--- rat/lonpageflip.pm	2000/10/03 20:33:06	1.1
+++ rat/lonpageflip.pm	2022/10/19 00:03:12	1.112
@@ -2,354 +2,943 @@
 #
 # Page flip handler
 #
-# (Page Handler
+# $Id: lonpageflip.pm,v 1.112 2022/10/19 00:03:12 raeburn Exp $
 #
-# (TeX Content Handler
+# Copyright Michigan State University Board of Trustees
 #
-# 05/29/00,05/30 Gerd Kortemeyer)
-# 08/30,08/31,09/06,09/14,09/15,09/16,09/19,09/20,09/21,09/23,
-# 10/02 Gerd Kortemeyer)
+# 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/
 #
-# 10/03 Gerd Kortemeyer
+
+
 
 package Apache::lonpageflip;
 
 use strict;
-use Apache::Constants qw(:common :http);
-use Apache::lonnet();
+use LONCAPA;
+use Apache::Constants qw(:common :http REDIRECT);
+use Apache::lonnet;
+use Apache::loncommon();
+use Apache::lonnavmaps();
+use Apache::lonuserstate;
+use Apache::lonlocal;
 use HTML::TokeParser;
 use GDBM_File;
 
-# -------------------------------------------------------------- Module Globals
+# ========================================================== Module Global Hash
+  
 my %hash;
-my @rows;
 
-# ------------------------------------------------------------------ Euclid gcd
-
-sub euclid {
-    my ($e,$f)=@_;
-    my $a; my $b; my $r;
-    if ($e>$f) { $b=$e; $r=$f; } else { $r=$e; $b=$f; }
-    while ($r!=0) {
-	$a=$b; $b=$r;
-        $r=$a%$b;
-    }
-    return $b;
-}
-
-# ------------------------------------------------------------ Build page table
-
-sub tracetable {
-    my ($sofar,$rid,$beenhere)=@_;
-    my $further=$sofar;
-    unless ($beenhere=~/\&$rid\&/) {
-       $beenhere.=$rid.'&';  
-
-       if (defined($hash{'is_map_'.$rid})) {
-           if ((defined($hash{'map_start_'.$hash{'src_'.$rid}})) &&
-               (defined($hash{'map_finish_'.$hash{'src_'.$rid}}))) {
-              my $frid=$hash{'map_finish_'.$hash{'src_'.$rid}};
-	      $sofar=
-                &tracetable($sofar,$hash{'map_start_'.$hash{'src_'.$rid}},
-                '&'.$frid.'&');
-              $sofar++;
-              if ($hash{'src_'.$frid}) {
-               my $brepriv=&Apache::lonnet::allowed('bre',$hash{'src_'.$frid});
-               if (($brepriv eq '2') || ($brepriv eq 'F')) {
-                 if (defined($rows[$sofar])) {
-                   $rows[$sofar].='&'.$frid;
-                 } else {
-                   $rows[$sofar]=$frid;
-                 }
-	       }
-	      }
-	   }
-       } else {
-          $sofar++;
-          if ($hash{'src_'.$rid}) {
-           my $brepriv=&Apache::lonnet::allowed('bre',$hash{'src_'.$rid});
-           if (($brepriv eq '2') || ($brepriv eq 'F')) {
-             if (defined($rows[$sofar])) {
-               $rows[$sofar].='&'.$rid;
-             } else {
-               $rows[$sofar]=$rid;
-             }
-	   }
-          }
-       }
-
-       if (defined($hash{'to_'.$rid})) {
-          map {
-              my $now=&tracetable($sofar,$hash{'goesto_'.$_},$beenhere);
-              if ($now>$further) { $further=$now; }
-          } split(/\,/,$hash{'to_'.$rid});
-       }
+sub cleanup {
+    if (tied(%hash)){
+	&Apache::lonnet::logthis('Cleanup pageflip: hash');
+        unless (untie(%hash)) {
+	    &Apache::lonnet::logthis('Failed cleanup pageflip: hash');
+        }
     }
-    return $further;
+    return OK;
 }
 
-# ================================================================ Main Handler
-
-sub handler {
-  my $r=shift;
+sub addrid {
+    my ($current,$new,$condid)=@_;
+    unless ($condid) { $condid=0; }
+
+	if ($current) {
+	    $current.=','.$new;
+        } else {
+            $current=''.$new;
+        }
 
-# ------------------------------------------- Set document type for header only
-
-#  if ($r->headers_only) {
-     $r->content_type('text/html');
-     $r->send_http_header;
-#     return OK;
-#  }
+    return $current;
+}
 
+sub fullmove {
+    my ($rid,$mapurl,$direction)=@_;
+    if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
+                        &GDBM_READER(),0640)) {
+	($rid,$mapurl)=&move($rid,$mapurl,$direction);
+        untie(%hash);
+    }
+    return($rid,$mapurl);
+}
 
+sub hash_src {
+    my ($id)=@_;
+    my ($mapid,$resid)=split(/\./,$id);
+    my $symb=&Apache::lonnet::encode_symb($hash{'map_id_'.$mapid},
+					  $resid,$hash{'src_'.$id});
+    my $anchor;
+    if ($hash{'ext_'.$id} eq 'true:') {
+        if ($hash{'src_'.$id} =~ /(\#.+)$/) {
+            $anchor = $1;
+        }
+    }
+    if ($hash{'encrypted_'.$id}) {
+	return (&Apache::lonenc::encrypted($hash{'src_'.$id}),
+		&Apache::lonenc::encrypted($symb),
+                $hash{'encrypted_'.$id},$anchor);
+    }
+    return ($hash{'src_'.$id},$symb,$hash{'encrypted_'.$id},$anchor);
+}
 
