"""Inject the project coordination reminder at Codex session start."""

from __future__ import annotations

import json
import subprocess
import sys
from pathlib import Path


def read_payload() -> dict:
    raw = sys.stdin.read()
    if not raw.strip():
        return {}
    try:
        return json.loads(raw)
    except json.JSONDecodeError:
        return {}


def find_repo_root(cwd: str | None) -> Path:
    start = Path(cwd or Path.cwd()).resolve()
    try:
        result = subprocess.run(
            ["git", "rev-parse", "--show-toplevel"],
            cwd=start,
            capture_output=True,
            text=True,
            check=True,
        )
        return Path(result.stdout.strip()).resolve()
    except Exception:
        return start


def main() -> int:
    payload = read_payload()
    root = find_repo_root(payload.get("cwd"))
    required = ["PLAN.md", "PROGRESS.md"]
    missing = [name for name in required if not (root / name).exists()]

    context = (
        "Before starting work in this repository, read PLAN.md and PROGRESS.md. "
        "Use PROGRESS.md as the factual state, update PLAN.md when sequencing changes, "
        "and keep samples/ out of commits unless the user explicitly requests otherwise."
    )

    output = {
        "continue": True,
        "hookSpecificOutput": {
            "hookEventName": "SessionStart",
            "additionalContext": context,
        },
    }
    if missing:
        output["systemMessage"] = "Missing project coordination file(s): " + ", ".join(missing)

    print(json.dumps(output, ensure_ascii=True))
    return 0


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