"""Opt-in explicit device binding for SAPIEN 3's legacy RoboTwin API."""
import os


def bind_sapien():
    shader = os.environ.get('EVAL_RENDER_SHADER', 'rt')
    if shader not in ('rt', 'default'):
        raise ValueError('Supported evaluation shaders: rt or default')
    if shader != 'rt':
        import sapien
        original_shader = sapien.render.set_camera_shader_dir
        # Override only the official rt request. All physics/camera geometry and
        # RNG remain unchanged; the new rendering protocol is recorded by the
        # scheduler and must never be merged with local rt measurements.
        def selected_shader(path):
            return original_shader(shader if path == 'rt' else path)
        sapien.render.set_camera_shader_dir = selected_shader
    if not os.environ.get('EVAL_GPU_UUID'):
        return
    if os.environ.get('CUDA_VISIBLE_DEVICES') != os.environ['EVAL_GPU_UUID']:
        raise RuntimeError('Simulator CUDA mask does not match the allocated GPU')
    import sapien
    device = sapien.Device('cuda:0')
    if not device.is_cuda() or not device.can_render():
        raise RuntimeError(f'Allocated GPU cannot render: {device}')
    native_init = sapien.pysapien.render.SapienRenderer.__init__
    sapien.SapienRenderer.__init__ = lambda self, **kw: native_init(self, device)
    from sapien.wrapper.scene import Scene
    original_init = Scene.__init__
    def bound_scene(self, systems=None):
        if systems is None:
            systems = [sapien.physx.PhysxCpuSystem(), sapien.render.RenderSystem(device)]
        original_init(self, systems)
        if self.render_system.device.pci_string != device.pci_string:
            raise RuntimeError('SAPIEN render device differs from allocation')
    Scene.__init__ = bound_scene