indexer
# (Login Screen
# YEAR=1999
# 5/21/99,5/22,5/25,5/26,5/31,6/2,6/10,7/12,7/14 Gerd Kortemeyer)
# 11/23 Gerd Kortemeyer)
# YEAR=2000
# 1/14,03/06,06/01,07/22,07/24,07/25,
# 09/04,09/06,09/28,09/29,09/30,10/2,10/5,10/26,10/28,
# 12/08,12/28,
# YEAR=2001
# 01/15/01 Gerd Kortemeyer
# 03/02,05/03,05/25,05/30,06/01,07/06,08/06 Gerd Kortemeyer
# 12/29 Gerd Kortemeyer
#
###

package Apache::lonroles;

use strict;
use Apache::lonnet();
use Apache::lonuserstate();
use Apache::Constants qw(:common);
use Apache::File();
use Apache::lonmenu;
use Apache::loncommon;
use Apache::lonannounce;
use Apache::lonlocal;

sub redirect_user {
    my ($r,$title,$url,$msg) = @_;
    $msg = $title if (! defined($msg));
    &Apache::loncommon::content_type($r,'text/html');
    &Apache::loncommon::no_cache($r);
    $r->send_http_header;
    my $swinfo=&Apache::lonmenu::rawconfig();
    my $bodytag=&Apache::loncommon::bodytag('Switching Role');
    $r->print (<<ENDREDIR);
<head><title>$title</title>
<meta HTTP-EQUIV="Refresh" CONTENT="1; url=$url">
</head>
<html>
$bodytag
<script>
$swinfo
</script>
<h1>$msg</h1>
</body>
</html>
ENDREDIR
    return;
}

sub handler {

    my $r = shift;

    my $now=time;
    my $then=$ENV{'user.login.time'};
    my $envkey;


# ================================================================== Roles Init

    if ($ENV{'form.selectrole'}) {
	if ($ENV{'request.course.id'}) {
	    my %temp=('logout_'.$ENV{'request.course.id'} => time);
	    &Apache::lonnet::put('email_status',\%temp);
        }
	&Apache::lonnet::appenv("request.course.id"   => '',
				"request.course.fn"   => '',
				"request.course.uri"  => '',
				"request.course.sec"  => '',
				"request.role"        => 'cm',
                                "request.role.adv"    => $ENV{'user.adv'},
				"request.role.domain" => $ENV{'user.domain'});
        foreach $envkey (keys %ENV) {
            next if ($envkey!~/^user\.role\./);
	    my (undef,undef,$role,@pwhere)=split(/\./,$envkey);
            my $where=join('.',@pwhere);
            my $trolecode=$role.'.'.$where;
            if ($ENV{'form.'.$trolecode}) {
		my ($tstart,$tend)=split(/\./,$ENV{$envkey});
		my $tstatus='is';
		if ($tstart) {
		    if ($tstart>$then) { 
			$tstatus='future';
		    }
		}
		if ($tend) {
		    if ($tend<$then) { $tstatus='expired'; }
		    if ($tend<$now) { $tstatus='will_not'; }
		}
		if ($tstatus eq 'is') {
		    $where=~s/^\///;
		    my ($cdom,$cnum,$csec)=split(/\//,$where);
# check for keyed access
		    if (($role eq 'st') && 
                       ($ENV{'course.'.$cdom.'_'.$cnum.'.keyaccess'} eq 'yes')) {
		         unless (&Apache::lonnet::validate_access_key(
				     $ENV{'environment.key.'.$cdom.'_'.$cnum},
					     $cdom,$cnum)) {
# there is no valid key
			     if ($ENV{'form.newkey'}) {
# student attempts to register a new key
			     } else {
# print form to enter a new key
				 &Apache::loncommon::content_type($r,'text/html');
				 &Apache::loncommon::no_cache($r);
				 $r->send_http_header;
				 my $swinfo=&Apache::lonmenu::rawconfig();
				 my $bodytag=&Apache::loncommon::bodytag
				    ('Enter Access Key to Unlock this Course');
				 $r->print(<<ENDENTERKEY);
<head><title>Entering Course Access Key</title>
</head>
<html>
$bodytag
<script>
$swinfo
</script>
<form method="post">
<input type="hidden" name="selectrole" value="$ENV{'form.selectrole'}" />
<input type="text" size="20" name="newkey" value="$ENV{'form.newkey'}" />
<input type="submit" value="Enter key" />
</form>
</body></html>
ENDENTERKEY
				 return OK;
			     }
			 }
		     }
                    my $tadv=0;
                    if (($trolecode!~/^st/) && 
                        ($trolecode!~/^ta/) && 
                        ($trolecode!~/^cm/)) { $tadv=1; }
		    &Apache::lonnet::appenv(
                                           'request.role'        => $trolecode,
					   'request.role.adv'    => $tadv,
					   'request.role.domain' => $cdom,
					   'request.course.sec'  => $csec);
		    my $msg=&mt('Entering course ...');

