--- rat/lonwrapper.pm	2003/01/20 17:03:25	1.6
+++ rat/lonwrapper.pm	2022/08/28 02:41:30	1.78
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Wrapper for external and binary files as standalone resources
 #
-# $Id: lonwrapper.pm,v 1.6 2003/01/20 17:03:25 www Exp $
+# $Id: lonwrapper.pm,v 1.78 2022/08/28 02:41:30 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -25,59 +25,652 @@
 #
 # http://www.lon-capa.org/
 #
-# (Edit Handler for RAT Maps
-# (TeX Content Handler
-#
-# 05/29/00,05/30 Gerd Kortemeyer)
-# 7/1,6/30 Gerd Kortemeyer)
-#
-# 7/5 Gerd Kortemeyer
+
 
 package Apache::lonwrapper;
 
 use strict;
 use Apache::Constants qw(:common);
-use Apache::lonnet();
-use Apache::lonxml();
+use Apache::lonenc();
+use Apache::lonnet;
+use Apache::lonlocal;
+use Apache::loncommon();
+use Apache::lonhtmlcommon();
+use Apache::lonextresedit();
+use Apache::lonexttool();
+use Apache::lonhomework();
+use Apache::lonnavmaps();
+use LONCAPA qw(:DEFAULT :match);
+use HTML::Entities();
+use Digest::MD5();
 
