/*!
 *
 * Copyright (c) 2024-2026 Diality Inc. - All Rights Reserved.
 * \copyright
 * THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 * WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 *
 * \file    CloudConnectServer.cpp
 * \author  (original)  Stephen Quong
 * \date    (original)  15-Jul-2026
 *
 */
#include "CloudConnectServer.h"

#include <QDebug>

/*!
 * \brief   CloudConnectServer::CloudConnectServer
 * \details Constructor
 * \param   parent  Optional QObject parent.
 */
CloudConnectServer::CloudConnectServer(QObject *parent) : QObject(parent)
{
    connect(&_server, &QLocalServer::newConnection, this, &CloudConnectServer::onNewConnection);
}

/*!
 * \brief   CloudConnectServer::listen
 * \details Removes any stale socket file, then starts the server.
 * \param   socketPath  Path to the Unix domain socket (UDS).
 * \return  true on success, false if the server could not bind.
 */
bool CloudConnectServer::listen(const QString &socketPath)
{
    QLocalServer::removeServer(socketPath);
    if (!_server.listen(socketPath)) {
        qCritical().noquote() << metaObject()->className() << ": failed to listen on" << socketPath
                              << "—" << _server.errorString();
        return false;
    }
    qInfo().noquote() << metaObject()->className() << ": listening on" << socketPath;
    return true;
}

/*!
 * \brief   CloudConnectServer::send
 * \details Builds a CloudConnectFrame and writes it to the connected client.
 * \param   topic     MQTT topic for the frame header.
 * \param   sequence  Caller-managed sequence number.
 * \param   payload   Message payload; pass empty for zero-length frames.
 * \return  true if written to the socket, false if no client is connected.
 */
bool CloudConnectServer::send(CloudConnectFrame::Topic topic, quint16 sequence, const QByteArray &payload)
{
    if (_client == nullptr || _client->state() != QLocalSocket::ConnectedState) {
        return false;
    }
    const QByteArray frame = CloudConnectFrame::build(topic, sequence, payload);
    _client->write(frame);
    _client->flush();
    return true;
}

/*!
 * \brief   CloudConnectServer::isConnected
 * \details Reports whether a client is currently connected to the server.
 * \return  true if a client is currently connected.
 */
bool CloudConnectServer::isConnected() const
{
    return _client != nullptr;
}

/*!
 * \brief   CloudConnectServer::onNewConnection
 * \details Accepts the pending connection. If a client is already connected the
 *          new socket is discarded with a warning.
 */
void CloudConnectServer::onNewConnection()
{
    if (_client) {
        qWarning().noquote() << metaObject()->className()
                             << ": previous client connected, new client connection refused";
        _server.nextPendingConnection()->deleteLater();
        return;
    }

    _client = _server.nextPendingConnection();
    qInfo().noquote() << metaObject()->className() << ": client connected";

    connect(_client, &QLocalSocket::readyRead, this, &CloudConnectServer::onReadyRead);
    connect(_client, &QLocalSocket::disconnected, this, &CloudConnectServer::onDisconnected);

    emit didConnect();
}

/*!
 * \brief   CloudConnectServer::onDisconnected
 * \details Releases the client socket and resets incoming frame state.
 */
void CloudConnectServer::onDisconnected()
{
    qInfo().noquote() << metaObject()->className() << ": client disconnected";
    _client->deleteLater();
    _client = nullptr;
    _rxBuf.clear();
    _rxFrame.reset();

    emit didDisconnect();
}

/*!
 * \brief   CloudConnectServer::onReadyRead
 * \details Handler for incoming data from the client.
 */
void CloudConnectServer::onReadyRead()
{
    _rxBuf.append(_client->readAll());

    CloudConnectFrame::ReadState state;
    do {
        state = _rxFrame.read(_rxBuf);
        switch (state) {
            case CloudConnectFrame::ReadState::Complete:
                emit didMessageReceive(_rxFrame.topic(), _rxFrame.sequence(), _rxFrame.payload());
                _rxFrame.reset();
                break;
            case CloudConnectFrame::ReadState::HeaderError:
                qWarning().noquote() << metaObject()->className() << ": header CRC error — frame dropped";
                break;
            case CloudConnectFrame::ReadState::PayloadError:
                qWarning().noquote() << metaObject()->className() << ": payload CRC error — frame dropped";
                break;
            case CloudConnectFrame::ReadState::Incomplete:
                break;
        }
    } while (state == CloudConnectFrame::ReadState::Complete && !_rxBuf.isEmpty());
}