<?php namespace System\Classes;

use App;
use View;
use Config;
use Request;
use Response;
use Cms\Classes\Theme;
use Cms\Classes\Router;
use Cms\Classes\Controller;
use System\Classes\BaseException;
use System\Classes\ApplicationException;

/**
 * System Error Handler, this class handles application exception events.
 *
 * @package october\system
 * @author Alexey Bobkov, Samuel Georges
 */
class ErrorHandler
{

    /**
     * @var System\Classes\ExceptionBase A prepared mask exception used to mask any exception fired.
     */
    protected static $activeMask;

    /**
     * @var array A collection of masks, so multiples can be applied in order.
     */
    protected static $maskLayers = [];

    /**
     * All exceptions are piped through this method from the framework workflow. This method will mask
     * any foreign exceptions with a "scent" of the native application's exception, so it can render
     * correctly when displayed on the error page.
     * @param Exception $proposedException The exception candidate that has been thrown.
     * @return View Object containing the error page.
     */
    public function handleException(\Exception $proposedException, $httpCode = 500)
    {
        // Disable the error handler for test and CLI environment
        if (App::runningUnitTests() || App::runningInConsole()) {
            return;
        }

        // Detect AJAX request and use error 500
        if (Request::ajax()) {
            return Response::make($proposedException->getMessage(), $httpCode);
        }

        // Clear the output buffer
        while (ob_get_level()) {
            ob_end_clean();
        }

        // Friendly error pages are used
        if (Config::get('cms.customErrorPage')) {
            return $this->handleCustomError();
        }

        // If the exception is already our brand, use it.
        if ($proposedException instanceof BaseException) {
            $exception = $proposedException;
        // If there is an active mask prepared, use that.
        }
        elseif (static::$activeMask !== null) {
            $exception = static::$activeMask;
            $exception->setMask($proposedException);
        // Otherwise we should mask it with our own default scent.
        }
        else {
            $exception = new ApplicationException($proposedException->getMessage(), 0);
            $exception->setMask($proposedException);
        }

        // Ensure System view path is registered
        View::addNamespace('system', base_path().'/modules/system/views');

        return View::make('system::exception', ['exception' => $exception]);
    }

    /**
     * Prepares a mask exception to be used when any exception fires.
     * @param Exception $exception The mask exception.
     * @return void
     */
    public static function applyMask(\Exception $exception)
    {
        if (static::$activeMask !== null) {
            array_push(static::$maskLayers, static::$activeMask);
        }

        static::$activeMask = $exception;
    }

    /**
     * Destroys the prepared mask by applyMask()
     * @return void
     */
    public static function removeMask()
    {
        if (count(static::$maskLayers) > 0) {
            static::$activeMask = array_pop(static::$maskLayers);
        }
        else {
            static::$activeMask = null;
        }
    }

    /**
     * Looks up an error page using the CMS route "/error". If the route does not
     * exist, this function will use the error view found in the Cms module.
     * @return mixed Error page contents.
     */
    public function handleCustomError()
    {
        $theme = Theme::getActiveTheme();

        // Use the default view if no "/error" URL is found.
        $router = new Router($theme);
        if (!$router->findByUrl('/error')) {
            return View::make('cms::error');
        }

        // Route to the CMS error page.
        $controller = new Controller($theme);
        return $controller->run('/error');
    }
}