#!/usr/bin/env python3
"""Reject commits consisting only of generated indexes/projection refreshes.

Applies to every author: automation must accompany an actual source change.
--staged supports a pre-commit hook; BASE..HEAD checks every commit for CI.
"""
import argparse
from pathlib import PurePosixPath
import subprocess


def generated(path):
    parsed = PurePosixPath(path.lower())
    name = parsed.name
    return (name in {"work-records.md", ".custodian-brief.md", "source-index.md",
                     "publication-index.md", "index.generated.md"}
            or name.startswith("source-inventory")
            or name.startswith("decision-packets")
            or name.startswith("publication-index") or name.startswith("projection-refresh")
            or str(parsed).startswith("generated/")
            or str(parsed).startswith("docs/attended-window/")
            or any(part in {"evidence", "decision-packets", "evidence-packets"}
                   for part in parsed.parts[:-1]))


def standalone(paths):
    return bool(paths) and all(generated(path) for path in paths)


def git(*args):
    return subprocess.check_output(["git", *args])


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--staged", action="store_true")
    parser.add_argument("--range", default="HEAD^..HEAD")
    args = parser.parse_args()
    commits = [None] if args.staged else git("rev-list", "--reverse", args.range).decode().splitlines()
    failed = []
    for commit in commits:
        raw = git("diff", "--cached", "--name-only", "-z") if commit is None else git(
            "diff-tree", "--root", "--no-commit-id", "-r", "--name-only", "-z", commit)
        paths = [path.decode() for path in raw.split(b"\0") if path]
        if standalone(paths):
            failed.append(commit or "staged")
    if failed:
        parser.exit(1, "Generated-only commits rejected: " + ", ".join(failed) + "\n")


if __name__ == "__main__":
    main()