"""Helpers for communicating with the MusicBrainz webservice. Provides rate-limited HTTP session and convenience methods to fetch and normalize API responses. This module centralizes request handling and response shaping so callers can work with consistently structured data without embedding HTTP or rate-limit logic throughout the codebase. """ from __future__ import annotations import operator from dataclasses import dataclass, field from functools import cached_property, singledispatchmethod, wraps from itertools import groupby from typing import TYPE_CHECKING, Any, Literal, ParamSpec, TypedDict, TypeVar from requests_ratelimiter import LimiterMixin from typing_extensions import NotRequired, Unpack from beets import config, logging from .requests import RequestHandler, TimeoutAndRetrySession if TYPE_CHECKING: from collections.abc import Callable from requests import Response from .._typing import JSONDict log = logging.getLogger(__name__) class LimiterTimeoutSession(LimiterMixin, TimeoutAndRetrySession): """HTTP session that enforces rate limits.""" Entity = Literal[ "area", "artist", "collection", "event", "genre", "instrument", "label", "place", "recording", "release", "release-group", "series", "work", "url", ] class LookupKwargs(TypedDict, total=False): includes: NotRequired[list[str]] class PagingKwargs(TypedDict, total=False): limit: NotRequired[int] offset: NotRequired[int] class SearchKwargs(PagingKwargs): query: NotRequired[str] class BrowseKwargs(LookupKwargs, PagingKwargs, total=False): pass class BrowseReleaseGroupsKwargs(BrowseKwargs, total=False): artist: NotRequired[str] collection: NotRequired[str] release: NotRequired[str] class BrowseRecordingsKwargs(BrowseReleaseGroupsKwargs, total=False): work: NotRequired[str] P = ParamSpec("P") R = TypeVar("R") def require_one_of(*keys: str) -> Callable[[Callable[P, R]], Callable[P, R]]: required = frozenset(keys) def deco(func: Callable[P, R]) -> Callable[P, R]: @wraps(func) def wrapper(*args: P.args, **kwargs: P.kwargs) -> R: # kwargs is a real dict at runtime; safe to inspect here if not required & kwargs.keys(): required_str = ", ".join(sorted(required)) raise ValueError( f"At least one of {required_str} filter is required" ) return func(*args, **kwargs) return wrapper return deco @dataclass class MusicBrainzAPI(RequestHandler): """High-level interface to the MusicBrainz WS/2 API. Responsibilities: - Configure the API host and request rate from application configuration. - Offer helpers to fetch common entity types and to run searches. - Normalize MusicBrainz responses so relation lists are grouped by target type for easier downstream consumption. Documentation: https://musicbrainz.org/doc/MusicBrainz_API """ api_host: str = field(init=False) rate_limit: float = field(init=False) def __post_init__(self) -> None: mb_config = config["musicbrainz"] mb_config.add( { "host": "musicbrainz.org", "https": False, "ratelimit": 1, "ratelimit_interval": 1, } ) hostname = mb_config["host"].as_str() if hostname == "musicbrainz.org": self.api_host, self.rate_limit = "https://musicbrainz.org", 1.0 else: https = mb_config["https"].get(bool) self.api_host = f"http{'s' if https else ''}://{hostname}" self.rate_limit = ( mb_config["ratelimit"].get(int) / mb_config["ratelimit_interval"].as_number() ) @cached_property def api_root(self) -> str: return f"{self.api_host}/ws/2" def create_session(self) -> LimiterTimeoutSession: return LimiterTimeoutSession(per_second=self.rate_limit) def request(self, *args, **kwargs) -> Response: """Ensure all requests specify JSON response format by default.""" kwargs.setdefault("params", {}) kwargs["params"]["fmt"] = "json" return super().request(*args, **kwargs) def _get_resource( self, resource: str, includes: list[str] | None = None, **kwargs ) -> JSONDict: """Retrieve and normalize data from the API resource endpoint. If requested, includes are appended to the request. The response is passed through a