from lyra_worker.types import Candidate, Quality

_SOURCE_TIERS = {"qobuz": 0, "soulseek": 1, "youtube": 2}


def quality_class(q: Quality) -> int:
    """3 = hi-res lossless, 2 = CD lossless, 1 = lossy."""
    if q.lossless:
        hires = (q.bit_depth is not None and q.bit_depth > 16) or (
            q.sample_rate is not None and q.sample_rate > 44100
        )
        return 3 if hires else 2
    return 1


def source_tier(source: str) -> int:
    """Lower is better. Unknown sources rank worst."""
    return _SOURCE_TIERS.get(source, 99)


def rank_key(c: Candidate) -> tuple[int, int]:
    """Sort key; larger is better. Quality class first, then source tier."""
    return (quality_class(c.quality), -source_tier(c.source))