// app/vpn/dragonrelaybackend.cpp
#include "dragonrelaybackend.h"

#include <QDebug>
#include <QMap>
#include <QProcess>
#include <QVariantMap>

// Constructor / Destructor

DragonRelayBackend::DragonRelayBackend(QObject *parent)
    : QObject(parent)
    , m_settings(QStringLiteral("WildDragon"), QStringLiteral("DragonMoonlight"))
{
    // Wire RelayClient signals
    connect(&m_relay, &RelayClient::loginSucceeded,
            this, [this]() { onLoginDone(true, QString()); });
    connect(&m_relay, &RelayClient::loginFailed,
            this, [this](const QString &err) { onLoginDone(false, err); });
    connect(&m_relay, &RelayClient::vpnProvisioned,
            this, [this](const RelayVPNConf &conf) { onVPNPeerProvisioned(conf); });
    connect(&m_relay, &RelayClient::vpnProvisionFailed,
            this, [this](const QString &err) { onVPNError(err); });
    connect(&m_relay, &RelayClient::hostsReady,
            this, [this](const QList<RelayHost> &hosts) { onHostsFetched(hosts); });
    connect(&m_relay, &RelayClient::hostsFetchFailed,
            this, [this](const QString &err) { onHostsError(err); });

    // Wire TunnelManager signals
    connect(&m_tunnel, &TunnelManager::tunnelUp,
            this, &DragonRelayBackend::onTunnelUp);
    connect(&m_tunnel, &TunnelManager::tunnelDown,
            this, &DragonRelayBackend::onTunnelDown);
    connect(&m_tunnel, &TunnelManager::tunnelError,
            this, &DragonRelayBackend::onTunnelError);

    // Host poll timer (every 30 s while tunnel is up)
    m_hostPollTimer.setInterval(30 * 1000);
    m_hostPollTimer.setSingleShot(false);
    connect(&m_hostPollTimer, &QTimer::timeout,
            this, &DragonRelayBackend::pollHosts);

    // Restore last-used connection settings so QML can pre-fill the form
    m_savedURL  = m_settings.value(QStringLiteral("relay/url")).toString();
    m_savedUser = m_settings.value(QStringLiteral("relay/username")).toString();
}

DragonRelayBackend::~DragonRelayBackend() {
    m_hostPollTimer.stop();
    m_tunnel.stop();
}

void DragonRelayBackend::setStatus(Status s, const QString &text) {
    bool changed = (m_status != s) || (!text.isEmpty() && text != m_statusText);
    m_status = s;
    if (!text.isEmpty())
        m_statusText = text;
    if (changed)
        emit statusChanged();
}

void DragonRelayBackend::connectRelay(const QString &url,
                                      const QString &username,
                                      const QString &password) {
    if (m_status == Connecting || m_status == TunnelUp || m_status == Ready)
        return;

    m_savedURL  = url;
    m_savedUser = username;
    m_savedPass = password;

    // Persist URL + username (NOT password - keychain integration is a TODO).
    m_settings.setValue(QStringLiteral("relay/url"),      url);
    m_settings.setValue(QStringLiteral("relay/username"), username);

    setStatus(Connecting, QStringLiteral("Logging in..."));
    m_relay.login(QUrl(url), username, password);
}

void DragonRelayBackend::disconnectRelay() {
    stopHostPoll();
    m_tunnel.stop();        // triggers onTunnelDown asynchronously
    m_relay.revokeVPN();    // fire-and-forget

    m_hosts.clear();
    m_hostDisplays.clear();
    m_tunnelIP.clear();
    emit hostsChanged();
    emit tunnelIPChanged();
    setStatus(Disconnected, QStringLiteral("Disconnected"));
}

void DragonRelayBackend::streamHost(const QString &ip, const QString &app, int displayIndex) {
    if (m_status != Ready && m_status != TunnelUp) {
        qWarning() << "DragonRelayBackend::streamHost called while not ready";
        return;
    }

    qDebug() << "DragonRelayBackend::streamHost ip=" << ip
             << "app=" << app << "displayIndex=" << displayIndex;

    QStringList args;
    args << QStringLiteral("stream") << ip << app;
    if (displayIndex > 0) {
        args << QStringLiteral("--display") << QString::number(displayIndex);
    }

