#!/usr/bin/env python3
"""Git pre-commit: validate headers on new files; refresh Updated/Digest on staged edits."""
from __future__ import annotations

import subprocess
import sys
from pathlib import Path

from header_lib import (
    REPO_ROOT,
    SOURCE_SUFFIXES,
    apply_header_to_content,
    has_valid_header,
    header_needs_identity_refresh,
    is_excluded_path,
    resolve_header_contributor,
    update_header_timestamps,
)


def staged_files() -> list[Path]:
    out = subprocess.check_output(
        ["git", "diff", "--cached", "--name-only", "--diff-filter=ACMR"],
        cwd=REPO_ROOT,
        text=True,
    )
    files = []
    for line in out.splitlines():
        p = REPO_ROOT / line.strip()
        if not p.is_file() or p.suffix.lower() not in SOURCE_SUFFIXES:
            continue
        if is_excluded_path(p):
            continue
        files.append(p)
    return files


def is_new_file(path: Path) -> bool:
    rel = path.relative_to(REPO_ROOT).as_posix()
    try:
        subprocess.check_call(
            ["git", "diff", "--cached", "--diff-filter=A", "--quiet", "--", rel],
            cwd=REPO_ROOT,
        )
        return False
    except subprocess.CalledProcessError:
        return True


def main() -> int:
    errors = []
    contributor = resolve_header_contributor()
    for path in staged_files():
        text = path.read_text(encoding="utf-8", errors="replace")
        if is_new_file(path):
            if not has_valid_header(text):
                errors.append(
                    f"{path.relative_to(REPO_ROOT)}: new file must include HEADER.txt block"
                )
                text = apply_header_to_content(path, text)
                text = update_header_timestamps(text, path, contributor)
        else:
            if has_valid_header(text):
                if header_needs_identity_refresh(text, path):
                    text = apply_header_to_content(path, text)
                text = update_header_timestamps(text, path, contributor)
            else:
                text = apply_header_to_content(path, text)
                text = update_header_timestamps(text, path, contributor)
        path.write_text(text, encoding="utf-8", newline="\n")
        rel = path.relative_to(REPO_ROOT).as_posix()
        subprocess.check_call(["git", "add", "--", rel], cwd=REPO_ROOT)

    if errors:
        for e in errors:
            print(e, file=sys.stderr)
        print(
            "Run: python3 scripts/apply-project-headers.py",
            file=sys.stderr,
        )
        return 1
    return 0


if __name__ == "__main__":
    sys.exit(main())