"""Dock panel registration helper.

Routes through the ``kcsdk`` C++ module (IPanelProvider / DockWindowManager)
when available, falling back to direct PySide QDockWidget creation for
backwards compatibility.
"""

import FreeCAD

# Try to import the C++ SDK module; None if not yet built/installed.
try:
    import kcsdk as _kcsdk
except ImportError:
    _kcsdk = None

_AREA_MAP = {
    "left": 1,  # Qt.LeftDockWidgetArea / DockArea.Left
    "right": 2,  # Qt.RightDockWidgetArea / DockArea.Right
    "top": 4,  # Qt.TopDockWidgetArea / DockArea.Top
    "bottom": 8,  # Qt.BottomDockWidgetArea / DockArea.Bottom
}

_DOCK_AREA_MAP = None  # lazily populated from kcsdk


def _get_dock_area(area_str):
    """Convert area string to kcsdk.DockArea enum value."""
    global _DOCK_AREA_MAP
    if _DOCK_AREA_MAP is None:
        _DOCK_AREA_MAP = {
            "left": _kcsdk.DockArea.Left,
            "right": _kcsdk.DockArea.Right,
            "top": _kcsdk.DockArea.Top,
            "bottom": _kcsdk.DockArea.Bottom,
        }
    return _DOCK_AREA_MAP.get(area_str)


def register_dock_panel(object_name, title, widget_factory, area="right", delay_ms=0):
    """Register a dock panel, optionally deferred.

    Parameters
    ----------
    object_name : str
        Qt object name for duplicate prevention.
    title : str
        Dock widget title bar text.
    widget_factory : callable
        Zero-argument callable returning a ``QWidget``.  Called only
        when the panel is actually created (after *delay_ms*).
    area : str, optional
        Dock area: ``"left"``, ``"right"``, ``"top"``, or ``"bottom"``.
        Default ``"right"``.
    delay_ms : int, optional
        Milliseconds to wait before creating the panel.  Default 0
        (immediate, but still posted to the event loop).
    """
    if not isinstance(object_name, str):
        raise TypeError(f"object_name must be str, got {type(object_name).__name__}")
    if not callable(widget_factory):
        raise TypeError("widget_factory must be callable")

    if area not in _AREA_MAP:
        raise ValueError(f"area must be one of {list(_AREA_MAP)}, got {area!r}")

    if _kcsdk is not None:
        _register_via_kcsdk(object_name, title, widget_factory, area, delay_ms)
    else:
        _register_via_pyside(object_name, title, widget_factory, area, delay_ms)


def _register_via_kcsdk(object_name, title, widget_factory, area, delay_ms):
    """Register using the C++ SDK panel provider system."""
    dock_area = _get_dock_area(area)

    class _AnonymousProvider(_kcsdk.IPanelProvider):
        def id(self):
            return object_name

        def title(self):
            return title

        def create_widget(self):
            return widget_factory()

        def preferred_area(self):
            return dock_area

    try:
        _kcsdk.register_panel(_AnonymousProvider())

        def _create():
            try:
                _kcsdk.create_panel(object_name)
            except Exception as e:
                FreeCAD.Console.PrintLog(
                    f"kindred_sdk: Panel '{object_name}' creation failed: {e}\n"
                )

        from PySide.QtCore import QTimer

        QTimer.singleShot(max(0, delay_ms), _create)
    except Exception as e:
        FreeCAD.Console.PrintLog(
            f"kindred_sdk: kcsdk panel registration failed for '{object_name}', "
            f"falling back: {e}\n"
        )
        _register_via_pyside(object_name, title, widget_factory, area, delay_ms)


def _register_via_pyside(object_name, title, widget_factory, area, delay_ms):
    """Legacy fallback: create dock widget directly via PySide."""
    qt_area = _AREA_MAP[area]

    def _create():
        try:
            import FreeCADGui
            from PySide import QtCore, QtWidgets

            mw = FreeCADGui.getMainWindow()
            if mw is None:
                return

            if mw.findChild(QtWidgets.QDockWidget, object_name):
                return

            widget = widget_factory()
            panel = QtWidgets.QDockWidget(title, mw)
            panel.setObjectName(object_name)
            panel.setWidget(widget)
            mw.addDockWidget(QtCore.Qt.DockWidgetArea(qt_area), panel)
        except Exception as e:
            FreeCAD.Console.PrintLog(
                f"kindred_sdk: Dock panel '{object_name}' skipped: {e}\n"
            )

    try:
        from PySide.QtCore import QTimer

        QTimer.singleShot(max(0, delay_ms), _create)
    except Exception as e:
        FreeCAD.Console.PrintLog(
            f"kindred_sdk: Could not schedule dock panel '{object_name}': {e}\n"
        )