 # ================================================================ Main Handler
+sub wrapper {
+    my ($r,$url,$brcrum,$absolute,$is_ext,$is_pdf,$exttool,$linktext,$explanation,
+        $title,$width,$height,$reuse) = @_;
+
+    my $forcereg;
+    unless ($env{'form.folderpath'}) {
+        $forcereg = 1;
+    }
+    my %lt = &Apache::lonlocal::texthash(
+                                          'noif' => 'No iframe support.',
+                                          'show' => 'Show content in pop-up window',
+                                        );
+
+    (undef,undef,undef,undef,undef,undef,my $clientmobile) =
+        &Apache::loncommon::decode_user_agent($r);
+
+    my ($anchor,$uselink);
+    if ($is_ext) {
+        if ($env{'form.symb'}) {
+            (undef,undef,my $res) = &Apache::lonnet::decode_symb($env{'form.symb'});
+            if ($res =~ /(#[^#]+)$/) {
+                $anchor = $1;
+            }
+        } elsif ($env{'form.anchor'} ne '') {
+            $anchor = '#'.$env{'form.anchor'};
+        }
+        if (($is_ext eq 'tab') || ($is_ext eq 'window')) {
+            $uselink = 1;
+        }
+        unless (($is_pdf && $clientmobile) || $uselink) {
+            my $hostname = $r->hostname();
+            my $lonhost = $r->dir_config('lonHostID');
+            my $ip = &Apache::lonnet::get_host_ip($lonhost);
+            $uselink = &Apache::loncommon::is_nonframeable($url,$absolute,$hostname,$ip);
+        }
+    }
+
+    my $noiframe = &Apache::loncommon::modal_link($url.$anchor,$lt{'show'},500,400);
+    my $args = {'bgcolor' => '#FFFFFF'};
+    if ($forcereg) {
+        $args->{'force_register'} = $forcereg;
+    }
+    if (ref($brcrum) eq 'ARRAY') {
+        $args->{'bread_crumbs'} = $brcrum;
+    }
+    if ($absolute) {
+        $args->{'use_absolute'} = $absolute;
+    }
+    if ($env{'form.only_body'}) {
+        $args->{'only_body'} = $env{'form.only_body'};
+    }
+
+    my ($countdown,$donemsg,$headjs);
+    if (($exttool) && (&Apache::lonnet::EXT('resource.0.gradable') =~ /^yes$/i)) {
+        $Apache::lonhomework::browse = &Apache::lonnet::allowed('bre',$url);
+        if ($env{'form.markaccess'}) {
+            my $symb=&Apache::lonnet::symbread($url);
+            my @interval=&Apache::lonnet::EXT('resource.0.interval',$symb);
+            my ($timelimit) = split(/_/,$interval[0]);
+            my $setres = &Apache::lonnet::set_first_access($interval[1],$timelimit);
+            if ($setres eq 'ok') {
+                delete($env{'form.markaccess'});
+            }
+        } elsif ($env{'form.LC_interval_done'} eq 'true') {
+            my $symb=&Apache::lonnet::symbread($url);
+            if ($symb) {
+                (my $donebuttonresult,$donemsg) = &Apache::lonhomework::zero_timer($symb);
+                undef($env{'form.LC_interval_done'});
+                undef($env{'form.LC_interval_done_proctorpass'});
+            }
+        }
+        my ($status,$result,$resource_due) =
+            &Apache::lonexttool::gradabletool_access_check();
+        undef($Apache::lonhomework::browse);
+        if ($status eq 'CAN_ANSWER') {
+            if ($resource_due) {
+                my $time_left = $resource_due - time();
+                if ($resource_due && ($time_left > 0)) {
+                    $countdown ='
+<script type="text/javascript">
+// <![CDATA['."\n".
+                             &Apache::lonhtmlcommon::countdown().'
+// ]]>
+</script>'."\n".
+                    &Apache::lonhtmlcommon::set_due_date($resource_due);
+                }
+            }
+        } else {
+            if ($status eq 'SHOW_ANSWER') {
+                $result = &Apache::lonexttool::display_score().
+                          &Apache::lonfeedback::list_discussion('tool','OPEN');
+            }
+            return &Apache::loncommon::start_page('Menu',undef,$args).
+                   $result.
+                   &Apache::loncommon::end_page();
+        }
+    }
+
+#
+# Where iframe is in use, if window.onload() executes before the custom resize function
+# has been defined (jQuery), two global javascript vars (LCnotready and LCresizedef)
+# are used to ensure document.ready() triggers a call to resize, so the iframe contents
+# do not obscure the Functions menu.
+#
+
+    unless ($clientmobile || ($exttool eq 'window') || ($exttool eq 'tab') || $uselink) {
+        $headjs = '
+<script type="text/javascript">
+// <![CDATA[
+var LCnotready = 0;
+var LCresizedef = 0;
+// ]]>
+</script>'."\n";
+    }
+
+    my $startpage = &Apache::loncommon::start_page('Menu',$headjs,$args).$countdown.$donemsg;
+    my $endpage = &Apache::loncommon::end_page();
+
+    if (($uselink) && ($title eq '')) {
+        if ($env{'form.symb'}) {
+            $title=&Apache::lonnet::gettitle($env{'form.symb'});
+        } else {
+            my $symb=&Apache::lonnet::symbread($r->uri);
+            if ($symb) {
+                $title=&Apache::lonnet::gettitle($symb);
+            }
+        }
+    }
+    if ($clientmobile || ($exttool eq 'window') || ($exttool eq 'tab') ||
+        ($is_ext eq 'tab') || ($is_ext eq 'window')) {
+        my $output = $startpage;
+        if ($is_pdf) {
+            $linktext = &mt('Link to PDF (for mobile devices)');
+            $output .= &create_link($url,$anchor,$title,$linktext);
+        } elsif (($exttool eq 'window') || ($exttool eq 'tab') ||
+                 ($is_ext eq 'tab') || ($is_ext eq 'window')) {
+            my $preamble;
+            if ($linktext eq '') {
+                if ($exttool) {
+                    $linktext = &mt('Launch External Tool');
+                } else {
+                    $linktext = &mt('Link to External Resource');
+                }
+            }
+            if ($exttool) {
+                $url = &HTML::Entities::encode($url,'"<>&');
+            } else {
+                $url = &HTML::Entities::encode($url.$anchor,'&<>"');
+            }
+            if (($exttool eq 'tab') || ($is_ext eq 'tab')) {
+                my $target;
+                if ($exttool) {
+                    $target = 'LCExternalToolTab';
+                } else {
+                    if ($reuse) {
+                        $target = 'LCExternalResTab';
+                    } else {
+                        $target = '_blank';
