Phase B: Add MediaServerEngine skeleton

`MediaServerEngine` reads the active server from config + dispatches
to the corresponding registered client. Per-server reaches still
work through `engine.client(name)`.

Required-method dispatch (is_connected, ensure_connection,
get_all_artists, get_all_album_ids) returns safe defaults when
the active client failed to initialize OR when the method raises.

Optional-method dispatch (search_tracks, trigger_library_scan,
is_library_scanning, get_library_stats, get_recently_added_albums)
checks hasattr first — SoulSync standalone has no
trigger_library_scan or get_library_stats, engine no-ops with
appropriate defaults instead of forcing every client to declare
stub methods.

10 new engine tests pin: active-server resolution, required
dispatch routing, exception safety, missing-optional-method
fallback shape. Suite still green (1951 passed).

Engine isn't on any production code path yet — Phase C migrates
the 33 web_server.py dispatch sites to call engine.method()
instead of hand-branching by active_server name.
pull/497/head
Broque Thomas 3 weeks ago
parent 50fe4bec97
commit 6b54ca6598

@ -18,6 +18,12 @@ phased plan.
"""
from core.media_server.contract import MediaServerClient
from core.media_server.engine import MediaServerEngine
from core.media_server.registry import MediaServerRegistry, build_default_registry
__all__ = ["MediaServerClient", "MediaServerRegistry", "build_default_registry"]
__all__ = [
"MediaServerClient",
"MediaServerEngine",
"MediaServerRegistry",
"build_default_registry",
]

