much progress

src/music_kraken/objects/collection.py

@@ -96,7 +96,7 @@ class Collection:
                     return AppendResult(True, existing_object, False)
 
                 # if the object does already exist
-                # thus merging and don't add it afterwards
+                # thus merging and don't add it afterward
                 if merge_into_existing:
                     existing_object.merge(element)
                     # in case any relevant data has been added (e.g. it remaps the old object)

src/music_kraken/objects/parents.py

@@ -11,6 +11,10 @@ class DatabaseObject:
     COLLECTION_ATTRIBUTES: tuple = tuple()
     SIMPLE_ATTRIBUTES: dict = dict()
 
+    # contains all collection attributes, which describe something "smaller"
+    # e.g. album has songs, but not artist.
+    DOWNWARDS_COLLECTION_ATTRIBUTES: tuple = tuple()
+
     def __init__(self, _id: int = None, dynamic: bool = False, **kwargs) -> None:
         self.automatic_id: bool = False
 

src/music_kraken/objects/song.py

@@ -204,6 +204,8 @@ class Album(MainObject):
         "notes": FormattedText()
     }
 
+    DOWNWARDS_COLLECTION_ATTRIBUTES = ("song_collection",)
+
     def __init__(
             self,
             _id: int = None,
@@ -422,6 +424,8 @@ class Artist(MainObject):
         "general_genre": ""
     }
 
+    DOWNWARDS_COLLECTION_ATTRIBUTES = ("feature_song_collection", "main_album_collection")
+
     def __init__(
             self,
             _id: int = None,
@@ -646,6 +650,8 @@ class Label(MainObject):
         "notes": FormattedText()
     }
 
+    DOWNWARDS_COLLECTION_ATTRIBUTES = COLLECTION_ATTRIBUTES
+
     def __init__(
             self,
             _id: int = None,

src/music_kraken/pages/abstract.py

@@ -237,6 +237,38 @@ class Page(threading.Thread):
     def fetch_label(self, source: Source, stop_at_level: int = 1) -> Label:
         return Label()
 
+    def download(self, music_object: DatabaseObject, download_all: bool = False) -> DownloadResult:
+        self._download(music_object, {}, download_all)
+
+        return DownloadResult()
+
+
+    def _download(self, music_object: DatabaseObject, naming_objects: Dict[Type[DatabaseObject], DatabaseObject], download_all: bool = False) -> list:
+        # Skips all releases, that are defined in shared.ALBUM_TYPE_BLACKLIST, if download_all is False
+        if isinstance(music_object, Album):
+            if not download_all and music_object.album_type in shared.ALBUM_TYPE_BLACKLIST:
+                return []
+
+        naming_objects[type(music_object)] = music_object
+
+        if isinstance(music_object, Song):
+            print("Downloading", music_object)
+            return [music_object]
+
+        return_values: List = []
+
+        for collection_name in music_object.DOWNWARDS_COLLECTION_ATTRIBUTES:
+            collection: Collection = getattr(self, collection_name)
+
+            sub_ordered_music_object: DatabaseObject
+            for sub_ordered_music_object in collection:
+                return_values.extend(self._download(sub_ordered_music_object, naming_objects.copy(), download_all))
+
+        return return_values
+
+    def download_song(self, song: Song, naming_objects: Dict[Type[DatabaseObject], DatabaseObject]):
+        pass
+
     @classmethod
     def download(
             cls,