		    if (($cnum) && ($role ne 'ca')) {
			my ($furl,$ferr)=
			    &Apache::lonuserstate::readmap($cdom.'/'.$cnum);
			if (($ENV{'form.orgurl'}) && 
			    ($ENV{'form.orgurl'}!~/^\/adm\/flip/)) {
			    my $dest=$ENV{'form.orgurl'};
			    if ( &Apache::lonnet::mod_perl_version() == 2 ) {
				&Apache::lonnet::cleanenv();
			    }
			    $r->internal_redirect($dest);
			    return OK;
			} else {
			    unless ($ENV{'request.course.id'}) {
				&Apache::lonnet::appenv(
				      "request.course.id"  => $cdom.'_'.$cnum);
				$furl='/adm/roles?tryagain=1';
				$msg=
				    '<h1><font color=red>'.
			 &mt('Could not initialize course at this time.').
		    '</font></h1><h3>'.&mt('Please try again.').'</h3>'.$ferr;
			    }

			    # Check to see if the user is a CC entering a course 
			    # for the first time
			    my (undef, undef, $role, $courseid) = split(/\./, $envkey);
			    if (substr($courseid, 0, 1) eq '/') {
				$courseid = substr($courseid, 1);
			    }
			    $courseid =~ s/\//_/;
			    if ($role eq 'cc' && $ENV{'course.' . $courseid . 
							  '.course.helper.not.run'}) {
				$furl = "/adm/helper/course.initialization.helper";
			    }
                            #
                            # Send the user to the course they selected
                            &redirect_user($r,&mt('Entering Course'),
                                           $furl,$msg);
                            return OK;
			}
		    }
                    #
                    # Send the user to the construction space they selected
                    if ($role =~ /^(au|ca)$/) {
                        my $redirect_url = '/priv/';
                        if ($role eq 'au') {
                            $redirect_url.=$ENV{'user.name'};
                        } else {
                            $where =~ /\/(.*)$/;
                            $redirect_url .= $1;
                        }
                        $redirect_url .= '/';
                        &redirect_user($r,&mt('Entering Construction Space'),
                                       $redirect_url);
                        return OK;
                    }
		}
            }
        }
    }


# =============================================================== No Roles Init

    &Apache::loncommon::content_type($r,'text/html');
    &Apache::loncommon::no_cache($r);
    $r->send_http_header;
    return OK if $r->header_only;

    my $swinfo=&Apache::lonmenu::rawconfig();
    my $bodytag=&Apache::loncommon::bodytag('User Roles');
    my $helptag='<table><tr><td>'.&Apache::loncommon::help_open_topic
     ("General_Intro",&mt("Click here for help")).'</td><td>'.
      &Apache::loncommon::help_open_faq(1,&mt('Click here for FAQ')).'</td><td>'.
      &Apache::loncommon::help_open_bug('',&mt('Click here to report bugs')).'</td></tr></table>';
    $r->print(<<ENDHEADER);
<html>
<head>
<title>LON-CAPA User Roles</title>
</head>
$bodytag
$helptag<br />
<script>
$swinfo
window.focus();
</script>
ENDHEADER