@ -0,0 +1,215 @@
"""MediaServerEngine — central dispatch for media server operations.
Replaces the historic 33+ ``if active_server == 'plex' / 'jellyfin' /
'navidrome' / 'soulsync'`` chains in ``web_server.py``. Each
operation web_server.py used to dispatch by hand becomes a single
``engine.method()`` call here that:
1. Reads the ``server.active`` config to find the current target.
2. Looks up the registered client.
3. Calls the corresponding method (with safe per-server fallbacks
for methods that don't exist on every client — e.g. SoulSync
has no library-scan API).
Per-server client objects stay accessible via ``engine.client(name)``
so any caller that needs a Plex-specific method (e.g.
``set_music_library_by_name`` for the settings page) keeps working
through ``engine.client('plex').set_music_library_by_name(...)``.
Engine itself is constructed once during web_server.py init and
held as a module-level singleton, mirroring the existing pattern
for the per-server client globals.
"""
from __future__ import annotations
from typing import Any, Dict, List, Optional
from utils.logging_config import get_logger
from core.media_server.contract import MediaServerClient
from core.media_server.registry import MediaServerRegistry, build_default_registry
logger = get_logger("media_server.engine")
class MediaServerEngine:
"""Single entry point for cross-server library operations.
The engine knows which server is "active" via the
``server.active`` config + falls back to direct dispatch for
server-specific calls via ``engine.client(name)``.
"""
def __init__(
self,
registry: Optional[MediaServerRegistry] = None,
active_server_resolver=None,
) -> None:
"""Initialize the engine.
Args:
registry: Plugin registry. Defaults to the four built-in
servers (Plex, Jellyfin, Navidrome, SoulSync).
active_server_resolver: Callable returning the current
active server name (e.g. ``'plex'``). Defaults to
``config_manager.get_active_media_server``. Tests
inject a custom resolver to switch active server
without touching real config.
"""
self.registry = registry if registry is not None else build_default_registry()
self.registry.initialize()
if active_server_resolver is None:
from config.settings import config_manager
active_server_resolver = config_manager.get_active_media_server
self._resolve_active = active_server_resolver
# ------------------------------------------------------------------
# Direct client access (backward-compat for source-specific reaches)
# ------------------------------------------------------------------
def client(self, name: str) -> Optional[MediaServerClient]:
"""Return the client instance for the given server name, or
None if it's not registered / failed to initialize. Used by
callers that need a server-specific method beyond the
contract surface."""
return self.registry.get(name)
@property
def active_server(self) -> str:
"""The currently-selected media server name."""
return self._resolve_active()
def active_client(self) -> Optional[MediaServerClient]:
"""The client for the currently-active server."""
return self.registry.get(self.active_server)
# ------------------------------------------------------------------
# Cross-server dispatch — required methods (always present)
# ------------------------------------------------------------------
def is_connected(self) -> bool:
"""Active server's connection state. False if no active
client (registered but failed to initialize)."""
client = self.active_client()
if client is None:
return False
try:
return client.is_connected()
except Exception as exc:
logger.debug("%s is_connected raised: %s", self.active_server, exc)
return False
def ensure_connection(self) -> bool:
"""Re-auth or reconnect the active server. Returns True if
usable after the call."""
client = self.active_client()
if client is None:
return False
try:
return client.ensure_connection()
except Exception as exc:
logger.debug("%s ensure_connection raised: %s", self.active_server, exc)
return False
def get_all_artists(self) -> List[Any]:
"""Active server's full artist list. Empty list if not
connected or call fails."""
client = self.active_client()
if client is None:
return []
try:
return client.get_all_artists()
except Exception as exc:
logger.debug("%s get_all_artists raised: %s", self.active_server, exc)
return []
def get_all_album_ids(self) -> set:
"""Active server's album-ID set. Empty set if not connected
or call fails."""
client = self.active_client()
if client is None:
return set()
try:
return client.get_all_album_ids()
except Exception as exc:
logger.debug("%s get_all_album_ids raised: %s", self.active_server, exc)
return set()
# ------------------------------------------------------------------
# Optional methods — engine routes if the client implements them,
# returns a safe default otherwise (mirrors the legacy web_server.py
# branches that special-cased SoulSync / Navidrome).
# ------------------------------------------------------------------
def search_tracks(self, title: str, artist: str, limit: int = 15) -> List[Any]:
"""Search the active server's library. Returns empty list
for servers that don't implement search_tracks (SoulSync
standalone reads filesystem; no live search API)."""
client = self.active_client()
if client is None or not hasattr(client, 'search_tracks'):
return []
try:
return client.search_tracks(title, artist, limit)
except Exception as exc:
logger.debug("%s search_tracks raised: %s", self.active_server, exc)
return []
def trigger_library_scan(self) -> bool:
"""Trigger a server-side library scan. No-op (returns True)
for SoulSync standalone filesystem walks happen in-process."""
client = self.active_client()
if client is None:
return False
if not hasattr(client, 'trigger_library_scan'):
return True
try:
return client.trigger_library_scan()
except Exception as exc:
logger.debug("%s trigger_library_scan raised: %s", self.active_server, exc)
return False
def is_library_scanning(self) -> bool:
"""True if the active server is currently scanning. Always
False for SoulSync standalone."""
client = self.active_client()
if client is None or not hasattr(client, 'is_library_scanning'):
return False
try:
return client.is_library_scanning()
except Exception as exc:
logger.debug("%s is_library_scanning raised: %s", self.active_server, exc)
return False
def get_library_stats(self) -> Dict[str, int]:
"""Counts of artists / albums / tracks. Default empty dict
if the server doesn't implement (SoulSync standalone)."""
client = self.active_client()
if client is None or not hasattr(client, 'get_library_stats'):
return {}
try:
return client.get_library_stats()
except Exception as exc:
logger.debug("%s get_library_stats raised: %s", self.active_server, exc)
return {}
def get_recently_added_albums(self, max_results: int = 400) -> List[Any]:
"""Recently-added albums view. Plex uses a different name;
engine routes to whichever method the active server has."""
client = self.active_client()
if client is None:
return []
# Plex uses recentlyAdded() on the music library object, not
# a top-level method. SoulSync, Jellyfin, Navidrome all
# expose get_recently_added_albums directly.
if hasattr(client, 'get_recently_added_albums'):
try:
return client.get_recently_added_albums(max_results)
except Exception as exc:
logger.debug(
"%s get_recently_added_albums raised: %s",
self.active_server, exc,
)
return []
return []

