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# The LearningOnline Network with CAPA
# Construct and maintain state and binary representation of course for user
#
# $Id: lonuserstate.pm,v 1.32 2002/06/27 14:08:26 www Exp $
#
# Copyright Michigan State University Board of Trustees
#
# 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/
#
# (Server for RAT Maps
#
# (Edit Handler for RAT Maps
# (TeX Content Handler
#
# YEAR=2000
# 05/29/00,05/30 Gerd Kortemeyer)
# 7/1 Gerd Kortemeyer)
# 7/1,7/3,7/4,7/7,7/8,7/10 Gerd Kortemeyer)
#
# 7/15,7/17,7/18,8/1,8/2,8/4,8/5,8/21,8/22,8/23,8/30,
# 9/2,9/4,9/29,9/30,10/2,10/11,10/30,10/31,
# 11/1,11/2,11/14,11/16,11/22,12/28,
# YEAR=2001
# 07/05/01,08/30,08/31 Gerd Kortemeyer
# 12/16 Scott Harrison
#
###

package Apache::lonuserstate;

# ------------------------------------------------- modules used by this module
use strict;
use Apache::Constants qw(:common :http);
use Apache::File;
use HTML::TokeParser;
use Apache::lonnet();
use Apache::loncommon();
use GDBM_File;
use Apache::lonmsg;
use Safe;
use Safe::Hole;
use Opcode;

# ---------------------------------------------------- Globals for this package

my $pc;      # Package counter
my %hash;    # The big tied hash
my %parmhash;# The hash with the parameters
my @cond;    # Array with all of the conditions
my $errtext; # variable with all errors
my $retfurl; # variable with the very first URL in the course
my %randompick; # randomly picked resources
# --------------------------------------------------------- Loads map from disk

sub loadmap { 
    my $uri=shift;
    if ($hash{'map_pc_'.$uri}) { return OK; }

    $pc++;
    my $lpc=$pc;
    $hash{'map_pc_'.$uri}=$lpc;
    $hash{'map_id_'.$lpc}=$uri;

    my $fn='/home/httpd/html'.$uri;

    unless (($fn=~/\.sequence$/) ||
            ($fn=~/\.page$/)) { 
       $errtext.="Invalid map: $fn\n";
       return OK; 
    }

    my $ispage=($fn=~/\.page$/);

    unless (-e $fn) {
	my $returned=Apache::lonnet::repcopy($fn);
        unless ($returned eq OK) {
           $errtext.="Could not import: $fn - ";
           if ($returned eq HTTP_SERVICE_UNAVAILABLE) {
	      $errtext.="Server unavailable\n";
           }
           if ($returned eq HTTP_NOT_FOUND) {
	      $errtext.="File not found\n";
           }
           if ($returned eq FORBIDDEN) {
	      $errtext.="Access forbidden\n";
           }
           return OK;
       }
    }

    if (-e $fn) {
        my @content;
        {
	    my $fh=Apache::File->new($fn);
            @content=<$fh>;
        }
        my $instr=join('',@content);
        my $parser = HTML::TokeParser->new(\$instr);
        my $token;

        my $linkpc=0;

        $fn=~/\.(\w+)$/;

        $hash{'map_type_'.$lpc}=$1;

        while ($token = $parser->get_token) {
	    if ($token->[0] eq 'S') {
                if ($token->[1] eq 'resource') {
# -------------------------------------------------------------------- Resource

                    my $rid=$lpc.'.'.$token->[2]->{'id'};

                    $hash{'kind_'.$rid}='res';
                    $hash{'title_'.$rid}=$token->[2]->{'title'};
                    my $turi=$token->[2]->{'src'};
                    unless ($ispage) {
                        $turi=~/\.(\w+)$/;
                        my $embstyle=&Apache::loncommon::fileembstyle($1);
                        if ($token->[2]->{'external'} eq 'true') {
                            $turi=~s/^http\:\/\//\/adm\/wrapper\/ext\//;
                        } else {
                           my $embstyle=&Apache::loncommon::fileembstyle($1);
                           if (($embstyle eq 'img') || ($embstyle eq 'emb')) {
			       $turi='/adm/wrapper'.$turi;
                           }
                        }
		    }
                    $hash{'src_'.$rid}=$turi;

