make_site_theme_from_default( string $theme_name, string $template )

function make_site_theme_from_default($theme_name, $template) {
	$site_dir = WP_CONTENT_DIR . "/themes/$template";
	$default_dir = WP_CONTENT_DIR . '/themes/' . WP_DEFAULT_THEME;

	// Copy files from the default theme to the site theme.
	//$files = array('index.php', 'comments.php', 'comments-popup.php', 'footer.php', 'header.php', 'sidebar.php', 'style.css');

	$theme_dir = @ opendir($default_dir);
	if ($theme_dir) {
		while(($theme_file = readdir( $theme_dir )) !== false) {
			if (is_dir("$default_dir/$theme_file"))
				continue;
			if (! @copy("$default_dir/$theme_file", "$site_dir/$theme_file"))
				return;
			chmod("$site_dir/$theme_file", 0777);
		}
	}
	@closedir($theme_dir);

	// Rewrite the theme header.
	$stylelines = explode("\n", implode('', file("$site_dir/style.css")));
	if ($stylelines) {
		$f = fopen("$site_dir/style.css", 'w');

		foreach ($stylelines as $line) {
			if (strpos($line, 'Theme Name:') !== false) $line = 'Theme Name: ' . $theme_name;
			elseif (strpos($line, 'Theme URI:') !== false) $line = 'Theme URI: ' . __get_option('url');
			elseif (strpos($line, 'Description:') !== false) $line = 'Description: Your theme.';
			elseif (strpos($line, 'Version:') !== false) $line = 'Version: 1';
			elseif (strpos($line, 'Author:') !== false) $line = 'Author: You';
			fwrite($f, $line . "\n");
		}
		fclose($f);
	}

	// Copy the images.
	umask(0);
	if (! mkdir("$site_dir/images", 0777)) {
		return false;
	}

	$images_dir = @ opendir("$default_dir/images");
	if ($images_dir) {
		while(($image = readdir($images_dir)) !== false) {
			if (is_dir("$default_dir/images/$image"))
				continue;
			if (! @copy("$default_dir/images/$image", "$site_dir/images/$image"))
				return;
			chmod("$site_dir/images/$image", 0777);
		}
	}
	@closedir($images_dir);
}