make_site_theme_from_oldschool( string $theme_name, string $template )

function make_site_theme_from_oldschool($theme_name, $template) {
	$home_path = get_home_path();
	$site_dir = WP_CONTENT_DIR . "/themes/$template";

	if (! file_exists("$home_path/index.php"))
		return false;

	/*
	 * Copy files from the old locations to the site theme.
	 * TODO: This does not copy arbitrary include dependencies. Only the standard WP files are copied.
	 */
	$files = array('index.php' => 'index.php', 'wp-layout.css' => 'style.css', 'wp-comments.php' => 'comments.php', 'wp-comments-popup.php' => 'comments-popup.php');

	foreach ($files as $oldfile => $newfile) {
		if ($oldfile == 'index.php')
			$oldpath = $home_path;
		else
			$oldpath = ABSPATH;

		// Check to make sure it's not a new index.
		if ($oldfile == 'index.php') {
			$index = implode('', file("$oldpath/$oldfile"));
			if (strpos($index, 'WP_USE_THEMES') !== false) {
				if (! @copy(WP_CONTENT_DIR . '/themes/' . WP_DEFAULT_THEME . '/index.php', "$site_dir/$newfile"))
					return false;

				// Don't copy anything.
				continue;
			}
		}

		if (! @copy("$oldpath/$oldfile", "$site_dir/$newfile"))
			return false;

		chmod("$site_dir/$newfile", 0777);

		// Update the blog header include in each file.
		$lines = explode("\n", implode('', file("$site_dir/$newfile")));
		if ($lines) {
			$f = fopen("$site_dir/$newfile", 'w');

			foreach ($lines as $line) {
				if (preg_match('/require.*wp-blog-header/', $line))
					$line = '//' . $line;

				// Update stylesheet references.
				$line = str_replace("<?php echo __get_option('siteurl'); ?>/wp-layout.css", "<?php bloginfo('stylesheet_url'); ?>", $line);

				// Update comments template inclusion.
				$line = str_replace("<?php include(ABSPATH . 'wp-comments.php'); ?>", "<?php comments_template(); ?>", $line);

				fwrite($f, "{$line}\n");
			}
			fclose($f);
		}
	}

	// Add a theme header.
	$header = "/*\nTheme Name: $theme_name\nTheme URI: " . __get_option('siteurl') . "\nDescription: A theme automatically created by the update.\nVersion: 1.0\nAuthor: Moi\n*/\n";

	$stylelines = file_get_contents("$site_dir/style.css");
	if ($stylelines) {
		$f = fopen("$site_dir/style.css", 'w');

		fwrite($f, $header);
		fwrite($f, $stylelines);
		fclose($f);
	}

	return true;
}