# ------------------------------------------ Get Error Message from Environment

    my ($fn,$priv,$nochoose,$error,$msg)=split(/:/,$ENV{'user.error.msg'});
    if ($ENV{'user.error.msg'}) {
	$r->log_reason(
   "$msg for $ENV{'user.name'} domain $ENV{'user.domain'} access $priv",$fn);
    }

# ------------------------------------------------- Can this user re-init, etc?

    my $advanced=$ENV{'user.adv'};
    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},['tryagain']);
    my $tryagain=$ENV{'form.tryagain'};

# -------------------------------------------------------- Generate Page Output
# --------------------------------------------------------------- Error Header?
    if ($error) {
	$r->print("<h1>LON-CAPA Access Control</h1>");
        $r->print("<hr><pre>Access  : ".
                  Apache::lonnet::plaintext($priv)."\n");
        $r->print("Resource: $fn\n");
        $r->print("Action  : $msg\n</pre><hr>");
    } else {
        if ($ENV{'user.error.msg'}) {
	    $r->print(
 '<h3><font color=red>'.
 &mt('You need to choose another user role or enter a specific course for this function').'</font></h3>');
	}
    }
# -------------------------------------------------------- Choice or no choice?
    if ($nochoose) {
        if ($advanced) {
	    $r->print("<h2>".&mt('Assigned User Roles')."</h2>\n");
        } else {
	    $r->print("<h2>".&mt('Sorry ...')."</h2>\n".
		      &mt('This resource might be part of'));
	    if ($ENV{'request.course.id'}) {
		$r->print(&mt(' another'));
	    } else {
		$r->print(&mt(' a certain'));
	    } 
	    $r->print(&mt(' course.').'</body></html>');
	    return OK;
        } 
    } else {
        if ($advanced) {
	    $r->print(&mt("Your home server is ").
		      $Apache::lonnet::hostname{&Apache::lonnet::homeserver
                      ($ENV{'user.name'},$ENV{'user.domain'})}.
		      "<br />\n");
	    $r->print(&mt(
      "Author and Co-Author roles may not be available on servers other than your home server."));
        }
        if (($ENV{'REDIRECT_QUERY_STRING'}) && ($fn)) {
    	    $fn.='?'.$ENV{'REDIRECT_QUERY_STRING'};
        }
        $r->print('<form method="post" name="rolechoice" action="'.(($fn)?$fn:$r->uri).'">');
        $r->print('<input type=hidden name=orgurl value="'.$fn.'">');
        $r->print('<input type=hidden name=selectrole value=1>');
    }
    if ($ENV{'user.adv'}) {
	$r->print(
	      '<br />'.&mt('Show all roles').': <input type="checkbox" name="showall"');
	if ($ENV{'form.showall'}) { $r->print(' checked'); }
	$r->print('><input type=submit value="'.&mt('Display').'">');
    }

