/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   Connection.hpp                                     :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: acossari <acossari@student.codam.nl>       +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2026/08/28 09:21:04 by acossari          #+#    #+#             */
/*   Updated: 2026/08/29 18:07:36 by acossari         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#pragma once

#include <cstddef>
#include <cstdint>

#include "net/ByteBuffer.hpp"
#include "net/FileDescriptor.hpp"

namespace webserv {

class Connection final {
  public:
    enum class Lifecycle { Alive, Done, Fatal };

    struct Outcome {
        Lifecycle lifecycle;
        std::uint32_t desiredEvents;
    };

    // ByteBuffer::CAPACITY is 64 KiB.
    // At most 16 KiB are copied per 48 KiB appended: 16 / 48 = 1 / 3.
    // A lower threshold reduces copying but leaves less unread work available.
    // The 16 KiB value is a fixed compromise, not a measured optimum.
    static constexpr std::size_t LOW_WATERMARK = 16uz * 1024;

    explicit Connection(FileDescriptor socket);

    // Each Connection has a unique identity and remains in its original slot.
    Connection(const Connection&) = delete;
    Connection& operator=(const Connection&) = delete;
    Connection(Connection&&) = delete;
    Connection& operator=(Connection&&) = delete;

    int fd() const noexcept { return socket_.get(); }

    Outcome onClientEvent(std::uint32_t events);

    std::uint32_t desiredEvents() noexcept;

    void close() noexcept { socket_.reset(); }

  private:
    // recv() returning zero means the client has finished sending data.
    // readClosed_ records this. receive() still returns true because this
    // is not an error and the socket may still send its buffered response.
    // Only a recv() error returns false.
    bool receive();
    bool transmit();
    // TEMP echo path: queues received bytes unchanged for sending back to
    // the client.
    void forwardReceivedBytes();

    FileDescriptor socket_;
    ByteBuffer receiveBuffer_;
    ByteBuffer sendBuffer_;
    bool readClosed_ = false;
};

}  // namespace webserv