feat(core): template/extension loaders and merge model (#27)

packages/create-python-app-core/src/create_python_app_core/__init__.py

@@ -25,7 +25,12 @@
  read_cache_meta,
  write_cache_meta,
 )
-from create_python_app_core.paths import default_cache_dir, resolve_source
+from create_python_app_core.loaders import load_layer, merge_layers
+from create_python_app_core.paths import (
+ default_cache_dir,
+ get_template_dir_path,
+ resolve_source,
+)
 
 __all__ = [
  "__version__",
@@ -42,6 +47,9 @@
  "CacheMeta",
  "read_cache_meta",
  "write_cache_meta",
+ "merge_layers",
+ "load_layer",
+ "get_template_dir_path",
  "CPA_USER_AGENT",
  "check_for_latest_version",
  "check_python_version",

packages/create-python-app-core/src/create_python_app_core/loaders.py

@@ -0,0 +1,51 @@
+"""Template/extension file loaders and merge model."""
+
+from __future__ import annotations
+
+import shutil
+from pathlib import Path
+
+from create_python_app_core.errors import ManifestLoadError
+from create_python_app_core.paths import ResolvedSource, get_template_dir_path
+
+
+def copy_tree(src: Path, dest: Path, *, overwrite: bool = True) -> list[Path]:
+ """Copy files from src into dest. Returns list of written paths."""
+ written: list[Path] = []
+ if not src.is_dir():
+ raise ManifestLoadError(f"template directory not found: {src}")
+ dest.mkdir(parents=True, exist_ok=True)
+ for path in src.rglob("*"):
+ if path.is_dir():
+ continue
+ rel = path.relative_to(src)
+ target = dest / rel
+ if target.exists() and not overwrite:
+ continue
+ target.parent.mkdir(parents=True, exist_ok=True)
+ shutil.copy2(path, target)
+ written.append(target)
+ return written
+
+
+def load_layer(
+ source: ResolvedSource,
+ root: Path,
+ dest: Path,
+ *,
+ overwrite: bool = True,
+) -> list[Path]:
+ """Load one template/extension layer into dest."""
+ template_root = get_template_dir_path(source, root)
+ return copy_tree(template_root, dest, overwrite=overwrite)
+
+
+def merge_layers(
+ layers: list[tuple[ResolvedSource, Path]],
+ dest: Path,
+) -> list[Path]:
+ """Apply layers in order: template → addons → extend (later wins)."""
+ written: list[Path] = []
+ for source, root in layers:
+ written.extend(load_layer(source, root, dest, overwrite=True))
+ return written

packages/create-python-app-core/tests/test_loaders.py

@@ -0,0 +1,24 @@
+from pathlib import Path
+
+from create_python_app_core.loaders import merge_layers
+from create_python_app_core.paths import ResolvedSource
+
+
+def _layer(tmp: Path, name: str, files: dict[str, str]) -> tuple[ResolvedSource, Path]:
+ root = tmp / name
+ tpl = root / "template"
+ for rel, content in files.items():
+ path = tpl / rel
+ path.parent.mkdir(parents=True, exist_ok=True)
+ path.write_text(content)
+ src = ResolvedSource(kind="file", url=f"file://{root}", local_path=root)
+ return src, root
+
+
+def test_merge_later_wins(tmp_path: Path) -> None:
+ a = _layer(tmp_path, "a", {"README.md": "a", "keep.txt": "keep"})
+ b = _layer(tmp_path, "b", {"README.md": "b"})
+ dest = tmp_path / "out"
+ merge_layers([a, b], dest)
+ assert (dest / "README.md").read_text() == "b"
+ assert (dest / "keep.txt").read_text() == "keep"