--- rat/lonpageflip.pm	2002/10/10 19:05:32	1.31
+++ rat/lonpageflip.pm	2022/10/19 00:03:12	1.112
@@ -2,7 +2,7 @@
 #
 # Page flip handler
 #
-# $Id: lonpageflip.pm,v 1.31 2002/10/10 19:05:32 www Exp $
+# $Id: lonpageflip.pm,v 1.112 2022/10/19 00:03:12 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,23 +26,19 @@
 #
 # http://www.lon-capa.org/
 #
-# (Page Handler
-#
-# (TeX Content Handler
-#
-# 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)
-#
-# 10/03,10/05,10/06,10/07,10/09,10/10,10/11,10/16,10/17,
-# 11/14,11/16,
-# 10/01/01,05/01,05/28,07/05 Gerd Kortemeyer
+
+
 
 package Apache::lonpageflip;
 
 use strict;
+use LONCAPA;
 use Apache::Constants qw(:common :http REDIRECT);
-use Apache::lonnet();
+use Apache::lonnet;
+use Apache::loncommon();
+use Apache::lonnavmaps();
+use Apache::lonuserstate;
+use Apache::lonlocal;
 use HTML::TokeParser;
 use GDBM_File;
 
@@ -50,6 +46,16 @@ use GDBM_File;
   
 my %hash;
 
+sub cleanup {
+    if (tied(%hash)){
+	&Apache::lonnet::logthis('Cleanup pageflip: hash');
+        unless (untie(%hash)) {
+	    &Apache::lonnet::logthis('Failed cleanup pageflip: hash');
+        }
+    }
+    return OK;
+}
+
 sub addrid {
     my ($current,$new,$condid)=@_;
     unless ($condid) { $condid=0; }
@@ -65,7 +71,7 @@ sub addrid {
 
 sub fullmove {
     my ($rid,$mapurl,$direction)=@_;
-    if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'.db',
+    if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
                         &GDBM_READER(),0640)) {
 	($rid,$mapurl)=&move($rid,$mapurl,$direction);
         untie(%hash);
@@ -73,7 +79,140 @@ sub fullmove {
     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,$endupmap);
+}
+
+sub get_next_possible_move {
     my ($rid,$mapurl,$direction)=@_;
     my $startoutrid=$rid;
 
@@ -83,71 +222,83 @@ sub move {
               my $posnext='';
               if ($direction eq 'forward') {
 # --------------------------------------------------------------------- Forward
-                  if ($hash{'type_'.$rid} eq 'finish') {
-	             $rid=$hash{'ids_'.&Apache::lonnet::clutter($mapurl)}; 
+                  while ($hash{'type_'.$rid} eq 'finish') {
+	             $rid=$hash{'ids_'.$hash{'map_id_'.(split(/\./,$rid))[0]}};
                   }
-                  map {
-                      my $thiscond=
-      &Apache::lonnet::directcondval($hash{'condid_'.$hash{'undercond_'.$_}});
-                      if ($thiscond>=$mincond) {
+		  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) {
-		             $posnext.=','.$_.':'.$thiscond;
+		             $posnext.=','.$id.':'.$thiscond;
                           } else {
-                             $posnext=$_.':'.$thiscond;
+                             $posnext=$id.':'.$thiscond;
 		          }
                           if ($thiscond>$mincond) { $mincond=$thiscond; }
 	              }
-                  } split(/\,/,$hash{'to_'.$rid});
-                  map {
-                      my ($linkid,$condval)=split(/\:/,$_);
+                  }
+		  foreach my $id (split(/\,/,$posnext))  {
+                      my ($linkid,$condval)=split(/\:/,$id);
                       if ($condval>=$mincond) {
 		          $next=&addrid($next,$hash{'goesto_'.$linkid},
                                 $hash{'condid_'.$hash{'undercond_'.$linkid}});
                       }
-                  } split(/\,/,$posnext);
+                  }
                   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
-                  if ($hash{'type_'.$rid} eq 'start') {
-	             $rid=$hash{'ids_'.&Apache::lonnet::clutter($mapurl)};
-                  }
-                  map {
-                      my $thiscond=
-      &Apache::lonnet::directcondval($hash{'condid_'.$hash{'undercond_'.$_}});
-                      if ($thiscond>=$mincond) {
-		          if ($posnext) {
-		             $posnext.=','.$_.':'.$thiscond;
-                          } else {
-                             $posnext=$_.':'.$thiscond;
-		          }
-                          if ($thiscond>$mincond) { $mincond=$thiscond; }
-	              }
-                  } split(/\,/,$hash{'from_'.$rid});
-                  map {
-                      my ($linkid,$condval)=split(/\:/,$_);
-                      if ($condval>=$mincond) {
-		          $next=&addrid($next,$hash{'comesfrom_'.$linkid},
-                                $hash{'condid_'.$hash{'undercond_'.$linkid}});
-                      }
-                  } split(/\,/,$posnext);
+                 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(/\./,$next))[0]) {
 # This comes back up from a map (going up one level);
@@ -157,6 +308,137 @@ sub move {
               return ($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 $result; 
+    } else {
+        return &first_accessible_resource(); 
+    }
+}
+
+sub check_http_req {
+    my ($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 $usehttp;
+}
+
+sub reinited_js {
+    my ($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
+}
+
+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;
+}
+
 # ================================================================ Main Handler
 
