# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.

import json

from tornado.websocket import WebSocketHandler

from tfw.networking import validate_message
from tfw.mixins import CallbackMixin
from tfw.config.logs import logging

LOG = logging.getLogger(__name__)


class TFWProxy:
    def __init__(self, to_source, to_destination):
        self.to_source = to_source
        self.to_destination = to_destination

        self.proxy_filters = CallbackMixin()
        self.proxy_callbacks = CallbackMixin()

        self.proxy_filters.subscribe_callback(validate_message)

        self.keyhandlers = {
            'mirror':    self.mirror,
            'broadcast': self.broadcast
        }

    def __call__(self, message):
        try:
            self.proxy_filters._execute_callbacks(message)
        except ValueError:
            LOG.exception('Invalid TFW message received!')
            return

        self.proxy_callbacks._execute_callbacks(message)

        if message['key'] not in self.keyhandlers:
            self.to_destination(message)
        else:
            handler = self.keyhandlers[message['key']]
            try:
                handler(message)
            except KeyError:
                LOG.error('Invalid "%s" message format! Ignoring.', handler.__name__)

    def mirror(self, message):
        message = message['data']
        LOG.debug('Mirroring message: %s', message)
        self.to_source(message)

    def broadcast(self, message):
        message = message['data']
        LOG.debug('Broadcasting message: %s', message)
        self.to_source(message)
        self.to_destination(message)


class ZMQWebSocketProxy(WebSocketHandler):
    instances = set()

    def initialize(self, **kwargs): # pylint: disable=arguments-differ
        self._event_handler_connector = kwargs['event_handler_connector']
        self._message_handlers = kwargs.get('message_handlers', [])
        self._proxy_filters = kwargs.get('proxy_filters', [])

        self.proxy_eventhandler_to_websocket = TFWProxy(
            self.send_eventhandler_message,
            self.send_websocket_message
        )
        self.proxy_websocket_to_eventhandler = TFWProxy(
            self.send_websocket_message,
            self.send_eventhandler_message
        )

        proxies = (self.proxy_eventhandler_to_websocket, self.proxy_websocket_to_eventhandler)
        for proxy in proxies:
            proxy.proxy_filters.subscribe_callbacks(*self._proxy_filters)
            proxy.proxy_callbacks.subscribe_callbacks(*self._message_handlers)

    def prepare(self):
        ZMQWebSocketProxy.instances.add(self)

    def on_close(self):
        ZMQWebSocketProxy.instances.remove(self)

    def open(self, *args, **kwargs):
        LOG.debug('WebSocket connection initiated')
        self._event_handler_connector.register_callback(self.eventhander_callback)

    def eventhander_callback(self, message):
        """
        Invoked on ZMQ messages from event handlers.
        """
        LOG.debug('Received on pull socket: %s', message)
        self.proxy_eventhandler_to_websocket(message)

    def on_message(self, message):
        """
        Invoked on WS messages from frontend.
        """
        message = json.loads(message)
        LOG.debug('Received on WebSocket: %s', message)
        self.proxy_websocket_to_eventhandler(message)

    def send_eventhandler_message(self, message):
        self._event_handler_connector.send_message(message)

    @staticmethod
    def send_websocket_message(message):
        for instance in ZMQWebSocketProxy.instances:
            instance.write_message(message)

    # much secure, very cors, wow
    def check_origin(self, origin):
        return True