                    if (defined($hash{'ids_'.$turi})) {
                        $hash{'ids_'.$turi}.=','.$rid;
                    } else {
                        $hash{'ids_'.$turi}=''.$rid;
                    }

                    if ($token->[2]->{'external'} eq 'true') {
                        $hash{'ext_'.$rid}='true:';
                    } else {
                        $hash{'ext_'.$rid}='false:';
                    }
                    if ($token->[2]->{'type'}) {
			$hash{'type_'.$rid}=$token->[2]->{'type'};
                        if ($token->[2]->{'type'} eq 'start') {
			    $hash{'map_start_'.$uri}="$rid";
                        }
                        if ($token->[2]->{'type'} eq 'finish') {
			    $hash{'map_finish_'.$uri}="$rid";
                        }
                    }  else {
                        $hash{'type_'.$rid}='normal';
                    }

                    if (($turi=~/\.sequence$/) ||
                        ($turi=~/\.page$/)) {
                        $hash{'is_map_'.$rid}=1;
                        &loadmap($turi);
                    } 
                    
                } elsif ($token->[1] eq 'condition') {
# ------------------------------------------------------------------- Condition

                    my $rid=$lpc.'.'.$token->[2]->{'id'};

                    $hash{'kind_'.$rid}='cond';
                    $cond[$#cond+1]=$token->[2]->{'value'};
                    $hash{'condid_'.$rid}=$#cond;
                    if ($token->[2]->{'type'}) {
                        $cond[$#cond].=':'.$token->[2]->{'type'};
                    }  else {
                        $cond[$#cond].=':normal';
                    }

                } elsif ($token->[1] eq 'link') {
# ----------------------------------------------------------------------- Links

                    $linkpc++;
                    my $linkid=$lpc.'.'.$linkpc;

                    my $goesto=$lpc.'.'.$token->[2]->{'to'};
                    my $comesfrom=$lpc.'.'.$token->[2]->{'from'};
                    my $undercond=0;

                    if ($token->[2]->{'condition'}) {
			$undercond=$lpc.'.'.$token->[2]->{'condition'};
                    }

                    $hash{'goesto_'.$linkid}=$goesto;
                    $hash{'comesfrom_'.$linkid}=$comesfrom;
                    $hash{'undercond_'.$linkid}=$undercond;

                    if (defined($hash{'to_'.$comesfrom})) {
                        $hash{'to_'.$comesfrom}.=','.$linkid;
                    } else {
                        $hash{'to_'.$comesfrom}=''.$linkid;
                    }
                    if (defined($hash{'from_'.$goesto})) {
                        $hash{'from_'.$goesto}.=','.$linkid;
                    } else {
                        $hash{'from_'.$goesto}=''.$linkid;
                    }
                } elsif ($token->[1] eq 'param') {
# ------------------------------------------------------------------- Parameter

                    my $referid=$lpc.'.'.$token->[2]->{'to'};
                    my $part=$token->[2]->{'part'};
                    unless ($part) { $part=0; }
                    my $newparam=
			&Apache::lonnet::escape($token->[2]->{'type'}).':'.
			&Apache::lonnet::escape($part.'.'.
                         $token->[2]->{'name'}).'='.
			&Apache::lonnet::escape($token->[2]->{'value'});
                    if (defined($hash{'param_'.$referid})) {
                        $hash{'param_'.$referid}.='&'.$newparam;
                    } else {
                        $hash{'param_'.$referid}=''.$newparam;
                    }
                    if ($token->[2]->{'name'} eq 'parameter_mapalias') {
			$hash{'mapalias_'.$token->[2]->{'value'}}=$referid;
                    }
                    if ($token->[2]->{'name'} eq 'parameter_randompick') {
			$randompick{$referid}=$token->[2]->{'value'};
                    }
                } 