+sub move {
+    my ($next,$endupmap,$direction,$firstres) = @_;
+    my $safecount=0;
+    my $allowed=0;
+    my $deeplinkonly=0;
+    my $deeplinkchecked;
+    my $deeplink_login_pc;
+    my $prev=$next;
+    my ($prevmapid)=split(/\./,$next);
+    do {
+	($next,$endupmap)=&get_next_possible_move($next,$endupmap,$direction);
+
+	my $url = $hash{'src_'.$next};
+	my ($mapid,$resid)=split(/\./,$next);
+	my $symb = &Apache::lonnet::encode_symb($hash{'map_id_'.$mapid},
+						$resid,$url);
+	if ($url eq '' || $symb eq '') {
+	    $allowed = 0;
+	} else {
+            my $nodeeplinkcheck = 0;
+            if ($hash{'is_map_'.$next}) {
+                $nodeeplinkcheck = 1;
+            }
+	    my $priv = &Apache::lonnet::allowed('bre',$url,$symb,'','','','',$nodeeplinkcheck);
+	    $allowed = (($priv eq 'F') || ($priv eq '2') || ($priv eq 'A'));
+	}
+        $deeplinkonly = 0;
+        if ($hash{'deeplinkonly_'.$next}) {
+            my ($value,$level) = map { &unescape($_); } split(/:/,$hash{'deeplinkonly_'.$next});
+            my ($state,$others,$listed,$scope,$protect) = split(/,/,$value);
+            unless (($state eq 'both') || ($hash{'is_map_'.$next})) {
+                if ($level eq 'resource') {
+                    $deeplinkonly = 1;
+                } elsif ($level eq 'map') {
+                    if ($scope eq 'rec') {
+                        unless ($mapid == $prevmapid) {
+                            unless ($deeplinkchecked) {
+                                $deeplink_login_pc = &get_deeplink_login_pc();
+                                $deeplinkchecked = 1;
+                            }
+                            if ($deeplink_login_pc) {
+                                my $poss_map_pc;
+                                if ($hash{'is_map_'.$next}) {
+                                    $poss_map_pc = $hash{'map_pc_'.$url};
+                                } else {
+                                    $poss_map_pc = $hash{'map_pc_'.$hash{'map_id_'.$mapid}};
+                                }
+                                unless ($deeplink_login_pc == $poss_map_pc) {
+                                    unless (grep(/^$deeplink_login_pc$/,split(/,/,$hash{'map_hierarchy_'.$poss_map_pc}))) {
+                                        $deeplinkonly = 1;
+                                    }
+                                }
+                            } else {
+                                $deeplinkonly = 1;
+                            }
+                        }
+                    } elsif ($mapid != $prevmapid) {
+                        $deeplinkonly = 1;
+                    }
+                }
+            }
+        } elsif (($hash{'deeplinkonly_'.$prev}) && (!$firstres)) {
+            my ($value,$level) = map { &unescape($_); } split(/:/,$hash{'deeplinkonly_'.$prev});
+            my ($state,$others,$listed,$scope,$protect) = split(/,/,$value);
+            unless (($state eq 'both') || ($hash{'is_map_'.$prev})) {
+                if ($level eq 'resource') {
+                    $deeplinkonly = 1;
+                } elsif ($level eq 'map') {
+                    if ($scope eq 'rec') {
+                        unless ($mapid == $prevmapid) {
+                            unless ($deeplinkchecked) {
+                                $deeplink_login_pc = &get_deeplink_login_pc();
+                                $deeplinkchecked = 1;
+                            }
+                            if ($deeplink_login_pc) {
+                                my $poss_map_pc;
+                                if ($hash{'is_map_'.$prev}) {
+                                    $poss_map_pc = $hash{'map_pc_'.$url};
+                                } else {
+                                    $poss_map_pc = $hash{'map_pc_'.$hash{'map_id_'.$mapid}};
+                                }
+                                unless ($deeplink_login_pc == $poss_map_pc) {
+                                    unless (grep(/^$deeplink_login_pc$/,split(/,/,$hash{'map_hierarchy_'.$poss_map_pc}))) {
+                                        $deeplinkonly = 1;
+                                    }
+                                }
+                            }
+                        }
+                    } else {
+                        if ($mapid != $prevmapid) {
+                            $deeplinkonly = 1;
+                        }
+                    }
+                }
+            }
+        }
+	$safecount++;
+    } while (   ($next)
+	     && ($next!~/\,/)
+	     && (
+		    (!$hash{'src_'.$next})
+		 || (
+                        (!$env{'request.role.adv'})
+                     && (($hash{'randomout_'.$next})
+                     ||  ($deeplinkonly)
+                     ||  ($hash{'deeplinkout_'.$next}))
+		    )
+		 || (!$allowed)
+		)
+	     && ($safecount<10000));
 