+                    }
+                    if ($title ne '') {
+                        $preamble = '<span style="font-weight:bold;">'.$title.'</span><br />';
+                    }
+                }
+                $output .= '<div>'.$preamble.
+                           '<a href="'.$url.'" target="'.$target.'" style="padding:0;clear:both;margin:0;border:0">'.
+                           $linktext.'</a>'.
+                           '</div>';
+            } else {
+                my ($target,$extlinkimg);
+                if ($exttool) {
+                    $target = 'LCExternalToolPopUp';
+                } else {
+                    $target = 'LCExternalResPopUp';
+                    if ($title ne '') {
+                        $preamble = '<span style="font-weight:bold;">'.$title.'</span><br />';
+                    }
+                    $extlinkimg = '<img src="'.&Apache::loncommon::lonhttpdurl($r->dir_config('lonIconsURL').'/externallink.gif').'" width="19" height="18" border="0" />';
+                    unless ($reuse) {
+                        my $resid;
+                        if ($env{'request.course.id'}) {
+                            unless ($env{'form.folderpath'} =~ /^supplemental/) {
+                                my $symb=&Apache::lonnet::symbread($r->uri);
+                                if ($symb) {
+                                    my $navmap = Apache::lonnavmaps::navmap->new();
+                                    if (ref($navmap)) {
+                                        my $res = $navmap->getBySymb($symb);
+                                        if (ref($res)) {
+                                            $resid = $res->id;
+                                            $resid =~ s/\./_/g;
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                        if ($resid eq '') {
+                            $resid = substr(Digest::MD5::md5_hex(Digest::MD5::md5_hex(time(). {}. rand(). $$)), 0, 8);
+                        }
+                        &js_escape(\$resid);
+                        $target .= $resid;
+                    }
+                }
+                $output .= <<"ENDLINK";
+<script type="text/javascript">
+// <![CDATA[
+var windowObjectReference = null;
+var PreviousUrl;
+
+function openSinglePopup(strUrl) {
+    if (windowObjectReference == null || windowObjectReference.closed) {
+        windowObjectReference = window.open(strUrl, "$target",
+                                            "height=$height,width=$width,scrollbars=yes,resizable=yes,status=yes,menubar=no,location=no'");
+    } else if(PreviousUrl != strUrl) {
+        windowObjectReference = window.open(strUrl, "$target",
+                                            "height=$height,width=$width,scrollbars=yes,resizable=yes,status=yes,menubar=no,location=no'");
+        windowObjectReference.focus();
+    } else {
+        windowObjectReference.focus();
+    };
+    PreviousUrl = strUrl;
+}
+// ]]>
+</script>
+<div>$preamble
+<a href="$url" target="$target" onclick="openSinglePopup(this.href); return false;">
+$linktext$extlinkimg</a>
+</div>
+ENDLINK
+            }
+            if ($exttool) {
+                if ($explanation ne '') {
+                    $output .= '<div>'.$explanation.'</div>';
+                }
+                if (&Apache::lonnet::EXT('resource.0.gradable')) {
+                    $output .= &Apache::lonfeedback::list_discussion('tool','OPEN');
+                }
+            }
+        } else {
+            if ($uselink) {
+                $linktext = &mt('Link to resource');
+                $output .= &create_link($url,$anchor,$title,$linktext);
+            } else {
+                my $dest = &HTML::Entities::encode($url.$anchor,'&<>"');
+                $output .= '<div style="overflow:scroll; -webkit-overflow-scrolling:touch;">'."\n".
+                           '<iframe src="'.$dest.'" height="100%" width="100%" frameborder="0">'."\n".
+                           "$lt{'noif'} $noiframe\n".
+                           "</iframe>\n".
+                           "</div>\n";
+            }
+        }
+        $output .= $endpage;
+        return $output;
+    } elsif ($uselink) {
+        $linktext = &mt('Link to resource');
+        return $startpage.&create_link($url,$anchor,$title,$linktext).$endpage;
+    } else {
+        my $offset = 5;
+        &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},['inhibitmenu']);
+        if ($env{'form.inhibitmenu'} eq 'yes') {
+            $offset = 0;
+        }
+        my $script = &Apache::lonhtmlcommon::scripttag(<<SCRIPT);
+        \$(document).ready( function() {
+            \$(window).unbind('resize').resize(function(){
+                var header = null;
+                var offset = $offset;
+                var height = 0;
+                var hdrtop = 0;
+                if (\$('div.LC_head_subbox:first').length) {
+                    header = \$('div.LC_head_subbox:first');
+                    offset = 9;
+                } else {
+                    if (\$('#LC_breadcrumbs').length) {
+                        header = \$('#LC_breadcrumbs');
+                    }
+                }
+                if (header != null && header.length) {
+                    height = header.height();
+                    hdrtop = header.position().top;
+                }
+                var pos = height + hdrtop + offset;
+                \$('.LC_iframecontainer').css('top', pos);
+            });
+            LCresizedef = 1;
+            if (LCnotready == 1) {
+                LCnotready = 0;
+                \$(window).trigger('resize');
+            }
+        });
+        window.onload = function(){
+             if (LCresizedef) {
+                 LCnotready = 0;
+                 \$(window).trigger('resize');
+             } else {
+                 LCnotready = 1;
+             }
+        };
+SCRIPT
+        # javascript will position the iframe if window was resized (or zoomed)
+        my $dest = &HTML::Entities::encode($url.$anchor,'&<>"');
+        return <<ENDFRAME;
+        $startpage
+        $script
+        <div class="LC_iframecontainer">
+            <iframe src="$dest">$lt{'noif'} $noiframe</iframe>
+        </div>
+        $endpage
+ENDFRAME
+    }
+}
 
