mpd-now-playable/src/mpd_now_playable/song_receiver.py

83 lines
2.1 KiB
Python

from asyncio import AbstractEventLoop, new_event_loop
from dataclasses import dataclass
from importlib import import_module
from typing import Generic, Iterable, Literal, Protocol, TypeVar, cast
from .config.model import BaseReceiverConfig
from .player import Player
from .song import Song
from .tools.types import not_none
T = TypeVar("T", bound=AbstractEventLoop, covariant=True)
class LoopFactory(Generic[T], Protocol):
@property
def is_replaceable(self) -> bool: ...
@classmethod
def make_loop(cls) -> T: ...
class Receiver(Protocol):
def __init__(self, config: BaseReceiverConfig): ...
@classmethod
def loop_factory(cls) -> LoopFactory[AbstractEventLoop]: ...
async def start(self, player: Player) -> None: ...
async def update(self, song: Song | None) -> None: ...
class ReceiverModule(Protocol):
receiver: type[Receiver]
class DefaultLoopFactory(LoopFactory[AbstractEventLoop]):
@property
def is_replaceable(self) -> Literal[True]:
return True
@classmethod
def make_loop(cls) -> AbstractEventLoop:
return new_event_loop()
@dataclass
class IncompatibleReceiverError(Exception):
a: Receiver
b: Receiver
def import_receiver(config: BaseReceiverConfig) -> type[Receiver]:
mod = cast(
ReceiverModule, import_module(f"mpd_now_playable.receivers.{config.kind}")
)
return mod.receiver
def construct_receiver(config: BaseReceiverConfig) -> Receiver:
cls = import_receiver(config)
return cls(config)
def choose_loop_factory(
receivers: Iterable[Receiver],
) -> LoopFactory[AbstractEventLoop]:
"""Given the desired receivers, determine which asyncio event loop implementation will support all of them. Will raise an IncompatibleReceiverError if no such implementation exists."""
chosen_fac: LoopFactory[AbstractEventLoop] = DefaultLoopFactory()
chosen_rec: Receiver | None = None
for rec in receivers:
fac = rec.loop_factory()
if fac.is_replaceable:
continue
if chosen_fac.is_replaceable:
chosen_fac = fac
elif type(fac) is not type(chosen_fac):
raise IncompatibleReceiverError(rec, not_none(chosen_rec))
chosen_rec = rec
return chosen_fac