🚧 WIP new location system

TODO
- Locations contain the schema key
- Schema key overriden at location resolve
- No need for callable candidates,
but need to represent "this location's key"

src/importer/sources/location.py

@@ -0,0 +1,64 @@
+from pathlib import Path
+from typing import Callable, Mapping, Iterable
+from os import PathLike
+
+PathSegment = str | PathLike | Path
+PathSegments = Iterable[PathSegment]
+Candidate = PathSegments | Callable[[], PathSegments]
+
+
+class UnresolvableLocationError(Exception):
+    pass
+
+
+class Location:
+    """
+    Class representing a filesystem location
+
+    * A location may have multiple candidate roots
+    * From its root, multiple subpaths are named and should exist
+    """
+
+    candidates: Iterable[Candidate]
+    paths: Mapping[str, tuple[bool, PathSegments]]
+    root: Path = None
+
+    def __init__(
+        self,
+        candidates: Iterable[Candidate],
+        paths: Mapping[str, tuple[bool, PathSegments]],
+    ) -> None:
+        super().__init__()
+        self.candidates = candidates
+        self.paths = paths
+
+    def check_candidate(self, candidate: Path) -> bool:
+        """Check if a candidate root has the necessary files and directories"""
+        for type_is_dir, subpath in self.paths.values():
+            subpath = Path(candidate) / Path(subpath)
+            if type_is_dir:
+                if not subpath.is_dir():
+                    return False
+            else:
+                if not subpath.is_file():
+                    return False
+        return True
+
+    def resolve(self) -> None:
+        """Choose a root path from the candidates for the location.
+        If none fits, raise a UnresolvableLocationError"""
+        if self.root is not None:
+            return
+        for candidate in self.candidates:
+            if callable(candidate):
+                candidate = candidate()
+            candidate = Path(candidate).expanduser()
+            if self.check_candidate(candidate):
+                self.root = candidate
+                return
+        raise UnresolvableLocationError()
+
+    def __getitem__(self, key: str):
+        """Get the computed path from its key for the location"""
+        self.resolve()
+        return self.root / self.paths[key][1]