Move subattachment parsing to the respective models

fbchat/_file.py

@@ -241,3 +241,13 @@ class VideoAttachment(Attachment):
             large_image=data.get("large_image"),
             uid=data.get("legacy_attachment_id"),
         )
+
+    @classmethod
+    def _from_subattachment(cls, data):
+        media = data["media"]
+        return cls(
+            duration=media.get("playable_duration_in_ms"),
+            preview_url=media.get("playable_url"),
+            medium_image=media.get("image"),
+            uid=data["target"].get("video_id"),
+        )

fbchat/_graphql.py

@@ -61,16 +61,12 @@ def graphql_to_extensible_attachment(a):
     return None
 
 
-def graphql_to_subattachment(a):
-    _type = a["target"]["__typename"]
+def graphql_to_subattachment(data):
+    _type = data["target"]["__typename"]
     if _type == "Video":
-        media = a["media"]
-        return VideoAttachment(
-            duration=media.get("playable_duration_in_ms"),
-            preview_url=media.get("playable_url"),
-            medium_image=media.get("image"),
-            uid=a["target"].get("video_id"),
-        )
+        return VideoAttachment._from_subattachment(data)
+
+    return None
 
 
 def graphql_to_quick_reply(q, is_response=False):