brightnucleus/view

<?php declare(strict_types=1);
/**
 * Bright Nucleus View Component.
 *
 * @package   BrightNucleus\View
 * @author    Alain Schlesser <alain.schlesser@gmail.com>
 * @license   MIT
 * @link      http://www.brightnucleus.com/
 * @copyright 2016-2017 Alain Schlesser, Bright Nucleus
 */

namespace BrightNucleus\View\Engine;

use BrightNucleus\View\Exception\FailedToLoadView;
use BrightNucleus\View\Support\URIHelper;
use Exception;

/**
 * Class PHPEngine.
 *
 * @since   0.1.0
 *
 * @package BrightNucleus\View\Engine
 * @author  Alain Schlesser <alain.schlesser@gmail.com>
 */
class PHPEngine extends AbstractEngine
{

    const PHP_EXTENSION = '.php';

    /**
     * Check whether the Findable can handle an individual criterion.
     *
     * @since 0.1.0
     *
     * @param mixed $criterion Criterion to check.
     *
     * @return bool Whether the Findable can handle the criterion.
     */
    public function canHandle($criterion): bool
    {
        return URIHelper::hasExtension($criterion, static::PHP_EXTENSION)
            && is_readable($criterion);
    }

    /**
     * Get the rendering callback for a given URI.
     *
     * @since 0.1.0
     *
     * @param string $uri     URI to render.
     * @param array  $context Context in which to render.
     *
     * @return callable Rendering callback.
     * @throws FailedToLoadView If the View URI is not accessible or readable.
     * @throws FailedToLoadView If the View URI could not be loaded.
     */
    public function getRenderCallback(string $uri, array $context = []): callable
    {
        if (! is_readable($uri)) {
            throw new FailedToLoadView(
                sprintf(
                    _('The View URI "%1$s" is not accessible or readable.'),
                    $uri
                )
            );
        }

        $closure = function () use ($uri, $context) {

            // Save current buffering level so we can backtrack in case of an error.
            // This is needed because the view itself might also add an unknown number of output buffering levels.
            $bufferLevel = ob_get_level();
            ob_start();

            try {
                include $uri;
            } catch (Exception $exception) {
                // Remove whatever levels were added up until now.
                while (ob_get_level() > $bufferLevel) {
                    ob_end_clean();
                }

                throw new FailedToLoadView(
                    sprintf(
                        _('Could not load the View URI "%1$s". Reason: "%2$s".'),
                        $uri,
                        $exception->getMessage()
                    ),
                    $exception->getCode(),
                    $exception
                );
            }

            return ob_get_clean();
        };

        return $closure;
    }
}