-sub handler {
-  my $r=shift;
-  $r->content_type('text/html');
-  $r->send_http_header;
-
-  return OK if $r->header_only;
-
-  my $url=$r->uri;
-  $url=~s/^\/adm\/wrapper//;
-  $url=~s/^\/ext\//http\:\/\//;
-  if ($url=~/^\/uploaded\//) {
-      $url=&Apache::lonnet::tokenwrapper($url);
-  }
-  my $events='onLoad="'.&Apache::lonxml::loadevents.
-           '" onUnload="'.&Apache::lonxml::unloadevents.'"';
-  my $script=&Apache::lonxml::registerurl(1,undef);
-  $r->print(<<ENDDOCUMENT);
-<html>
-<head>
-$script
-</head>
-<frameset rows="1,*" border=0 $events>
-<frame src="/adm/rat/empty.html">
-<frame src="$url">
-</frameset>
-</html>
-ENDDOCUMENT
-  return OK;
+sub create_link {
+    my ($url,$anchor,$title,$linktext) = @_;
+    my $shownlink;
+    if ($title eq '') {
+        $title = $env{'form.title'};
+        if ($title eq '') {
+            unless ($env{'request.enc'}) {
+                ($title) = ($url =~ m{/([^/]+)$});
+                $title =~ s/(\?[^\?]+)$//;
+            }
+        }
+    }
+    unless ($title eq '') {
+        $shownlink = '<span style="font-weight:bold;">'.$title.'</span><br />';
+    }
+    my $dest = &HTML::Entities::encode($url.$anchor,'&<>"');
+    $shownlink .= '<a href="'.$dest.'">'.$linktext.'</a>';
+    return $shownlink;
 }
 