+    return ($next,$endupmap);
+}
 
-  $r->print('<html><body>'.$ENV{'form.postdata'}.'</body></html>');
-  return OK;
+sub get_next_possible_move {
+    my ($rid,$mapurl,$direction)=@_;
+    my $startoutrid=$rid;
+
+    my $next='';
+
+              my $mincond=1;
+              my $posnext='';
+              if ($direction eq 'forward') {
+# --------------------------------------------------------------------- Forward
+                  while ($hash{'type_'.$rid} eq 'finish') {
+	             $rid=$hash{'ids_'.$hash{'map_id_'.(split(/\./,$rid))[0]}};
+                  }
+		  foreach my $id (split(/\,/,$hash{'to_'.$rid})) {
+		     my $condition= $hash{'conditions_'.$hash{'goesto_'.$id}};
+		     my $rescond  = &Apache::lonnet::docondval($condition);
+		     my $linkcond = &Apache::lonnet::directcondval($hash{'condid_'.$hash{'undercond_'.$id}});
+		     my $thiscond = ($rescond<$linkcond)?$rescond:$linkcond;
+		     if ($thiscond>=$mincond) {
+		          if ($posnext) {
+		             $posnext.=','.$id.':'.$thiscond;
+                          } else {
+                             $posnext=$id.':'.$thiscond;
+		          }
+                          if ($thiscond>$mincond) { $mincond=$thiscond; }
+	              }
+                  }
+		  foreach my $id (split(/\,/,$posnext))  {
+                      my ($linkid,$condval)=split(/\:/,$id);
+                      if ($condval>=$mincond) {
+		          $next=&addrid($next,$hash{'goesto_'.$linkid},
+                                $hash{'condid_'.$hash{'undercond_'.$linkid}});
+                      }
+                  }
+                  if ($hash{'is_map_'.$next}) {
+# This jumps to the beginning of a new map (going down level)
+                      if (
+      $hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$next}}} eq 'sequence') {
+			  $mapurl=$hash{'src_'.$next};
+			  $next=$hash{'map_start_'.$hash{'src_'.$next}};
+                     } elsif (
+# This jumps back up from an empty sequence, to a page up one level
+                         $hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$next}}} eq 'page') {
+                         $mapurl=$hash{'map_id_'.(split(/\./,$next))[0]};
+                     }
+                  } elsif 
+                    ((split(/\./,$startoutrid))[0]!=(split(/\./,$next))[0]) {
+# This comes up from a map (coming up one level);
+		      $mapurl=$hash{'map_id_'.(split(/\./,$next))[0]};
+		  }
+              } elsif ($direction eq 'back') {
+# ------------------------------------------------------------------- Backwards
+                 while ($hash{'type_'.$rid} eq 'start') {
+	             $rid=$hash{'ids_'.$hash{'map_id_'.(split(/\./,$rid))[0]}};
+		 }
+		 foreach my $id (split(/\,/,$hash{'from_'.$rid})) {
+		     my $condition= $hash{'conditions_'.$hash{'comesfrom_'.$id}};
+		     my $rescond  = &Apache::lonnet::docondval($condition);
+		     my $linkcond = &Apache::lonnet::directcondval($hash{'condid_'.$hash{'undercond_'.$id}});
+		     my $thiscond = ($rescond<$linkcond)?$rescond:$linkcond;
+		     if ($thiscond>=$mincond) {
+			 if ($posnext) {
+		             $posnext.=','.$id.':'.$thiscond;
+			 } else {
+                             $posnext=$id.':'.$thiscond;
+			 }
+			 if ($thiscond>$mincond) { $mincond=$thiscond; }
+		     }
+		 }
+		 foreach my $id (split(/\,/,$posnext)) {
+		     my ($linkid,$condval)=split(/\:/,$id);
+		     if ($condval>=$mincond) {
+			 $next=&addrid($next,$hash{'comesfrom_'.$linkid},
+				       $hash{'condid_'.$hash{'undercond_'.$linkid}});
+		     }
+		 }
+                  if ($hash{'is_map_'.$next}) {
+# This jumps to the end of a new map (going down one level)
+                      if (
+      $hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$next}}} eq 'sequence') {
+			  $mapurl=$hash{'src_'.$next};
+			  $next=$hash{'map_finish_'.$hash{'src_'.$next}};
+                      } elsif (
+      $hash{'map_type_'.$hash{'map_pc_'.$hash{'src_'.$next}}} eq 'page') {
+# This jumps back up from an empty sequence, to a page up one level
+                          $mapurl=$hash{'map_id_'.(split(/\./,$next))[0]};
+                      }
+                  } elsif 
+                    ((split(/\./,$startoutrid))[0]!=(split(/\./,$next))[0]) {
+# This comes back up from a map (going up one level);
+		      $mapurl=$hash{'map_id_'.(split(/\./,$next))[0]};
+                  }
+	      }
+              return ($next,$mapurl);
+}
 
+sub first_accessible_resource {
+    my $furl;
+    if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
+	    &GDBM_READER(),0640)) {
+	$furl=$hash{'first_url'};
+	my (%args,$url,$argstr);
+	if ($furl =~ m{^/enc/}) {
+	    ($url,$argstr) = split(/\?/,&Apache::lonenc::unencrypted($furl));
+	} else {
+	    ($url,$argstr) = split(/\?/,$furl);
+	}
+	foreach my $pair (split(/\&/,$argstr)) {
+	    my ($name,$value) = split(/=/,$pair);
+	    $args{&unescape($name)} = &unescape($value);
+	}
+        my $priv = &Apache::lonnet::allowed('bre',$url,$args{'symb'});
+        my $allowed = (($priv eq 'F') || ($priv eq '2') || ($priv eq 'A'));
+        if (!$allowed) {
+# Wow, we cannot see this ... move forward to the next one that we can see
+	    my ($newrid,$newmap)=&move($hash{'first_rid'},$hash{'first_mapurl'},'forward',1);
+# Build the new URL
+            if ($newrid eq '') {
+                $furl = '/adm/navmaps';
+            } else {
+	        my ($newmapid,$newresid)=split(/\./,$newrid);
+	        my $symb=&Apache::lonnet::encode_symb($newmap,$newresid,$hash{'src_'.$newrid});
+	        $furl=&add_get_param($hash{'src_'.$newrid},{ 'symb' => $symb });
+	        if ($hash{'encrypted_'.$newrid}) {
+		    $furl=&Apache::lonenc::encrypted($furl);
+	        }
+            }
+	}
+	untie(%hash);
+	return $furl;
+    } else {
+	return '/adm/navmaps';
+    }
+}
 
+sub first_answerable_ressymb {
+    my $navmap = Apache::lonnavmaps::navmap->new;
+    return unless (ref($navmap));
+    my $iterator = $navmap->getIterator(undef,undef,undef,1);
+    return unless (ref($iterator));
+    my ($curRes,$result);
+    while ($curRes = $iterator->next()) {
+        if (ref($curRes) && $curRes->is_problem()) {
+            foreach my $part (@{$curRes->parts()}) {
+                if ($curRes->tries($part) < $curRes->maxtries($part)) {
+                    $result = $curRes->link().'?symb='.$curRes->shown_symb();
+                    last;
+                }    
+            }
+        }
+    }
+    if ($result) {
+        return $result; 
+    } else {
+        return &first_accessible_resource(); 
+    }
+}
 
-  my $requrl=$r->uri;
-# ----------------------------------------------------------------- Tie db file
-  if ($ENV{'request.course.fn'}) {
-      my $fn=$ENV{'request.course.fn'};
-      if (-e "$fn.db") {
-          if (tie(%hash,'GDBM_File',"$fn.db",&GDBM_READER,0640)) {
-# ------------------------------------------------------------------- Hash tied
-              my $firstres=$hash{'map_start_'.$requrl};
-              my $lastres=$hash{'map_finish_'.$requrl};
-              if (($firstres) && ($lastres)) {
-# ----------------------------------------------------------------- Render page
+sub check_http_req {
+    my ($srcref,$hostname) = @_;
+    return unless (ref($srcref) eq 'SCALAR');
+    my $usehttp;
+    if ($env{'request.course.id'}) {
+        my $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
+        my $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
+        if (($$srcref =~ m{^\Q/public/$cdom/$cnum/syllabus\E($|\?)}) &&
+            ($ENV{'SERVER_PORT'} == 443) &&
+            ($env{'course.'.$env{'request.course.id'}.'.externalsyllabus'} =~ m{^http://})) {
+            unless ((&Apache::lonnet::uses_sts()) ||
+                    (&Apache::lonnet::waf_allssl($hostname))) {
+                $$srcref .= (($$srcref =~/\?/)? '&':'?') . 'usehttp=1';
+                $usehttp = 1;
+            }
+        } elsif (($$srcref =~ m{^\Q/adm/wrapper/ext/\E(?!https:)}) &&
+                 ($ENV{'SERVER_PORT'} == 443)) {
+            unless ((&Apache::lonnet::uses_sts()) ||
+                    (&Apache::lonnet::waf_allssl($hostname))) {
+                my ($url,$anchor) = ($$srcref =~ /^([^\#]+)(?:|(\#[^\#]+))$/);
+                $$srcref = $url . (($$srcref =~/\?/)? '&':'?') . 'usehttp=1' .$anchor; 
+                $usehttp = 1;
+            }
+        }
+    }
+    return $usehttp;
+}
 
