--- rat/lonsequence.pm	2003/09/22 03:02:06	1.16
+++ rat/lonsequence.pm	2005/03/01 00:22:57	1.23
@@ -2,7 +2,7 @@
 #
 # Sequence Handler
 #
-# $Id: lonsequence.pm,v 1.16 2003/09/22 03:02:06 www Exp $
+# $Id: lonsequence.pm,v 1.23 2005/03/01 00:22:57 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -28,13 +28,6 @@
 #
 # (Handler to resolve ambiguous file locations
 #
-# (TeX Content Handler
-#
-# 05/29/00,05/30,10/11 Gerd Kortemeyer)
-#
-# 10/11,10/12 Gerd Kortemeyer)
-#
-# 10/16 Gerd Kortemeyer
 
 package Apache::lonsequence;
 
@@ -246,6 +239,8 @@ sub handler {
 # ------------------------------------------------------------ Tie symb db file
   my $disurl='';
   my $dismapid='';
+  my $exitdisid = '';
+  my $arrow_dir = '';
 
   if (($ENV{'request.course.fn'}) && (!$ENV{'form.forceselect'})) {
        my $last;
@@ -257,24 +252,32 @@ sub handler {
        my $direction='';
        my $prevmap='';
        if ($last) {
-	  ($prevmap,$direction)=(split(/\_\_\_/,$last));
+	   ($prevmap,undef,$direction)=&Apache::lonnet::decode_symb($last);
        }
 # ------------------------------------------------------------- Tie big db file
        if (tie(%bighash,'GDBM_File',$ENV{'request.course.fn'}.'.db',
                     &GDBM_READER(),0640)) {
 	   my $disid='';
+           my $randomout ='';
 
            if ($direction eq 'back') {
 	       $disid=$bighash{'map_finish_'.$requrl};
            } else {
                $disid=$bighash{'map_start_'.$requrl};
-           } 
+           }
            if ($disid) {
 	       $disurl=$bighash{'src_'.$disid};
                $dismapid=(split(/\./,$disid))[1];
+               $randomout = $bighash{'randomout_'.$disid};
+           } elsif (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
+                    &GDBM_READER(),0640)) {
+               $last=$hash{'last_known'};
+               untie(%hash);
            }
-# ------------------------- If this is an empty one, skip to next non-empty one
-           if ((!$disurl) && ($disid)) {
+
+
+# ----------- If this is an empty one, or hidden, skip to next non-empty or non-hidden one
+           while ( ((!$disurl) && ($disid)) || ($randomout && $disid) ) {
 	       $direction=($direction?$direction:'forward');
                ($disid,$requrl)=
                          &Apache::lonpageflip::fullmove($disid,
@@ -282,8 +285,11 @@ sub handler {
                if ($disid) {
 	           $disurl=$bighash{'src_'.$disid};
                    $dismapid=(split(/\./,$disid))[1];
+                   $randomout = $bighash{'randomout_'.$disid};
                }
  	   }
+           $exitdisid = $disid;
+           $arrow_dir = $direction;
 
 # --------------------------------------- Untie hash, make sure to come by here
            untie(%bighash);
@@ -291,18 +297,48 @@ sub handler {
    }
 
 # now either disurl is set (going to first page), or we need another display
-
    if ($disurl) {
 # -------------------------------------------------- Has first or last resource
-      &Apache::lonnet::symblist($requrl,$disurl => $dismapid,
-                   'last_known' => &Apache::lonnet::declutter($disurl)); 
+      &Apache::lonnet::symblist($requrl,$disurl => [$disurl,$dismapid],
+				'last_known' => [$disurl,$dismapid]); 
       &Apache::loncommon::content_type($r,'text/html');
       $r->header_out(Location => 'http://'.$ENV{'HTTP_HOST'}.$disurl);
       return REDIRECT;
    } else {
        &Apache::loncommon::content_type($r,'text/html');
        $r->send_http_header;
-       &viewmap($r,$requrl);
+       if ($exitdisid eq '' && $arrow_dir ne '') {
+           my %lt =&Apache::lonlocal::texthash(
+                   'back' => 'beginning',
+                   'forward' => 'end',
+                   'emfo' => 'Empty Folder/Sequence',
+                   'nere' => 'Next resource could not be displayed',
+                   'goba' => 'Go Back',
+                   'nacc' => 'Navigate Course Content',
+                          );
+           my $warnmsg = 'As all folders and sequences ';
+           if ($arrow_dir eq 'forward') {
+               $warnmsg .= &mt('following the current resource were empty').',';
+           } elsif ($arrow_dir eq 'back') {
+               $warnmsg .= &mt('preceding the current resource were empty').',';
+           }
+           $warnmsg .= &mt('you have now reached the').' '.$lt{$arrow_dir}.' '.&mt('of the course.');
+           my $bodytag=&Apache::loncommon::bodytag('Empty Folder/Sequence');
+           $r->print(<<ENDNONE);
+<head><title>$lt{'emfo'}</title></head>
+$bodytag
+<h3>$lt{'nere'}</h3>
+<p>$warnmsg</p>
+<ul>
+  <li><a href="javascript:history.go(-1)">$lt{'goba'}</a></li>
+  <li><a href="/adm/navmaps">$lt{'nacc'}</a></li>
+</ul>
+</body>
+ </html>
+ENDNONE
+       } else {
+           &viewmap($r,$requrl);
+       }
        return OK;
    }
 }