 sub handler {
@@ -165,70 +447,215 @@ sub handler {
 # ------------------------------------------- Set document type for header only
 
   if ($r->header_only) {
-     $r->content_type('text/html');
-     $r->send_http_header;
-     return OK;
+      &Apache::loncommon::content_type($r,'text/html');
+      $r->send_http_header;
+      return OK;
   }
 
   my %cachehash=(); 
   my $multichoice=0;
   my %multichoicehash=();
-  my $redirecturl='';
+  my %prog_state=();
+  my ($redirecturl,$redirectsymb,$enc,$anchor,$deeplinklevel);
   my $next='';
+  my $hostname = $r->hostname();
   my @possibilities=();
-  if (($ENV{'form.postdata'})&&($ENV{'request.course.fn'})) {
-      $ENV{'form.postdata'}=~/(\w+)\:(.*)/;
-      my $direction=$1;
-      my $currenturl=$2;
+   &Apache::loncommon::get_unprocessed_cgi($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') {
-# -------------------------------------------------------- Return to last known
-         my $last;
-         if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
+          if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'_symb.db',
                     &GDBM_READER(),0640)) {
-	     $last=$hash{'last_known'};
-             untie(%hash);
+              $last=$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);
+                  }
+              }
+              &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';
          }
-         my $newloc;
-         if ($last) {
-            $newloc=&Apache::lonnet::clutter((split(/\_\_\_/,$last))[1]);
+         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 {
-	    $newloc='/adm/noidea.html';
-         }  
-	 $r->content_type('text/html');
-         $r->header_out(Location => 
-			'http://'.$ENV{'HTTP_HOST'}.$newloc);
-                               
-         return REDIRECT;
+	     &Apache::loncommon::content_type($r,'text/html');
+	     $r->header_out(Location => $newloc);
+	     return REDIRECT;
+         }
       }
-      $currenturl=~s/^http\:\/\///;
-      $currenturl=~s/^[^\/]+//;
-      unless ($currenturl=~/^\/(res|adm\/wrapper|public|adm\/coursedocs)\//) {
-	 my $last;
-         if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
-                    &GDBM_READER(),0640)) {
-	     $last=$hash{'last_known'};
+#
+# Is the current URL on the map? If not, start with last known URL
+#
+
+      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) {
-	     $currenturl=&Apache::lonnet::clutter((split(/\_\_\_/,$last))[1]);
+	     $currenturl=&Apache::lonnet::clutter((&Apache::lonnet::decode_symb($last))[2]);
 	 } else {
-	     $r->content_type('text/html');
-             $r->header_out(Location => 
-                               'http://'.$ENV{'HTTP_HOST'}.'/adm/noidea.html');
-             return REDIRECT;
+             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 $position;
-      if ($position=Apache::lonnet::symbread($currenturl)) {
+      if ($preupdatepos) {
+          $position = $preupdatepos;
+      } else {
+          $position=Apache::lonnet::symbread($currenturl);
+      }
+      if ($position) {
 # ------------------------------------------------------------------------- Yes
-	  my ($startoutmap,$mapnum,$thisurl)=split(/\_\_\_/,$position);
-          $cachehash{$startoutmap}{$thisurl}=$mapnum;
+	  my ($startoutmap,$mapnum,$thisurl)=&Apache::lonnet::decode_symb($position);
+          $cachehash{$startoutmap}{$thisurl}=[$thisurl,$mapnum];
           $cachehash{$startoutmap}{'last_known'}=
-                                       &Apache::lonnet::declutter($currenturl);
+                             [&Apache::lonnet::declutter($currenturl),$mapnum];
 