normalizer that groups relation entries by their target type so that callers receive a consistently structured mapping. """ if includes: kwargs["inc"] = "+".join(includes) return self._group_relations( self.get_json(f"{self.api_root}/{resource}", params=kwargs) ) def _lookup( self, entity: Entity, id_: str, **kwargs: Unpack[LookupKwargs] ) -> JSONDict: return self._get_resource(f"{entity}/{id_}", **kwargs) def _browse(self, entity: Entity, **kwargs) -> list[JSONDict]: return self._get_resource(entity, **kwargs).get(f"{entity}s", []) def search( self, entity: Entity, filters: dict[str, str], **kwargs: Unpack[SearchKwargs], ) -> list[JSONDict]: """Search for MusicBrainz entities matching the given filters. * Query is constructed by combining the provided filters using AND logic * Each filter key-value pair is formatted as 'key:"value"' unless - 'key' is empty, in which case only the value is used, '"value"' - 'value' is empty, in which case the filter is ignored * Values are lowercased and stripped of whitespace. """ query = " AND ".join( ":".join(filter(None, (k, f'"{_v}"'))) for k, v in filters.items() if (_v := v.lower().strip()) ) log.debug("Searching for MusicBrainz {}s with: {!r}", entity, query) kwargs["query"] = query return self._get_resource(entity, **kwargs)[f"{entity}s"] def get_release(self, id_: str, **kwargs: Unpack[LookupKwargs]) -> JSONDict: """Retrieve a release by its MusicBrainz ID.""" return self._lookup("release", id_, **kwargs) def get_recording( self, id_: str, **kwargs: Unpack[LookupKwargs] ) -> JSONDict: """Retrieve a recording by its MusicBrainz ID.""" return self._lookup("recording", id_, **kwargs) def get_work(self, id_: str, **kwargs: Unpack[LookupKwargs]) -> JSONDict: """Retrieve a work by its MusicBrainz ID.""" return self._lookup("work", id_, **kwargs) @require_one_of("artist", "collection", "release", "work") def browse_recordings( self, **kwargs: Unpack[BrowseRecordingsKwargs] ) -> list[JSONDict]: """Browse recordings related to the given entities. At least one of artist, collection, release, or work must be provided. """ return self._browse("recording", **kwargs) @require_one_of("artist", "collection", "release") def browse_release_groups( self, **kwargs: Unpack[BrowseReleaseGroupsKwargs] ) -> list[JSONDict]: """Browse release groups related to the given entities. At least one of artist, collection, or release must be provided. """ return self._get_resource("release-group", **kwargs)["release-groups"] @singledispatchmethod @classmethod def _group_relations(cls, data: Any) -> Any: """Normalize MusicBrainz 'relations' into type-keyed fields recursively. This helper rewrites payloads that use a generic 'relations' list into a structure that is easier to consume downstream. When a mapping contains 'relations', those entries are regrouped by their 'target-type' and stored under keys like '-relations'. The original 'relations' key is removed to avoid ambiguous access patterns. The transformation is applied recursively so that nested objects and sequences are normalized consistently, while non-container values are left unchanged. """ return data @_group_relations.register(list) @classmethod def _(cls, data: list[Any]) -> list[Any]: return [cls._group_relations(i) for i in data] @_group_relations.register(dict) @classmethod def _(cls, data: JSONDict) -> JSONDict: for k, v in list(data.items()): if k == "relations": get_target_type = operator.methodcaller("get", "target-type") for target_type, group in groupby( sorted(v, key=get_target_type), get_target_type ): relations = [ {k: v for k, v in item.items() if k != "target-type"} for item in group ] data[f"{target_type}-relations"] = cls._group_relations( relations ) data.pop("relations") else: data[k] = cls._group_relations(v) return data class MusicBrainzAPIMixin: """Mixin that provides a cached MusicBrainzAPI helper instance.""" @cached_property def mb_api(self) -> MusicBrainzAPI: return MusicBrainzAPI()