Univerxel/src/core/net/Client.hpp

#pragma once

#include "data.hpp"

namespace net {

class Client {
public:
    static constexpr auto HEADER_SIZE = sizeof(client_packet_type) + sizeof(salt_t);

    Client(const connection& ct) {
        auto addr = [&] {
            if(auto addr = ct.toAddress())
                return addr.value();

            FATAL("Invalid ip server address format");
        }();

        host = enet_host_create(NULL, 1, CHANNEL_COUNT, 0, 0);
        if(host == nullptr) {
            FATAL("Network client creation failed");
        }

        LOG_D("Connecting to " << ct);
        salt = std::rand();
        peer = enet_host_connect(host, &addr, CHANNEL_COUNT, salt);
        if(peer == nullptr) {
            FATAL("Cannot contact server " << ct);
        }

        if(ENetEvent event; enet_host_service(host, &event, TIMEOUT) <= 0 || event.type != ENET_EVENT_TYPE_CONNECT) {
            enet_peer_reset(peer);
            FATAL("Connection to server " << ct << " failed");
        }

        LOG_I("Connected to server " << ct);
    }
    ~Client() {
        LOG_D("Leaving server");
        enet_peer_disconnect_now(peer, 1);
        enet_host_destroy(host);
    }

    void pull(int delay = 0) {
        ENetEvent event;
        while(enet_host_service(host, &event, delay) > 0) {
            switch(event.type) {
                case ENET_EVENT_TYPE_CONNECT:
                    LOG_D("Client reconnected");
                    break;

                case ENET_EVENT_TYPE_DISCONNECT:
                    onDisconnect(event.data);
                    break;

                case ENET_EVENT_TYPE_RECEIVE: {
                    if(event.packet->dataLength < sizeof(server_packet_type)) {
                        LOG_D("Empty packet from server");
                        break;
                    }
                    const server_packet_type type = static_cast<server_packet_type>(*event.packet->data);
                    if(type < server_packet_type::CHUNK) {
                        if(event.packet->dataLength < sizeof(server_packet_type) + sizeof(salt)) {
                            LOG_D("Wrong salted packet size");
                            break;
                        }
                        if(memcmp(&salt, event.packet->data + sizeof(server_packet_type), sizeof(salt)) != 0) {
                            LOG_D("Wrong server salt");
                            break;
                        }
                    }
                    if(type == server_packet_type::CHALLENGE) {
                        if(event.packet->dataLength != sizeof(server_packet_type) + 2 * sizeof(salt)) {
                            LOG_D("Wrong challenge packet size");
                            break;
                        }

                        salt_t l;
                        memcpy(&l, event.packet->data + sizeof(server_packet_type) + sizeof(salt), sizeof(l));
                        salt ^= l;
                        LOG_D("Handshake done");
                        ready = true;
                        break;
                    }

                    onData(event.channelID, event.packet);
                    enet_packet_destroy(event.packet);
                    break;
                }

                case ENET_EVENT_TYPE_NONE:
                    break;
            }
        }
    }

    virtual void onDisconnect(enet_uint32 reason) {
        LOG_D("Client disconnected with reason " << reason);
        ready = false;
    }
    virtual void onData(enet_uint8 channel, ENetPacket* packet) {
        LOG_D("Data from server " << packet->dataLength << " on " << channel);
    }

    bool send(client_packet_type type, ENetPacket* packet, channel_type channel) {
        assert(packet->dataLength >= HEADER_SIZE);
        if(!ready) {
            LOG_W("Contacting server before handshake");
            enet_packet_destroy(packet);
            return false;
        }
        memcpy(packet->data, &type, sizeof(client_packet_type));
        memcpy(packet->data + sizeof(client_packet_type), &salt, sizeof(salt));
        return enet_peer_send(peer, (enet_uint8)(channel), packet) == 0;
    }
    bool send(client_packet_type type, const void* data, size_t size, channel_type channel, std::optional<enet_uint32> flags = {}) {
        auto packet = enet_packet_create(NULL, HEADER_SIZE + size, flags.value_or(channel == channel_type::RELIABLE ? ENET_PACKET_FLAG_RELIABLE : 0));
        memcpy(packet->data + HEADER_SIZE, data, size);
        return send(type, packet, channel);
    }
    template<typename D>
    bool send(client_packet_type type, const D& payload, channel_type channel, std::optional<enet_uint32> flags = {}) {
        return send(type, &payload, sizeof(payload), channel, flags);
    }

    constexpr bool isReady() const { return ready; }

protected:
    ENetHost *host;
    ENetPeer *peer;
    salt_t salt;
    bool ready = false;
};
}