            }
        }

    } else {
        $errtext.='Map not loaded: The file does not exist. ';
    }
}

# --------------------------------------------------------- Simplify expression

sub simplify {
   my $expression=shift;
# (8)=8
   $expression=~s/\((\d+)\)/$1/g;
# 8&8=8
   $expression=~s/(\D)(\d+)\&\2(\D)/$1$2$3/g;
# 8|8=8
   $expression=~s/(\D)(\d+)\|\2(\D)/$1$2$3/g;
# (5&3)&4=5&3&4
   $expression=~s/\((\d+)((?:\&\d+)+)\)\&(\d+\D)/$1$2\&$3/g;
# (((5&3)|(4&6)))=((5&3)|(4&6))
   $expression=~
       s/\((\(\(\d+(?:\&\d+)*\)(?:\|\(\d+(?:\&\d+)*\))+\))\)/$1/g;
# ((5&3)|(4&6))|(1&2)=(5&3)|(4&6)|(1&2)
   $expression=~
       s/\((\(\d+(?:\&\d+)*\))((?:\|\(\d+(?:\&\d+)*\))+)\)\|(\(\d+(?:\&\d+)*\))/\($1$2\|$3\)/g;
   return $expression;
}

# -------------------------------------------------------- Build condition hash

sub traceroute {
    my ($sofar,$rid,$beenhere)=@_;
    $sofar=simplify($sofar);
    unless ($beenhere=~/\&$rid\&/) {
       $beenhere.=$rid.'&';  
       if ($retfurl eq '') {
           my ($mapid,$resid)=split(/\./,$rid);
           $retfurl=$hash{'src_'.$rid}.'?symb='.
           &Apache::lonnet::symbclean(
                           &Apache::lonnet::declutter($hash{'map_id_'.$mapid}).
                           '___'.$resid.'___'.
                           &Apache::lonnet::declutter($hash{'src_'.$rid}));
       }
       if (defined($hash{'conditions_'.$rid})) {
	   $hash{'conditions_'.$rid}=simplify(
           '('.$hash{'conditions_'.$rid}.')|('.$sofar.')');
       } else {
           $hash{'conditions_'.$rid}=$sofar;
       }
       if (defined($hash{'is_map_'.$rid})) {
           if (defined($hash{'map_start_'.$hash{'src_'.$rid}})) {
	       &traceroute($sofar,$hash{'map_start_'.$hash{'src_'.$rid}},'&');
               if (defined($hash{'map_finish_'.$hash{'src_'.$rid}})) {
		   $sofar=
                  $hash{'conditions_'.$hash{'map_finish_'.$hash{'src_'.$rid}}};
               }
           }
       }
       if (defined($hash{'to_'.$rid})) {
          foreach (split(/\,/,$hash{'to_'.$rid})) {
		my $further=$sofar;
                if ($hash{'undercond_'.$_}) {
		   if (defined($hash{'condid_'.$hash{'undercond_'.$_}})) {
  		       $further=simplify('('.$further.')&('.
                              $hash{'condid_'.$hash{'undercond_'.$_}}.')');
		   } else {
                       $errtext.='Undefined condition ID: '
                                 .$hash{'undercond_'.$_}.'. ';
                   }
                }
                &traceroute($further,$hash{'goesto_'.$_},$beenhere);
          }
       }
    }
}