 # ============================================================ Tie the big hash
-          if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'.db',
+          if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'.db',
                         &GDBM_READER(),0640)) {
               my $rid=$hash{'map_pc_'.&Apache::lonnet::clutter($startoutmap)}.
                       '.'.$mapnum;
@@ -237,124 +664,236 @@ sub handler {
               my $endupmap;
               ($next,$endupmap)=&move($rid,$startoutmap,$direction);
 # -------------------------------------- Do we have one and only one empty URL?
-              my $safecount=0;
-              while (($next) && ($next!~/\,/) && 
-                     ((!$hash{'src_'.$next}) || ($hash{'randomout_'.$next}))
-                     && ($safecount<10000)) {
-                  ($next,$endupmap)=&move($next,$endupmap,$direction);
-                  $safecount++;
-              }
 # We are now at at least one non-empty URL
 # ----------------------------------------------------- Check out possibilities
               if ($next) {
                   @possibilities=split(/\,/,$next);
                   if ($#possibilities==0) {
 # ---------------------------------------------- Only one possibility, redirect
-	              $redirecturl=$hash{'src_'.$next};
-                      $cachehash{$endupmap}
-                                {&Apache::lonnet::declutter($redirecturl)}
-		                                 =(split(/\./,$next))[1];
+	              ($redirecturl,$redirectsymb,$enc,$anchor)=&hash_src($next);
+                      $cachehash{$endupmap}{$redirecturl}=
+			  [$redirecturl,(split(/\./,$next))[1]];
                   } else {
 # ------------------------ There are multiple possibilities for a next resource
                       $multichoice=1;
-                      map {
-			  $multichoicehash{'src_'.$_}=$hash{'src_'.$_};
-                          $multichoicehash{'title_'.$_}=$hash{'title_'.$_};
-                          $multichoicehash{'type_'.$_}=$hash{'type_'.$_};
-                          my ($choicemap,$choiceres)=split(/\./,$_);
-                          $cachehash
-			 {&Apache::lonnet::declutter($hash{'src_'.$choicemap})}
-                         {&Apache::lonnet::declutter(
-						      $multichoicehash
-                                                         {'src_'.$_}
-                                                       )}
-		                                 =$choiceres;
-                      } @possibilities;
+		      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];
+                      }
                   }
 	      } 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;
-              foreach my $thismap (keys %cachehash) {
-                 &Apache::lonnet::symblist($thismap,%{$cachehash{$thismap}});
+              $cachehash{$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 ($redirecturl) {
 # ----------------------------------------------------- There is a URL to go to
-# ------------------------------------------------- Check for critical messages
-		  if ((time-$ENV{'user.criticalcheck.time'})>300) {
-                     my @what=&Apache::lonnet::dump
-                                  ('critical',$ENV{'user.domain'},
-                                              $ENV{'user.name'});
-                     if ($what[0]) {
-	                if (($what[0] ne 'con_lost') && 
-                            ($what[0]!~/^error\:/)) {
-	                   $redirecturl='/adm/email?critical=display';
-                        }
-                     }
-                     &Apache::lonnet::appenv('user.criticalcheck.time'=>time);
+		  if ($direction eq 'forward') {
+                     &Apache::lonnet::linklog($currenturl,$redirecturl);
 		  }
-
-		  $r->content_type('text/html');
-                  $r->header_out(Location => 
