private function scanThemes()
    {
        $themeDirectories = glob($this->basePath . '/*', GLOB_ONLYDIR);

        $themes = [];
        foreach ($themeDirectories as $themePath) {
            $json = $themePath . '/theme.json';

            if (file_exists($json)) {
                $contents = file_get_contents($json);
                if (!$contents === false) {
                    $th = $this->parseThemeInfo(json_decode($contents, true));
                    $themes[$th->getDirectory()] = $th;
                }
            }
        }

        $this->themes = $themes;

        // if no active theme & if found 1+ theme, set first as default
        if (count($themes) && !$this->activeTheme) {
            $this->set(array_keys($themes)[0]);
        }
    }