extract osu file usecases and add s3 writes on new .osu file discovered

app/api/internal/v1/osu_api_v1.py

@@ -1,24 +1,16 @@
 from fastapi import APIRouter
 from fastapi import Response
 
-from app.adapters import aws_s3
-from app.adapters import osu_api_v1
+from app.usecases import osu_files
 
 router = APIRouter(tags=["osu Files"])
 
 
 @router.get("/api/osu-api/v1/osu-files/{beatmap_id}")
 async def download_beatmap_osu_file(beatmap_id: int) -> Response:
-    beatmap_osu_file_data = await aws_s3.get_object_data(f"/beatmaps/{beatmap_id}.osu")
+    beatmap_osu_file_data = await osu_files.fetch_beatmap_osu_file_data(beatmap_id)
     if beatmap_osu_file_data is None:
-        beatmap_osu_file_data = await osu_api_v1.fetch_beatmap_osu_file_data(beatmap_id)
-        # TODO: consider at which points in beatmaps-service we should update
-        #       the .osu file that is currently saved in wasabi s3 storage.
-        if beatmap_osu_file_data is None:
-            return Response(status_code=404)
-    else:
-        # TODO: consider cache expiry
-        ...
+        return Response(status_code=404)
 
     return Response(
         beatmap_osu_file_data,

app/usecases/osu_files.py

@@ -0,0 +1,31 @@
+import logging
+
+from app.adapters import aws_s3
+from app.adapters import osu_api_v1
+
+
+async def fetch_beatmap_osu_file_data(beatmap_id: int) -> bytes | None:
+    beatmap_osu_file_data = await aws_s3.get_object_data(f"/beatmaps/{beatmap_id}.osu")
+    if beatmap_osu_file_data is None:
+        beatmap_osu_file_data = await osu_api_v1.fetch_beatmap_osu_file_data(beatmap_id)
+        if beatmap_osu_file_data is None:
+            return None
+
+        await aws_s3.save_object_data(
+            f"/beatmaps/{beatmap_id}.osu",
+            beatmap_osu_file_data,
+        )
+        logging.info(
+            "Saved beatmap osu file to s3",
+            extra={"beatmap_id": beatmap_id},
+        )
+        # NOTE: this is a place where .osu files could become desynced
+        #       with akatsuki beatmaps in the mysql database, however we've
+        #       decided to not worry about this for now, as most use cases
+        #       which rely on .osu files will also fetch the beatmap metadata,
+        #       forcing an update to occur.
+    else:
+        # TODO: consider cache expiry
+        ...
+
+    return beatmap_osu_file_data