from typing import Callable, Protocol

from lyra_worker.types import Candidate, DownloadResult, MBTarget, Quality

_YT_QUALITY = Quality(fmt="OPUS", lossless=False, bitrate_kbps=160)


class YtClient(Protocol):
    def search_album(self, artist: str, album: str) -> list[dict]:
        """Return album matches: dicts with keys source_ref, title, artist, track_count."""
        ...

    def download(self, source_ref: str, dest: str, on_progress: Callable[[float], None]) -> dict:
        """Download into dest; return {track_count, path}. Raise on failure."""
        ...


class YouTubeAdapter:
    name = "youtube"
    tier = 2

    def __init__(self, client: YtClient):
        self._client = client

    def health(self) -> bool:
        return True

    def search(self, target: MBTarget) -> list[Candidate]:
        candidates: list[Candidate] = []
        for r in self._client.search_album(target.artist, target.album):
            candidates.append(
                Candidate(
                    source="youtube",
                    source_ref=r["source_ref"],
                    matched_artist=r.get("artist", ""),
                    matched_album=r.get("title", ""),
                    quality=_YT_QUALITY,
                    track_count=r.get("track_count", 1) or 1,
                    source_tier=self.tier,
                )
            )
        return candidates

    def download(
        self, candidate: Candidate, dest: str, on_progress: Callable[[float], None]
    ) -> DownloadResult:
        try:
            info = self._client.download(candidate.source_ref, dest, on_progress)
        except Exception as e:  # network/extraction failures -> fall-through in the pipeline
            return DownloadResult(ok=False, error=str(e))
        return DownloadResult(
            ok=True,
            path=info.get("path", dest),
            track_count=info.get("track_count", candidate.track_count),
        )