/*!
 *
 * 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    AgentSimController.cpp
 * \author  (original)  Stephen Quong
 * \date    (original)  24-May-2026
 *
 */
#include "AgentSimController.h"
#include "LeahiMsgProtoUtils.h"

#include <google/protobuf/descriptor.h>
#include <google/protobuf/dynamic_message.h>
#include <google/protobuf/util/json_util.h>

#include <QDebug>

/*!
 * \brief   AgentSimController::AgentSimController
 * \details Constructor. Loads the INI configuration and wires the server newConnection signal.
 * \param   configPath  Path to the INI configuration file.
 * \param   parent      Optional QObject parent.
 */
AgentSimController::AgentSimController(const QString &configPath, QObject *parent)
    : QObject(parent), _settings(configPath, QSettings::IniFormat)
{
    connect(&_server, &QLocalServer::newConnection, this, &AgentSimController::onNewConnection);
}

/*!
 * \brief   AgentSimController::listen
 * \details Reads the socket path from the INI configuration, removes any stale
 *          socket file, then starts the server.
 * \return  true on success, false if the server could not bind.
 */
bool AgentSimController::listen()
{
    const QString socketPath = _settings.value("Socket/LocalSocketName", "/tmp/leahi_rt.sock").toString();
    QLocalServer::removeServer(socketPath);
    if (!_server.listen(socketPath)) {
        qCritical().noquote() << "AgentSim: failed to listen on" << socketPath << "—" << _server.errorString();
        return false;
    }
    qInfo().noquote() << "AgentSim: listening on" << socketPath;
    return true;
}

/*!
 * \brief   AgentSimController::onNewConnection
 * \details Accepts the pending connection. If a client is already connected the
 *          new socket is discarded with a warning.
 */
void AgentSimController::onNewConnection()
{
    if (_client) {
        qWarning().noquote() << "AgentSim: second connection attempt rejected — already connected";
        _server.nextPendingConnection()->deleteLater();
        return;
    }

    _client = _server.nextPendingConnection();
    qInfo().noquote() << "AgentSim: client connected";

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

/*!
 * \brief   AgentSimController::onDisconnected
 * \details Releases the client socket and resets inbound parser state.
 */
void AgentSimController::onDisconnected()
{
    qInfo().noquote() << "AgentSim: client disconnected";
    _client->deleteLater();
    _client = nullptr;
    _rxBuf.clear();
    _rxMsg.reset();
}

/*!
 * \brief   AgentSimController::onReadyRead
 * \details Appends incoming bytes to the receive buffer and drains it through
 *          the AgentMessage parser. Logs each complete frame and sends an Ack.
 */
void AgentSimController::onReadyRead()
{
    _rxBuf.append(_client->readAll());

    AgentMessage::FeedResult result;
    do {
        result = _rxMsg.feed(_rxBuf);
        switch (result) {
            case AgentMessage::FeedResult::Complete:
                handleMessage(_rxMsg);
                _rxMsg.reset();
                break;
            case AgentMessage::FeedResult::HeaderError:
                qWarning().noquote() << "AgentSim: header CRC error — frame dropped";
                break;
            case AgentMessage::FeedResult::PayloadError:
                qWarning().noquote() << "AgentSim: payload CRC error — frame dropped";
                break;
            case AgentMessage::FeedResult::Incomplete:
                break;
        }
    } while (result == AgentMessage::FeedResult::Complete && !_rxBuf.isEmpty());
}

/*!
 * \brief   AgentSimController::handleMessage
 * \details Decodes a received frame and prints its typed body as JSON, generically
 *          via the protobuf descriptor pool (msgId -> message name -> dynamic parse).
 * \param   msg  The complete AgentMessage frame.
 */
void AgentSimController::handleMessage(const AgentMessage &msg)
{
    const QByteArray payload = msg.payload();
    logMessage(msg.msgId(), msg.sequence(), payload);

    // Read the Header (field 1, shared by every typed message) to learn the msgId.
    leahi::messages::Envelope envelope;
    if (!envelope.ParseFromArray(payload.constData(), payload.size())) {
        qWarning().noquote() << "AgentSim: could not parse Envelope header — frame dropped";
        return;
    }
    const leahi::messages::Header &header = envelope.header();

    // Identify the concrete message type from the msgId and decode it generically.
    const std::string &typeName = leahi::msgIdToProtoName(static_cast<quint16>(header.msgid()));
    if (typeName.empty()) {
        qWarning().noquote() << QString("AgentSim: unknown msgId=0x%1 — cannot decode typed body")
            .arg(header.msgid(), 4, 16, QChar('0'));
        return;
    }

    const google::protobuf::Descriptor *desc =
        google::protobuf::DescriptorPool::generated_pool()->FindMessageTypeByName(typeName);
    if (desc == nullptr) {
        qWarning().noquote() << "AgentSim: no descriptor for" << QString::fromStdString(typeName);
        return;
    }

    google::protobuf::DynamicMessageFactory factory;
    std::unique_ptr<google::protobuf::Message> body(factory.GetPrototype(desc)->New());
    if (!body->ParseFromArray(payload.constData(), payload.size())) {
        qWarning().noquote() << "AgentSim: could not parse" << QString::fromStdString(typeName);
        return;
    }

    std::string json;
    google::protobuf::util::JsonPrintOptions opts;
    opts.add_whitespace = true;
    opts.always_print_primitive_fields = true;
    google::protobuf::util::MessageToJsonString(*body, &json, opts);

    // protobuf renders msgId as a decimal integer; rewrite it as 0x + 4-digit hex.
    QString jsonStr = QString::fromStdString(json);
    jsonStr.replace(QString("\"msgId\": %1").arg(header.msgid()),
                    QString("\"msgId\": \"0x%1\"").arg(header.msgid(), 4, 16, QChar('0')));
    qDebug().noquote() << QString::fromStdString(typeName) << ":" << Qt::endl
                       << jsonStr;
}

/*!
 * \brief   AgentSimController::logMessage
 * \details Logs the message identifier, sequence number, and payload length.
 * \param   msgId     Message identifier from the parsed frame.
 * \param   sequence  Sequence number from the parsed frame.
 * \param   payload   Payload bytes of the parsed frame.
 */
void AgentSimController::logMessage(AgentMessage::MsgId msgId, quint16 sequence, const QByteArray &payload)
{
    qInfo().noquote() << QString("AgentSim: rx  MsgId=0x%1  seq=%2  payloadLen=%3")
                             .arg(static_cast<quint16>(msgId), 4, 16, QChar('0'))
                             .arg(sequence)
                             .arg(payload.size());
}