From 55d82c72c39b169b35c2d8b27a06839fb83db01a Mon Sep 17 00:00:00 2001
From: Danielle McLean <dani@00dani.me>
Date: Tue, 14 May 2024 13:25:13 +1000
Subject: [PATCH] Support MPD_NOW_PLAYABLE_CACHE setting (Redis or Memcached)

---
 src/mpd_now_playable/cache.py             | 55 +++++++++++++++++++++++
 src/mpd_now_playable/cli.py               |  3 +-
 src/mpd_now_playable/mpd/artwork_cache.py | 40 ++++++-----------
 src/mpd_now_playable/mpd/listener.py      |  6 ++-
 stubs/aiocache/base.pyi                   |  7 +++
 stubs/aiocache/factory.pyi                | 29 +++++++++---
 stubs/aiocache/serializers.pyi            | 14 ++++++
 7 files changed, 118 insertions(+), 36 deletions(-)
 create mode 100644 src/mpd_now_playable/cache.py
 create mode 100644 stubs/aiocache/base.pyi
 create mode 100644 stubs/aiocache/serializers.pyi

diff --git a/src/mpd_now_playable/cache.py b/src/mpd_now_playable/cache.py
new file mode 100644
index 0000000..05e586d
--- /dev/null
+++ b/src/mpd_now_playable/cache.py
@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+from contextlib import suppress
+from typing import Any, Optional, TypeVar
+from urllib.parse import parse_qsl, urlparse
+
+from aiocache import Cache
+from aiocache.serializers import BaseSerializer, PickleSerializer
+
+T = TypeVar("T")
+
+HAS_ORMSGPACK = False
+with suppress(ImportError):
+	import ormsgpack
+
+	HAS_ORMSGPACK = True
+
+
+class OrmsgpackSerializer(BaseSerializer):
+	DEFAULT_ENCODING = None
+
+	def dumps(self, value: Any) -> bytes:
+		return ormsgpack.packb(value)
+
+	def loads(self, value: Optional[bytes]) -> Any:
+		if value is None:
+			return None
+		return ormsgpack.unpackb(value)
+
+
+def make_cache(url: str, namespace: str = "") -> Cache[T]:
+	parsed_url = urlparse(url)
+	backend = Cache.get_scheme_class(parsed_url.scheme)
+	if backend == Cache.MEMORY:
+		return Cache(backend)
+	kwargs: dict[str, Any] = dict(parse_qsl(parsed_url.query))
+
+	if parsed_url.path:
+		kwargs.update(backend.parse_uri_path(parsed_url.path))
+
+	if parsed_url.hostname:
+		kwargs["endpoint"] = parsed_url.hostname
+
+	if parsed_url.port:
+		kwargs["port"] = parsed_url.port
+
+	if parsed_url.password:
+		kwargs["password"] = parsed_url.password
+
+	namespace = ":".join(s for s in [kwargs.get("namespace"), namespace] if s)
+	del kwargs["namespace"]
+
+	serializer = OrmsgpackSerializer if HAS_ORMSGPACK else PickleSerializer
+
+	return Cache(backend, serializer=serializer(), namespace=namespace, **kwargs)
diff --git a/src/mpd_now_playable/cli.py b/src/mpd_now_playable/cli.py
index 2b822d3..5cd7031 100644
--- a/src/mpd_now_playable/cli.py
+++ b/src/mpd_now_playable/cli.py
@@ -11,10 +11,11 @@ async def listen() -> None:
 	port = int(environ.get("MPD_PORT", "6600"))
 	host = environ.get("MPD_HOST", "localhost")
 	password = environ.get("MPD_PASSWORD")
+	cache = environ.get("MPD_NOW_PLAYABLE_CACHE")
 	if password is None and "@" in host:
 		password, host = host.split("@", maxsplit=1)
 
-	listener = MpdStateListener()
+	listener = MpdStateListener(cache)
 	now_playing = CocoaNowPlaying(listener)
 	await listener.start(host=host, port=port, password=password)
 	await listener.loop(now_playing)
diff --git a/src/mpd_now_playable/mpd/artwork_cache.py b/src/mpd_now_playable/mpd/artwork_cache.py
index 13819b1..c0d4d23 100644
--- a/src/mpd_now_playable/mpd/artwork_cache.py
+++ b/src/mpd_now_playable/mpd/artwork_cache.py
@@ -1,30 +1,16 @@
-from dataclasses import dataclass
+from __future__ import annotations
 
-from aiocache import Cache
+from typing import TypedDict
 
 from ..async_tools import run_background_task
+from ..cache import Cache, make_cache
 from .types import CurrentSongResponse, MpdStateHandler
 
 CACHE_TTL = 60 * 10  # ten minutes
 
 
-@dataclass(frozen=True)
-class HasArt:
-	data: bytes
-
-
-@dataclass(frozen=True)
-class HasNoArt:
-	data = None
-
-
-ArtCacheEntry = HasArt | HasNoArt
-
-
-def make_cache_entry(art: bytes | None) -> ArtCacheEntry:
-	if art is None:
-		return HasNoArt()
-	return HasArt(art)
+class ArtCacheEntry(TypedDict):
+	data: bytes | None
 
 
 def calc_album_key(song: CurrentSongResponse) -> str:
@@ -39,18 +25,18 @@ def calc_track_key(song: CurrentSongResponse) -> str:
 
 class MpdArtworkCache:
 	mpd: MpdStateHandler
-	album_cache: "Cache[ArtCacheEntry]"
-	track_cache: "Cache[ArtCacheEntry]"
+	album_cache: Cache[ArtCacheEntry]
+	track_cache: Cache[ArtCacheEntry]
 
