Service.php

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<?php

namespace Elgg\Ajax;

use Elgg\Amd\Config;
use Elgg\EventsService;
use Elgg\Exceptions\RuntimeException;
use Elgg\Http\Request;
use Elgg\Services\AjaxResponse;
use Elgg\SystemMessagesService;
use Symfony\Component\HttpFoundation\JsonResponse;

class Service {

    private $events;

    private $msgs;

    private $request;

    private $amd_config;

    private $response_sent = false;

    private $allowed_views = [];

    public function __construct(EventsService $events, SystemMessagesService $msgs, Request $request, Config $amdConfig) {
        $this->events = $events;
        $this->msgs = $msgs;
        $this->request = $request;
        $this->amd_config = $amdConfig;

        $message_filter = [$this, 'prepareResponse'];
        $this->events->registerHandler(AjaxResponse::RESPONSE_EVENT, 'all', $message_filter, 999);
    }

    public function isAjax2Request(): bool {
        $version = $this->request->headers->get('X-Elgg-Ajax-API');
        return ($version === '2');
    }

    public function isReady(): bool {
        return !$this->response_sent && $this->isAjax2Request();
    }

    public function decodeJson($string) {
        if (!is_string($string)) {
            return $string;
        }
        
        $object = json_decode($string);
        return ($object === null) ? $string : $object;
    }

    public function respondFromOutput($output, string $event_type = '', bool $try_decode = true) {
        if ($try_decode) {
            $output = $this->decodeJson($output);
        }

        $api_response = new Response();
        if (is_object($output) && isset($output->value)) {
            $api_response->setData($output);
        } elseif (is_array($output) && isset($output['value'])) {
            $api_response->setData((object) $output);
        } else {
            $api_response->setData((object) ['value' => $output]);
        }
        
        $api_response = $this->filterApiResponse($api_response, $event_type);
        $response = $this->buildHttpResponse($api_response);

        $this->response_sent = true;
        return _elgg_services()->responseFactory->send($response);
    }

    public function respondFromApiResponse(AjaxResponse $api_response, string $event_type = '') {
        $api_response = $this->filterApiResponse($api_response, $event_type);
        $response = $this->buildHttpResponse($api_response);

        $this->response_sent = true;
        return _elgg_services()->responseFactory->send($response);
    }

    public function respondWithError(string $msg = '', int $status = 400) {
        $response = new JsonResponse(['error' => $msg], $status);
        
        // clear already set system messages as we respond directly with an error as message body
        $this->msgs->dumpRegister();

        $this->response_sent = true;
        return _elgg_services()->responseFactory->send($response);
    }

    private function filterApiResponse(AjaxResponse $api_response, string $event_type = ''): AjaxResponse {
        $api_response->setTtl($this->request->getParam('elgg_response_ttl', 0, false));

        if ($event_type) {
            $event_name = AjaxResponse::RESPONSE_EVENT;
            $api_response = $this->events->triggerResults($event_name, $event_type, [], $api_response);
            if (!$api_response instanceof AjaxResponse) {
                throw new RuntimeException("The value returned by event [{$event_name}, {$event_type}] was not an ApiResponse");
            }
        }

        return $api_response;
    }

    private function buildHttpResponse(AjaxResponse $api_response): JsonResponse {
        if ($api_response->isCancelled()) {
            return new JsonResponse(['error' => 'The response was cancelled'], 400);
        }

        $response = _elgg_services()->responseFactory->prepareJsonResponse($api_response->getData());

        $ttl = $api_response->getTtl();
        if ($ttl > 0) {
            // JsonRequest sets a default Cache-Control header we don't want
            $response->headers->remove('Cache-Control');

            $response->setClientTtl($ttl);

            // if we don't set Expires, Apache will add a far-off max-age and Expires for us.
            $response->headers->set('Expires', gmdate('D, d M Y H:i:s \G\M\T', time() + $ttl));
        }

        return $response;
    }

    public function prepareResponse(\Elgg\Event $event) {
        $response = $event->getValue();
        if (!$response instanceof AjaxResponse) {
            return;
        }

        if ($this->request->getParam('elgg_fetch_messages', true)) {
            $messages = $this->msgs->dumpRegister();
            foreach ($messages as $type => $msgs) {
                $messages[$type] = array_map(function($value) {
                    return (string) $value;
                }, $msgs);
            }
            
            $response->getData()->_elgg_msgs = (object) $messages;
        }

        if ($this->request->getParam('elgg_fetch_deps', true)) {
            $response->getData()->_elgg_deps = (array) $this->amd_config->getDependencies();
        }

        return $response;
    }

    public function registerView(string $view): void {
        $this->allowed_views[$view] = true;
    }

    public function unregisterView(string $view): void {
        unset($this->allowed_views[$view]);
    }

    public function getViews(): array {
        return array_keys($this->allowed_views);
    }
}