-                  @rows=();
+sub reinited_js {
+    my ($url,$cid,$timeout) = @_;
+    if (!$timeout) {
+        $timeout = 0;
+    }
+    return <<"END";
+<script type="text/javascript">
+// <![CDATA[
+setTimeout(function() {
+    var newurl = '$url';
+    if (document.getElementById('LC_update_$cid')) {
+        document.getElementById('LC_update_$cid').style.display = 'none';
+    }
+    if ((newurl !== null) && (newurl !== '') && (newurl !== 'undefined')) {
+        window.location.href = "$url";
+    }
+}, $timeout);
+// ]]>
+</script>
+END
+}
 
-                  &tracetable(0,$firstres,'&'.$lastres.'&');
-                  if ($hash{'src_'.$lastres}) {
-                     my $brepriv=
-                        &Apache::lonnet::allowed('bre',$hash{'src_'.$lastres});
-                     if (($brepriv eq '2') || ($brepriv eq 'F')) {
-                        $rows[$#rows+1]=''.$lastres;
-		     }
-		  }
+sub get_deeplink_login_pc {
+    my $deeplink_login_pc;
+    if (($env{'request.deeplink.login'}) && ($env{'request.course.id'})) {
+        my $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
+        my $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
+        my $deeplink_symb = &Apache::loncommon::deeplink_login_symb($cnum,$cdom);
+        if ($deeplink_symb) {
+            my $loginmap;
+            if ($deeplink_symb =~ /\.(page|sequence)$/) {
+                $loginmap = &Apache::lonnet::clutter((&Apache::lonnet::decode_symb($deeplink_symb))[2]);
+            } else {
+                $loginmap = &Apache::lonnet::clutter((&Apache::lonnet::decode_symb($deeplink_symb))[0]);
+            }
+            $deeplink_login_pc = $hash{'map_pc_'.$loginmap};
+        }
+    }
+    return $deeplink_login_pc;
+}
 
-# ------------------------------------------------------------ Add to symb list
+# ================================================================ Main Handler
 
-                  my $i;
-                  my %symbhash=();
-                  for ($i=0;$i<=$#rows;$i++) {
-		     if ($rows[$i]) {
-                        my @colcont=split(/\&/,$rows[$i]);
-                        map {
-                           $symbhash{$hash{'src_'.$_}}='';
-		        } @colcont;
-		     }
-		  }
-                  &Apache::lonnet::symblist($requrl,%symbhash);
+sub handler {
+   my $r=shift;
 
-# ------------------------------------------------------------------ Page parms
+# ------------------------------------------- Set document type for header only
 
-                  my $j;
-                  my $lcm=1;
-                  my $contents=0;
-                  my $nforms=0;
-                  
-                  my %ssibody=();
-                  my %ssibgcolor=();
-                  my %ssitext=();
-                  my %ssilink=();
-                  my %ssivlink=();
-                  my %ssialink=();
-                  my %cellemb=();
-
-                  my $allscript='';
-                  my $allmeta='';
-
-                  my $isxml=0;
-                  my $xmlheader='';
-                  my $xmlbody='';
-
-# --------------------------------------------- Get SSI output, post parameters
-
-                  for ($i=0;$i<=$#rows;$i++) {
-		     if ($rows[$i]) {
-		      $contents++;
-                      my @colcont=split(/\&/,$rows[$i]);
-                      $lcm*=($#colcont+1)/euclid($lcm,($#colcont+1));
-                      map {
-                          my $src=$hash{'src_'.$_};
-                          $src=~/\.(\w+)$/;
-                          $cellemb{$_}=Apache::lonnet::fileembstyle($1);
-                          if ($cellemb{$_} eq 'ssi') {
-# --------------------------------------------------------- This is an SSI cell
-			      my $prefix=$_.'_';
-                              my %posthash=('request.prefix' => $prefix);
-                              if (($ENV{'form.'.$prefix.'submit'}) 
-                               || ($ENV{'form.all_submit'})) {
-                               map {
-				  if ($_=~/^form.$prefix/) {
-				      my $name=$_;
-                                      $name=~s/^form.$prefix//;
-                                      $posthash{$name}=$ENV{$_};
-                                  }
-                               } keys %ENV;
-			      }
-                              my $output=Apache::lonnet::ssi($src,%posthash);
-                              my $parser=HTML::TokeParser->new(\$output);
-                              my $token;
-                              my $bodydef=0;
-                              my $thisxml=0;
-                              if ($output=~/\?xml/) {
-                                 $isxml=1;
-                                 $thisxml=1;
-                                 $output=~
-         /((?:\<(?:\?xml|\!DOC|html)[^\>]*(?:\>|\>\]\>)\s*)+)\<body[^\>]*\>/si;
-                                 $xmlheader=$1;
-			      }
-                              while (($bodydef==0) &&
-                                     ($token=$parser->get_token)) {
-				  if ($token->[1] eq 'body') {
-				      $bodydef=1;
-                                      $ssibgcolor{$_}=$token->[2]->{'bgcolor'};
-                                      $ssitext{$_}=$token->[2]->{'text'};
-                                      $ssilink{$_}=$token->[2]->{'link'};
-                                      $ssivlink{$_}=$token->[2]->{'vlink'};
-                                      $ssialink{$_}=$token->[2]->{'alink'};
-                                      if ($thisxml) {
-					  $xmlbody=$token->[4];
-                                      }
-                                  }
-                                  if ($token->[1] eq 'meta') {
-				      $allmeta.="\n".$token->[4].'</meta>';
-                                  }
-                                  if ($token->[1] eq 'script') {
-				      $allscript.="\n\n"
-                                                .$parser->get_text('/script');
-                                  }
-                              }
-                              if ($output=~/\<body[^\>]*\>(.*)/si) {
-                                 $output=$1; 
-                              }
-                              $output=~s/\<\/body\>.*//si;
-                              if ($output=~/\<form/si) {
-				  $nforms++;
-                                  $output=~s/\<form[^\>]*\>//gsi;
-                                  $output=~s/\<\/form[^\>]*\>//gsi;
-                              }
-			      $ssibody{$_}=$output;
+  if ($r->header_only) {
+      &Apache::loncommon::content_type($r,'text/html');
+      $r->send_http_header;
+      return OK;
+  }
 
