import os
import importlib


class Model(object):
    LABEL = None

    not_found_error = type('NotFoundError', (Exception, ), {})

    def __init__(self, **kwargs):
        self.initialized = False
        self._uses = {}
        self.attributes = kwargs

    def detect(self, *args, **kwargs):
        raise NotImplementedError

    def load(self, *args, **kwargs):
        raise NotImplementedError

    def unload(self, *args, **kwargs):
        raise NotImplementedError

    def filter(self, *args, **kwargs):
        raise NotImplementedError

    @classmethod
    def list(cls):
        models = {}
        for module in os.listdir(os.path.dirname(__file__)):
            if module[-3:] != '.py':
                continue
            if module[:-3] == 'model' or module[:-3] == "__init__":
                continue
            capital_only_first = "{}{}".format(module[0].upper(), module[1:-3])
            class_imported = getattr(importlib.import_module("AI.tools.models.{}".format(module[:-3])),
                                     capital_only_first)
            try:
                models[class_imported.LABEL] = class_imported
            except AttributeError:
                print('WARNING, Model {} has no attribute LABEL, it is required'.format(capital_only_first))
        return models

    @classmethod
    def search_by(cls, field, value):
        # Listing all models
        models = cls.list()
        for model in models:
            if getattr(models[model], field) == value:
                return models[model]
        else:
            print('No model found, field: {}; Value:{}'.format(field, value))

    def _add_use(self, task_id):
        self._uses[task_id] = True

    def _remove_use(self, task_id):
        self._uses[task_id] = False

    def _load(self, task_id):
        if not self.initialized:
            super(Model, self).__getattribute__('load')()
            self.initialized = True
        self._add_use(task_id)

    def _unload(self, task_id):
        # Check all uses
        self._remove_use(task_id)
        uses_true = [not self._uses[i] for i in self._uses]
        if all(uses_true):
            super(Model, self).__getattribute__('unload')()
            self.initialized = False
            self._uses = {}

    def __getattribute__(self, item):
        if item in ['load', 'unload']:
            return super(Model, self).__getattribute__('_{}'.format(item))
        return super(Model, self).__getattribute__(item)

    def __getitem__(self, item):
        return self.attributes[item]