-                                'http://'.$ENV{'HTTP_HOST'}.$redirecturl);
-                  return REDIRECT;
+		  if ($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 {
+                          $url=&Apache::lonnet::absolute_url().$redirecturl;
+                      }
+                      my $addanchor;
+                      if (($anchor ne '') && (!$enc || $env{'request.role.adv'})) {
+                          $addanchor = 1;
+                          $url =~ s/\#.+$//;
+                      }
+                      $url = &add_get_param($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
-                  $r->content_type('text/html');
+                  &Apache::loncommon::content_type($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');
                      $r->print(<<ENDSTART);
-<head><title>Choose Next Location</title></head>
-<body bgcolor="#FFFFFF">
-<h1>LON-CAPA</h1>
-There are several possibilities of where to go next.
+$start_page
+<h3>$lt{'wherenext'}</h3>
 <p>
-Please click on the the resource you intend to access:
+$lt{'pick'}:
 <p>
-<table border=2>
-<tr><th>Title</th><th>Type</th></tr>
+<table border="2">
+<tr><th>$lt{'titleheader'}</th><th>$lt{'type'}</th></tr>
 ENDSTART
-                     foreach (@possibilities) {
+                     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="'.
-                              $multichoicehash{'src_'.$_}.'">'.
-                              $multichoicehash{'title_'.$_}.
-                              '</a></td><td>'.$multichoicehash{'type_'.$_}.
+				  &add_get_param($src,
+						 {'symb' =>
+						      $multichoicehash{'symb_'.$id},
+						  }).'">'.
+                              $multichoicehash{'title_'.$id}.
+                              '</a></td><td>'.$multichoicehash{'type_'.$id}.
 			      '</td></tr>');
                      }
-                     $r->print('</table></body></html>');
-		     return OK;
+                     $r->print('</table>');
                   } else {
-                     $r->print(<<ENDNONE);
-<head><title>Choose Next Location</title></head>
-<body bgcolor="#FFFFFF">
-<img src="/adm/lonIcons/lonlogos.gif" align=right>
-<h1>Sorry!</h1>
-<h2>Next resource could not be identified.</h2>
-<h3>You probably are at the beginning or the end of the course.</h3>
-</body>
-</html>
-ENDNONE
-                     return OK;
-	         }
-	     }
+                      if ($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>'.$lt{'explain'}.'</p>');
+                              }
+                          }
+                      }
+		  }
+                  unless (($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 {
+                          $r->print(
+                              &Apache::lonhtmlcommon::actionbox(
+                                  ['<a href="/adm/flip?postdata=return:">'.$lt{'back'}.'</a></li>',
+                                   '<a href="/adm/navmaps">'.$lt{'nav'}.'</a></li>'
+                                  ]));
+                      }
+
+                  }
+                  $r->print(&Apache::loncommon::end_page());
+      
+                  return OK;
+	      }
 	  } else {
 # ------------------------------------------------- Problem, could not tie hash
-              $ENV{'user.error.msg'}="/adm/flip:bre:0:1:Course Data Missing";
+              if ($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; 
           }
       } else {
 # ---------------------------------------- No, could not determine where we are
-         $r->internal_redirect('/adm/ambiguous');
+          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";
+      $env{'user.error.msg'}="/adm/flip:bre:0:0:Choose Course";
       return HTTP_NOT_ACCEPTABLE; 
   } 
 }
@@ -362,6 +901,44 @@ ENDNONE
 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