-# ---------------------------------------------------------------- End SSI cell
-                          }
-                      } @colcont;
-                     } 
+  my %cachehash=(); 
+  my $multichoice=0;
+  my %multichoicehash=();
+  my %prog_state=();
+  my ($redirecturl,$redirectsymb,$enc,$anchor,$deeplinklevel);
+  my $next='';
+  my $hostname = $r->hostname();
+  my @possibilities=();
+   &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},['postdata']);
+  if (($env{'form.postdata'})&&($env{'request.course.fn'})) {
+      my ($direction,$currenturl) = ($env{'form.postdata'}=~/(\w+)\:(.*)/);
+      if ($currenturl=~m|^/enc/|) {
+          $currenturl=&Apache::lonenc::unencrypted($currenturl);
+      }
+      $currenturl=~s/\.\d+\.(\w+)$/\.$1/;
+      $currenturl=~s/^https?\:\/\///;
+      $currenturl=~s/^[^\/]+//;
+      my ($preupdatepos,$last,$reinitcheck);
+      if ($direction eq 'return') {
+          if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'_symb.db',
+                    &GDBM_READER(),0640)) {
+              $last=$hash{'last_known'};
+              untie(%hash);
+          }
+      } elsif ($direction eq 'firstanswerable') {
+          my $furl = &first_answerable_ressymb();
+          my $usehttp = &check_http_req(\$furl,$hostname);
+          if (($usehttp) && ($hostname ne '')) {
+              $furl='http://'.$hostname.$furl;
+          } else {
+              $furl=&Apache::lonnet::absolute_url().$furl;
+          }
+          &Apache::loncommon::content_type($r,'text/html');
+          $r->header_out(Location => $furl);
+          return REDIRECT;
+      } elsif ($direction eq 'endplacement') {
+          &Apache::loncommon::content_type($r,'text/html');
+          $r->send_http_header;
+          $r->print(&Apache::lonplacementtest::showresult());
+          return OK;
+      }
+      if ($env{'request.course.id'}) {
+          # Check if course needs to be re-initialized
+          my $loncaparev = $r->dir_config('lonVersion');
+          ($reinitcheck,my @reinit) = &Apache::loncommon::needs_coursereinit($loncaparev);
+          if ($reinitcheck eq 'switch') {
+              &Apache::loncommon::content_type($r,'text/html');
+              $r->send_http_header;
+              $r->print(&Apache::loncommon::check_release_result(@reinit));
+              return OK;
+          }
+          my ($cnum,$cdom);
+          if ($reinitcheck) {
+              $cnum = $env{'course.'.$env{'request.course.id'}.'.num'};
+              $cdom = $env{'course.'.$env{'request.course.id'}.'.domain'};
+          }
+          if (($reinitcheck eq 'main') || ($reinitcheck eq 'both')) {
+              $preupdatepos = &Apache::lonnet::symbread($currenturl);
+              unless ($direction eq 'return') {
+                  if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'_symb.db',
+                                &GDBM_READER(),0640)) {
+                      $last=$hash{'last_known'};
+                      untie(%hash);
                   }
-                  unless ($contents) {
-                      $r->content_type('text/html');
-                      $r->send_http_header;
-                      $r->print('<html><body>Empty page.</body></html>');
-                  } else {
-# ------------------------------------------------------------------ Build page
+              }
+              &Apache::loncommon::content_type($r,'text/html');
+              $r->send_http_header;
+              $r->print(&Apache::loncommon::start_page('Content Changed'));
+              my $preamble = '<div id="LC_update_'.$env{'request.course.id'}.'" class="LC_info">'.
+                             '<br />'.
+                             &mt('Your course session is being updated because of recent changes by course personnel.').
+                             ' '.&mt('Please be patient').'.<br /></div>'.
+                             '<div style="padding:0;clear:both;margin:0;border:0"></div>';
+              %prog_state = &Apache::lonhtmlcommon::Create_PrgWin($r,undef,$preamble);
+              &Apache::lonhtmlcommon::Update_PrgWin($r,\%prog_state,&mt('Updating course'));
+              my ($furl,$ferr) = &Apache::lonuserstate::readmap("$cdom/$cnum");
+              &Apache::lonhtmlcommon::Update_PrgWin($r,\%prog_state,&mt('Finished!'));
+              if ($ferr) {
+                  &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+                  my $requrl = $r->uri;
+                  $env{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
+                  $env{'user.reinit'} = 1;
+                  return HTTP_NOT_ACCEPTABLE;
+              } else {
+                  if ($last) {
+                      my ($murl,$id,$fn)=&Apache::lonnet::decode_symb($last);
+                      unless (&Apache::lonnet::symbverify($last,$fn)) {
+                          undef($last);
+                      }
+                  }
+              }
+          }
+          if (($reinitcheck eq 'both') || ($reinitcheck eq 'supp')) {
+              my ($supplemental,$refs_updated) = &Apache::lonnet::get_supplemental($cnum,$cdom);
+              unless ($refs_updated) {
+                  &Apache::loncommon::set_supp_httprefs($cnum,$cdom,$supplemental);
+              }
+          }
+      }
+      if ($direction eq 'firstres') {
+	  my $furl=&first_accessible_resource();
+          my $usehttp = &check_http_req(\$furl,$hostname);
+          if (($usehttp) && ($hostname ne '')) {
+              $furl='http://'.$hostname.$furl;
+          } else {
+              $furl=&Apache::lonnet::absolute_url().$furl;
+          }
+          if ($reinitcheck eq 'update') {
+              &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+              $r->print(&reinited_js($furl,$env{'request.course.id'},100));
+              $r->print(&Apache::loncommon::end_page());
+              return OK;
+          } else {
+	      &Apache::loncommon::content_type($r,'text/html');
+	      $r->header_out(Location => $furl);
+	      return REDIRECT;
+          }
+      }
+      if ($direction eq 'return') {
+# -------------------------------------------------------- Return to last known
+         my ($newloc,$usehttp);
+         if (($last) && (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
+                        &GDBM_READER(),0640))) {
+            my ($murl,$id,$fn)=&Apache::lonnet::decode_symb($last);
+	    $id=$hash{'map_pc_'.&Apache::lonnet::clutter($murl)}.'.'.$id;
+	    $newloc=$hash{'src_'.$id};
+	    if ($newloc) {
+                $usehttp = &check_http_req(\$newloc,$hostname);
+		if ($hash{'encrypted_'.$id}) { 
+                    $newloc=&Apache::lonenc::encrypted($newloc);
+                }
+                if ($newloc =~ m{^(/adm/wrapper/ext/[^\#]+)(?:|(\#[^\#]+))$}) {
+                    my ($url,$anchor) = ($1,$2);
+                    if ($anchor) {
+                        $newloc = $url.(($url=~/\?/)?'&':'?').'symb='.&escape($last).$anchor;
+                    }
+                }
+	    } else {
+		$newloc='/adm/navmaps';
+	    }
+            untie %hash;
+         } else {
+	    $newloc='/adm/navmaps';
+         }
+         if (($usehttp) && ($hostname ne '')) {
+             $newloc='http://'.$hostname.$newloc;
+         } else {
+             $newloc=&Apache::lonnet::absolute_url().$newloc
+         }
+         if ($reinitcheck eq 'update') {
+             $r->print(&reinited_js($newloc,$env{'request.course.id'},100));
+             $r->print(&Apache::loncommon::end_page());
+             return OK;
+         } else {
+	     &Apache::loncommon::content_type($r,'text/html');
+	     $r->header_out(Location => $newloc);
+	     return REDIRECT;
+         }
+      }
+#
+# Is the current URL on the map? If not, start with last known URL
+#
 