    my (%roletext,%sortrole,%roleclass);
    my $countactive=0;
    my $inrole=0;
    my $possiblerole='';
    foreach $envkey (sort keys %ENV) {
        my $button = 1;
        my $switchserver='';
	my $roletext;
	my $sortkey;
        if ($envkey=~/^user\.role\./) {
	    my (undef,undef,$role,@pwhere)=split(/\./,$envkey);
            next if (!defined($role) || $role eq '');
            my $where=join('.',@pwhere);
            my $trolecode=$role.'.'.$where;
            my ($tstart,$tend)=split(/\./,$ENV{$envkey});
            my $tremark='';
            my $tstatus='is';
            my $tpstart='&nbsp;';
            my $tpend='&nbsp;';
            my $tfont='#000000';
            if ($tstart) {
		if ($tstart>$then) { 
                    $tstatus='future';
                    if ($tstart<$now) { $tstatus='will'; }
                }
                $tpstart=&Apache::lonlocal::locallocaltime($tstart);
            }
            if ($tend) {
                if ($tend<$then) { 
                    $tstatus='expired'; 
                } elsif ($tend<$now) { 
                    $tstatus='will_not'; 
                }
                $tpend=&Apache::lonlocal::locallocaltime($tend);
            }
            if ($ENV{'request.role'} eq $trolecode) {
		$tstatus='selected';
            }
            my $tbg;
            if (($tstatus eq 'is') || ($tstatus eq 'selected') ||
                ($ENV{'form.showall'})) {
                if ($tstatus eq 'is') {
                    $tbg='#77FF77';
                    $tfont='#003300';
		    $possiblerole=$trolecode;
		    $countactive++;
                } elsif ($tstatus eq 'future') {
                    $tbg='#FFFF77';
                    $button=0;
                } elsif ($tstatus eq 'will') {
                    $tbg='#FFAA77';
                    $tremark.=&mt('Active at next login. ');
                } elsif ($tstatus eq 'expired') {
                    $tbg='#FF7777';
                    $tfont='#330000';
                    $button=0;
                } elsif ($tstatus eq 'will_not') {
                    $tbg='#AAFF77';
                    $tremark.=&mt('Expired after logout. ');
                } elsif ($tstatus eq 'selected') {
                    $tbg='#11CC55';
                    $tfont='#002200';
		    $inrole=1;
                    $tremark.=&mt('Currently selected. ');
                }
                my $trole;
                if ($role =~ /^cr\//) {
                    my ($rdummy,$rdomain,$rauthor,$rrole)=split(/\//,$role);
                    $tremark.='<br>'.&mt('Defined by ').$rauthor.
			&mt(' at ').$rdomain.'.';
                    $trole=$rrole;
                } else {
                    $trole=Apache::lonnet::plaintext($role);
                }
                my $ttype;
                my $twhere;
                my ($tdom,$trest,$tsection)=
                    split(/\//,Apache::lonnet::declutter($where));
                # First, Co-Authorship roles
                if ($role eq 'ca') {
                    my $home = &Apache::lonnet::homeserver($trest,$tdom);
		    my $allowed=0;
		    my @ids=&Apache::lonnet::current_machine_ids();
		    foreach my $id (@ids) { if ($id eq $home) { $allowed=1; } }
                    if (!$allowed) {
			$button=0;
                        $switchserver=&Apache::lonnet::escape('http://'.
                         $Apache::lonnet::hostname{$home}.
                         '/adm/login?domain='.$ENV{'user.domain'}.
			  '&username='.$ENV{'user.name'}.
                          '&firsturl=/priv/'.$trest);
