<?php

namespace NoccyLabs\Mercureact\Broker;

use SplObjectStorage;

class TopicManager
{
    /** @var array<string,Topic> */
    private array $topics = [];

    private SplObjectStorage $subscribers;

    public function __construct()
    {
        $this->subscribers = new SplObjectStorage();
    }

    public function getTopic(string $topic): Topic
    {
        if (!isset($this->topics[$topic])) {
            $this->topics[$topic] = new Topic($topic);
        }
        return $this->topics[$topic];
    }

    public function publish(Message $message): void
    {
        foreach ($message->topic as $topic) {
            $this->getTopic($topic)->publish($message);
        }
    }

    public function subscribe(SubscriberInterface $subscriber, array $topics): void
    {
        $this->subscribers->attach($subscriber);
        foreach ($topics as $topic) {
            $this->getTopic($topic)->addSubscriber($subscriber);
        }
    }

    public function unsubscribe(SubscriberInterface $subscriber, ?array $topics=null): void
    {
        $this->subscribers->detach($subscriber);
        if (!$topics) {
            foreach ($this->topics as $topic) {
                $topic->removeSubscriber($subscriber);
            }
            return;
        }
        foreach ($topics as $topic) {
            $this->getTopic($topic)->removeSubscriber($subscriber);
        }
    }

    public function getTopicCount(): int
    {
        return count($this->topics);
    }

    public function getSubscriberCount(): int
    {
        return count($this->subscribers);
    }

    public function garbageCollect(): void
    {
        $this->topics = array_filter(
            $this->topics,
            function (Topic $topic) {
                $topic->garbageCollect();
                return ($topic->getHistorySize() > 0 || $topic->getSubscriberCount() > 0) || ($topic->getAge() < 60);
            }
        );
    }

}