-# ---------------------------------------------------------------- Send headers
-                      if ($isxml) {
-			  $r->content_type('text/xml');
-                          $r->send_http_header;
-                          $r->print($xmlheader);
-		      } else {
-                          $r->content_type('text/html');
-                          $r->send_http_header;
-                          $r->print('<html>');
-		      }
-# ------------------------------------------------------------------------ Head
-                      $r->print("\n<head>\n".$allmeta);
-                      if ($allscript) {
-			  $r->print("\n<script>\n".$allscript."\n</script>\n");
+      unless (&Apache::lonnet::is_on_map($currenturl)) {
+         if ($preupdatepos) {
+             undef($preupdatepos);
+         } elsif (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'_symb.db',
+                            &GDBM_READER(),0640)) {
+             $last=$hash{'last_known'};
+             untie(%hash);
+         }
+         if ($last) {
+	     $currenturl=&Apache::lonnet::clutter((&Apache::lonnet::decode_symb($last))[2]);
+	 } else {
+             my $newloc = &Apache::lonnet::absolute_url().
+                          '/adm/navmaps'; 
+             if ($reinitcheck eq 'update') {
+                 &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+                 $r->print(&reinited_js($newloc,$env{'request.course.id'},100));
+                 $r->print(&Apache::loncommon::end_page());
+                 return OK;
+             } else {
+	         &Apache::loncommon::content_type($r,'text/html');
+	         $r->header_out(Location => $newloc); 
+	         return REDIRECT;
+             }
+         }
+      }
+# ------------------------------------------- Do we have any idea where we are?
+      my $position;
+      if ($preupdatepos) {
+          $position = $preupdatepos;
+      } else {
+          $position=Apache::lonnet::symbread($currenturl);
+      }
+      if ($position) {
+# ------------------------------------------------------------------------- Yes
+	  my ($startoutmap,$mapnum,$thisurl)=&Apache::lonnet::decode_symb($position);
+          $cachehash{$startoutmap}{$thisurl}=[$thisurl,$mapnum];
+          $cachehash{$startoutmap}{'last_known'}=
+                             [&Apache::lonnet::declutter($currenturl),$mapnum];
+
+# ============================================================ Tie the big hash
+          if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
+                        &GDBM_READER(),0640)) {
+              my $rid=$hash{'map_pc_'.&Apache::lonnet::clutter($startoutmap)}.
+                      '.'.$mapnum;
+
+# ------------------------------------------------- Move forward, backward, etc
+              my $endupmap;
+              ($next,$endupmap)=&move($rid,$startoutmap,$direction);
+# -------------------------------------- Do we have one and only one empty URL?
+# We are now at at least one non-empty URL
+# ----------------------------------------------------- Check out possibilities
+              if ($next) {
+                  @possibilities=split(/\,/,$next);
+                  if ($#possibilities==0) {
+# ---------------------------------------------- Only one possibility, redirect
+	              ($redirecturl,$redirectsymb,$enc,$anchor)=&hash_src($next);
+                      $cachehash{$endupmap}{$redirecturl}=
+			  [$redirecturl,(split(/\./,$next))[1]];
+                  } else {
+# ------------------------ There are multiple possibilities for a next resource
+                      $multichoice=1;
+		      foreach my $id (@possibilities) {
+			  $multichoicehash{'src_'.$id}=$hash{'src_'.$id};
+                          $multichoicehash{'title_'.$id}=$hash{'title_'.$id};
+                          $multichoicehash{'type_'.$id}=$hash{'type_'.$id};
+                          (my $first, my $second) = $id =~ /(\d+).(\d+)/;
+                          my $symbSrc = Apache::lonnet::declutter($hash{'src_'.$id});
+                          $multichoicehash{'symb_'.$id} = 
+                              Apache::lonnet::declutter($hash{'map_id_'.$first}.'___'.
+                                                        $second.'___'.$symbSrc);
+                                                         
+                          my ($choicemap,$choiceres)=split(/\./,$id);
+			  my $map=&Apache::lonnet::declutter($hash{'src_'.$choicemap});
+			  my $url=$multichoicehash{'src_'.$id};
+                          $cachehash{$map}{$url}=[$url,$choiceres];
                       }
-                      $r->print("\n</head>\n");
-# ------------------------------------------------------------------ Start body
-                      if ($isxml) {
-                          $r->print($xmlbody);
+                  }
+	      } else {
+# -------------------------------------------------------------- No place to go
+                  $multichoice=-1;
+                  if ($position && $env{'request.deeplink.login'}) {
+                      my ($map,$resid,$url) = &Apache::lonnet::decode_symb($position);
+                      my $mapid = $hash{'map_pc_'.&Apache::lonnet::clutter($map)};
+                      my $position_deeplink = $hash{'deeplinkonly_'.$mapid.'.'.$resid};
+                      if ($position_deeplink) {
+                          (my $value,$deeplinklevel) = map { &unescape($_); } 
+                                                       split(/:/,$position_deeplink);
+                      }
+                  }
+              }
+# ----------------- The program must come past this point to untie the big hash
+	      untie(%hash);
+# --------------------------------------------------------- Store position info
+              $cachehash{$startoutmap}{'last_direction'}=[$direction,'notasymb'];
+              foreach my $thismap (keys(%cachehash)) {
+		  my $mapnum=$cachehash{$thismap}->{'mapnum'};
+		  delete($cachehash{$thismap}->{'mapnum'});
+		  &Apache::lonnet::symblist($thismap,
+					    %{$cachehash{$thismap}});
+	      }
+# ============================================== Do not return before this line
+              if ($redirecturl) {
+# ----------------------------------------------------- There is a URL to go to
+		  if ($direction eq 'forward') {
+                     &Apache::lonnet::linklog($currenturl,$redirecturl);
+		  }
+		  if ($direction eq 'back') {
+                     &Apache::lonnet::linklog($redirecturl,$currenturl);
