blue-twilight/app/Helpers/ThemeHelper.php

<?php

namespace App\Helpers;

use App\Configuration;

class ThemeHelper
{
    const DEFAULT_THEME = 'base';

    public function current()
    {
        return $this->getThemeName();
    }

    public function hasStylesheet()
    {
        $cssFilename = sprintf('%s/%s/theme.css', $this->getThemePublicPath(), $this->getThemeName());
        return file_exists($cssFilename);
    }

    public function info()
    {
        $themeName = $this->getThemeName();
        $jsonFile = sprintf('%s/%s/theme.json', $this->getThemePrivatePath(), $this->sanitiseThemeName($themeName));
        if (file_exists($jsonFile))
        {
            return json_decode(file_get_contents($jsonFile), true);
        }

        return array();
    }

    public function render($viewPath, array $viewData = array())
    {
        $themeName = $this->getThemeName();

        // First see if the current theme has the specified file
        $requestedViewFilename = $this->getRealFilePath($themeName, $viewPath);

        if (!file_exists($requestedViewFilename))
        {
            // If it doesn't, revert to the base theme
            // TODO allow themes to specify another theme as the parent, and traverse up the theme tree to find the
            // relevant file - this allows for sub-themes
            $themeName = ThemeHelper::DEFAULT_THEME;
        }

        return view(sprintf('themes.%s.%s', $themeName, $viewPath), $viewData);
    }

    private function getRealFilePath($themeName, $viewPath)
    {
        return sprintf(
            '%s/%s/%s.blade.php',
            $this->getThemePrivatePath(),
            $themeName,
            str_replace('.', DIRECTORY_SEPARATOR, $viewPath)
        );
    }

    private function getThemePrivatePath()
    {
        return sprintf('%s/resources/views/themes', dirname(dirname(__DIR__)));
    }

    private function getThemePublicPath()
    {
        return sprintf('%s/public/themes', dirname(dirname(__DIR__)));
    }

    private function getThemeName()
    {
        $themeName = ThemeHelper::DEFAULT_THEME;

        $currentTheme = Configuration::where('key', 'theme')->first();
        if (!is_null($currentTheme))
        {
            $themeName = $currentTheme->value;
        }

        return $this->sanitiseThemeName($themeName);
    }

    private function sanitiseThemeName($themeName)
    {
        // Ensure nasty people can't try and trick us into traversing the directory tree
        return preg_replace('/[\\\.\/]/', '', strtolower($themeName));
    }
}