                    }
                    #next if ($home eq 'no_host');
                    $home = $Apache::lonnet::hostname{$home};
                    $ttype='Construction Space';
                    $twhere=&mt('User').': '.$trest.'<br />'.&mt('Domain').
			': '.$tdom.'<br />'.
                        ' '.&mt('Server').':&nbsp;'.$home;
                    $ENV{'course.'.$tdom.'_'.$trest.'.description'}='ca';
		    $tremark.=&Apache::lonhtmlcommon::authorbombs('/res/'.$tdom.'/'.$trest.'/');
		    $sortkey=$role."$trest:$tdom";
                } elsif ($role eq 'au') {
                    # Authors
                    my $home = &Apache::lonnet::homeserver
                        ($ENV{'user.name'},$ENV{'user.domain'});
		    my $allowed=0;
		    my @ids=&Apache::lonnet::current_machine_ids();
		    foreach my $id (@ids) { if ($id eq $home) { $allowed=1; } }
                    if (!$allowed) {
			$button=0;
                        $switchserver=&Apache::lonnet::escape('http://'.
                         $Apache::lonnet::hostname{$home}.
                          '/adm/login?domain='.$ENV{'user.domain'}.
			   '&username='.$ENV{'user.name'}.
                           '&firsturl=/priv/'.$ENV{'user.name'});
                    }
                    #next if ($home eq 'no_host');
                    $home = $Apache::lonnet::hostname{$home};
                    $ttype='Construction Space';
                    $twhere=&mt('Domain').': '.$tdom.'<br />'.&mt('Server').
			':&nbsp;'.$home;
                    $ENV{'course.'.$tdom.'_'.$trest.'.description'}='ca';
		    $tremark.=&Apache::lonhtmlcommon::authorbombs('/res/'.$tdom.'/'.$ENV{'user.name'}.'/');
		    $sortkey=$role;
                } elsif ($trest) {
                    $ttype='Course';
                    if ($tsection) {
                        $ttype.='<br>'.&mt('Section/Group').': '.$tsection;
		    }
                    my $tcourseid=$tdom.'_'.$trest;
                    if ($ENV{'course.'.$tcourseid.'.description'}) {
                        $twhere=$ENV{'course.'.$tcourseid.'.description'};
			$sortkey=$role."\0".$tdom."\0".$twhere."\0".$envkey;
                        unless ($twhere eq &mt('Currently not available')) {
			    $twhere.=' <font size="-2">'.
        &Apache::loncommon::syllabuswrapper(&mt('Syllabus'),$trest,$tdom,$tfont).
                                    '</font>';
			}
                    } else {
                        my %newhash=Apache::lonnet::coursedescription
                            ($tcourseid);
                        if (%newhash) {
			    $sortkey=$role."\0".$tdom."\0".$newhash{'description'}.
				"\0".$envkey;
                            $twhere=$newhash{'description'}.
                              ' <font size="-2">'.
        &Apache::loncommon::syllabuswrapper(&mt('Syllabus'),$trest,$tdom,$tfont).
                              '</font>';
                        } else {
                            $twhere=&mt('Currently not available');
                            $ENV{'course.'.$tcourseid.'.description'}=$twhere;
			    $sortkey=$role."\0".$tdom."\0".$twhere."\0".$envkey;
                        }
                    }
		    if ($role ne 'st') { $twhere.="<br />".&mt('Domain').":".$tdom; }
                } elsif ($tdom) {
                    $ttype='Domain';
                    $twhere=$tdom;
		    $sortkey=$role.$twhere;
                } else {
                    $ttype='System';
                    $twhere=&mt('system wide');
		    $sortkey=$role.$twhere;
                }
 
