# The LearningOnline Network with CAPA
# Handler to show differences between file versions
#
# $Id: londiff.pm,v 1.38 2017/05/07 13:26:40 raeburn 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/
#
###




package Apache::londiff;

use strict;
use Apache::File;
use File::Copy;
use File::Compare;
use Algorithm::Diff qw(diff);
use Apache::Constants qw(:common :http :methods);
use Apache::lonnet;
use Apache::loncommon();
use Apache::lonretrieve();
use Apache::lonlocal;
use LONCAPA();

sub get_split_file {
    my ($fn,$style)=@_;
    my $f1;
    my @f1;
    if ($style eq 'local') {
	if (-e $fn) {
	    my $fh=Apache::File->new($fn);
	    my $line;	
	    while($line=<$fh>) {
		$f1.=$line;
	    }
	}
    } elsif ($style eq 'remote') {
	$f1=&Apache::lonnet::getfile($fn);
    }
    @f1=split(/\r\n|\r|\n/,$f1);
    return @f1;
}

sub are_different_files {
    my ($fileone,$filetwo)=@_;
    return &compare($fileone,$filetwo);
}

sub handler {

    my $r=shift;
# Get query string for limited number of parameters

    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
					    ['filename','versiontwo',
					     'versionone','filetwo']);

# Check permissions
    my $allowed=0;
    my $cuname=$env{'user.name'};
    my $cudom=$env{'user.domain'};

    if ($env{'form.filename'}=~ m{^/res/}) {
        if (&Apache::lonnet::allowed('bre',$env{'form.filename'})) {
            if ($env{'request.course.id'}) {
                if ((&Apache::lonnet::allowed('mdc',$env{'request.course.id'})) ||
                    (&Apache::lonnet::allowed('cev',$env{'request.course.id'}))) {
                    $allowed = 1;
                }
            } else {
                $allowed = 1;
            }
        } elsif (&Apache::lonnet::allowed('bro',$env{'form.filename'})) {
            $allowed = 1;
        }
        if ($allowed) {
            ($cudom,$cuname,$env{'form.filename'})=
                ($env{'form.filename'}=~m{^/res/($LONCAPA::domain_re)/($LONCAPA::username_re)(/.*)$});

            if (($env{'form.versionone'} eq 'priv') || ($env{'form.versiontwo'} eq 'priv')) {
                my ($cstrname,$cstrdom) =
                    &Apache::lonnet::constructaccess("/priv/$cudom/$cuname".$env{'form.filename'});
                unless (($cstrname eq $cuname) && ($cstrdom eq $cudom)) {
                    $allowed = 0;
                }
            }
        }
    } else {
	($cuname,$cudom)=
	    &Apache::lonnet::constructaccess($env{'form.filename'});
        if ($cuname ne '' && $cudom ne '') {
            $allowed = 1;
        } else {
	    $r->log_reason($env{'user.name'}.':'.$env{'user.domain'}.
			   ' trying to get diffs file '.$env{'form.filename'}.
			   '  - not authorized',
			   $r->filename);
	}
    }
    unless ($allowed) {
        return HTTP_NOT_ACCEPTABLE;
    }

# Get the files

    my $efn=$env{'form.filename'};
    $efn=~s{^/priv/$LONCAPA::domain_re/$LONCAPA::username_re}{};

    my @f1=();
    my @f2=();

    &Apache::loncommon::content_type($r,'text/html');
    $r->send_http_header;

    $r->print(&Apache::loncommon::start_page('Resource Differences',undef,
                                             {'no_nav_bar'  => 1, }));
  
    $r->print(($env{'form.filetwo'}?'':&mt('Compare versions of')).
	      ' <span class="LC_filename">'.$efn.'</span>');
   
    if (($cuname ne $env{'user.name'}) || ($cudom ne $env{'user.domain'})) {
        my $nameshown = &Apache::loncommon::plainname($cuname,$cudom).
                        ' ('.$cuname.':'.$cudom.')';
        $r->print('<p><span class="LC_info">');
        if ($env{'request.role'} =~ /^ca\./) {
            $r->print(&mt('Co-Author in Authoring Space for: [_1]',$nameshown));
        } elsif ($env{'request.role'} =~ /^aa\./) {
            $r->print(&mt('Assistant Author in Authoring Space for: [_1]',$nameshown));
        } else {
            $r->print(&mt('Resource Author is: [_1]',$nameshown));
        }
        $r->print('</span></p>');
    }