+		  }
+# ------------------------------------- Check for and display critical messages
+                  my ($redirect, $url) = &Apache::loncommon::critical_redirect(300,'flip');
+                  unless ($redirect) {
+                      my $usehttp = &check_http_req(\$redirecturl,$hostname);
+                      if (($usehttp) && ($hostname ne '')) {
+                          $url='http://'.$hostname.$redirecturl;
                       } else {
-			  $r->print('<body bgcolor="#FFFFFF">');
+                          $url=&Apache::lonnet::absolute_url().$redirecturl;
                       }
-# ------------------------------------------------------------------ Start form
-                      if ($nforms) {
-			  $r->print('<form method="post" action="'.
-				    $requrl.'">');
+                      my $addanchor;
+                      if (($anchor ne '') && (!$enc || $env{'request.role.adv'})) {
+                          $addanchor = 1;
+                          $url =~ s/\#.+$//;
                       }
-# ----------------------------------------------------------------- Start table
-                      $r->print('<table cols="'.$lcm.'" border="0">');
-                      for ($i=0;$i<=$#rows;$i++) {
-			if ($rows[$i]) {
-                          $r->print("\n<tr>");
-                          my @colcont=split(/\&/,$rows[$i]);
-                          my $avespan=$lcm/($#colcont+1);
-                          for ($j=0;$j<=$#colcont;$j++) {
-                              my $rid=$colcont[$j];
-                              $r->print('<td colspan="'.$avespan.'"');
-                              if ($cellemb{$rid} eq 'ssi') {
-				  if ($ssibgcolor{$rid}) {
-                                     $r->print(' bgcolor="'.
-                                               $ssibgcolor{$rid}.'"');
-                                  }
-                                  $r->print('><font');
-                                  if ($ssitext{$rid}) {
-				     $r->print(' text="'.$ssitext{$rid}.'"');
-                                  }
-                                  if ($ssilink{$rid}) {
-				     $r->print(' link="'.$ssilink{$rid}.'"');
-                                  }
-                                  if ($ssitext{$rid}) {
-				     $r->print(' vlink="'.$ssivlink{$rid}.'"');
-                                  }
-                                  if ($ssialink{$rid}) {
-				     $r->print(' alink="'.$ssialink{$rid}.'"');
-                                  }
-                            
-                                  $r->print('>'.$ssibody{$rid}.'</font>');
-                              } elsif ($cellemb{$rid} eq 'img') {
-                                  $r->print('><img src="'.
-                                    $hash{'src_'.$rid}.'"></img>');
-			      }
-                              $r->print('</td>');
+                      $url = &add_get_param($url, { 'symb' => $redirectsymb});
+                      if ($addanchor) {
+                          $url .= $anchor;
+                      }
+                  }
+                  if ($reinitcheck eq 'update') {
+                      &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+                      $r->print(&reinited_js($url,$env{'request.course.id'},100)); 
+                      $r->print(&Apache::loncommon::end_page());
+                      return OK;
+                  } else {
+                      &Apache::loncommon::content_type($r,'text/html');
+                      $r->header_out(Location => $url);
+                      return REDIRECT;
+                  }
+	      } else {
+# --------------------------------------------------------- There was a problem
+                  &Apache::loncommon::content_type($r,'text/html');
+                  $r->send_http_header;
+		  my %lt=&Apache::lonlocal::texthash('title' => 'End of Sequence',
+                                                     'deeplink' => 'No link available',
+                                                     'deeplinkres' =>
+                                                     'Navigation to other content is unavailable when accessing content via deep-linking',
+                                                     'deeplinkmap' =>
+                                                     'You have reached the end of the sequence of available materials for access via deep-linking',
+						     'explain' =>
+						     'You have reached the end of the sequence of materials.',
+						     'back' => 'Go Back',
+						     'nav' => 'Course Contents',
+						     'wherenext' =>
+						     'There are several possibilities of where to go next',
+						     'pick' =>
+						     'Please click on the the resource you intend to access',
+						     'titleheader' => 'Title',
+						     'type' => 'Type',
+                                                     'update' => 'Content updated',
+                                                     'expupdate' => 'As a result of a recent update to the sequence of materials, it is not possible to complete the page flip.',
+                                                     'gonav' => 'Go to the Contents page to select a resource to display.',
+                                                     );
+                  if (&Apache::loncommon::course_type() eq 'Community') {
+                      $lt{'nav'} = &mt('Community Contents');
+                  }
+                  if ($#possibilities>0) {
+		      my $start_page=
+			  &Apache::loncommon::start_page('Multiple Resources');
+                     $r->print(<<ENDSTART);
+$start_page
+<h3>$lt{'wherenext'}</h3>
+<p>
+$lt{'pick'}:
+<p>
+<table border="2">
+<tr><th>$lt{'titleheader'}</th><th>$lt{'type'}</th></tr>
+ENDSTART
+                     foreach my $id (@possibilities) {
+                        my $src = $multichoicehash{'src_'.$id};
+                        my $usehttp = &check_http_req(\$src,$hostname);
+                        if (($usehttp) && ($hostname ne '')) {
+                            $src = 'http://'.$hostname.$src;
+                        }
+                        $r->print(
+                              '<tr><td><a href="'.
+				  &add_get_param($src,
+						 {'symb' =>
+						      $multichoicehash{'symb_'.$id},
+						  }).'">'.
+                              $multichoicehash{'title_'.$id}.
+                              '</a></td><td>'.$multichoicehash{'type_'.$id}.
+			      '</td></tr>');