                $roletext.='<tr bgcolor='.$tbg.'>';
                unless ($nochoose) {
                    if (!$button) {
			if ($switchserver) {
			    $roletext.='<td><a href="/adm/logout?handover='.
                              $switchserver.'">'.&mt('Switch Server').'</a></td>';
                        } else {
                            $roletext.=('<td>&nbsp;</td>');
                        }
                    } elsif ($tstatus eq 'is') {
                        $roletext.=('<td><input type=submit value="'.
				  &mt('Select').'" name="'.
                                  $trolecode.'"></td>');
                    } elsif ($tryagain) {
                        $roletext.=
			    '<td><input type=submit value="'.
		  &mt('Try Selecting Again').'" name="'.$trolecode.'"></td>';
                    } elsif ($advanced) {
                        $roletext.=
                            '<td><input type=submit value="'.
		        &mt('Re-Initialize').'" name="'.$trolecode.'"></td>';
                    } else {
                        $roletext.='<td>&nbsp;</td>';
                    }
                }
                $tremark.=&Apache::lonannounce::showday(time,1,
                         &Apache::lonannounce::readcalendar($tdom.'_'.$trest));
                
		$roletext.='<td><font color="'.$tfont.'">'.$trole.
                      '</font></td><td><font color="'.$tfont.'">'.$ttype.
                      '</font></td><td><font color="'.$tfont.'">'.$twhere.
                      '</font></td><td><font color="'.$tfont.'">'.$tpstart.
                      '</font></td><td><font color="'.$tfont.'">'.$tpend.
                      '</font></td><td><font color="'.$tfont.'">'.$tremark.
                      '&nbsp;</font></td></tr>'."\n";
		$roletext{$envkey}=$roletext;
		if (!$sortkey) {$sortkey=$twhere."\0".$envkey;}
		$sortrole{$sortkey}=$envkey;
		$roleclass{$envkey}=$ttype;
	    }
        }
    }
# No active roles
    if ($countactive==0) {
	if ($inrole) {
	    $r->print('<h2>'.&mt('Currently no additional roles or courses').'</h2>');
	} else {
	    $r->print('<h2>'.&mt('Currently no active roles or courses').'</h2>');
	}
	$r->print('</form></body></html>');
	return OK;
# Is there only one choice?
    } elsif ($countactive==1) {
	$r->print('<h3>'.&mt('Please stand by.').'</h3>'.
	    '<input type="hidden" name="'.$possiblerole.'" value="1" />');
	$r->print("</form>\n");
	$r->rflush();
	$r->print('<script>document.forms.rolechoice.submit();</script>');
	$r->print('</body></html>');
	return OK;
    }
# More than one possible role
# ----------------------------------------------------------------------- Table
    unless (($advanced) || ($nochoose)) {
	$r->print("<h2>".&mt('Select a Course to Enter')."</h2>\n");
    }
    $r->print('<br /><table><tr>');
    unless ($nochoose) { $r->print('<th>&nbsp;</th>'); }
    $r->print('<th>'.&mt('User Role').'</th><th colspan=2>'.&mt('Extent').
         '</th><th>'.&mt('Start').'</th><th>'.&mt('End').'</th><th>'.
	      &mt('Remark').'</th></tr>'."\n");
    my $doheaders=-1;
    foreach my $type ('Construction Space','Course','Domain','System') {
	my $haverole=0;
	foreach my $which (sort {uc($a) cmp uc($b)} (keys(%sortrole))) {
	    if ($roleclass{$sortrole{$which}} =~ /^\Q$type\E/) { 
		$haverole=1;
	    }
	}
	if ($haverole) { $doheaders++; }
    }
    foreach my $type ('Construction Space','Course','Domain','System') {
	my $output;
	foreach my $which (sort {uc($a) cmp uc($b)} (keys(%sortrole))) {
	    if ($roleclass{$sortrole{$which}} =~ /^\Q$type\E/) { 
		$output.=&mt($roletext{$sortrole{$which}});
	    }
	}
	if ($output) {
	    if ($doheaders > 0) {
		$r->print("<tr bgcolor='#BBffBB'>".
			  "<td align='center' colspan='7'>".&mt($type)."</td>");
	    }
	    $r->print($output);	    
	}
    }
    my $tremark='';
    my $tfont='#003300';
    if ($ENV{'request.role'} eq 'cm') {
	$r->print('<tr bgcolor="#11CC55">');
        $tremark=&mt('Currently selected. ');
        $tfont='#002200';
    } else {
        $r->print('<tr bgcolor="#77FF77">');
    }
    unless ($nochoose) {
	if ($ENV{'request.role'} ne 'cm') {
	    $r->print('<td><input type=submit value="'.
		      &mt('Select').'" name="cm"></td>');
	} else {
	    $r->print('<td>&nbsp;</td>');
	}
    }
    $r->print('<td colspan=5><font color="'.$tfont.'">'.&mt('No role specified').
      '</font></td><td><font color="'.$tfont.'">'.$tremark.
      '&nbsp;</font></td></tr>'."\n");

    $r->print('</table>');
    unless ($nochoose) {
	$r->print("</form>\n");
    }
# ------------------------------------------------------------ Privileges Info
    if (($advanced) && (($ENV{'user.error.msg'}) || ($error))) {
	$r->print('<hr><h2>Current Privileges</h2>');

