import warnings

try:
    _has_django = True
    from django.utils.module_loading import autodiscover_modules
except ImportError:
    # Not a django project
    autodiscover_modules = None
    _has_django = False

from .utils import qualname

_REGISTRY = {}
_initialized = False


def register(cls):
    _REGISTRY[qualname(cls)] = cls
    _REGISTRY[cls.__name__] = cls
    return cls


def get_machine_cls(name):
    init_registry()
    if "." not in name:
        warnings.warn(
            """Use fully qualified names (<module>.<class>) for state machine mixins.""",
            DeprecationWarning,
            stacklevel=2,
        )
    return _REGISTRY[name]


def init_registry():
    global _initialized
    if not _initialized:
        load_modules(["statemachine", "statemachines"])
        _initialized = True


def load_modules(modules=None):
    if not _has_django:
        return

    for module in modules:
        autodiscover_modules(module)