import requests

from lyra_worker.similarity.base import SimilarArtist

_BASE = "https://ws.audioscrobbler.com/2.0/"


class LastfmSource:
    """SimilaritySource backed by Last.fm's artist.getsimilar.

    Last.fm rows often carry an empty mbid, so names are resolved to a real
    MusicBrainz artist MBID via the injected browser. Unresolvable rows are
    skipped -- every emitted SimilarArtist.mbid must be a real MB artist MBID,
    since downstream keys on it.
    """

    name = "lastfm"

    def __init__(self, api_key, browser, base_url=_BASE, timeout: float = 15.0,
                 similar_limit: int = 50):
        self._key = api_key
        self._browser = browser  # MbBrowser: .search_artist(name) -> list[ArtistHit]
        self._base = base_url
        self._timeout = timeout
        self._limit = similar_limit
        self._name_cache: dict[str, str | None] = {}

    def _get(self, method: str, **params):
        res = requests.get(
            self._base,
            params={"method": method, "api_key": self._key, "format": "json", **params},
            timeout=self._timeout,
        )
        res.raise_for_status()  # a 4xx/5xx (rate limit, auth) → RequestException, handled by callers
        return res.json()

    def health(self) -> bool:
        try:
            data = self._get("artist.getsimilar", artist="Radiohead", limit="1")
            return not isinstance(data.get("error"), (int, float))
        except requests.RequestException:
            return False

    def _resolve(self, name: str) -> str | None:
        key = name.lower()
        if key in self._name_cache:
            return self._name_cache[key]
        hits = self._browser.search_artist(name)
        mbid = hits[0].mbid if hits else None
        self._name_cache[key] = mbid
        return mbid

    def similar_artists(self, mbid: str) -> list[SimilarArtist]:
        data = self._get("artist.getsimilar", mbid=mbid, limit=str(self._limit))
        if isinstance(data.get("error"), (int, float)):
            return []
        rows = data.get("similarartists", {}).get("artist", [])
        if isinstance(rows, dict):
            rows = [rows]
        out: list[SimilarArtist] = []
        for row in rows:
            name = row.get("name") or ""
            cand = row.get("mbid") or None
            if not cand:
                cand = self._resolve(name)
            if not cand or cand == mbid or not name:
                continue
            score = float(row.get("match") or 0)
            out.append(SimilarArtist(mbid=cand, name=name, score=score))
        return out