	foreach $envkey (sort keys %ENV) {
	    if ($envkey=~/^user\.priv\.$ENV{'request.role'}\./) {
		my $where=$envkey;
		$where=~s/^user\.priv\.$ENV{'request.role'}\.//;
		my $ttype;
		my $twhere;
		my ($tdom,$trest,$tsec)=
		    split(/\//,Apache::lonnet::declutter($where));
		if ($trest) {
		    if ($ENV{'course.'.$tdom.'_'.$trest.'.description'} eq 'ca') {
			$ttype='Construction Space';
			$twhere='User: '.$trest.', Domain: '.$tdom;
		    } else {
			$ttype='Course';
			$twhere=$ENV{'course.'.$tdom.'_'.$trest.'.description'};
			if ($tsec) {
			    $twhere.=' (Section/Group: '.$tsec.')';
			}
		    }
		} elsif ($tdom) {
		    $ttype='Domain';
		    $twhere=$tdom;
		} else {
		    $ttype='System';
		    $twhere='/';
		}
		$r->print("\n<h3>".$ttype.': '.$twhere.'</h3><ul>');
		foreach (sort split(/:/,$ENV{$envkey})) {
		    if ($_) {
			my ($prv,$restr)=split(/\&/,$_);
			my $trestr='';
			if ($restr ne 'F') {
			    my $i;
			    $trestr.=' (';
			    for ($i=0;$i<length($restr);$i++) {
				$trestr.=
			       Apache::lonnet::plaintext(substr($restr,$i,1));
				if ($i<length($restr)-1) { $trestr.=', '; }
			    }
			    $trestr.=')';
			}
			$r->print('<li>'.
				  Apache::lonnet::plaintext($prv).$trestr.
				  '</li>');
		    }
		}
		$r->print('</ul>');
	    }
	}
    }
    $r->print(&Apache::lonnet::getannounce());
    if ($advanced) {
	$r->print('<p><small><i>This is LON-CAPA '.
		  $r->dir_config('lonVersion').'</i></small></p>');
    }
    $r->print("</body></html>\n");
    return OK;
} 

1;
__END__

=head1 NAME

Apache::lonroles - User Roles Screen

=head1 SYNOPSIS

Invoked by /etc/httpd/conf/srm.conf:

 <Location /adm/roles>
 PerlAccessHandler       Apache::lonacc
 SetHandler perl-script
 PerlHandler Apache::lonroles
 ErrorDocument     403 /adm/login
 ErrorDocument	  500 /adm/errorhandler
 </Location>

=head1 OVERVIEW

=head2 Choosing Roles

C<lonroles> is a handler that allows a user to switch roles in
mid-session. LON-CAPA attempts to work with "No Role Specified", the
default role that a user has before selecting a role, as widely as
possible, but certain handlers for example need specification which
course they should act on, etc. Both in this scenario, and when the
handler determines via C<lonnet>'s C<&allowed> function that a certain
action is not allowed, C<lonroles> is used as error handler. This
allows the user to select another role which may have permission to do
what they were trying to do. C<lonroles> can also be accessed via the
B<CRS> button in the Remote Control. 

=begin latex

\begin{figure}
\begin{center}
\includegraphics[width=0.45\paperwidth,keepaspectratio]{Sample_Roles_Screen}
  \caption{\label{Sample_Roles_Screen}Sample Roles Screen} 
\end{center}
\end{figure}

=end latex

=head2 Role Initialization

The privileges for a user are established at login time and stored in the session environment. As a consequence, a new role does not become active till the next login. Handlers are able to query for privileges using C<lonnet>'s C<&allowed> function. When a user first logs in, their role is the "common" role, which means that they have the sum of all of their privileges. During a session it might become necessary to choose a particular role, which as a consequence also limits the user to only the privileges in that particular role.

=head1 INTRODUCTION

This module enables a user to select what role he wishes to
operate under (instructor, student, teaching assistant, course
coordinator, etc).  These roles are pre-established by the actions
of upper-level users.

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

=head1 HANDLER SUBROUTINE

This routine is called by Apache and mod_perl.

=over 4

=item *

Roles Initialization (yes/no)

=item *

Get Error Message from Environment

=item *

Who is this?

=item *

Generate Page Output

=item *

Choice or no choice

=item *

Table

=item *

Privileges

=back

=cut
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