5 files changed, 82 insertions, 17 deletions

diff --git a/tools/cru-py/cru/_iter.py b/tools/cru-py/cru/_iter.py
index 12d1d1f..5d3766a 100644
--- a/tools/cru-py/cru/_iter.py
+++ b/tools/cru-py/cru/_iter.py
@@ -415,8 +415,8 @@ class CruIterator(Generic[_T]):
         return self.first_n(1).single_or(fallback)
 
     @_wrap
-    def flatten(self) -> Iterable[_T | Iterable[_T]]:
-        return _Generic.iterable_flatten(self)
+    def flatten(self, max_depth: int = -1) -> Iterable[Any]:
+        return _Generic.iterable_flatten(self, max_depth)
 
     def select_by_indices(self, indices: Iterable[int]) -> CruIterator[_T]:
         index_set = set(indices)
diff --git a/tools/cru-py/cru/app.py b/tools/cru-py/cru/app.py
index c9e57f4..d45fd30 100644
--- a/tools/cru-py/cru/app.py
+++ b/tools/cru-py/cru/app.py
@@ -40,6 +40,10 @@ class ApplicationPath:
         return self._full_path
 
     @property
+    def full_path_str(self) -> str:
+        return str(self._full_path)
+
+    @property
     def is_dir(self) -> bool:
         return self._is_dir
 
diff --git a/tools/cru-py/cru/service/_base.py b/tools/cru-py/cru/service/_base.py
index 707fb66..7bb09ad 100644
--- a/tools/cru-py/cru/service/_base.py
+++ b/tools/cru-py/cru/service/_base.py
@@ -1,23 +1,73 @@
+from __future__ import annotations
+
 from argparse import ArgumentParser, Namespace
-from typing import Protocol
+from abc import ABC, abstractmethod
+from collections.abc import Iterable
+
+from cru import CruIterator, CruInternalError
 from cru.app import ApplicationPath, CruApplication
 
 
-class AppFunction(Protocol):
+class AppFeatureProvider(ABC):
+    def __init__(self, name: str, /, app: AppBase | None = None):
+        super().__init__()
+        self._name = name
+        self._app = app if app else AppBase.get_instance()
+        self._app_paths: list[ApplicationPath] = []
+        self.app.add_app_feature(self)
+
+    @property
+    def app(self) -> AppBase:
+        return self._app
+
+    @property
+    def name(self) -> str:
+        return self._name
+
     @property
-    def name(self) -> str: ...
+    def app_paths(self) -> list[ApplicationPath]:
+        return self._app_paths
+
+    def add_app_path(self, subpath: str, is_dir: bool) -> ApplicationPath:
+        p = ApplicationPath(self.app.app_dir, subpath, is_dir)
+        self._app_paths.append(p)
+        return p
 
+    @abstractmethod
     def add_arg_parser(self, arg_parser: ArgumentParser) -> None: ...
 
+    @abstractmethod
     def run_command(self, args: Namespace) -> None: ...
 
 
 class AppBase(CruApplication):
+    _instance: AppBase | None = None
+
+    @staticmethod
+    def get_instance() -> AppBase:
+        if AppBase._instance is None:
+            raise CruInternalError("App instance not initialized")
+        return AppBase._instance
+
     def __init__(self, name: str, app_dir: str):
         super().__init__(name)
+        AppBase._instance = self
         self._app_dir = app_dir
-        self._template_dir = ApplicationPath(app_dir, "templates", True)
+        self._app_features: list[AppFeatureProvider] = []
 
     @property
     def app_dir(self) -> str:
         return self._app_dir
+
+    @property
+    def app_features(self) -> list[AppFeatureProvider]:
+        return self._app_features
+
+    @property
+    def app_paths(self) -> Iterable[ApplicationPath]:
+        return (
+            CruIterator(self._app_features).transform(lambda x: x.app_paths).flatten(1)
+        )
+
+    def add_app_feature(self, feature: AppFeatureProvider) -> None:
+        self._app_features.append(feature)
diff --git a/tools/cru-py/cru/service/_template.py b/tools/cru-py/cru/service/_template.py
index 0ca4b63..5da00ba 100644
--- a/tools/cru-py/cru/service/_template.py
+++ b/tools/cru-py/cru/service/_template.py
@@ -1,20 +1,31 @@
 from argparse import ArgumentParser, Namespace
 
-from ._base import AppBase, AppFunction
 
+from ._base import AppFeatureProvider
+from cru.app import ApplicationPath
+from cru.template import TemplateTree
 
-class TemplateManager(AppFunction):
-    def __init__(self, app: AppBase):
-        self._app = app
-        pass
+
+class TemplateManager(AppFeatureProvider):
+    def __init__(self, prefix: str = "CRUPEST"):
+        super().__init__("template-manager")
+        self._templates_dir = self.add_app_path("templates", True)
+        self._generated_dir = self.add_app_path("generated", True)
+        self._template_tree = TemplateTree(
+            prefix, self._templates_dir.full_path_str, self._generated_dir.full_path_str
+        )
+
+    @property
+    def templates_dir(self) -> ApplicationPath:
+        return self._templates_dir
 
     @property
-    def name(self):
-        return "template-manager"
+    def generated_dir(self) -> ApplicationPath:
+        return self._generated_dir
 
     def add_arg_parser(self, arg_parser: ArgumentParser) -> None:
         subparsers = arg_parser.add_subparsers(dest="template_command")
-        list_parser = subparsers.add_parser("list", help="List templates")
-        generate_parser = subparsers.add_parser("generate", help="Generate template")
+        list_parser = subparsers.add_parser("list", help="List templates.")
+        generate_parser = subparsers.add_parser("generate", help="Generate template.")
 
     def run_command(self, args: Namespace) -> None: ...
diff --git a/tools/cru-py/cru/template.py b/tools/cru-py/cru/template.py
index 2161804..ccb3ad8 100644
--- a/tools/cru-py/cru/template.py
+++ b/tools/cru-py/cru/template.py
@@ -79,14 +79,14 @@ class TemplateTree:
         prefix: str,
         source: str,
         destination: str,
-        exclude: Iterable[str],
+        exclude: Iterable[str] | None = None,
         template_file_suffix: str = ".template",
     ):
         self._prefix = prefix
         self._files: list[CruTemplateFile] | None = None
         self._source = source
         self._destination = destination
-        self._exclude = [os.path.normpath(p) for p in exclude]
+        self._exclude = [os.path.normpath(p) for p in exclude or []]
         self._template_file_suffix = template_file_suffix
 
     @property