#include "BackendConnection.h"

#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QQmlEngine>
#include <QTimer>
#include <QUrl>

namespace PhpQml::Bridge {

namespace {
constexpr int kInitialProbeMs = 0;
constexpr int kProbeIntervalMs = 5000;
constexpr int kProbeTimeoutMs = 2000;
} // namespace

BackendConnection::BackendConnection(QObject* parent)
    : QObject(parent)
    , m_nam(new QNetworkAccessManager(this))
    , m_retryTimer(new QTimer(this))
{
    m_url = QString::fromUtf8(qgetenv("BRIDGE_URL"));
    m_token = QString::fromUtf8(qgetenv("BRIDGE_TOKEN"));

    if (m_url.isEmpty()) {
        // Dev-mode fallback: matches the spike's hardcoded port and
        // documents the convention. See PLAN.md §11 *Open Questions*
        // (system FrankenPHP collision on :8080).
        m_url = QStringLiteral("http://127.0.0.1:8765");
    }

    m_retryTimer->setSingleShot(false);
    m_retryTimer->setInterval(kProbeIntervalMs);
    connect(m_retryTimer, &QTimer::timeout, this, &BackendConnection::probe);

    QTimer::singleShot(kInitialProbeMs, this, &BackendConnection::probe);
    m_retryTimer->start();
}

BackendConnection::~BackendConnection() = default;

BackendConnection* BackendConnection::create(QQmlEngine* engine, QJSEngine*)
{
    return new BackendConnection(engine);
}

void BackendConnection::restart()
{
    // No-op in dev mode (Phase 1). Phase 4 re-spawns the bundled child.
    probe();
}

void BackendConnection::probe()
{
    if (m_pendingReply) return;

    QNetworkRequest req;
    req.setUrl(QUrl(m_url + QStringLiteral("/healthz")));
    req.setTransferTimeout(kProbeTimeoutMs);
    if (!m_token.isEmpty()) {
        req.setRawHeader("Authorization", "Bearer " + m_token.toUtf8());
    }

    m_pendingReply = m_nam->get(req);
    connect(m_pendingReply, &QNetworkReply::finished, this, &BackendConnection::onProbeFinished);
}

void BackendConnection::onProbeFinished()
{
    QNetworkReply* reply = m_pendingReply;
    m_pendingReply = nullptr;
    if (!reply) return;
    reply->deleteLater();

    bool ok = false;
    if (reply->error() == QNetworkReply::NoError) {
        const int status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        if (status == 200) {
            ok = true;
        } else {
            setError(QStringLiteral("/healthz returned HTTP %1").arg(status));
        }
    } else {
        setError(reply->errorString());
    }

    if (ok) {
        setError(QString());
        m_firstFailureSinceOnline.invalidate();
        setState(ConnectionState::Online);
        return;
    }

    // Probe failed. Decide between Reconnecting and Offline based on how
    // long we've been failing since the last Online. (PLAN.md §5.)
    if (!m_firstFailureSinceOnline.isValid()) {
        m_firstFailureSinceOnline.start();
    }
    if (m_firstFailureSinceOnline.hasExpired(m_offlineThresholdMs)) {
        setState(ConnectionState::Offline);
    } else {
        setState(ConnectionState::Reconnecting);
    }
}

void BackendConnection::setState(ConnectionState s)
{
    if (m_state == s) return;
    m_state = s;
    emit connectionStateChanged();
}

void BackendConnection::setError(const QString& msg)
{
    if (m_error == msg) return;
    m_error = msg;
    emit errorChanged();
}

} // namespace PhpQml::Bridge