from abc import ABC, abstractmethod
from contextlib import suppress

from .message_sender import MessageSender


class MessageStorage(ABC):
    def __init__(self):
        self._messages = []

    def save_message(self, message):
        with suppress(KeyError, AttributeError):
            if self._filter_message(message):
                self._messages.extend(self._transform_message(message))

    @abstractmethod
    def _filter_message(self, message):
        raise NotImplementedError

    def _transform_message(self, message):   # pylint: disable=no-self-use
        yield message

    def clear(self):
        self._messages.clear()

    @property
    def messages(self):
        yield from self._messages


class FrontendMessageStorage(MessageStorage):
    def __init__(self, keys):
        self._keys = keys
        super().__init__()

    def _filter_message(self, message):
        key = message['key']
        return key in self._keys

    def _transform_message(self, message):
        if message['key'] == 'queueMessages':
            yield from MessageSender.generate_messages_from_queue(message)
        else:
            yield message