# ------------------------------ Cascading conditions, quick access, parameters

sub accinit {
    my ($uri,$short,$fn)=@_;
    my %acchash=();
    my %captured=();
    my $condcounter=0;
    $acchash{'acc.cond.'.$short.'.0'}=0;
    foreach (keys %hash) {
       if ($_=~/^conditions/) {
	  my $expr=$hash{$_};
         foreach ($expr=~m/(\(\(\d+(?:\&\d+)+\)(?:\|\(\d+(?:\&\d+)+\))+\))/g) {
             my $sub=$_;
             my $orig=$_;
      $sub=~/\(\((\d+\&(:?\d+\&)*)(?:\d+\&*)+\)(?:\|\(\1(?:\d+\&*)+\))+\)/;
             my $factor=$1;
             $sub=~s/$factor//g;
             $sub=~s/^\(/\($factor\(/;
	     $sub.=')';
             $sub=simplify($sub);
             $orig=~s/(\W)/\\$1/g;
 	     $expr=~s/$orig/$sub/;
	  }
          $hash{$_}=$expr;
          unless (defined($captured{$expr})) {
	      $condcounter++;
              $captured{$expr}=$condcounter;
              $acchash{'acc.cond.'.$short.'.'.$condcounter}=$expr;
          } 
       } elsif ($_=~/^param_(\d+)\.(\d+)/) {
          my $prefix=&Apache::lonnet::declutter($hash{'map_id_'.$1}).
      '___'.$2.'___'.&Apache::lonnet::declutter($hash{'src_'.$1.'.'.$2});
          foreach (split(/\&/,$hash{$_})) {
	     my ($typename,$value)=split(/\=/,$_);
             my ($type,$name)=split(/\:/,$typename);
             $parmhash{$prefix.'.'.&Apache::lonnet::unescape($name)}=
                                   &Apache::lonnet::unescape($value);
	     $parmhash{$prefix.'.'.&Apache::lonnet::unescape($name).'.type'}=
                                   &Apache::lonnet::unescape($type);
          }
       }
    }
    foreach (keys %hash) {
	if ($_=~/^ids/) {
	  foreach (split(/\,/,$hash{$_})) {
	    my $resid=$_;
            my $uri=$hash{'src_'.$resid};
            $uri=~s/^\/adm\/wrapper//;
            my @uriparts=split(/\//,$uri);
            my $urifile=$uriparts[$#uriparts];
            $#uriparts--;
            my $uripath=join('/',@uriparts);
            $uripath=~s/^\/res\///;
           if ($uripath) {
            my $uricond='0';
            if (defined($hash{'conditions_'.$resid})) {
 		$uricond=$captured{$hash{'conditions_'.$resid}};
            }
            if (defined($acchash{'acc.res.'.$short.'.'.$uripath})) {
                if ($acchash{'acc.res.'.$short.'.'.$uripath}=~
                   /(\&$urifile\:[^\&]*)/) {
		    my $replace=$1;
                    my $regexp=$replace;
                    $regexp=~s/\|/\\\|/g;
                    $acchash{'acc.res.'.$short.'.'.$uripath}
                     =~s/$regexp/$replace\|$uricond/;
                } else {
		   $acchash{'acc.res.'.$short.'.'.$uripath}.=
                     $urifile.':'.$uricond.'&';
	        }
            } else {
                $acchash{'acc.res.'.$short.'.'.$uripath}=
                 '&'.$urifile.':'.$uricond.'&';
            }
           } 
         }
      }
    }
    $acchash{'acc.res.'.$short.'.'}='&:0&';
    my $courseuri=$uri;
    $courseuri=~s/^\/res\///;
    &Apache::lonnet::delenv('(acc\.|httpref\.)');
    &Apache::lonnet::appenv(%acchash,
                            "request.course.id"  => $short,
                            "request.course.fn"  => $fn,
                            "request.course.uri" => $courseuri); 
}

# ------------------------------------- Selectively delete from randompick maps

sub pickrandom {
    my $randomoutentry='';
    foreach my $rid (keys %randompick) {
        my $rndpick=$randompick{$rid};
        my $mpc=$hash{'map_pc_'.$hash{'src_'.$rid}};
# ------------------------------------------- put existing resources into array
        my @currentrids=();
        foreach (keys %hash) {
	    if ($_=~/^src_($mpc\.\d+)/) {
		if ($hash{'src_'.$1}) { push @currentrids, $1; }
            }
        }
        next if ($#currentrids<$rndpick);
# -------------------------------- randomly eliminate the ones that should stay
	srand(&Apache::lonnet::rndseed($rid)); # use rid instead of symb
        for (my $i=1;$i<=$#currentrids+1-$rndpick;$i++) {
            while (1) {
		my $randomidx=int(rand($#currentrids+1));
                if ($currentrids[$randomidx]) {
		    $currentrids[$randomidx]='';
                    last;
                }
            }
        }
# -------------------------------------------------------- delete the leftovers
        for (my $k=0; $k<=$#currentrids; $k++) {
            if ($currentrids[$k]) {
		$hash{'randomout_'.$currentrids[$k]}=1;
                my ($mapid,$resid)=split(/\./,$currentrids[$k]);
                $randomoutentry.='&'.
                 &Apache::lonnet::symbclean(
		    &Apache::lonnet::declutter($hash{'map_id_'.$mapid}).
                    '___'.$resid.'___'.
		    &Apache::lonnet::declutter($hash{'src_'.$currentrids[$k]})
                 ).'&';
            }
        }
    }
    if ($randomoutentry) {
	&Apache::lonnet::appenv('acc.randomout' => $randomoutentry);
    }
}

