# YOLOv5 🚀 by Ultralytics, AGPL-3.0 license

"""

Callback utils

"""

import threading

class Callbacks:

    """"

    Handles all registered callbacks for YOLOv5 Hooks

    """

    def __init__(self):

        # Define the available callbacks

        self._callbacks = {

            'on_pretrain_routine_start': [],

            'on_pretrain_routine_end': [],

            'on_train_start': [],

            'on_train_epoch_start': [],

            'on_train_batch_start': [],

            'optimizer_step': [],

            'on_before_zero_grad': [],

            'on_train_batch_end': [],

            'on_train_epoch_end': [],

            'on_val_start': [],

            'on_val_batch_start': [],

            'on_val_image_end': [],

            'on_val_batch_end': [],

            'on_val_end': [],

            'on_fit_epoch_end': [],  # fit = train + val

            'on_model_save': [],

            'on_train_end': [],

            'on_params_update': [],

            'teardown': [], }

        self.stop_training = False  # set True to interrupt training

    def register_action(self, hook, name='', callback=None):

        """

        Register a new action to a callback hook

        Args:

            hook: The callback hook name to register the action to

            name: The name of the action for later reference

            callback: The callback to fire

        """

        assert hook in self._callbacks, f"hook '{hook}' not found in callbacks {self._callbacks}"

        assert callable(callback), f"callback '{callback}' is not callable"

        self._callbacks[hook].append({'name': name, 'callback': callback})

    def get_registered_actions(self, hook=None):

        """"

        Returns all the registered actions by callback hook

        Args:

            hook: The name of the hook to check, defaults to all

        """

        return self._callbacks[hook] if hook else self._callbacks

    def run(self, hook, *args, thread=False, **kwargs):

        """

        Loop through the registered actions and fire all callbacks on main thread

        Args:

            hook: The name of the hook to check, defaults to all

            args: Arguments to receive from YOLOv5

            thread: (boolean) Run callbacks in daemon thread

            kwargs: Keyword Arguments to receive from YOLOv5

        """

        assert hook in self._callbacks, f"hook '{hook}' not found in callbacks {self._callbacks}"

        for logger in self._callbacks[hook]:

            if thread:

                threading.Thread(target=logger['callback'], args=args, kwargs=kwargs, daemon=True).start()

            else:

                logger['callback'](*args, **kwargs)