#pragma once
#include <QElapsedTimer>
#include <QList>
#include <QObject>
#include <QSettings>
#include <QString>
#include <QVariantMap>

namespace fincept {

/// Manages session state: uptime, last-used tabs, window geometry, etc.
class SessionManager : public QObject {
    Q_OBJECT
  public:
    static SessionManager& instance();

    void start_session();
    qint64 uptime_seconds() const;
    QString uptime_string() const;

    // Tab session state
    void save_tab_state(const QString& tab_id, const QVariantMap& state);
    QVariantMap load_tab_state(const QString& tab_id) const;

    // Window geometry — scoped per window_id (0 = primary)
    void save_geometry(int window_id, const QByteArray& geometry, const QByteArray& state);
    QByteArray load_geometry(int window_id) const;
    QByteArray load_state(int window_id) const;

    // Track the exact set of window IDs that were open at last shutdown.
    // Used on startup to restore every window (not just window 0) so that
    // multi-monitor layouts survive across app relaunches.
    void save_window_ids(const QList<int>& ids);
    QList<int> load_window_ids() const;

    // Per-window QScreen name — used to restore a window onto the correct
    // monitor when multiple are connected. Empty on first run / fallback
    // to primary screen when the saved screen is no longer available.
    void save_screen_name(int window_id, const QString& screen_name);
    QString load_screen_name(int window_id) const;

    // Per-window boolean flags — used by always-on-top and similar window
    // state toggles. Namespaced under window_<id>/flags/<name>.
    void save_window_flag(int window_id, const QString& name, bool value);
    bool load_window_flag(int window_id, const QString& name, bool default_value = false) const;

    // ADS dock layout — scoped per window_id
    void save_dock_layout(int window_id, const QByteArray& layout);
    QByteArray load_dock_layout(int window_id) const;

    // Dock layout version — used to auto-discard stale layouts after code changes
    void set_dock_layout_version(int window_id, int version);
    int dock_layout_version(int window_id) const;

    // Named perspectives (saved layouts)
    void save_perspectives(QSettings& source);
    void load_perspectives(QSettings& target) const;

    // Last active screen — scoped per window_id so multi-window users don't
    // overwrite each other's restore target. Reads fall back to the legacy
    // global key when no per-window value is recorded (migration path for
    // existing users; auto-cleaned the first time the new key is written).
    void set_last_screen(int window_id, const QString& screen_id);
    QString last_screen(int window_id) const;

    /// Force an immediate snapshot of the current QSettings-backed state
    /// into the WorkspaceDb ring buffer. Used by closeEvent paths that
    /// want to bypass the auto-rate limit on a real shutdown. The Phase 2
    /// auto path still rate-limits so this is the only "always now" hook.
    /// No-op if WorkspaceDb isn't open (early init or shutdown teardown).
    void flush_snapshot_now();

  signals:
    void session_started();

  private:
    SessionManager() = default;

    /// Internal: triggered by every save_* call. Builds a JSON payload
    /// from the union of `window_<id>/*` keys + `window_ids` + `last_screen`
    /// and pushes through WorkspaceSnapshotRing::add_auto, which rate-limits
    /// to 60s. This is the Phase 2 "double-write" — QSettings still gets
    /// the per-key write (legacy reads keep working) and WorkspaceDb gets
    /// the consolidated snapshot.
    ///
    /// Phase 6 replaces this with proper Workspace serialisation once
    /// FrameLayout/PanelState are wired through WindowFrame.
    void request_snapshot_(bool force);

    /// Build a JSON payload representing the current QSettings state.
    /// Used by request_snapshot_() and exposed for testing.
    QByteArray build_snapshot_payload_() const;

    QElapsedTimer elapsed_;
    mutable QSettings settings_{"Fincept", "FinceptTerminal"};
};

} // namespace fincept