#pragma once

#include <QByteArray>
#include <QObject>
#include <QString>
#include <QStringList>
#include <QtQmlIntegration>

class QNetworkAccessManager;
class QNetworkReply;
class QTimer;

namespace PhpQml::Bridge {

/// Single-topic Mercure SSE subscriber.
///
/// Implements the `text/event-stream` line protocol on top of QNetworkReply,
/// with exponential reconnect (1s → 2s → … → cap 30s) and `Last-Event-ID`
/// resume across reconnects. See PLAN.md §7 (MercureClient) and §3
/// *Edge cases — Sleep / wake* for the resume contract.
///
/// One client = one topic. Application code instantiates one per
/// subscribed topic; multi-topic aggregation is a Phase 2 concern.
class MercureClient : public QObject
{
    Q_OBJECT
    QML_ELEMENT

    Q_PROPERTY(QString hubUrl READ hubUrl WRITE setHubUrl NOTIFY hubUrlChanged)
    Q_PROPERTY(QString topic READ topic WRITE setTopic NOTIFY topicChanged)
    Q_PROPERTY(QString token READ token WRITE setToken NOTIFY tokenChanged)
    Q_PROPERTY(bool active READ active NOTIFY activeChanged)
    Q_PROPERTY(QString lastEventId READ lastEventId NOTIFY lastEventIdChanged)

public:
    explicit MercureClient(QObject* parent = nullptr);
    ~MercureClient() override;

    QString hubUrl() const { return m_hubUrl; }
    void setHubUrl(const QString& url);
    QString topic() const { return m_topic; }
    void setTopic(const QString& t);
    QString token() const { return m_token; }
    void setToken(const QString& t);
    bool active() const noexcept { return m_active; }
    QString lastEventId() const { return m_lastEventId; }

    Q_INVOKABLE void start();
    Q_INVOKABLE void stop();

signals:
    void hubUrlChanged();
    void topicChanged();
    void tokenChanged();
    void activeChanged();
    void lastEventIdChanged();

    /// Emitted for every dispatched SSE event with a `data:` field.
    /// `data` is the joined data lines as the hub sent them; `id` is
    /// the SSE event id (often a UUIDv7).
    void update(const QString& data, const QString& id);
    void error(const QString& detail);

private slots:
    void onReadyRead();
    void onFinished();
    void doConnect();

private:
    void scheduleReconnect();
    void teardownReply();
    void emitMessage();
    void setActive(bool a);

    QNetworkAccessManager* m_nam = nullptr;
    QNetworkReply* m_reply = nullptr;
    QTimer* m_reconnectTimer = nullptr;

    QString m_hubUrl;
    QString m_topic;
    QString m_token;
    QString m_lastEventId;

    QStringList m_dataLines;
    QByteArray m_pendingEventId;

    bool m_active = false;
    bool m_userStopped = false;
    int m_currentBackoffMs = kInitialBackoffMs;

    static constexpr int kInitialBackoffMs = 1000;
    static constexpr int kMaxBackoffMs = 30000;
};

} // namespace PhpQml::Bridge