feat(remote): forward HLS segment filters to remote clients

Add POST /api/session/{id}/segment_filter: the server runs the service's OnSegmentFilter and returns only the unwanted segment URIs, so ads and bumpers are dropped over --remote-only without exposing service code.

tests/remote/unit/test_segment_filter.py

@@ -0,0 +1,92 @@
+"""The server runs a track's OnSegmentFilter and the client skips the segments it names."""
+
+from __future__ import annotations
+
+import json
+from types import SimpleNamespace
+
+import pytest
+import responses
+
+from unshackle.core.api import handlers
+from unshackle.core.remote_service import RemoteClient, RemoteService
+
+pytestmark = pytest.mark.unit
+
+PLAYLIST = """#EXTM3U
+#EXT-X-TARGETDURATION:4
+#EXTINF:4,
+main0.ts
+#EXTINF:4,
+ad1.ts
+#EXTINF:4,
+main2.ts
+#EXT-X-ENDLIST
+"""
+
+BASE = "https://cdn.test/hls/media.m3u8"
+
+
+def make_session(monkeypatch, track):
+    session = SimpleNamespace(
+        tracks={"t1": track},
+        service_instance=SimpleNamespace(session=SimpleNamespace(get=lambda url: SimpleNamespace(text=PLAYLIST))),
+    )
+
+    async def get_validated_session(session_id, request):
+        return session
+
+    monkeypatch.setattr(handlers, "get_validated_session", get_validated_session)
+    return session
+
+
+async def test_handler_returns_unwanted_absolute_uris(monkeypatch):
+    track = SimpleNamespace(url=BASE, OnSegmentFilter=lambda segment: "ad" in segment.uri)
+    make_session(monkeypatch, track)
+
+    response = await handlers.session_segment_filter_handler({"track_id": "t1"}, "s1")
+
+    assert json.loads(response.body) == {"unwanted": ["https://cdn.test/hls/ad1.ts"]}
+
+
+async def test_handler_returns_null_without_a_filter(monkeypatch):
+    make_session(monkeypatch, SimpleNamespace(url=BASE, OnSegmentFilter=None))
+
+    response = await handlers.session_segment_filter_handler({"track_id": "t1"}, "s1")
+
+    assert json.loads(response.body) == {"unwanted": None}
+
+
+def make_service(unwanted, status=200):
+    service = RemoteService.__new__(RemoteService)
+    service.client = RemoteClient(server_url="http://srv:8786", api_key="k")
+    service._session_id = "s1"
+    service._segment_filters = {}
+    responses.add(
+        responses.POST,
+        "http://srv:8786/api/session/s1/segment_filter",
+        json={"unwanted": unwanted} if status == 200 else {"message": "no"},
+        status=status,
+    )
+    return service
+
+
+@responses.activate
+def test_client_filter_drops_only_the_unwanted_segments():
+    service = make_service(["https://cdn.test/hls/ad1.ts"])
+    segment_filter = service.remote_segment_filter("t1")
+
+    assert segment_filter(SimpleNamespace(absolute_uri="https://cdn.test/hls/ad1.ts")) is True
+    # a token-differing query string still matches on the path
+    assert segment_filter(SimpleNamespace(absolute_uri="https://cdn.test/hls/ad1.ts?token=2")) is True
+    assert segment_filter(SimpleNamespace(absolute_uri="https://cdn.test/hls/main0.ts")) is False
+    # fetched once, then cached per track id
+    assert len(responses.calls) == 1
+
+
+@responses.activate
+def test_client_filter_keeps_everything_when_the_server_has_no_route():
+    service = make_service(None, status=404)
+    segment_filter = service.remote_segment_filter("t1")
+
+    assert segment_filter(SimpleNamespace(absolute_uri="https://cdn.test/hls/ad1.ts")) is False