/*
 * msg_client.cpp — C++ транспортный клиент
 */

#include "msg_client.h"
#include <cstring>

MsgClient::MsgClient(QObject* parent) : QObject(parent), m_socket(new QTcpSocket(this)) {
    QObject::connect(m_socket, &QTcpSocket::connected,           this, &MsgClient::connected);
    QObject::connect(m_socket, &QTcpSocket::disconnected,        this, [this]() {
        if (m_boundPeerId) {
            m_boundPeerId = 0;
            emit unbound();
        }
        emit disconnected();
    });
    QObject::connect(m_socket, &QTcpSocket::readyRead,           this, &MsgClient::onReadyRead);
    QObject::connect(m_socket, &QAbstractSocket::errorOccurred,  this, &MsgClient::onSocketError);
}

MsgClient::~MsgClient() {
    disconnectFromHost();
}

void MsgClient::connectToHost(const QString& host, quint16 port) {
    m_recvBuffer.clear();
    m_boundPeerId = 0;
    m_socket->connectToHost(host, port);
}

void MsgClient::disconnectFromHost() {
    if (m_socket->state() != QAbstractSocket::UnconnectedState)
        m_socket->disconnectFromHost();
    m_recvBuffer.clear();
    if (m_boundPeerId) {
        m_boundPeerId = 0;
        emit unbound();
    }
}

bool MsgClient::isConnected() const {
    return m_socket->state() == QAbstractSocket::ConnectedState;
}

void MsgClient::bind(quint64 peerId) {
    QByteArray msg = buildMessage(kCtlBind, peerId, 0, QByteArray());
    m_socket->write(msg);
}

void MsgClient::unbind() {
    if (!m_boundPeerId) return;
    QByteArray msg = buildMessage(kCtlUnbind, 0, 0, QByteArray());
    m_socket->write(msg);
    m_boundPeerId = 0;
    emit unbound();
}

void MsgClient::send(const QByteArray& data) {
    if (!m_boundPeerId) return;
    QByteArray msg = buildMessage(kDataSend, m_boundPeerId, 0, data);
    m_socket->write(msg);
}

void MsgClient::send(const uint8_t* data, size_t len) {
    send(QByteArray(reinterpret_cast<const char*>(data), static_cast<int>(len)));
}

void MsgClient::sendSigned(const QByteArray& data) {
    if (!m_boundPeerId) return;
    QByteArray msg = buildMessage(kDataSend, m_boundPeerId, kOptSigned, data);
    m_socket->write(msg);
}

/* ============================================================================
 * Внутренние
 * ============================================================================ */

void MsgClient::onReadyRead() {
    m_recvBuffer.append(m_socket->readAll());
    if (m_recvBuffer.size() > static_cast<int>(kMaxMsgSize)) {
        m_recvBuffer.clear();
        emit errorOccurred(0xFF, "recv buffer overflow");
        return;
    }
    processMessages();
}

void MsgClient::onSocketError(QAbstractSocket::SocketError) {
    emit errorOccurred(0xFF, m_socket->errorString());
}

void MsgClient::processMessages() {
    while (static_cast<size_t>(m_recvBuffer.size()) >= kHdrSize) {
        uint16_t totalSize;
        std::memcpy(&totalSize, m_recvBuffer.constData(), 2);
        if (totalSize < kHdrSize || totalSize > kMaxMsgSize) {
            m_recvBuffer.clear();
            emit errorOccurred(0xFF, "invalid message size");
            return;
        }
        if (m_recvBuffer.size() < totalSize) break;

        uint8_t  type    = static_cast<uint8_t>(m_recvBuffer[2]);
        uint64_t id;
        std::memcpy(&id, m_recvBuffer.constData() + 3, 8);
        QByteArray payload = m_recvBuffer.mid(static_cast<int>(kHdrSize),
                                              totalSize - static_cast<uint16_t>(kHdrSize));

        dispatch(type, id, payload);

        m_recvBuffer.remove(0, totalSize);
    }
}

void MsgClient::dispatch(uint8_t type, quint64 id, const QByteArray& payload) {
    switch (type) {
    case kRspBindOk:
        m_boundPeerId = id;
        emit bound(id);
        break;
    case kDataRecv:
        emit received(id, payload);
        break;
    case kRspError:
        uint8_t code = payload.size() > 0 ? static_cast<uint8_t>(payload[0]) : 0;
        QString msg = QString::fromUtf8(payload.mid(1));
        emit errorOccurred(code, msg);
        break;
    }
}

QByteArray MsgClient::buildMessage(uint8_t type, quint64 id, uint8_t options, const QByteArray& data) {
    uint16_t totalSize = static_cast<uint16_t>(kHdrSize + data.size());
    QByteArray msg;
    msg.resize(totalSize);
    std::memcpy(msg.data(), &totalSize, 2);
    msg[2]  = static_cast<char>(type);
    std::memcpy(msg.data() + 3, &id, 8);
    msg[11] = static_cast<char>(options);
    if (!data.isEmpty())
        std::memcpy(msg.data() + kHdrSize, data.constData(), data.size());
    return msg;
}