php-qml/framework/qml/src/BackendConnection.h

#pragma once

#include <QElapsedTimer>
#include <QObject>
#include <QProcess>
#include <QString>
#include <QtQmlIntegration>

class QNetworkAccessManager;
class QNetworkReply;
class QTimer;
class QQmlEngine;
class QJSEngine;

namespace PhpQml::Bridge {

/// Owns the backend lifecycle and exposes its health to QML.
///
/// Mode is auto-detected on construction:
///   - `BRIDGE_URL` env set → **dev mode**: connect to a developer-managed
///     backend at that URL.
///   - `BRIDGE_URL` unset → **bundled mode** (Phase 4a): spawn the embedded
///     `frankenphp` next to the host binary, generate a per-session bearer
///     token, run first-launch migrations, and supervise the child.
///
/// See PLAN.md §3 (Run modes), §7 (BackendConnection), §13 Phase 4a.
class BackendConnection : public QObject
{
    Q_OBJECT
    QML_ELEMENT
    QML_SINGLETON

    Q_PROPERTY(Mode mode READ mode CONSTANT)
    Q_PROPERTY(QString url READ url NOTIFY urlChanged)
    Q_PROPERTY(QString token READ token NOTIFY tokenChanged)
    Q_PROPERTY(ConnectionState connectionState READ connectionState NOTIFY connectionStateChanged)
    Q_PROPERTY(QString error READ error NOTIFY errorChanged)

public:
    enum class Mode {
        Dev,
        Bundled,
    };
    Q_ENUM(Mode)

    /// Full Update Semantics enum (PLAN.md §5).
    enum class ConnectionState {
        Connecting,
        Online,
        Reconnecting,
        Offline,
    };
    Q_ENUM(ConnectionState)

    explicit BackendConnection(QObject* parent = nullptr);
    ~BackendConnection() override;

    static BackendConnection* create(QQmlEngine* engine, QJSEngine*);

    Mode mode() const noexcept { return m_mode; }
    QString url() const { return m_url; }
    QString token() const { return m_token; }
    ConnectionState connectionState() const noexcept { return m_state; }
    QString error() const { return m_error; }

    /// Bundled mode: re-spawn the FrankenPHP child (e.g. after the user
    /// hits Retry on the Offline overlay). Dev mode: re-probe.
    Q_INVOKABLE void restart();

signals:
    void urlChanged();
    void tokenChanged();
    void connectionStateChanged();
    void errorChanged();
    /// Emitted in bundled mode when the supervisor restarts the FrankenPHP
    /// child and a fresh per-session secret is generated. RestClient and
    /// MercureClient pick the new value up on next request (§3 *Edge cases*).
    void tokenRotated(const QString& newToken);

private slots:
    void probe();
    void onProbeFinished();
    void onChildFinished(int exitCode, QProcess::ExitStatus status);

private:
    void initDevMode();
    void initBundledMode();
    bool runMigrations();
    bool spawnChild(QString* errorOut = nullptr);
    void teardownChild();
    QString resolveFrankenphpBin() const;
    QString resolveSymfonyDir() const;
    QString resolveCaddyfilePath() const;
    QString userDataDir() const;
    QString databaseUrl() const;
    void setState(ConnectionState s);
    void setError(const QString& msg);
    void setUrl(const QString& url);
    void setToken(const QString& token);
    static QString randomSecret(int bytes);

    Mode m_mode = Mode::Dev;
    QString m_url;
    QString m_token;
    QString m_jwtSecret;
    ConnectionState m_state = ConnectionState::Connecting;
    QString m_error;
    QString m_appName;
    QString m_dataDir;
    quint16 m_port = 8765;

    QNetworkAccessManager* m_nam = nullptr;
    QNetworkReply* m_pendingReply = nullptr;
    QTimer* m_retryTimer = nullptr;
    QElapsedTimer m_firstFailureSinceOnline;
    int m_offlineThresholdMs = 30000;

    QProcess* m_child = nullptr;
    int m_supervisorRetries = 0;
    static constexpr int kMaxSupervisorRetries = 5;
};

} // namespace PhpQml::Bridge