add settings support

mypy_django_plugin_newsemanal/transformers/settings.py

@@ -1,5 +1,5 @@
-from mypy.nodes import TypeInfo
-from mypy.plugin import FunctionContext
+from mypy.nodes import TypeInfo, MemberExpr
+from mypy.plugin import FunctionContext, AttributeContext
 from mypy.types import Type as MypyType, TypeType, Instance
 
 from mypy_django_plugin_newsemanal.django.context import DjangoContext
@@ -16,3 +16,30 @@ def get_user_model_hook(ctx: FunctionContext, django_context: DjangoContext) ->
 
     return TypeType(Instance(model_info, []))
 
+
+def get_type_of_settings_attribute(ctx: AttributeContext, django_context: DjangoContext) -> MypyType:
+    assert isinstance(ctx.context, MemberExpr)
+    setting_name = ctx.context.name
+    if not hasattr(django_context.settings, setting_name):
+        ctx.api.fail(f"'Settings' object has no attribute {setting_name!r}", ctx.context)
+        return ctx.default_attr_type
+
+    # first look for the setting in the project settings file, then global settings
+    settings_module = ctx.api.modules.get(django_context.django_settings_module)
+    global_settings_module = ctx.api.modules.get('django.conf.global_settings')
+    for module in [settings_module, global_settings_module]:
+        if module is not None:
+            sym = module.names.get(setting_name)
+            if sym is not None and sym.type is not None:
+                return sym.type
+
+    # if by any reason it isn't present there, get type from django settings
+    value = getattr(django_context.settings, setting_name)
+    value_fullname = helpers.get_class_fullname(value.__class__)
+
+    value_info = helpers.lookup_fully_qualified_typeinfo(ctx.api, value_fullname)
+    if value_info is None:
+        return ctx.default_attr_type
+
+    return Instance(value_info, [])
+