
def lazy_import(module_name, submodules, submod_attrs):
    import importlib
    import os
    name_to_submod = {
        func: mod for mod, funcs in submod_attrs.items()
        for func in funcs
    }

    def __getattr__(name):
        if name in submodules:
            attr = importlib.import_module(
                '{module_name}.{name}'.format(
                    module_name=module_name, name=name)
            )
        elif name in name_to_submod:
            submodname = name_to_submod[name]
            module = importlib.import_module(
                '{module_name}.{submodname}'.format(
                    module_name=module_name, submodname=submodname)
            )
            attr = getattr(module, name)
        else:
            raise AttributeError(
                'No {module_name} attribute {name}'.format(
                    module_name=module_name, name=name))
        globals()[name] = attr
        return attr

    if os.environ.get('EAGER_IMPORT', ''):
        for name in name_to_submod.values():
            __getattr__(name)

        for attrs in submod_attrs.values():
            for attr in attrs:
                __getattr__(attr)
    return __getattr__


__getattr__ = lazy_import(
    __name__,
    submodules={
        'fusion',
        'invariants',
        'landcover',
        'materials',
        'reflectance',
        'semantics',
        'template',
        'uky_temporal_prediction',
        'tracking',
    },
    submod_attrs={},
)


def __dir__():
    return __all__


__all__ = ['fusion', 'invariants', 'landcover', 'materials', 'reflectance',
           'semantics', 'template', 'uky_temporal_prediction', 'tracking']
