/**
 * @file MessageServer.cpp
 * @brief Implementation of the external client message server
 */

#include "MessageServer.h"

#include <QLoggingCategory>

#include <stdexcept>

Q_DECLARE_LOGGING_CATEGORY(messageserver_js8)

MessageServer::MessageServer(QObject *parent) : QTcpServer(parent) {}

MessageServer::~MessageServer() { stop(); }

bool MessageServer::start() {
    if (isListening()) {
        qCDebug(messageserver_js8)
            << "MessageServer already listening:" << m_host << m_port;
        return false;
    }

    auto address = QHostAddress();
    if (m_host.isEmpty() || !address.setAddress(m_host)) {
        qCDebug(messageserver_js8)
            << "MessageServer address invalid:" << m_host << m_port;
        return false;
    }

    if (m_port <= 0) {
        qCDebug(messageserver_js8)
            << "MessageServer port invalid:" << m_host << m_port;
        return false;
    }

    bool listening = listen(address, m_port);
    qCDebug(messageserver_js8)
        << "MessageServer listening:" << listening << m_host << m_port;

    return listening;
}

void MessageServer::stop() {
    // disconnect all clients
    foreach (auto client, m_clients) {
        client->close();
    }

    // then close the server
    close();
}

void MessageServer::setServer(QString host, quint16 port) {
    bool listening = isListening();
    if (listening && (m_host != host || m_port != port)) {
        stop();
    }

    m_host = host;
    m_port = port;

    if (listening) {
        start();
    }
}

void MessageServer::setPause(bool paused) {
    m_paused = paused;

    if (paused) {
        pauseAccepting();
    } else {
        resumeAccepting();
    }
}

void MessageServer::setMaxConnections(int n) {
    // set the maximum number of connections allowed
    m_maxConnections = n;

    // then, prune old ones greater than the max (fifo)
    pruneConnections();
}

int MessageServer::activeConnections() {
    int i = 0;
    foreach (auto client, m_clients) {
        if (client->isConnected())
            i++;
    }
    return i;
}

void MessageServer::pruneConnections() {
    // keep only the n most recent connections (fifo)
    if (m_maxConnections && m_maxConnections < activeConnections()) {
        for (int i = m_maxConnections; i < activeConnections(); i++) {
            auto client = m_clients.first();
            client->close();
            m_clients.removeFirst();
        }
    }
}

void MessageServer::send(const Message &message) {
    foreach (auto client, m_clients) {
        if (!client->awaitingResponse(message.id())) {
            continue;
        }
        client->send(message);
    }
}

void MessageServer::incomingConnection(qintptr handle) {
    qCDebug(messageserver_js8) << "MessageServer incomingConnection" << handle;

    auto client = new Client(this, this);
    client->setSocket(handle);

#if JS8_MESSAGESERVER_IS_SINGLE_CLIENT
    while (!m_clients.isEmpty()) {
        auto client = m_clients.first();
        client->close();
        m_clients.removeFirst();
    }
#endif

    if (m_maxConnections && m_maxConnections <= activeConnections()) {
        qCDebug(messageserver_js8)
            << "MessageServer connections full, dropping incoming connection";
        client->send(Message("API.ERROR", "Connections Full"));
        client->close();
        return;
    }

    m_clients.append(client);
}

Client::Client(MessageServer *server, QObject *parent)
    : QObject(parent), m_server{server} {
    setConnected(true);
}

void Client::setSocket(qintptr handle) {
    m_socket = new QTcpSocket(this);

    connect(m_socket, &QTcpSocket::disconnected, this, &Client::onDisconnected);
    connect(m_socket, &QTcpSocket::readyRead, this, &Client::readyRead);

    m_socket->setSocketDescriptor(handle);
}

void Client::setConnected(bool connected) { m_connected = connected; }

void Client::close() {
    if (!m_socket) {
        return;
    }

    m_socket->close();
    m_socket = nullptr;
}

void Client::send(const Message &message) {
    if (!isConnected()) {
        return;
    }

    if (!m_socket) {
        return;
    }

    if (!m_socket->isOpen()) {
        qCDebug(messageserver_js8) << "client socket isn't open";
        return;
    }

    qCDebug(messageserver_js8) << "client writing" << message.toJson();
    m_socket->write(message.toJson());
    m_socket->write("\n");
    m_socket->flush();

    // remove if needed
    if (m_requests.contains(message.id())) {
        m_requests.remove(message.id());
    }
}

void Client::onDisconnected() {
    qCDebug(messageserver_js8) << "MessageServer client disconnected";
    setConnected(false);
}

void Client::readyRead() {
    qCDebug(messageserver_js8) << "MessageServer client readyRead";

    while (m_socket->canReadLine()) {
        auto const msg = m_socket->readLine().trimmed();
        qCDebug(messageserver_js8)
            << "-> Client" << m_socket->socketDescriptor() << msg;

        if (msg.isEmpty())
            return;

        try {
            auto m = Message::fromJson(msg);
            m_requests[m.ensureId()] = m;
            emit m_server->message(m);
        } catch (std::exception const &e) {
            send({"API.ERROR", e.what()});
            return;
        }
    }
}

Q_LOGGING_CATEGORY(messageserver_js8, "messageserver.js8", QtWarningMsg)