@ -0,0 +1,192 @@
"""Tests for MediaServerEngine cross-server dispatch."""
from __future__ import annotations
from unittest.mock import MagicMock
import pytest
from core.media_server import MediaServerEngine, MediaServerRegistry
from core.media_server.registry import ServerSpec
class _FakeClient:
"""Stand-in client supporting all required + optional methods.
Tests selectively override per-test to assert dispatch behavior."""
def __init__(self, name='fake', connected=True):
self.name = name
self._connected = connected
self._artists = []
self._album_ids = set()
self._search_results = []
self._scan_triggered = False
def is_connected(self):
return self._connected
def ensure_connection(self):
return self._connected
def get_all_artists(self):
return self._artists
def get_all_album_ids(self):
return self._album_ids
def search_tracks(self, title, artist, limit=15):
return self._search_results
def trigger_library_scan(self):
self._scan_triggered = True
return True
def is_library_scanning(self):
return False
def get_library_stats(self):
return {'artists': 0, 'albums': 0, 'tracks': 0}
def get_recently_added_albums(self, max_results=400):
return []
@pytest.fixture
def make_engine():
"""Build an engine with mock clients. Test passes a dict of
name client; engine wires them via a registry + custom
active-server resolver."""
def _make(clients_by_name, active='plex'):
registry = MediaServerRegistry()
for name, client in clients_by_name.items():
registry.register(ServerSpec(
name=name,
factory=lambda c=client: c,
display_name=name.title(),
))
return MediaServerEngine(
registry=registry,
active_server_resolver=lambda: active,
)
return _make
# ---------------------------------------------------------------------------
# Active-server resolution
# ---------------------------------------------------------------------------
def test_active_server_property_reflects_resolver(make_engine):
plex = _FakeClient('plex')
jelly = _FakeClient('jellyfin')
engine = make_engine({'plex': plex, 'jellyfin': jelly}, active='jellyfin')
assert engine.active_server == 'jellyfin'
assert engine.active_client() is jelly
def test_client_lookup_by_name(make_engine):
plex = _FakeClient('plex')
engine = make_engine({'plex': plex}, active='plex')
assert engine.client('plex') is plex
assert engine.client('made_up') is None
# ---------------------------------------------------------------------------
# Required-method dispatch
# ---------------------------------------------------------------------------
def test_is_connected_routes_to_active_client(make_engine):
plex = _FakeClient('plex', connected=True)
jelly = _FakeClient('jellyfin', connected=False)
engine = make_engine({'plex': plex, 'jellyfin': jelly}, active='jellyfin')
assert engine.is_connected() is False # follows jellyfin
engine = make_engine({'plex': plex, 'jellyfin': jelly}, active='plex')
assert engine.is_connected() is True # follows plex
def test_get_all_album_ids_returns_active_clients_set(make_engine):
plex = _FakeClient('plex')
plex._album_ids = {'p-1', 'p-2'}
jelly = _FakeClient('jellyfin')
jelly._album_ids = {'j-1'}
engine = make_engine({'plex': plex, 'jellyfin': jelly}, active='plex')
assert engine.get_all_album_ids() == {'p-1', 'p-2'}
engine = make_engine({'plex': plex, 'jellyfin': jelly}, active='jellyfin')
assert engine.get_all_album_ids() == {'j-1'}
def test_engine_returns_safe_defaults_when_active_client_failed_to_init(make_engine):
"""When the active client failed to initialize (registry stored
None), the engine returns safe defaults instead of raising."""
registry = MediaServerRegistry()
registry.register(ServerSpec(
name='broken',
factory=lambda: (_ for _ in ()).throw(RuntimeError("init failed")),
display_name='Broken',
))
registry.initialize() # captures the exception
engine = MediaServerEngine(registry=registry, active_server_resolver=lambda: 'broken')
assert engine.is_connected() is False
assert engine.get_all_artists() == []
assert engine.get_all_album_ids() == set()
assert engine.search_tracks('t', 'a') == []
assert engine.trigger_library_scan() is False
assert engine.is_library_scanning() is False
def test_engine_swallows_per_method_exceptions(make_engine):
"""A method that raises must NOT propagate to the dispatch
site engine returns the safe default instead, mirroring the
legacy web_server.py defensive try/except chains."""
plex = _FakeClient('plex')
plex.is_connected = MagicMock(side_effect=RuntimeError("boom"))
plex.get_all_album_ids = MagicMock(side_effect=RuntimeError("boom"))
engine = make_engine({'plex': plex}, active='plex')
assert engine.is_connected() is False
assert engine.get_all_album_ids() == set()
# ---------------------------------------------------------------------------
# Optional-method dispatch (engine returns safe default when missing)
# ---------------------------------------------------------------------------
class _MinimalClient:
"""Stand-in for SoulSync standalone — only the required methods,
NO optional methods. Used to assert engine routes around missing
optional methods with safe defaults."""
def is_connected(self): return True
def ensure_connection(self): return True
def get_all_artists(self): return []
def get_all_album_ids(self): return set()
def test_search_tracks_returns_empty_when_client_lacks_method(make_engine):
"""SoulSync standalone has no search_tracks — engine returns
[] instead of raising AttributeError."""
engine = make_engine({'soulsync': _MinimalClient()}, active='soulsync')
assert engine.search_tracks('t', 'a') == []
def test_trigger_library_scan_returns_true_when_client_lacks_method(make_engine):
"""SoulSync has no trigger_library_scan (filesystem walks
happen in-process). Engine no-ops with True so callers don't
treat it as a failure."""
engine = make_engine({'soulsync': _MinimalClient()}, active='soulsync')
assert engine.trigger_library_scan() is True
def test_is_library_scanning_returns_false_when_client_lacks_method(make_engine):
engine = make_engine({'soulsync': _MinimalClient()}, active='soulsync')
assert engine.is_library_scanning() is False
def test_get_library_stats_returns_empty_dict_when_client_lacks_method(make_engine):
engine = make_engine({'soulsync': _MinimalClient()}, active='soulsync')
assert engine.get_library_stats() == {}
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