<?php

namespace NoccyLabs\Mercureact\Http\Middleware;

use NoccyLabs\Mercureact\Broker\TopicManager;
use NoccyLabs\Mercureact\Configuration;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use React\Http\Message\Response;
use React\Promise\Promise;
use React\Promise\PromiseInterface;

class ApiHandler
{

    public function __construct(
        private Configuration $config,
        private TopicManager $topicManager
    )
    {
    }

    /**
     * 
     * 
     * @param ServerRequestInterface $request
     * @param callable $next
     * @return PromiseInterface
     */
    public function __invoke(ServerRequestInterface $request, callable $next): PromiseInterface
    {
        return new Promise(
            function (callable $resolve, callable $reject) use ($next, $request) {

                $path = $request->getUri()->getPath();

                switch (true) {
                    case preg_match('<^/.well-known/mercure/subscriptions(/.+?){0,1}$>', $path, $m):
                        $query = explode("/", trim($m[1]??null, "/"));
                        $topic = array_shift($query);
                        $subscription = array_shift($query);
                        $resolve($this->apiGetSubscriptions($topic, $subscription));
                        return;
                
                    case preg_match('<^/.well-known/mercure/status$>', $path):
                        $resolve([
                            'server' => 'Mercureact/1.0',
                            'topics' => $this->topicManager->getTopicCount(),
                            'subscriptions' => $this->topicManager->getSubscriberCount(),
                            'memoryPeak' => memory_get_peak_usage(true),
                            'memoryUsage' => memory_get_usage(true)
                        ]);
                        return;
                }

                $resolve($next($request));
            }
        );
    }

    /**
     * 
     * 
     * @return ResponseInterface
     */
    private function apiGetSubscriptions(string|null $topic, string|null $subscription): ResponseInterface
    {
        $subscriptions = $this->topicManager->getSubscriptions();
        $lastEventId = $this->topicManager->getLastEventId();
        $data = [
            "@context" => "https://mercure.rocks/",
            "id" => "/.well-known/mercure/subscriptions",
            "type" => "Subscriptions",
            "lastEventID" => $lastEventId,
            "subscriptions" => $subscriptions
        ];

        return Response::json($data)
            ->withHeader('Content-Type', 'application/ld+json')
            ->withHeader('ETag', $lastEventId);
    }

}