kygui/client.cpp

#include <client.hpp>
#include <arpa/inet.h>
#include <netdb.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <functional>
#include <cstring>
#include <QDebug>
#include <QByteArray>
#include <iostream>
#include <vector>
#include <future>
#include <headers/kmessage_codec.hpp>
#include <headers/json.hpp>
#include <headers/util.hpp>

using namespace KData;

using json = nlohmann::json;

static const int MAX_BUFFER_SIZE = 2048;

flatbuffers::FlatBufferBuilder builder(1024);

/**
 * @brief Client::createMessageHandler
 * @param cb
 * @return
 */
Client::MessageHandler Client::createMessageHandler(
    std::function<void()> cb) {
  return MessageHandler(cb);
}

/**
 * @brief Client::Client
 * @constructor
 * @param parent
 * @param count
 * @param arguments
 */
Client::Client(QWidget *parent, int count, char** arguments) : QDialog(parent), argc(count), argv(arguments), m_client_socket_fd(-1) {}

/**
 * @brief Client::~Client
 * @destructor
 */
Client::~Client() {
    closeConnection();
}

 /**
 * @brief Client::handleMessages
 */
void Client::handleMessages() {
    char receive_buffer[2048];
    for (;;) {
        memset(receive_buffer, 0, 2048);
        ssize_t bytes_received = 0;
        bytes_received = recv(m_client_socket_fd, receive_buffer, 2048 - 2, 0);
        receive_buffer[2047] = 0;
        if (bytes_received == 0) {
            break;
        }
        emit Client::messageReceived(QString::fromUtf8(receive_buffer, 2048));
    }
    memset(receive_buffer, 0, 2048);
    ::close(m_client_socket_fd);
}

/**
 * @brief Client::start
 * @return A meaningless integer
 */
void Client::start() {
    if (m_client_socket_fd == -1) {
        m_client_socket_fd = socket(AF_INET, SOCK_STREAM, 0);
        if (m_client_socket_fd != -1) {
            sockaddr_in server_socket;
            char* end;
            server_socket.sin_family = AF_INET;
            auto port_value = strtol(argv[2], &end, 10);
            if (port_value < 0 || end == argv[2]) {
                return;
            }

            int socket_option = 1;
            // Free up the port to begin listening again
            setsockopt(m_client_socket_fd, SOL_SOCKET, SO_REUSEADDR, &socket_option,
                       sizeof(socket_option));

            server_socket.sin_port = htons(port_value);
            inet_pton(AF_INET, argv[1], &server_socket.sin_addr.s_addr);

            if (::connect(m_client_socket_fd, reinterpret_cast<sockaddr*>(&server_socket),
                          sizeof(server_socket)) != -1) {
                std::string start_operation_string = createOperation("start", {});
                // Send operation as an encoded message
                sendEncoded(start_operation_string);
                // Delegate message handling to its own thread
                std::function<void()> message_send_fn = [this]() {
                    this->handleMessages();
                };
                MessageHandler message_handler = createMessageHandler(message_send_fn);
                // Handle received messages on separate thread
                std::thread (message_handler).detach();

            } else {
                qDebug() << errno;
                ::close(m_client_socket_fd);
            }
        } else {
            qDebug() << "Failed to create new connection";
        }
    } else {
        qDebug() << "Connection already in progress";
    }
}

/**
 * @brief Client::sendMessage
 * @param s[in] <const QString&> The message to send
 */
void Client::sendMessage(const QString& s) {
    if (m_client_socket_fd != -1) {
        std::string json_string = createMessage(s.toUtf8().data());
        // Send custom message as an encoded message
        sendEncoded(json_string);
    } else {
        qDebug() << "You must first open a connection";
    }
}

void Client::sendEncoded(std::string message) {
    std::vector<uint8_t> fb_byte_vector{message.begin(), message.end()};
    auto byte_vector = builder.CreateVector(fb_byte_vector);
    auto k_message = CreateMessage(builder, 69, byte_vector);

    builder.Finish(k_message);

    uint8_t* encoded_message_buffer = builder.GetBufferPointer();
    uint32_t size = builder.GetSize();

    qDebug() << "Size is " << size;

    uint8_t send_buffer[MAX_BUFFER_SIZE];
    memset(send_buffer, 0, MAX_BUFFER_SIZE);
    send_buffer[0] = (size & 0xFF) >> 24;
    send_buffer[1] = (size & 0xFF) >> 16;
    send_buffer[2] = (size & 0xFF) >> 8;
    send_buffer[3] = (size & 0xFF);
    std::memcpy(send_buffer + 4, encoded_message_buffer, size);
    qDebug() << "Ready to send:";
    std::string message_to_send{};
    for (unsigned int i = 0; i < (size + 4); i++) {
        message_to_send += (char)*(send_buffer + i);
    }
    qDebug() << message_to_send.c_str();
    // Send start operation
    ::send(m_client_socket_fd, send_buffer, size + 4, 0);
    builder.Clear();
}

void Client::closeConnection() {
    if (m_client_socket_fd != -1) {
        std::string stop_operation_string = createOperation("stop", {});
        // Send operation as an encoded message
        sendEncoded(stop_operation_string);
        // Clean up socket file descriptor
        ::shutdown(m_client_socket_fd, SHUT_RDWR);
        ::close(m_client_socket_fd);
        m_client_socket_fd = -1;
    }
}