# The LearningOnline Network with CAPA
# Navigate Maps Handler
#
# (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,
# 10/02,10/10,10/14,10/16,10/18,10/19,10/31,11/6,11/14,11/16 Gerd Kortemeyer)
#
# 3/1/1,6/1 Gerd Kortemeyer

package Apache::lonnavmaps;

use strict;
use Apache::Constants qw(:common :http);
use Apache::lonnet();
use HTML::TokeParser;
use GDBM_File;

# -------------------------------------------------------------- Module Globals
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})) {
           $sofar++;      
           if (defined($rows[$sofar])) {
              $rows[$sofar].='&h'.$rid;
           } else {
              $rows[$sofar]='h'.$rid;
           }
           if ((defined($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})) {
	  my $mincond=1;
          my $next='';
          map {
              my $thiscond=
      &Apache::lonnet::directcondval($hash{'condid_'.$hash{'undercond_'.$_}});
              if ($thiscond>=$mincond) {
		  if ($next) {
		      $next.=','.$_.':'.$thiscond;
                  } else {
                      $next=$_.':'.$thiscond;
		  }
                  if ($thiscond>$mincond) { $mincond=$thiscond; }
	      }
          } split(/\,/,$hash{'to_'.$rid});
          map {
              my ($linkid,$condval)=split(/\:/,$_);
              if ($condval>=$mincond) {
                my $now=&tracetable($sofar,$hash{'goesto_'.$linkid},$beenhere);
                if ($now>$further) { $further=$now; }
	      }
          } split(/\,/,$next);

       }
    }
    return $further;
}

# ================================================================ Main Handler

sub handler {
  my $r=shift;


# ------------------------------------------- Set document type for header only

  if ($r->header_only) {
       if ($ENV{'browser.mathml'}) {
           $r->content_type('text/xml');
       } else {
           $r->content_type('text/html');
       }
       $r->send_http_header;
       return OK;
   }

  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_/res/'.$ENV{'request.course.uri'}};
              my $lastres=$hash{'map_finish_/res/'.$ENV{'request.course.uri'}};
              if (($firstres) && ($lastres)) {
# ----------------------------------------------------------------- Render page

                  @rows=();

                  &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;
		     }
		  }

# ------------------------------------------------------------------ Page parms

                  my $j;
                  my $i;
                  my $lcm=1;
                  my $contents=0;

# ---------------------------------------------- Go through table to get layout

                  for ($i=0;$i<=$#rows;$i++) {
		     if ($rows[$i]) {
		      $contents++;
                      my @colcont=split(/\&/,$rows[$i]);
                      $lcm*=($#colcont+1)/euclid($lcm,($#colcont+1));
                     } 
                  }


                  unless ($contents) {
                      $r->content_type('text/html');
                      $r->send_http_header;
                      $r->print('<html><body>Empty Map.</body></html>');
                  } else {
# ------------------------------------------------------------------ Build page

# ---------------------------------------------------------------- Send headers

                          $r->content_type('text/html');
                          $r->send_http_header;
                          $r->print(
                   '<html><head><title>Navigate LON-CAPA Maps</title></head>');

			  $r->print('<body bgcolor="#FFFFFF">'.
                           '<img align=right src=/adm/lonIcons/lonlogos.gif>'.
                                    '<h1>Navigate Course Map</h1>');
                          $r->rflush();
# ----------------------------------------------------------------- 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];
                              my $add='<td>&nbsp;&nbsp;';
                              if ($rid=~/^h(.+)/) {
				  $rid=$1;
                                  $add='<th bgcolor="#AAFF55">';
                              }
                              $r->print($add.'<a href="'.
                                $hash{'src_'.$rid}.'">'.
                                $hash{'title_'.$rid}.'</a>');
                              $r->print('</td>');
                          }
                          $r->print('</tr>');
		        }
                      }
                      $r->print("\n</table>");

                      $r->print('</body></html>');
# -------------------------------------------------------------------- End page
                  }                  
# ------------------------------------------------------------- End render page
              } else {
                  $r->content_type('text/html');
                  $r->send_http_header;
		  $r->print('<html><body>Coursemap 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
          }
      } 
  }

  $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
  return HTTP_NOT_ACCEPTABLE; 
}

1;
__END__