    QProcess::startDetached(QStringLiteral("moonlight"), args);
}

QVariantList DragonRelayBackend::displaysForHost(const QString &hostIP) const {
    return m_hostDisplays.value(hostIP);
}

void DragonRelayBackend::streamHostDisplay(const QString &hostIP, int displayIndex) {
    qDebug() << "Streaming host" << hostIP << "display index" << displayIndex;

    const QVariantList displays = displaysForHost(hostIP);
    if (displayIndex < 0 || (!displays.isEmpty() && displayIndex >= displays.size())) {
        qWarning() << "DragonRelayBackend: displayIndex" << displayIndex
                   << "out of bounds for host" << hostIP
                   << "(has" << displays.size() << "displays)";
        displayIndex = 0; // fall back to primary
    }

    streamHost(hostIP, QStringLiteral("Desktop"), displayIndex);
}

void DragonRelayBackend::refreshHosts() {
    if (m_status == TunnelUp || m_status == Ready)
        m_relay.fetchHosts();
}

void DragonRelayBackend::pollHosts() {
    m_relay.fetchHosts();
}

void DragonRelayBackend::startHostPoll() {
    m_relay.fetchHosts();
    m_hostPollTimer.start();
}

void DragonRelayBackend::stopHostPoll() {
    m_hostPollTimer.stop();
}

void DragonRelayBackend::onLoginDone(bool ok, const QString &err) {
    if (!ok) {
        setStatus(Error, QStringLiteral("Login failed: ") + err);
        return;
    }
    setStatus(Connecting, QStringLiteral("Provisioning VPN peer..."));
    m_relay.provisionVPN();
}

void DragonRelayBackend::onVPNPeerProvisioned(const RelayVPNConf &conf) {
    setStatus(Connecting, QStringLiteral("Starting WireGuard tunnel..."));

    WireGuardConfig cfg = WireGuardConfig::fromConf(conf.conf);
    if (!cfg.isValid()) {
        setStatus(Error, QStringLiteral(
            "Bad VPN config: missing PrivateKey, Address, PublicKey, or Endpoint"));
        m_relay.revokeVPN();
        return;
    }

    if (!m_tunnel.start(cfg)) {
        // tunnel.start() emits tunnelError() synchronously on failure,
        // which routes through onTunnelError().
    }
}

void DragonRelayBackend::onVPNError(const QString &err) {
    setStatus(Error, QStringLiteral("VPN error: ") + err);
}

void DragonRelayBackend::onHostsFetched(const QList<RelayHost> &hosts) {
    m_hosts.clear();
    m_hostDisplays.clear();

    for (const auto &h : hosts) {
        QVariantMap m;
        m[QStringLiteral("name")]   = h.name;
        m[QStringLiteral("ip")]     = h.ip;
        m[QStringLiteral("port")]   = h.port;
        m[QStringLiteral("online")] = true;
        m[QStringLiteral("source")] = QStringLiteral("relay");
        m_hosts.append(m);

        m_hostDisplays[h.ip] = h.displays;
    }
    emit hostsChanged();

    Status next = m_hosts.isEmpty() ? TunnelUp : Ready;
    if (m_status != next) {
        QString text = m_hosts.isEmpty()
            ? QStringLiteral("Tunnel up - no hosts yet")
            : QStringLiteral("Connected - %1 host(s)").arg(m_hosts.size());
        setStatus(next, text);
    }
}

void DragonRelayBackend::onHostsError(const QString &err) {
    qWarning() << "DragonRelayBackend: hosts fetch error:" << err;
    // Don't downgrade to Error state - tunnel is still up.
}

void DragonRelayBackend::onTunnelUp(const QString &localIP) {
    if (m_tunnelIP == localIP && (m_status == TunnelUp || m_status == Ready))
        return; // ignore duplicate signals (first-packet path + 1.5 s fallback timer)

    m_tunnelIP = localIP;
    emit tunnelIPChanged();
    setStatus(TunnelUp,
              QStringLiteral("Tunnel up (%1) - fetching hosts...").arg(localIP));
    startHostPoll();
}

void DragonRelayBackend::onTunnelDown() {
    stopHostPoll();
    m_tunnelIP.clear();
    emit tunnelIPChanged();
    if (m_status != Disconnected)
        setStatus(Disconnected, QStringLiteral("Tunnel closed"));
}

void DragonRelayBackend::onTunnelError(const QString &err) {
    stopHostPoll();
    m_relay.revokeVPN();
    setStatus(Error, QStringLiteral("Tunnel error: ") + err);
}