#include "EpollInstance.hpp"

#include <string>
#include <cerrno>
#include <unistd.h>
#include <array>

#include "src/Exceptions/Exception.hpp"

namespace Bloom
{
    using Exceptions::Exception;

    EpollInstance::EpollInstance() {
        this->fileDescriptor = ::epoll_create(1);

        if (this->fileDescriptor < 0) {
            throw Exception(
                "Failed to create epoll instance - error number " + std::to_string(errno)
                    + " returned."
            );
        }
    }

    void EpollInstance::addEntry(int fileDescriptor, std::uint16_t eventMask) {
        struct ::epoll_event event = {
            .events = eventMask,
            .data = {
                .fd = fileDescriptor
            }
        };

        if (::epoll_ctl(this->fileDescriptor.value(), EPOLL_CTL_ADD, fileDescriptor, &event) != 0) {
            throw Exception(
                "Failed to add entry to epoll instance - error number " + std::to_string(errno) + " returned."
            );
        }
    }

    void EpollInstance::removeEntry(int fileDescriptor) {
        if (::epoll_ctl(this->fileDescriptor.value(), EPOLL_CTL_DEL, fileDescriptor, NULL) != 0) {
            throw Exception(
                "Failed to remove entry from epoll instance - error number " + std::to_string(errno)
                    + " returned."
            );
        }
    }

    std::optional<int> EpollInstance::waitForEvent(std::optional<std::chrono::milliseconds> timeout) const {
        std::array<struct epoll_event, 1> events = {};

        const auto eventCount = ::epoll_wait(
            this->fileDescriptor.value(),
            events.data(),
            1,
            timeout.has_value() ? static_cast<int>(timeout->count()) : -1
        );

        if (eventCount < 1) {
            return std::nullopt;
        }

        return static_cast<int>(events.at(0).data.fd);
    }

    EpollInstance::EpollInstance(EpollInstance&& other) noexcept
        : fileDescriptor(other.fileDescriptor)
    {
        other.fileDescriptor = std::nullopt;
    }

    EpollInstance::~EpollInstance() noexcept {
        if (this->fileDescriptor.value_or(-1) >= 0) {
            ::close(this->fileDescriptor.value());
        }
    }
}