+                     }
+                     $r->print('</table>');
+                  } else {
+                      if ($reinitcheck) {
+                          if (&Apache::loncommon::course_type() eq 'Community') {
+                              $r->print(
+                                  &Apache::loncommon::start_page('Community Contents Updated'));
+                          } else { 
+                              $r->print(
+                                  &Apache::loncommon::start_page('Course Contents Updated'));
+                          }
+                          $r->print('<h2>'.$lt{'update'}.'</h2>'
+                                  .'<p>'.$lt{'expupdate'}.'<br />'
+                                  .$lt{'gonav'}.'</p>');
+                      } else {
+                          if (($env{'course.'.$env{'request.course.id'}.'.type'} eq 'Placement') && 
+                              (!$env{'request.role.adv'})) {
+                              my ($score,$incomplete) = &Apache::lonplacementtest::check_completion(undef,undef,1); 
+                              if ($incomplete) {
+                                  $r->print(&Apache::lonplacementtest::showincomplete($incomplete)); 
+                              } else {
+                                  $r->print(&Apache::lonplacementtest::showresult(1));
+                              }
+                          } else {
+                              $r->print(
+                                  &Apache::loncommon::start_page('No Resource'));
+                              if ($deeplinklevel eq 'resource') {
+                                  $r->print('<h2>'.$lt{'deeplink'}.'</h2>'
+                                           .'<p>'.$lt{'deeplinkres'}.'</p>');
+                              } elsif ($deeplinklevel eq 'map') {
+                                  $r->print('<h2>'.$lt{'title'}.'</h2>'
+                                           .'<p>'.$lt{'deeplinkmap'}.'</p>');
+                              } else {
+                                  $r->print('<h2>'.$lt{'title'}.'</h2>'
+                                           .'<p>'.$lt{'explain'}.'</p>');
+                              }
                           }
-                          $r->print('</tr>');
-		        }
                       }
-                      $r->print("\n</table>");
-# ---------------------------------------------------------------- Submit, etc.
-                      if ($nforms) {
+		  }
+                  unless (($env{'course.'.$env{'request.course.id'}.'.type'} eq 'Placement') &&
+                          (!$env{'request.role.adv'})) {
+                      if ($deeplinklevel) {
+                          $r->print(
+                              &Apache::lonhtmlcommon::actionbox(
+                                  ['<a href="/adm/flip?postdata=return:">'.$lt{'back'}.'</a>']));
+                      } elsif ((!@possibilities) && ($reinitcheck))  {
+                          $r->print(
+                              &Apache::lonhtmlcommon::actionbox(
+                                  ['<a href="/adm/navmaps">'.$lt{'nav'}.'</a></li>'
+                                  ]));
+                      } else {
                           $r->print(
-	                  '<input name="all_submit" value="Submit All" type="'.
-			  (($nforms>1)?'submit':'hidden').'"></input></form>');
+                              &Apache::lonhtmlcommon::actionbox(
+                                  ['<a href="/adm/flip?postdata=return:">'.$lt{'back'}.'</a></li>',
+                                   '<a href="/adm/navmaps">'.$lt{'nav'}.'</a></li>'
+                                  ]));
                       }
-                      $r->print('</body></html>');
-# -------------------------------------------------------------------- End page
-                  }                  
-# ------------------------------------------------------------- End render page
-              } else {
-                  $r->content_type('text/html');
-                  $r->send_http_header;
-		  $r->print('<html><body>Page undefined.</body></html>');
-              }
-# ------------------------------------------------------------------ Untie hash
-              unless (untie(%hash)) {
-                   &Apache::lonnet::logthis("<font color=blue>WARNING: ".
-                       "Could not untie coursemap $fn (browse).</font>"); 
-              }
-# -------------------------------------------------------------------- All done
-	      return OK;
-# ----------------------------------------------- Errors, hash could no be tied
+
+                  }
+                  $r->print(&Apache::loncommon::end_page());
+      
+                  return OK;
+	      }
+	  } else {
+# ------------------------------------------------- Problem, could not tie hash
+              if ($reinitcheck eq 'update') {
+                  &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+                  $r->print(&Apache::loncommon::end_page());
+              } 
+              $env{'user.error.msg'}="/adm/flip:bre:0:1:Course Data Missing";
+              return HTTP_NOT_ACCEPTABLE; 
           }
-      } 
-  }
-  $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
-  return HTTP_NOT_ACCEPTABLE; 
+      } else {
+# ---------------------------------------- No, could not determine where we are
+          my $newloc = '/adm/ambiguous';
+          if ($reinitcheck eq 'update') {
+              &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
+              $r->print(&reinited_js($newloc,$env{'request.course.id'},100));
+              $r->print(&Apache::loncommon::end_page());
+          } else {
+	      $r->internal_redirect($newloc);
+          }
+          return OK;
+      }
+  } else {
+# -------------------------- Class was not initialized or page fliped strangely
+      $env{'user.error.msg'}="/adm/flip:bre:0:0:Choose Course";
+      return HTTP_NOT_ACCEPTABLE; 
+  } 
 }
 
 1;
 __END__
 
+=pod
+
+=head1 NAME
+
+Apache::lonpageflip
+
+=head1 SYNOPSIS
+
+Deals with forward, backward, and other page flips.
+
+This is part of the LearningOnline Network with CAPA project
+described at http://www.lon-capa.org.
+
+=head1 OVERVIEW
+
+(empty)
+
+=head1 SUBROUTINES
+
+=over cleanup()
+
+=item addrid()
+
+=item fullmove()
+
+=item hash_src()
+
+=item move()
+
+=item get_next_possible_move()
+
+=item first_accessible_resource()
+
+=item handler()
+
+=back
+
+=cut