#!/usr/bin/perl
use v5.14;
use warnings;

use CSS::Minifier::XS qw/minify/;
use Digest::SHA qw/sha256_base64/;
use IO::Compress::Gzip qw/gzip/;
use File::Slurp qw/read_file write_file edit_file_lines/;
use File::Which;
use List::Util qw/first/;

mkdir 'static';
mkdir 'static/css';
mkdir 'static/js';

sub gzip_file {
	my ($file) = @_;
	my $zopfli = which 'zopfli';
	system $zopfli => $file if $zopfli;
	gzip $file => "$file.gz", -Level => 9, Minimal => 1 unless $zopfli;
}

sub write_gzfile {
	my ($file, @content) = @_;
	write_file $file, @content;
	gzip_file $file
}

sub read_css_into_blocks {
	my ($file) = @_;
	my (@blocks, $block);
	for (read_file $file) {
		$block .= $_;
		if (/^}/) {
			push @blocks, $block;
			$block = '';
		}
	}
	\@blocks
}

my $default_theme = 'cyborg';

sub theme_prefix {
	my ($theme, $decl, $default) = @_;
	return $decl if $theme eq $default_theme || !$decl;
	return '' if $decl eq $default;

	$default =~ s/[^{]*{\n//;
	$default =~ s/\n}[^}]*//;
	$decl =~ s/^$_$//m for split "\n", $default;
	$decl =~ s/\n+/\n/g;

	my $prefix = "html.$theme";
	my ($first_line) = $decl =~ /([^{]*){/;
	$first_line =~ s/(,\s+)/$1 $prefix /g;
	$first_line = "$prefix $first_line";
	$decl =~ s/([^{]*){/$first_line\{/;
	$decl
}

sub make_css {
	my $css = join '', map { read_file $_ } <css/*.css>;

	my (%themes);
	for (<css/themes/*>) {
		my ($theme) = m,themes/(.*)\.css,;
		$themes{$theme} = read_css_into_blocks $_;
	}
	my @themes = sort grep { $_ ne $default_theme } keys %themes;

	while (grep { scalar @$_ } values %themes) {
		my %blocks = map { $_ => (shift @{$themes{$_}}) // '' } keys %themes;
		$css .= $blocks{$default_theme};
		$css .= theme_prefix $_, $blocks{$_}, $blocks{$default_theme} for @themes
	}

	write_gzfile "static/css/all.css", minify $css
}

sub make_js {
	system java => -jar => 'compiler.jar', qw,-O SIMPLE --create_source_map static/js/js.map --js_output_file static/js/all.js --language_in ECMASCRIPT6_STRICT --language_out ECMASCRIPT5_STRICT --source_map_location_mapping js/|/static/js/,, <js/*>;
	my $js = read_file 'static/js/all.js';
	write_gzfile 'static/js/all.js', '//# sourceMappingURL=/static/js/js.map', "\n", $js;
	system 'cp', '-rp', 'js', 'static/';
}

my $css_mtime = -M 'static/css/all.css' // 0;
for (<css/*>, <css/themes/*>) {
	if (!$css_mtime || $css_mtime > -M) {
		make_css;
		last
	}
}

my $js_mtime = -M 'static/js/all.js' // 0;
for (<js/*>) {
	if (!$js_mtime || $js_mtime > -M) {
		make_js;
		last
	}
}

edit_file_lines {
	my ($file) = m,(static.*\.(?:css|js)),;
	return unless $file;
	my $hash = sha256_base64 scalar read_file $file;
	s/integrity=".*"/integrity="sha256-$hash="/;
} 'tmpl/skel.en'