-	def __init__(self, mpd: MpdStateHandler):
+	def __init__(self, mpd: MpdStateHandler, cache_url: str = "memory://"):
 		self.mpd = mpd
-		self.album_cache = Cache()
-		self.track_cache = Cache()
+		self.album_cache = make_cache(cache_url, "album")
+		self.track_cache = make_cache(cache_url, "track")
 
 	async def get_cached_artwork(self, song: CurrentSongResponse) -> bytes | None:
 		art = await self.track_cache.get(calc_track_key(song))
 		if art:
-			return art.data
+			return art["data"]
 
 		# If we don't have track artwork cached, go find some.
 		run_background_task(self.cache_artwork(song))
@@ -58,12 +44,12 @@ class MpdArtworkCache:
 		# Even if we don't have cached track art, we can try looking for cached album art.
 		art = await self.album_cache.get(calc_album_key(song))
 		if art:
-			return art.data
+			return art["data"]
 
 		return None
 
 	async def cache_artwork(self, song: CurrentSongResponse) -> None:
-		art = make_cache_entry(await self.mpd.readpicture(song["file"]))
+		art = ArtCacheEntry(data=await self.mpd.readpicture(song["file"]))
 		try:
 			await self.album_cache.add(calc_album_key(song), art, ttl=CACHE_TTL)
 		except ValueError:
diff --git a/src/mpd_now_playable/mpd/listener.py b/src/mpd_now_playable/mpd/listener.py
index 81d2174..9559937 100644
--- a/src/mpd_now_playable/mpd/listener.py
+++ b/src/mpd_now_playable/mpd/listener.py
@@ -44,9 +44,11 @@ class MpdStateListener(Player):
 	art_cache: MpdArtworkCache
 	idle_count = 0
 
-	def __init__(self) -> None:
+	def __init__(self, cache: str | None = None) -> None:
 		self.client = MPDClient()
-		self.art_cache = MpdArtworkCache(self)
+		self.art_cache = (
+			MpdArtworkCache(self, cache) if cache else MpdArtworkCache(self)
+		)
 
 	async def start(
 		self, host: str = "localhost", port: int = 6600, password: str | None = None
diff --git a/stubs/aiocache/base.pyi b/stubs/aiocache/base.pyi
new file mode 100644
index 0000000..8b7578f
--- /dev/null
+++ b/stubs/aiocache/base.pyi
@@ -0,0 +1,7 @@
+from typing import Generic, TypeVar
+
+T = TypeVar("T")
+
+class BaseCache(Generic[T]):
+	@staticmethod
+	def parse_uri_path(path: str) -> dict[str, str]: ...
diff --git a/stubs/aiocache/factory.pyi b/stubs/aiocache/factory.pyi
index e1f7226..78cc6a5 100644
--- a/stubs/aiocache/factory.pyi
+++ b/stubs/aiocache/factory.pyi
@@ -1,8 +1,25 @@
-from typing import Generic, Optional, TypeVar
+from typing import ClassVar, Optional, TypeVar
 
-T = TypeVar('T')
+from .base import BaseCache
+from .serializers import BaseSerializer
 
-class Cache(Generic[T]):
-    async def add(self, key: str, value: T, ttl: Optional[int]) -> None: ...
-    async def set(self, key: str, value: T, ttl: Optional[int]) -> None: ... # noqa: A003
-    async def get(self, key: str, default: T | None = None) -> T | None: ...
+T = TypeVar("T")
+
+class Cache(BaseCache[T]):
+	MEMORY: ClassVar[type[BaseCache]]
+	REDIS: ClassVar[type[BaseCache] | None]
+	MEMCACHED: ClassVar[type[BaseCache] | None]
+
+	def __new__(
+		cls,
+		cache_class: type[BaseCache] = MEMORY,
+		*,
+		serializer: Optional[BaseSerializer] = None,
+		namespace: str = "",
+		**kwargs,
+	) -> Cache[T]: ...
+	@staticmethod
+	def get_scheme_class(scheme: str) -> type[BaseCache]: ...
+	async def add(self, key: str, value: T, ttl: Optional[int]) -> None: ...
+	async def set(self, key: str, value: T, ttl: Optional[int]) -> None: ...  # noqa: A003
+	async def get(self, key: str, default: T | None = None) -> T | None: ...
diff --git a/stubs/aiocache/serializers.pyi b/stubs/aiocache/serializers.pyi
new file mode 100644
index 0000000..577ba11
--- /dev/null
+++ b/stubs/aiocache/serializers.pyi
@@ -0,0 +1,14 @@
+from abc import ABC, abstractmethod
+from typing import Any, Optional
+
+class BaseSerializer(ABC):
+	DEFAULT_ENCODING: Optional[str] = "utf-8"
+	@abstractmethod
+	def dumps(self, value: Any, /) -> Any: ...
+	@abstractmethod
+	def loads(self, value: Any, /) -> Any: ...
+
+class PickleSerializer(BaseSerializer):
+	DEFAULT_ENCODING = None
+	def dumps(self, value: Any, /) -> Any: ...
+	def loads(self, value: Any, /) -> Any: ...