"""The studio-side three-dimensional skeleton: importable, inert, Qt-safe.

Acceptance for stage 0 (``docs/architecture/studio-3d-stages.md``): the module
tree exists, it can be imported without PyOpenGL, and the one piece that must run
before ``QApplication`` — the surface format — selects a complete profile.

Nothing here renders. These tests are the floor a later stage must keep: the GL
binding is imported only once a real context exists, and the stubs say which stage
fills them in.
"""

from __future__ import annotations

import sys

import pytest


@pytest.fixture
def restore_surface_format():
    """The default surface format is process-wide; put it back afterwards."""
    from PyQt5.QtGui import QSurfaceFormat

    previous = QSurfaceFormat.defaultFormat()
    try:
        yield
    finally:
        QSurfaceFormat.setDefaultFormat(previous)


def test_the_skeleton_does_not_import_a_gl_binding(qt_app):
    """PyOpenGL must be imported for the platform Qt chose, not at import time.

    The binding decides GLX versus EGL when it first loads, so importing it while
    merely constructing the module tree would freeze a guess. The test fails if a
    future change adds a module-level ``import OpenGL``.
    """
    for name in [name for name in sys.modules if name == "OpenGL" or name.startswith("OpenGL.")]:
        del sys.modules[name]

    import orisys_studio.scene3d.camera  # noqa: F401
    import orisys_studio.scene3d.coordinator  # noqa: F401
    import orisys_studio.scene3d.gl_backend  # noqa: F401
    import orisys_studio.scene3d.panel  # noqa: F401
    import orisys_studio.scene3d.widget  # noqa: F401

    loaded = [name for name in sys.modules if name == "OpenGL" or name.startswith("OpenGL.")]
    assert loaded == [], f"importing the skeleton pulled in {loaded}"


def test_configure_surface_format_selects_a_complete_profile(qt_app, restore_surface_format):
    from PyQt5.QtGui import QSurfaceFormat

    from orisys_studio.scene3d.gl_backend import configure_surface_format

    configure_surface_format("desktop33")
    desktop = QSurfaceFormat.defaultFormat()
    assert desktop.renderableType() == QSurfaceFormat.OpenGL
    assert (desktop.majorVersion(), desktop.minorVersion()) == (3, 3)
    assert desktop.profile() == QSurfaceFormat.CoreProfile
    assert desktop.depthBufferSize() == 24
    assert desktop.samples() == 0, "v1 does not pay for multisampling"

    configure_surface_format("gles30")
    embedded = QSurfaceFormat.defaultFormat()
    assert embedded.renderableType() == QSurfaceFormat.OpenGLES
    assert (embedded.majorVersion(), embedded.minorVersion()) == (3, 0)

    with pytest.raises(ValueError):
        configure_surface_format("vulkan")  # type: ignore[arg-type]


def test_the_widget_holds_cpu_state_and_touches_no_context(qt_app):
    """Constructing the widget must not need a current context or a GPU."""
    from orisys_app_shared.scene3d.contracts import DisplaySettings, FrameIdentity
    from orisys_studio.scene3d.camera import OrbitCamera
    from orisys_studio.scene3d.gl_backend import GLRenderer
    from orisys_studio.scene3d.widget import Sensor3DWidget

    widget = Sensor3DWidget(GLRenderer(), OrbitCamera())
    try:
        assert isinstance(widget, Sensor3DWidget)
        widget.set_settings(DisplaySettings(display_gain=3.0))
        assert widget._settings.display_gain == 3.0
        # Nothing has been presented yet, and no context was needed to get here.
        assert widget._frame is None
    finally:
        widget.deleteLater()


def test_the_remaining_stub_says_which_stage_fills_it_in(qt_app):
    """What is implemented is exercised elsewhere; what is not says so.

    Stages 1 to 3 landed the camera, the dispatcher, the renderer, the sampler, the
    composer, the schedule and the adapters. ``ThreeDPanel`` is the one piece left,
    and it must still fail loudly with the stage that owns it rather than quietly
    doing nothing.
    """
    from orisys_app_shared.scene3d.contracts import (
        CameraPreset,
        DisplaySettings,
        FrameIdentity,
        RenderStats,
    )
    from orisys_studio.scene3d.camera import OrbitCamera
    from orisys_studio.scene3d.coordinator import ThreeDCoordinator
    from orisys_studio.scene3d.gl_backend import GLRenderer
    from orisys_studio.scene3d.panel import ThreeDPanel
    from orisys_studio.scene3d.widget import Sensor3DWidget

    camera = OrbitCamera()
    renderer = GLRenderer()
    widget = Sensor3DWidget(renderer, camera)
    coordinator = ThreeDCoordinator(widget, composer=object(), executor=None, max_fps=30)  # type: ignore[arg-type]
    panel = ThreeDPanel(coordinator, widget)
    try:
        # Stage 1 is real: the camera works with no context at all.
        camera.set_preset(
            CameraPreset("default", (0.0, 0.0, 1.0), (0.0, 0.0, 0.0), (0.0, 1.0, 0.0), 0.7)
        )
        assert camera.matrices((100, 100)).view.shape == (4, 4)

        # Stage 3 is real too: the coordinator's schedule exists with no Qt event.
        assert coordinator.state == "disabled"
        assert coordinator.generation == 0
        assert coordinator.superseded_frames == 0
        coordinator.close()  # idempotent, and safe before any scene is active

        for call, stage in (
            (lambda: panel.set_state("ready"), "stage 4"),
            (lambda: panel.set_render_stats(RenderStats()), "stage 4"),
            (lambda: panel.set_diagnostic(None), "stage 4"),
        ):
            with pytest.raises(NotImplementedError) as excinfo:
                call()
            assert stage in str(excinfo.value), (stage, str(excinfo.value))
        del DisplaySettings, FrameIdentity
    finally:
        widget.deleteLater()