+sub handler {
+    my $r=shift;
+    &Apache::loncommon::content_type($r,'text/html');
+    $r->send_http_header;
+
+    return OK if $r->header_only;
+
+    my $url = $r->uri;
+    my ($is_ext,$brcrum,$absolute,$is_pdf,$exttool,$cdom,$cnum,$hostname,
+        $linktext,$explanation,$width,$height,$reuse);
+
+    for ($url){
+        s|^/adm/wrapper||;
+        $is_ext = $_ =~ s|^/ext/|http://|;
+        s|http://https://|https://| if ($is_ext);
+        s|&colon;|:|g;
+    }
+
+    if ($url =~ /\.pdf$/i) {
+        $is_pdf = 1;
+    } elsif (($is_ext) && ($env{'request.course.id'})) {
+        if ($env{'course.'.$env{'request.course.id'}.'.extresource'}) {
+            (my $selected,$reuse,$width,$height) = split(/:/,$env{'course.'.$env{'request.course.id'}.'.extresource'});
+            if ($selected eq 'tab') {
+                $is_ext = 'tab';
+                $width = '';
+                $height = '';
+            } elsif ($selected eq 'window') {
+                $is_ext = 'window';
+                unless ($width =~ /^\d+$/) {
+                    $width = '';
+                }
+                unless ($height =~ /^\d+$/) {
+                    $height = '';
+                } 
+            } else {
+                $width = '';
+                $height = '';
+                $reuse = '';
+            }
+        }
+    } elsif ($url =~ m{^/adm/($match_domain)/($match_courseid)/(\d+)/ext\.tool$}) {
+        $cdom = $1;
+        $cnum = $2;
+        my $marker = $3;
+        $exttool = 'iframe';
+        my $exttoolremote;
+        my %toolhash = &Apache::lonnet::get('exttool_'.$marker,['target','linktext','explanation','id','width','height'],
+                                            $cdom,$cnum);
+        if ($toolhash{'id'}) {
+            my %ltitools = &Apache::lonnet::get_domain_lti($cdom,'consumer');
+            if (ref($ltitools{$toolhash{'id'}}) eq 'HASH') {
+                $exttoolremote = $ltitools{$toolhash{'id'}}{'url'};
+            }
+        }
+        if ($toolhash{'target'} eq 'window') {
+            $exttool = 'window';
+            $width = $toolhash{'width'};
+            $height = $toolhash{'height'};
+        } elsif ($toolhash{'target'} eq 'tab') {
+            $exttool = 'tab';
+        }
+        if (($exttool eq 'window') || ($exttool eq 'tab')) {
+            $linktext = $toolhash{'linktext'};
+            $explanation = $toolhash{'explanation'};
+        } elsif (($exttoolremote =~ /^http:/) && ($ENV{'SERVER_PORT'} == 443)) {
+            $exttool = 'tab';
+        }
+    }
+    if (($is_ext) || ($exttool)) {
+        &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
+            ['forceedit','register','folderpath','symb','idx','title','anchor']);
+        if (($env{'form.forceedit'}) &&
+            (&Apache::lonnet::allowed('mdc',$env{'request.course.id'})) &&
+            (($env{'form.folderpath'} =~ /^supplemental/) ||
+             ($env{'form.symb'} =~ /^uploaded/))) {
+            if ($env{'form.symb'}) {
+                (undef,undef,my $res) = &Apache::lonnet::decode_symb($env{'form.symb'});
+                if ($res =~ /(#[^#]+)$/) {
+                    $url .= $1;
+                }
+            } elsif ($env{'form.folderpath'} =~ /^supplemental/) {
+                if ($env{'form.anchor'} ne '') {
+                    $url .= '#'.$env{'form.anchor'};
+                }
+            }
+            my $type = 'ext';
+            if ($exttool) {
+                $type = 'tool';
+            } elsif (($url =~ /^http:/) && ($ENV{'SERVER_PORT'} == 443)) {
+                $hostname = $r->hostname();
+            }
+            $r->print(
+                &Apache::lonextresedit::display_editor($url,$env{'form.folderpath'},
+                                                       $env{'form.symb'},
+                                                       $env{'form.idx'},$type,$cdom,
+                                                       $cnum,$hostname));
+            return OK;
+        } elsif ($env{'form.folderpath'} =~ /^supplemental/) {
+            my $crstype = &Apache::loncommon::course_type();
+            my $title = $env{'form.title'};
+            if ($title eq '') {
+                if ($is_ext) {
+                    $title = &mt('External Resource');
+                } else {
+                    $title = &mt('External Tool');
+                }
+            }
+            $brcrum =
+                &Apache::lonhtmlcommon::docs_breadcrumbs(undef,$crstype,undef,$title,1);
+        }
+    }
+
+#
+# Actual URL
+#
+    if (($url=~/$LONCAPA::assess_re/) && (!$exttool)) {
+#
+# This is uploaded homework
+#
+        $env{'request.state'}='uploaded';
+        &Apache::lonhomework::renderpage($r,$url);
+    } else {
+#
+# This is not homework
+#
+        if (($is_ext) || ($exttool)) {
+            $absolute = $env{'request.use_absolute'};
+            $ENV{'QUERY_STRING'} =~ s/(^|\&)symb=[^\&]*/$1/;
+            $ENV{'QUERY_STRING'} =~ s/\&$//;
+        }
+
+        unless ($ENV{'QUERY_STRING'} eq '') {
+            $url.=(($url=~/\?/)?'&':'?').$ENV{'QUERY_STRING'};
+        }
+
+        # encrypt url if not external
+        unless ($is_ext) {
+            &Apache::lonenc::check_encrypt(\$url);
+        }
+
+        $r->print( wrapper($r,$url,$brcrum,$absolute,$is_ext,$is_pdf,$exttool,
+                           $linktext,$explanation,undef,$width,$height,$reuse) );
+
+    } # not just the menu
+    
+    return OK;
+} # handler
+
 1;
 __END__
 
