from typing import Callable, Protocol, runtime_checkable

from lyra_worker.types import Candidate, DownloadResult, MBTarget


@runtime_checkable
class SourceAdapter(Protocol):
    name: str
    tier: int

    def health(self) -> bool:
        """Is this source configured and reachable?"""
        ...

    def search(self, target: MBTarget) -> list[Candidate]:
        """Return zero or more candidates matching target. No downloading."""
        ...

    def download(
        self, candidate: Candidate, dest: str, on_progress: Callable[[float], None]
    ) -> DownloadResult:
        """Fetch candidate into dest, reporting progress 0.0..1.0."""
        ...