"""Bash-environment Claude Code PostToolUse example (Python 3.11+).

Install as .claude/hooks/check_changed_file.py in an ESLint-configured project.
No --fix, shell interpolation or package install. Exit 2 reports a validation
failure to Claude; PostToolUse cannot undo a completed edit.
"""
from __future__ import annotations

import json
import os
from pathlib import Path
import subprocess
import sys


def check(payload: dict, project_root: Path) -> int:
    root = project_root.resolve(strict=True)
    raw_path = payload.get("tool_input", {}).get("file_path")
    if not isinstance(raw_path, str) or not raw_path:
        raise ValueError("missing tool_input.file_path")
    path = Path(raw_path)
    target = (path if path.is_absolute() else root / path).resolve(strict=True)
    if not target.is_relative_to(root) or not target.is_file():
        raise ValueError("file is outside project or is not a regular file")
    if target.suffix not in {".js", ".jsx", ".ts", ".tsx", ".mjs", ".cjs"}:
        return 0
    result = subprocess.run(
        ["npx", "--no-install", "eslint", "--", str(target)],
        cwd=root, capture_output=True, text=True, timeout=60, check=False,
    )
    if result.returncode:
        print(result.stdout + result.stderr, file=sys.stderr)
        return 2
    return 0


def main() -> int:
    try:
        raw = sys.stdin.read(1024 * 1024 + 1)
        if len(raw) > 1024 * 1024:
            raise ValueError("hook input exceeds budget")
        return check(json.loads(raw), Path(os.environ["CLAUDE_PROJECT_DIR"]))
    except (OSError, ValueError, KeyError, TypeError, AttributeError, subprocess.SubprocessError) as exc:
        print(f"Changed-file validation failed: {exc}", file=sys.stderr)
        return 2


if __name__ == "__main__":
    raise SystemExit(main())