#!/usr/bin/perl -w                                         # -*- perl -*-
#
# gifsplash  (bin/gifsplash)
#
# This script explodes the set of black images distributed with the
# Template Toolkit (images/splash/black/*) into the colours specified
# in the html/rgb template (templates/html/rgb).  It is run at "make
# install" time and operates on the TT2 installation directory.  Note
# that the main loop runs in template space where there is convenient
# access to the RGB definitions.
#
#  

use strict;
use Template;
use Getopt::Std;

my $PROGRAM = 'gifsplash';
my $VERSION = 0.03;
my $MASKDIR = 'black';


my $args = { };
getopts('vs:d:i:h', $args);
usage() if $args->{ h };
my ($verbose, $src, $dest, $inst) = @$args{ qw( v s d i ) };

$inst ||= Template::Config->instdir()
      || die "Cannot determine Template Toolkit installation directory\n";

$src  ||= "$inst/images/splash/$MASKDIR";
$dest ||= "$inst/images/splash";

if ($verbose) {
    print STDERR <<EOF;
Weaving the rainbow: blowing colour into Splash! GIFs
   src: $src
  dest: $dest/*
EOF
}

my $tt = Template->new( 
    INCLUDE_PATH => "$inst/templates",
    PRE_PROCESS  => 'html/rgb',
    OUTPUT_PATH  => $dest,
) || die Template->error(), "\n";

my $vars = {
    gifs    => load_gifs($src),
    colour  => \&colour_gif,
    verbose => $verbose,
};    
my $out;

$tt->process(\*DATA, $vars, \$out)
    || die $tt->error(), "\n";


#------------------------------------------------------------------------

sub load_gifs {
    my $gifdir = shift;
    my (@files, $gifs);
    local (*DIR, *GIF);
    local $" = ', ';
    local $/ = undef;

    opendir(DIR, $gifdir) || die "$gifdir: $!";
    @files = grep { /\.gif$/ } readdir(DIR);
    closedir DIR;

    if ($verbose) {
	my $filenames = '';
	my @tmpfiles = @files;
	while (@tmpfiles) {
	    $filenames .= '  ' . join(', ', splice(@tmpfiles, 0, 6)) . "\n";
	}
	print STDERR "Found ", scalar @files, " GIF files:\n$filenames";
    }

    foreach my $f (@files) {
	open(GIF, "$gifdir/$f") || die "$gifdir/$f: $!\n";
	$gifs->{ $f } = <GIF>;
	close(GIF);
    }

    return $gifs;
}

sub colour_gif {
    my ($gif, $r, $g, $b) = @_;

    unless (defined $g) {
	($r, $g, $b) = make_rgb($r);
    }

    # the first and only RGB entry in the colour table runs from 
    # bytes 13 to 15
    vec($gif, 13, 8) = $r;
    vec($gif, 14, 8) = $g;
    vec($gif, 15, 8) = $b;

    return $gif;
}

sub make_rgb {
    my $rgbhash = shift;
    $rgbhash =~ /^\#?(..)(..)(..)$/;
    return map { hex($_) } ($1, $2, $3);
}

sub usage {
    print STDERR <<EOF;
$PROGRAM: colorise source GIFs to create Splash! colour sets

usage: $PROGRAM [options]
    -s /src/dir    source directory
    -d /dest/dir   destination directory
    -i /tt2/dir    TT2 installation directory
    -v             verbose mode
    -h             this help
EOF
    exit();
}


#------------------------------------------------------------------------
__END__
[%  "Bursting into colour...\n  " | stderr IF verbose;
    n = 0;
    FOREACH col = rgb.keys; 
	"\n  " | stderr IF verbose and ! loop.count % 8;
	NEXT IF rgb.${col}.keys;
	"$col, " | stderr IF verbose;
	FOREACH gifname = gifs.keys;
   	    colour(gifs.$gifname, rgb.$col) | redirect("$col/$gifname", 1);
	END;
	n = n + 1;
    END;
    "\nGenerated $n background colours\n\n" | stderr IF verbose;
%]