+=pod
+
+=head1 NAME
+
+Apache::lonwrapper - External and binary file management.
+
+=head1 SYNOPSIS
+
+Wrapper for external and binary files as standalone resources. Edit handler for rat maps; TeX content handler.
+
+This is part of the LearningOnline Network with CAPA project
+described at http://www.lon-capa.org.
+
+=head1 Subroutines
+
+=over
+
+=item wrapper($r,$url,$brcrum,$absolute,$is_ext,$is_pdf,$exttool,$linktext,$explanation,$title,$width,$height,$reuse)
+
+=over
+
+=item $r
+
+request object
+
+=item $url
+
+url to display either by including in an iframe within a
+LON-CAPA page which has a standard LON-CAPA inline menu,
+or in some cases launched in a separate tab or window,
+launched via a link in a LON-CAPA page with standard inline
+menu.
+
+=item $brcrum
+
+breadcrumbs for unregistered urls
+(i.e., external resources in Supplemental Content).
+
+=item $absolute
+
+contains protocol (http or https) followed by
+the hostname, if menu items in the standard LON-CAPA
+interface created by the call to loncommon::start_page()
+within &wrapper() need to use absolute URLs rather than
+relative URLs.
+
+That will be the case where an external resource has been 
+served from port 80, when the server customarily serves
+requests using Apache/SSL (i.e., port 443). mod_rewrite 
+is used to switch requests for external resources and
+the syllabus: /public/<domain>/<courseid>/syllabus
+(which might also point at an external resource)
+from https:// to http:// where the the URL of the remote site 
+specified in the resource itself is http://.
+
+This is done to avoid default mixed content blocking
+in Firefox 23 and later, when serving from Apache/SSL.
+
+=item $is_ext
+
+true if URL is for an external resource. Default true value
+is 1 (display in iframe, unless $uselink is true). 
+If external resource is to be displayed in a tab,
+value of $is_ext will be tab, if to be displayed in a pop-up window,
+value of $is_ext will be window.  
+
+=item $is_pdf
+
+true if URL is for a PDF (based on file extension).
+
+=item $exttool
+
+If URL is for an External Tool, will contain the target type: iframe, window or tab.
+
+=item $linktext
+
+optional. If URL is for an External Tool, and target type is window or tab, 
+then the link text may be an option set in the course for each tool instance,
+or may be a default defined in the domain for all instances of the tool.
+
+=item $explanation
+
+optional. If URL is for an External Tool, and target type is window or tab, 
+then the explanation is an option set in the course for each tool instance,
+or may be a default defined in the domain for all instances of the tool.
+
+=item $title
+
+optional. If wrapped item is a PDF, and $clientmobile is true,
+a link to a PDF is shown. The "title" will be displayed
+above the link, but if not provided as an arg, $env{'form.title'}
+will be used, otherwise, the filename will be displayed (unless
+hidden URL set for the resource).
+
+=item $width
+
+optional. If URL is for an External Tool, and target type is window,
+then a default width may have been defined in the domain for all instances of 
+the tool.  If so, that width will be used for the window opened (via a link)
+to launch the external tool. If the URL is for an External Resource, and 
+$is_ext is window, then a default width (px) may have been defined in the current
+course for all external resource instances.
+
+=item $height
+
+optional. If URL is for an External Tool, and target type is window,
+then a default height may have been defined in the domain for all instances of 
+the tool.  If so, that height will be used for the window opened (via a link)
+to launch the external tool.  If the URL is for an External Resource, and 
+$is_ext is window, then a default height (px) may have been defined in the current
+course for all external resource instances.
+
+=item $reuse
+
+optional. If the URL is for an External Resource, and $is_ext is tab or window,
+then $reuse will be true if the same tab or window is to be reused for display
+of all external resource instances in a a course.
+
+=back
+
+Returns markup for the entire page.
+
+=item handler()
+
+Content handler for requests for: /adm/wrapper/...
+used for content to be displayed in an iframe, or launched in a separate tab
+or window via a link.  The target URL is extracted from the requested URL, by
+removing the /adm/wrapper prefix. 
 
+The target URL will typically be a PDF served from the current server, an 
+external resource URL served from a different server, or an external tool
+(from an LTI Provider) launched from LON-CAPA (as LTI Consumer) and launched
+via a link.
 
+If the request included forceedit in the query string, and the requester has
+rights to modify course content, then the editor will be didplayed to allow
+changes to be made to the resource (e.g., change the URL of the external resource,
+or change the setting for the external tool instance.
 
+If not in edit mode, then the wrapper() subroutine will be called to generate the
+standard LON-CAPA inline menu, and then either a link to launch a separate tab or
+window, or an iframe to display the content inline. 
 
+=back
 
+=cut