# ---------------------------------------------------- Read map and all submaps

sub readmap {
   my $short=shift;
   $short=~s/^\///;
   my %cenv=&Apache::lonnet::coursedescription($short);
   my $fn=$cenv{'fn'};
   my $uri;
   $short=~s/\//\_/g;
   unless ($uri=$cenv{'url'}) { 
      &Apache::lonnet::logthis("<font color=blue>WARNING: ".
                       "Could not load course $short.</font>"); 
      return 'No course data available.';
   }
   @cond=('true:normal');
   unlink($fn.'.db');
   unlink($fn.'_symb.db');
   unlink($fn.'.state');
   unlink($fn.'parms.db');
   undef %randompick;
   $retfurl='';
   if ((tie(%hash,'GDBM_File',"$fn.db",&GDBM_WRCREAT,0640)) &&
       (tie(%parmhash,'GDBM_File',$fn.'_parms.db',&GDBM_WRCREAT,0640))) {
    %hash=();
    %parmhash=();
    $errtext='';
    $pc=0;
    my $furi='/res/'.&Apache::lonnet::declutter($uri);
    $hash{'src_0.0'}=$furi;
    $hash{'title_0.0'}=&Apache::lonnet::metadata($uri,'title');
    $hash{'ids_'.$furi}='0.0';
    $hash{'is_map_0.0'}=1;
    loadmap($uri);
    if (defined($hash{'map_start_'.$uri})) {
        &traceroute('0',$hash{'map_start_'.$uri},'&');
        &accinit($uri,$short,$fn);
        &pickrandom();
    }
    unless ((untie(%hash)) && (untie(%parmhash))) {
      &Apache::lonnet::logthis("<font color=blue>WARNING: ".
                       "Could not untie coursemap $fn for $uri.</font>"); 
    }
    {
     my $cfh;
     if ($cfh=Apache::File->new(">$fn.state")) {
        print $cfh join("\n",@cond);
     } else {
      &Apache::lonnet::logthis("<font color=blue>WARNING: ".
                       "Could not write statemap $fn for $uri.</font>"); 
     }
    }  
   } else {
      &Apache::lonnet::logthis("<font color=blue>WARNING: ".
                       "Could not tie coursemap $fn for $uri.</font>"); 
   }
   &Apache::lonmsg::author_res_msg($ENV{'request.course.uri'},$errtext);
   return ($retfurl,$errtext);
}

# ------------------------------------------------------- Evaluate state string

sub evalstate {

    my $fn=$ENV{'request.course.fn'}.'.state';
    my $state='2';
    if (-e $fn) {
       my @conditions=();
       {
        my $fh=Apache::File->new($fn);
        @conditions=<$fh>;
       }  
       my $safeeval = new Safe;
       my $safehole = new Safe::Hole;
       $safeeval->permit("entereval");
       $safeeval->permit(":base_math");
       $safeeval->deny(":base_io");
       $safehole->wrap(\&Apache::lonnet::EXT,$safeeval,'&EXT');
       foreach (@conditions) {
	   my $line=$_;
           chomp($line);
	   my ($condition,$weight)=split(/\:/,$_);
           if ($safeeval->reval($condition)) {
	       if ($weight eq 'force') {
		   $state.='3';
               } else {
                   $state.='2';
               }
           } else {
               if ($weight eq 'stop') {
		   $state.='0';
               } else {
                   $state.='1';
               }
           }
       }
    }
    &Apache::lonnet::appenv('user.state.'.$ENV{'request.course.id'} => $state);
    return $state;
}

1;
__END__

=head1 NAME

Apache::lonuserstate - Construct and maintain state and binary representation
of course for user

=head1 SYNOPSIS

Invoked by lonroles.pm.

&Apache::lonuserstate::readmap($cdom.'/'.$cnum);

=head1 INTRODUCTION

This module constructs and maintains state and binary representation
of course for user.

This is part of the LearningOnline Network with CAPA project
described at http://www.lon-capa.org.

=head1 HANDLER SUBROUTINE

There is no handler subroutine.

=head1 OTHER SUBROUTINES

=over 4

=item *

loadmap() : Loads map from disk

=item *

simplify() : Simplify expression

=item *

traceroute() : Build condition hash

=item *

accinit() : Cascading conditions, quick access, parameters

=item *

readmap() : Read map and all submaps

=item *

evalstate() : Evaluate state string

=back

=cut