Martin Bauer
d44c24ec97
- event bus systen - all components are independent - preparation for web frontend
108 lines
3.5 KiB
Python
108 lines
3.5 KiB
Python
"""Shared plumbing for Home-Assistant-discoverable MQTT entities.
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Adding an entity should be about thirty lines: a discovery payload, a state payload,
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and whatever bus subscriptions keep it current.
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"""
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from __future__ import annotations
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import json
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import logging
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from abc import ABC, abstractmethod
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from typing import Any, ClassVar
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from musicmouse.bus import EventBus
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from musicmouse.config import MqttConfig
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from musicmouse.services.base import Publisher
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_log = logging.getLogger(__name__)
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__all__ = ["Entity"]
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class Entity(ABC):
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#: Home Assistant MQTT component, e.g. "light", "sensor", "device_automation".
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component: ClassVar[str]
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def __init__(self, bus: EventBus, config: MqttConfig, object_id: str, name: str) -> None:
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self.bus = bus
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self.config = config
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self.object_id = object_id
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self.name = name
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self._publisher: Publisher | None = None
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self.subscribe()
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# -------------------------------------------------------------------- topics
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@property
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def unique_id(self) -> str:
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return f"{self.config.device_id}_{self.object_id}"
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@property
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def base_topic(self) -> str:
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return f"{self.config.base_topic}/{self.object_id}"
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@property
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def state_topic(self) -> str:
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return f"{self.base_topic}/state"
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@property
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def command_topic(self) -> str:
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return f"{self.base_topic}/set"
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@property
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def discovery_topic(self) -> str:
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return f"{self.config.discovery_prefix}/{self.component}/{self.unique_id}/config"
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def command_topics(self) -> tuple[str, ...]:
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"""Topics the service should route to :meth:`handle`."""
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return ()
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# ------------------------------------------------------------------ contract
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@abstractmethod
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def discovery_payload(self) -> dict[str, Any]:
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"""The retained config Home Assistant reads to create this entity."""
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def subscribe(self) -> None:
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"""Register bus handlers. Called once, at construction."""
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async def handle(self, topic: str, payload: str) -> None:
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"""React to a command on one of :meth:`command_topics`."""
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async def publish_state(self) -> None:
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"""Push current state out. Called on connect and whenever state changes."""
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# ------------------------------------------------------------------- runtime
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def attach(self, publisher: Publisher | None) -> None:
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self._publisher = publisher
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@property
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def online(self) -> bool:
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return self._publisher is not None
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async def publish(self, topic: str, payload: Any, *, retain: bool = False) -> None:
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"""Send ``payload`` (JSON-encoded unless it is already a string).
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A no-op while the broker is unreachable: state is republished on reconnect.
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"""
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if self._publisher is None:
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return
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text = payload if isinstance(payload, str) else json.dumps(payload)
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await self._publisher.publish(topic, text, retain=retain)
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async def announce(self) -> None:
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"""Publish discovery, then current state."""
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await self.publish(self.discovery_topic, self.discovery_payload(), retain=True)
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await self.publish_state()
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def device_block(self) -> dict[str, Any]:
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"""Ties every entity to one device in Home Assistant's UI."""
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return {
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"identifiers": [self.config.device_id],
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"name": self.config.device_name,
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"manufacturer": "bauer.tech",
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"model": "MusicMouse",
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}
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