# Plugin for TWiki Collaboration Platform, http://TWiki.org/
#
# Copyright (C) 2004-2005 Cole Beck, cole.beck@vanderbilt.edu
#
# This program 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.
#
# This program 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, published at 
# http://www.gnu.org/copyleft/gpl.html
#
# =========================
#
# Each plugin is a package that may contain these functions:        VERSION:
#
#   initPlugin              ( $topic, $web, $user, $installWeb )    1.000
#   commonTagsHandler       ( $text, $topic, $web )                 1.000
#
# =========================
#
# This plugin creates a png file by using the graphviz dot command.
# See http://www.graphviz.org/ for more information.
# Note that png files created with this plugin can only be deleted manually; 
# it stays there even after the dot tags are removed.

package TWiki::Plugins::DirectedGraphPlugin;

# =========================
use vars qw(
        $web $topic $user $installWeb $VERSION $pluginName
        $debug $exampleCfgVar
    );

$VERSION = '1.010';
$pluginName = 'DirectedGraphPlugin';
use Digest::MD5 qw( md5_hex );
#the MD5 and hash table are used to create a unique name for each graph
use File::Path;

my $HASH_CODE_LENGTH=32;
my %hashed_math_strings=();

# =========================
sub initPlugin
{
    ( $topic, $web, $user, $installWeb ) = @_;
    
    # check for Plugins.pm versions
    if( $TWiki::Plugins::VERSION < 1 ) {
        TWiki::Func::writeWarning( "Version mismatch between $pluginName and Plugins.pm" );
        return 0;
    }

    # Get plugin debug flag
    $debug = TWiki::Func::getPreferencesFlag( "\U$pluginName\E_DEBUG" );
    
    # Get plugin preferences, the variable defined by:          * Set EXAMPLE = ...
    $exampleCfgVar = &TWiki::Prefs::getPreferencesValue( "EMPTYPLUGIN_EXAMPLE" ) || "default";

    # Plugin correctly initialized
    TWiki::Func::writeDebug( "- TWiki::Plugins::${pluginName}::initPlugin( $web.$topic ) is OK" ) if $debug;
    return 1;
}

# =========================
sub commonTagsHandler
{
### my ( $text, $topic, $web ) = @_;   # do not uncomment, use $_[0], $_[1]... instead

    TWiki::Func::writeDebug( "- ${pluginName}::commonTagsHandler( $_[2].$_[1] )" ) if $debug;

    # This is the place to define customized tags and variables
    # Called by sub handleCommonTags, after %INCLUDE:"..."%

    #pass everything within <dot> tags to handleDot function
    #$_[0] =~ s/%DOT{(.*?)}%/&handleDot($1)/gise;
    $_[0] =~ s/<DOT>(.*?)<\/DOT>/&handleDot($1)/giseo;
    $_[0] =~ s/<NEATO>(.*?)<\/NEATO>/&handleNeato($1)/giseo;
}

# =========================
sub handleDot
{
    # Create topic directory "pub/$web/$topic" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkpath($dir, 0, 0755) or return "<noc>DirectedGraph Error: *folder $dir could not be created*";
    }
    # compute the MD5 hash of this string
    my $hash_code = md5_hex( "DOT$_[0]" );
    # store the string in a hash table, indexed by the MD5 hash
    $hashed_math_strings{"$hash_code"} = $_[0];

    # output the parameter into the file "foo.dot"
    open OUTFILE, ">/tmp/foo.dot$$" or return "<noc>DirectedGraph Error: could not create file";
    print OUTFILE $_[0];
    close OUTFILE;

    # run the "dot" command to create a png file with the directed graph
    $image="${dir}/graph${hash_code}.png";
    # don't do anything if it already exists
    if (open TMP, "$image") {
        close TMP;
    }
    # create the png
    else {
        $command=system("/usr/bin/dot -Tpng /tmp/foo.dot$$ | pngtopnm | pnmscale 0.6 | pnmtopng > $image");
        if($command) {
            # errors existed so remove created files
            unlink "$image";
            unlink "/tmp/foo.dot$$";
            return "<noc>DirectedGraph Error: syntax error";
        }
    }

    # delete the file "foo.dot"
    unlink "/tmp/foo.dot$$";

    # attach "foo.png" at the source of the <dot> tag in $Web.$Topic
    $loc=&TWiki::Func::getUrlHost() . &TWiki::Func::getPubUrlPath() . "/$web/$topic";
    return "<img src=\"$loc/graph$hash_code.png\"/>";
}

sub handleNeato
{
    # Create topic directory "pub/$web/$topic" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkpath($dir, 0, 0755) or return "<noc>DirectedGraph Error: *folder $dir could not be created*";
    }
    # compute the MD5 hash of this string
    my $hash_code = md5_hex( "NEATO$_[0]" );
    # store the string in a hash table, indexed by the MD5 hash
    $hashed_math_strings{"$hash_code"} = $_[0];

    # output the parameter into the file "foo.dot"
    open OUTFILE, ">/tmp/foo.dot$$" or return "<noc>DirectedGraph Error: could not create file";
    print OUTFILE $_[0];
    close OUTFILE;

    # run the "dot" command to create a png file with the directed graph
    $image="${dir}/graph${hash_code}.png";
    # don't do anything if it already exists
    if (open TMP, "$image") {
        close TMP;
    }
    # create the png
    else {
        $command=system("/usr/bin/neato -Tpng /tmp/foo.dot$$ | pngtopnm | pnmscale 0.6 | pnmtopng > $image");
        if($command) {
            # errors existed so remove created files
            unlink "$image";
            unlink "/tmp/foo.dot$$";
            return "<noc>DirectedGraph Error: syntax error";
        }
    }

    # delete the file "foo.dot"
    unlink "/tmp/foo.dot$$";

    # attach "foo.png" at the source of the <dot> tag in $Web.$Topic
    $loc=&TWiki::Func::getUrlHost() . &TWiki::Func::getPubUrlPath() . "/$web/$topic";
    return "<img src=\"$loc/graph$hash_code.png\"/>";
}

1;