git-config-include

#!/bin/sh
"exec" "uv" "--quiet" "run" "--no-project" "--script" "--" "$0" "$@"
# vim: ft=python ts=4 sw=4 noet:
# https://peps.python.org/pep-0723/
# https://github.com/astral-sh/uv
# /// script
# requires-python = ">=3.14,<4"
# dependencies = [
# ]
# ///

__doc__ = """
Idempotently append an `include.path` entry to the local git config,
stored as a path relative to the config file. Any existing entries that
resolve to the same target file are removed first.
"""

import argparse, os, subprocess, sys
from pathlib import Path


def main(*, file_path):
	try:
		target = file_path.resolve(strict=True)
		config_path = Path(run(
			"git", "rev-parse", "--git-path", "config"
		).stdout.strip()).resolve()
		config_dir = config_path.parent

		existing = run(
			"git", "config", "get", "--local", "--all", "include.path",
			allow=(0, 1),
		).stdout.splitlines()

		for value in sorted(set(existing)):
			if resolve_include(config_dir, value) == target:
				run(
					"git", "config", "unset", "--local", "--all",
					"--fixed-value", "--value", value, "include.path",
				)

		file_path_resolved = include_value(target, config_dir)
		run(
			"git", "config", "set", "--local", "--append",
			"include.path", file_path_resolved
		)
		print(f"file:{config_path}\t{file_path_resolved}")
	except CmdError as e:
		sys.stderr.write(e.stderr)
		return e.returncode
	return 0


def include_value(target, config_dir):
	"""Prefers `core.worktree` verbatim when target is inside that worktree."""
	worktree = run(
		"git", "config", "get", "--local", "core.worktree", allow=(0, 1),
	).stdout.rstrip("\n")
	if worktree:
		worktree_abs = (config_dir / Path(worktree).expanduser()).resolve()
		if target.is_relative_to(worktree_abs):
			return f"{worktree}/{target.relative_to(worktree_abs)}"
	return os.path.relpath(target, config_dir)


def resolve_include(config_dir, value):
	return (config_dir / Path(value).expanduser()).resolve()


def run(*cmd, allow=(0,)):
	r = subprocess.run(cmd, text=True, capture_output=True)
	if r.returncode not in allow:
		raise CmdError(r.returncode, r.stderr)
	return r


class CmdError(Exception):
	def __init__(self, returncode, stderr):
		self.returncode = returncode
		self.stderr = stderr


if __name__ == "__main__":
	ap = argparse.ArgumentParser(description=__doc__)
	ap.add_argument("file_path", metavar="PATH", type=Path,
					help="File to include from git's local config.")
	args = ap.parse_args()
	sys.exit(main(**vars(args)))