import requests

from lyra_worker.apicache import cached_api

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


def _parse_top_albums(data) -> list[list]:
    """Parse a Last.fm artist.gettopalbums response into [[name, mbid|None, playcount], …]
    ordered by playcount desc. A single-album body arrives as a dict; an error body → []."""
    if isinstance(data.get("error"), (int, float)):
        return []
    rows = data.get("topalbums", {}).get("album", [])
    if isinstance(rows, dict):
        rows = [rows]
    out: list[list] = []
    for r in rows:
        name = r.get("name") or ""
        if not name:
            continue
        out.append([name, r.get("mbid") or None, int(r.get("playcount") or 0)])
    out.sort(key=lambda a: a[2], reverse=True)
    return out


class LastfmAlbumPopularity:
    """Ranks an artist's albums by Last.fm playcount, so discovery can surface each similar
    artist's most-played album (alongside their newest). Read-through cached in ApiCache; any
    failure yields [] so the sweep just falls back to newest-only."""

    def __init__(self, api_key, base_url=_BASE, timeout: float = 15.0, limit: int = 25):
        self._key = api_key
        self._base = base_url
        self._timeout = timeout
        self._limit = limit

    def _fetch(self, artist_name: str) -> list[list]:
        try:
            res = requests.get(self._base, params={
                "method": "artist.gettopalbums", "artist": artist_name,
                "api_key": self._key, "format": "json", "limit": str(self._limit),
                "autocorrect": "1",
            }, timeout=self._timeout)
            return _parse_top_albums(res.json())
        except Exception:  # a Last.fm outage must never abort the sweep
            return []

    def top_albums(self, conn, artist_name: str) -> list[list]:
        norm = (artist_name or "").strip().lower()
        if not norm:
            return []
        return cached_api(conn, f"lfm-artist-top-albums:{norm}", 43200,
                          lambda: self._fetch(artist_name))