soulsync/core/download_plugins/base.py
Broque Thomas 19fbcf267d Add DownloadSourcePlugin contract + registry
`core/download_plugins/` defines the canonical interface every
download source must satisfy and the registry that holds them.
Single source of truth replacing the orchestrator's hardcoded
`[self.soulseek, self.youtube, ...]` lists scattered across 6+
dispatch sites.

Pure additive — no consumers wired through the registry yet.
2026-05-04 11:16:03 -07:00

128 lines
5 KiB
Python

"""Canonical contract every download source plugin must satisfy.
`DownloadSourcePlugin` is a structural Protocol — any class that
implements these methods with matching signatures is automatically
treated as a download source. No inheritance required, no manual
registration required beyond the registry entry.
The protocol is intentionally narrow — only the methods the
orchestrator dispatches generically across all sources. Source-
specific extras (Soulseek's slskd internals, Lidarr's album-only
flow, etc.) stay on the underlying client and are accessed through
the registry's typed accessor.
This file is the FOUNDATION step. Existing client classes
(SoulseekClient, YouTubeClient, TidalDownloadClient, etc.) already
conform structurally — they grew the same shape independently
because every consumer site needed the same calls. This file just
makes the implicit contract explicit so:
- Type checkers can flag drift if a new source forgets a method.
- The orchestrator can iterate plugins generically instead of
hardcoding `[self.soulseek, self.youtube, ...]` everywhere.
- Future PRs can move shared logic INTO the contract (a base
class with default implementations) without changing the
signature surface every consumer already depends on.
"""
from __future__ import annotations
from typing import List, Optional, Protocol, Tuple, runtime_checkable
# Soulseek client owns the canonical TrackResult / AlbumResult / DownloadStatus
# dataclasses — every other source already imports from there. Keep it that way
# until a future PR lifts those into a neutral location.
from core.soulseek_client import AlbumResult, DownloadStatus, TrackResult
@runtime_checkable
class DownloadSourcePlugin(Protocol):
"""Structural contract for a download source.
`runtime_checkable` lets `isinstance(client, DownloadSourcePlugin)`
work for the conformance test, but it ONLY checks method names —
not signatures or async-ness. The conformance test in
``tests/test_download_plugin_conformance.py`` does the deeper
signature check.
"""
# ------------------------------------------------------------------
# Configuration / lifecycle
# ------------------------------------------------------------------
def is_configured(self) -> bool:
"""Return True iff this source has the credentials / settings
it needs to function. Used by the orchestrator to skip
unconfigured sources during hybrid fallback."""
...
async def check_connection(self) -> bool:
"""Probe the source's API / endpoint. Return True if the
source is reachable. May make a live network call."""
...
# ------------------------------------------------------------------
# Search
# ------------------------------------------------------------------
async def search(
self,
query: str,
timeout: Optional[int] = None,
progress_callback=None,
) -> Tuple[List[TrackResult], List[AlbumResult]]:
"""Search the source for tracks (and albums where supported).
Returns a tuple of (track_results, album_results). Either
list may be empty. Sources that don't expose album-level
search return ``[]`` as the second element.
"""
...
# ------------------------------------------------------------------
# Download
# ------------------------------------------------------------------
async def download(
self,
username: str,
filename: str,
file_size: int = 0,
) -> Optional[str]:
"""Kick off a download. Returns a download_id string the
caller can poll via ``get_download_status``. Returns ``None``
if the source can't / won't handle this download.
``username`` is the source-name string for streaming sources
(e.g. ``'youtube'``, ``'tidal'``) and the actual slskd peer
username for Soulseek. ``filename`` is source-specific —
Soulseek file path, YouTube ``video_id||title``, Tidal /
Qobuz ``track_id||display``, etc.
"""
...
async def get_all_downloads(self) -> List[DownloadStatus]:
"""Return live status of all downloads currently tracked by
this source. The orchestrator concatenates results from
every plugin to build the global download list."""
...
async def get_download_status(self, download_id: str) -> Optional[DownloadStatus]:
"""Return status for a single download or ``None`` if this
source doesn't know about that download_id."""
...
async def cancel_download(
self,
download_id: str,
username: Optional[str] = None,
remove: bool = False,
) -> bool:
"""Cancel an active download. ``remove=True`` also drops
the row from the source's active-downloads tracking."""
...
async def clear_all_completed_downloads(self) -> bool:
"""Drop completed downloads from active tracking. Sources
that don't keep completed history return True with no-op."""
...