baseimage-tutorial-framework/lib/tfw/builtins/frontend_event_handler.py

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from abc import ABC, abstractmethod
from contextlib import suppress
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from tfw.networking import Scope
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from .message_sender import MessageSender
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from .event_handler import EventHandler
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class FrontendEventHandler(EventHandler):
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def __init__(self):
frontend_keys = ('message', 'queueMessages', 'dashboard', 'console')
self._frontend_message_storage = FrontendMessageStorage(frontend_keys)
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super().__init__((*frontend_keys, 'recover'), scope=Scope.WEBSOCKET)
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def handle_event(self, message):
self._frontend_message_storage.save_message(message)
if message['key'] == 'recover':
self.recover_frontend()
self.send_message(message)
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def recover_frontend(self):
for message in self._frontend_message_storage.messages:
self.send_message(message)
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