Core: allow loading worlds from zip modules (#747)

* Core: allow loading worlds from zip modules
RoR2: make it zipimport compatible (remove relative imports beyond local top-level)

* WebHost: add support for .apworld

worlds/__init__.py

@@ -1,29 +1,57 @@
 import importlib
+import zipimport
 import os
+import typing
 
-__all__ = {"lookup_any_item_id_to_name",
-           "lookup_any_location_id_to_name",
-           "network_data_package",
-           "AutoWorldRegister"}
+folder = os.path.dirname(__file__)
+
+__all__ = {
+    "lookup_any_item_id_to_name",
+    "lookup_any_location_id_to_name",
+    "network_data_package",
+    "AutoWorldRegister",
+    "world_sources",
+    "folder",
+}
+
+if typing.TYPE_CHECKING:
+    from .AutoWorld import World
+
+
+class WorldSource(typing.NamedTuple):
+    path: str  # typically relative path from this module
+    is_zip: bool = False
+
+
+# find potential world containers, currently folders and zip-importable .apworld's
+world_sources: typing.List[WorldSource] = []
+file: os.DirEntry  # for me (Berserker) at least, PyCharm doesn't seem to infer the type correctly
+for file in os.scandir(folder):
+    if not file.name.startswith("_"):  # prevent explicitly loading __pycache__ and allow _* names for non-world folders
+        if file.is_dir():
+            world_sources.append(WorldSource(file.name))
+        elif file.is_file() and file.name.endswith(".apworld"):
+            world_sources.append(WorldSource(file.name, is_zip=True))
 
 # import all submodules to trigger AutoWorldRegister
-world_folders = []
-for file in os.scandir(os.path.dirname(__file__)):
-    if file.is_dir():
-        world_folders.append(file.name)
-world_folders.sort()
-for world in world_folders:
-    if not world.startswith("_"):  # prevent explicitly loading __pycache__ and allow _* names for non-world folders
-        importlib.import_module(f".{world}", "worlds")
+world_sources.sort()
+for world_source in world_sources:
+    if world_source.is_zip:
+
+        importer = zipimport.zipimporter(os.path.join(folder, world_source.path))
+        importer.load_module(world_source.path.split(".", 1)[0])
+    else:
+        importlib.import_module(f".{world_source.path}", "worlds")
 
-from .AutoWorld import AutoWorldRegister
 lookup_any_item_id_to_name = {}
 lookup_any_location_id_to_name = {}
 games = {}
 
+from .AutoWorld import AutoWorldRegister
+
 for world_name, world in AutoWorldRegister.world_types.items():
     games[world_name] = {
-        "item_name_to_id" : world.item_name_to_id,
+        "item_name_to_id": world.item_name_to_id,
         "location_name_to_id": world.location_name_to_id,
         "version": world.data_version,
         # seems clients don't actually want this. Keeping it here in case someone changes their mind.
@@ -41,5 +69,6 @@ network_data_package = {
 if any(not world.data_version for world in AutoWorldRegister.world_types.values()):
     network_data_package["version"] = 0
     import logging
+
     logging.warning(f"Datapackage is in custom mode. Custom Worlds: "
                     f"{[world for world in AutoWorldRegister.world_types.values() if not world.data_version]}")