From fd2f76325c2d73d08fb98c2f7df45234be9417fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Avil=C3=A9s?= <ome@unconventional.dev>
Date: Wed, 27 Sep 2023 04:08:23 +0200
Subject: [PATCH] Fix import errors in Python 3.9

---
 src/unbeheader/config.py  | 13 ++++++++-----
 src/unbeheader/headers.py |  9 ++++++---
 src/unbeheader/typing.py  |  9 ++++++---
 src/unbeheader/util.py    |  9 +++++++--
 4 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/src/unbeheader/config.py b/src/unbeheader/config.py
index cd9c1d9..f69eb8b 100644
--- a/src/unbeheader/config.py
+++ b/src/unbeheader/config.py
@@ -4,11 +4,13 @@
 import sys
 from collections.abc import Iterator
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import click
 import yaml
 
-from .typing import ConfigDict
+if TYPE_CHECKING:
+    from .typing import ConfigDict
 
 # The substring which must be part of a comment block in order for the comment to be updated by the header
 DEFAULT_SUBSTRING = 'This file is part of'
@@ -17,7 +19,7 @@
 CONFIG_FILE_NAME = '.header.yaml'
 
 
-def get_config(path: Path, end_year: int) -> ConfigDict:
+def get_config(path: Path, end_year: int) -> 'ConfigDict':
     """Get configuration from headers files."""
     config = _load_config(path)
     _validate_config(config)
@@ -26,8 +28,9 @@ def get_config(path: Path, end_year: int) -> ConfigDict:
     return config
 
 
-def _load_config(path: Path) -> ConfigDict:
-    config: ConfigDict = {}
+def _load_config(path: Path) -> 'ConfigDict':
+    # TODO: remove noqa when py3.9 is dropped
+    config: 'ConfigDict' = {}  # noqa: UP037 (py3.9 compat)
     found = False
     for dir_path in _walk_to_root(path):
         check_path = dir_path / CONFIG_FILE_NAME
@@ -42,7 +45,7 @@ def _load_config(path: Path) -> ConfigDict:
     return config
 
 
-def _validate_config(config: ConfigDict) -> None:
+def _validate_config(config: 'ConfigDict') -> None:
     valid_keys = {'owner', 'start_year', 'substring', 'template'}
     mandatory_keys = {'owner', 'template'}
     config_keys = set(config)
diff --git a/src/unbeheader/headers.py b/src/unbeheader/headers.py
index b20ce8d..e2fe2f2 100644
--- a/src/unbeheader/headers.py
+++ b/src/unbeheader/headers.py
@@ -6,15 +6,18 @@
 from dataclasses import asdict
 from pathlib import Path
 from re import Pattern
+from typing import TYPE_CHECKING
 
 import click
 
 from . import SUPPORTED_FILE_TYPES
 from .config import get_config
 from .typing import CommentSkeleton
-from .typing import ConfigDict
 from .util import cformat
 
+if TYPE_CHECKING:
+    from .typing import ConfigDict
+
 
 def update_header(file_path: Path, year: int, check: bool = False) -> bool:
     """Update the header of a file."""
@@ -29,7 +32,7 @@ def update_header(file_path: Path, year: int, check: bool = False) -> bool:
     )
 
 
-def _do_update_header(file_path: Path, config: ConfigDict, regex: Pattern[str], comments: CommentSkeleton,
+def _do_update_header(file_path: Path, config: 'ConfigDict', regex: Pattern[str], comments: CommentSkeleton,
                       check: bool) -> bool:
     found = False
     content = orig_content = file_path.read_text()
@@ -70,7 +73,7 @@ def _do_update_header(file_path: Path, config: ConfigDict, regex: Pattern[str],
     return True
 
 
-def _generate_header(data: ConfigDict) -> str:
+def _generate_header(data: 'ConfigDict') -> str:
     if 'start_year' not in data:
         data['start_year'] = data['end_year']
     if data['start_year'] == data['end_year']:
diff --git a/src/unbeheader/typing.py b/src/unbeheader/typing.py
index 1003cc8..8089449 100644
--- a/src/unbeheader/typing.py
+++ b/src/unbeheader/typing.py
@@ -4,12 +4,15 @@
 from dataclasses import dataclass
 from pathlib import Path
 from re import Pattern
+from typing import TYPE_CHECKING
 from typing import Any
 from typing import NamedTuple
-from typing import TypeAlias
 
-ConfigDict: TypeAlias = dict[str, Any]
-PathCache: TypeAlias = dict[Path, bool]
+# XXX: Backwards compatibility with Python 3.9
+if TYPE_CHECKING:
+    from typing import TypeAlias
+    ConfigDict: TypeAlias = dict[str, Any]
+    PathCache: TypeAlias = dict[Path, bool]
 
 
 @dataclass
diff --git a/src/unbeheader/util.py b/src/unbeheader/util.py
index b918792..d71116b 100644
--- a/src/unbeheader/util.py
+++ b/src/unbeheader/util.py
@@ -4,10 +4,13 @@
 import re
 from pathlib import Path
 from re import Match
+from typing import TYPE_CHECKING
+from typing import Union
 
 from colorclass import Color
 
-from .typing import PathCache
+if TYPE_CHECKING:
+    from .typing import PathCache
 
 # The name of the files that exclude the directory from header updates
 EXCLUDE_FILE_NAME = '.no-header'
@@ -35,7 +38,9 @@ def repl(m: Match[str]) -> Color:
     return Color(string)
 
 
-def is_excluded(path: Path, root_path: Path | None = None, cache: PathCache | None = None) -> bool:
+# TODO: remove noqa when py3.9 is dropped
+def is_excluded(path: Path, root_path: Union[Path, None] = None,  # noqa: UP007 (py3.9 compat)
+                cache: Union['PathCache', None] = None) -> bool:  # noqa: UP007 (py3.9 compat)
     """"Whether the path is excluded by a .no-headers file.
 
     The .no-headers file is searched for in the path and all parents up to the root.