from dataclasses import fields
import enum
import logging
import paho.mqtt.client as mqtt

from .aircon import Device
from .properties import AcWorkMode, FglOperationMode


class MqttClient(mqtt.Client):

  def __init__(self, client_id: str, mqtt_topics: dict, devices: [Device]):
    super().__init__(client_id=client_id, clean_session=True)
    self._mqtt_topics = mqtt_topics
    self._devices = devices

    self.on_connect = self.mqtt_on_connect
    self.on_message = self.mqtt_on_message

  def mqtt_on_connect(self, client: mqtt.Client, userdata, flags, rc):
    for device in self._devices:
      topics_fmt = [(self._mqtt_topics['sub'].format(device.mac_address, data_field.name), 0)
                        for data_field in fields(device.get_all_properties())]
      logging.debug(f"Subscribing to topics{topics_fmt} for device {device}")
      client.subscribe(topics_fmt)
    # Subscribe to subscription updates.
    client.subscribe('$SYS/broker/log/M/subscribe/#')

    # Publish current status of all properties for available devices.
    for device in self._devices:
      if device.available:
        for prop_name in fields(device.get_all_properties()):
          self.mqtt_publish_update(device.mac_address,
                                   prop_name,
                                   device.get_property(prop_name),
                                   retain=False)

  def mqtt_on_message(self, client: mqtt.Client, userdata, message: mqtt.MQTTMessage):
    logging.info('MQTT message Topic: {}, Payload {}'.format(message.topic, message.payload))
    if message.topic.startswith('$SYS/broker/log/M/subscribe'):
      return self.mqtt_on_subscribe(message.payload)
    mac_address = message.topic.rsplit('/', 3)[1]
    prop_name = message.topic.rsplit('/', 3)[2]
    payload = message.payload.decode('utf-8')
    if prop_name == 't_work_mode':
      if payload == 'fan_only':
        payload = 'FAN'

    for device in self._devices:
      if device.mac_address != mac_address:
        continue
      chosen_device = device

    try:
      chosen_device.queue_command(prop_name, payload.upper())
    except Exception:
      logging.exception('Failed to parse value {} for property {}'.format(
          payload.upper(), prop_name))

  def mqtt_on_subscribe(self, payload: bytes):
    # The last segment in the space delimited string is the topic.
    topic = payload.decode('utf-8').rsplit(' ', 1)[-1]
    if topic not in self._mqtt_topics['pub']:
      return
    mac_address = topic.rsplit('/', 3)[1]
    prop_name = topic.rsplit('/', 3)[2]

    for device in self._devices:
      if device.mac_address != mac_address:
        continue
      chosen_device = device

    self.mqtt_publish_update(chosen_device.mac_address,
                             prop_name,
                             chosen_device.get_property(prop_name),
                             retain=False)

  def mqtt_publish_update(self,
                          mac_address: str,
                          property_name: str,
                          value,
                          retain: bool = False) -> None:
    if isinstance(value, enum.Enum):
      payload = 'fan_only' if (value is AcWorkMode.FAN or
                               value is FglOperationMode.FAN_ONLY) else value.name.lower()
    else:
      payload = str(value)
    topic = self._mqtt_topics['pub'].format(mac_address, property_name)
    logging.info('Sending MQTT update Topic: {}, Payload {}'.format(topic, payload))
    self.publish(topic,
                 payload=payload.encode('utf-8'),
                 retain=retain)