#!/usr/bin/perl
package IkiWiki::Plugin::highlight;

use warnings;
use strict;
use IkiWiki 3.00;
use highlight;

# locations of highlight's files
my $filetypes="/etc/highlight/filetypes.conf";
my $langdefdir="/usr/share/highlight/langDefs";

sub import {
	hook(type => "getsetup", id => "highlight",  call => \&getsetup);
	hook(type => "checkconfig", id => "highlight", call => \&checkconfig);
}

sub getsetup () {
	return
		plugin => {
			safe => 1,
			rebuild => 1, # format plugin
		},
		tohighlight => {
			type => "string",
			example => ".c, .h, .cpp, .pl, .py, Makefile:make",
			description => "source files to syntax highlight",
			safe => 1,
			rebuild => 1,
		},
}

sub checkconfig () {
	if (exists $config{tohighlight}) {
		foreach my $file (split /, /, $config{tohighlight}) {
			my @opts = $file=~s/^\.// ?
				(keepextension => 1) :
				(noextension => 1);
			my $ext = $file=~s/:(.*)// ? $1 : $file;
		
			my $langfile=ext2langfile($ext);
			if (! defined $langfile) {
				error(sprintf(gettext(
					"tohighlight contains unknown file type '%s'"),
					$ext));
			}
	
			hook(
				type => "htmlize",
				id => $file,
				call => sub {
					my %params=@_;
				       	highlight($langfile, $params{content});
				},
				longname => sprintf(gettext("Source code: %s"), $file),
				@opts,
			);
		}
	}
}

my %ext2lang;
my $filetypes_read=0;

# Parse highlight's config file to get extension => language mappings.
sub read_filetypes () {
	open (IN, $filetypes);
	while (<IN>) {
		chomp;
		if (/^\$ext\((.*)\)=(.*)$/) {
			$ext2lang{$_}=$1 foreach $1, split ' ', $2;
		}
	}
	close IN;
	$filetypes_read=1;
}

sub langfile ($) {
	return "$langdefdir/$_[0].lang";
}

# Given a filename extension, determines the language definition to
# use to highlight it.
sub ext2langfile ($) {
	my $ext=shift;

	read_filetypes() unless $filetypes_read;
	if (exists $ext2lang{$ext}) {
		return langfile($ext2lang{$ext});
	}
	# If a language only has one common extension, it will not
	# be listed in filetypes, so check the langfile.
	elsif (-e langfile($ext)) {
		return langfile($ext);
	}
	else {
		return undef;
	}
}

# Interface to the highlight C library.
sub highlight ($$) {
	my $langfile=shift;
	my $input=shift;

	my $gen = highlightc::CodeGenerator_getInstance($highlightc::XHTML);
	$gen->setFragmentCode(1); # generate html fragment
	$gen->setHTMLEnclosePreTag(1); # include stylish <pre>
	$gen->initLanguage($langfile);
	$gen->initTheme("/dev/null"); # theme is not needed because CSS is not emitted
	$gen->setEncoding("utf-8");

	my $output=$gen->generateString($input);
	highlightc::CodeGenerator_deleteInstance($gen);
	return $output;
}

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