Magic-Scrolls/src/engine/core/event_bus.cpp

#include <engine/core/engine_bus.hpp>
#include <utility>
#include <cstddef>

void MscEventBus::publish(MscEvent &event)
{
    std::vector<ListenerWithId> listeners;

    {
        std::lock_guard<std::mutex> lock(_listenersMutex);
        auto it = _listeners.find(event.getName());
        if (it == _listeners.end())
            return;

        for (const auto &entry : it->second)
            listeners.push_back(entry);
    }

    for (const auto &entry : listeners)
    {
        if (event.isCanceled())
            break;

        entry.listener(event);
        if (entry.once)
            unsubscribe(entry.id);
    }
}

MscEventBus::SubscriptionId MscEventBus::_subscribe(const std::string &name, MscEventBus::Listener listener, bool once)
{
    std::lock_guard<std::mutex> lock(_listenersMutex);

    const SubscriptionId id = ++_lastId;
    auto listenerWithId = ListenerWithId{
        .id = id,
        .listener = std::move(listener),
        .once = once};

    _listeners[name].push_back(std::move(listenerWithId));
    _listenersPaths[id] = name;

    return id;
}

MscEventBus::SubscriptionId MscEventBus::subscribe(const std::string &name, Listener listener)
{
    return _subscribe(name, std::move(listener), false);
}

MscEventBus::SubscriptionId MscEventBus::subscribeOnce(const std::string &name, Listener listener)
{
    return _subscribe(name, std::move(listener), true);
}

bool MscEventBus::unsubscribe(SubscriptionId id)
{
    std::lock_guard<std::mutex> lock(_listenersMutex);

    auto it = _listenersPaths.find(id);
    if (it == _listenersPaths.end())
        return false;

    auto &listeners = _listeners.at(it->second);
    for (std::size_t i = 0; i < listeners.size(); i++)
    {
        if (listeners.at(i).id != id)
            continue;

        listeners.erase(listeners.begin() + i);
        _listenersPaths.erase(id);

        if (listeners.empty())
            _listeners.erase(it->second);

        return true;
    }

    return false;
}