    if (&Apache::loncommon::fileembstyle(($efn=~/\.(\w+)$/)) eq 'ssi'
	|| $efn =~ /\.meta$/) {
	$r->print('<p><span class="LC_diff_removed">');
	if ($env{'form.versionone'} eq 'priv') {
	    my $fn=$r->dir_config('lonDocRoot')."/priv/$cudom/$cuname".$efn;
	    @f1=&get_split_file($fn,'local');
	    $r->print('<b>'.&mt('Authoring Space Version').'</b>');
	} else {
	    my $fn=$r->dir_config('lonDocRoot')."/res/$cudom/$cuname";
	    if ($env{'form.versionone'}) {
		my ($main,$suffix,$is_meta)=
		    &Apache::lonretrieve::get_file_info($efn);
		
		$fn.=($efn =~m|(.*/)[^/]+|)[0];
		# add on to $fn the path information in $efn
		$fn.=$main.'.'.$env{'form.versionone'}.'.'.$suffix;
		$r->print('<b>'.&mt('Version').' '.$env{'form.versionone'}.'</b>');
	    } else {
		$fn.=$efn;
		$r->print('<b>'.&mt('Current Version').'</b>');
	    }
	    @f1=&get_split_file($fn,'remote');
	}
	
	$r->print('</span><br />'.&mt('versus').'<br /><span class="LC_diff_added">');

	if ($env{'form.filetwo'}) {
	    my $efn2=$env{'form.filetwo'};
	    $efn2=~s{^/priv/$LONCAPA::domain_re/$LONCAPA::username_re}{};
	    my $fn=$r->dir_config('lonDocRoot')."/priv/$cudom/$cuname".$efn2;
	    @f2=&get_split_file($fn,'local');
	    $r->print('<tt>'.$efn2.'</tt>');
	} elsif ($env{'form.versiontwo'} eq 'priv') {
	    my $fn=$r->dir_config('lonDocRoot')."/priv/$cudom/$cuname".$efn;
	    @f2=&get_split_file($fn,'local');
	    $r->print('<b>'.&mt('Authoring Space Version').'</b>');
	} else {
	    my $fn=$r->dir_config('lonDocRoot')."/res/$cudom/$cuname/";
	    if ($env{'form.versiontwo'}) {
		my ($main,$suffix,$is_meta)=
		    &Apache::lonretrieve::get_file_info($efn);
		# add on to $fn the path information in $efn
		$fn.=($efn =~m|(.*/)[^/]+|)[0];
		$fn.=$main.'.'.$env{'form.versiontwo'}.'.'.$suffix;
		$r->print('<b>'.&mt('Version').' '.$env{'form.versiontwo'}.'</b>');
	    } else {
		$fn.=$efn;
		$r->print('<b>'.&mt('Current Version').'</b>');
	    }
	    @f2=&get_split_file($fn,'remote');
	}
	$r->print('</span></p>');
# Run diff

	my $diffs = diff(\@f1, \@f2);

        if (@$diffs) {
            # Start page output
            my $chunk;
            my $line;
            $r->print('<pre>');
            foreach $chunk (@$diffs) {
                foreach $line (@$chunk) {
                    my ($sign, $lineno, $text) = @$line;
                    $text=&HTML::Entities::encode($text,'<>&"');
                    $lineno=substr($lineno.'        ',0,7);
                    $r->print('<span class="'.(($sign eq '+')?'LC_diff_added'
                                                             :'LC_diff_removed').'">'.
                              $sign.' '.$lineno.' '.$text."</span>\n");
                }
                $r->print("</pre><hr /><pre>\n");
            }
            $r->print('</pre>');
        } else {
            $r->print('<p class="LC_info">'.&mt('No differences found').'</p>');
        }
    } else {
	$r->print('<h1><span class="LC_warning">'.&mt('Binary File').'</span></h1>');
    }
    $r->print(&Apache::loncommon::end_page()); 
    return OK;  
}


1;
__END__


=pod

=head1 NAME

Apache::londiff

=head1 SYNOPSIS

Handler to show difference between two files.

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

=head1 Subroutines

=over

=item get_split_file()

=item are_different_files()

=item handler()

=cut