# -*- coding: utf-8 -*-
"""
collatz_calculate_Nstar.py

Scan certificats/*.json for N0 values in clauses, compute N* = max of all N0,
write markdown with "N* = <value>".

Usage:
  python collatz_calculate_Nstar.py --certificats-dir DIR --output MD_PATH
"""

from __future__ import annotations
import argparse
import json
from pathlib import Path


def scan_n0_values(certificats_dir: Path) -> list[int]:
    """Scan certificat_*.json and candidats_*.csv for N0 values."""
    import csv

    n0_values: list[int] = []
    for p in sorted(certificats_dir.glob("certificat_*.json")):
        data = json.loads(p.read_text(encoding="utf-8"))
        clauses = data.get("clauses", data.get("closed", []))
        for c in clauses:
            if isinstance(c, dict) and "N0" in c:
                n0_values.append(int(c["N0"]))

    parent = certificats_dir.resolve().parent
    for search_dir in (parent, parent / "candidats"):
        if not search_dir.is_dir():
            continue
        for p in sorted(search_dir.glob("candidats_*.csv")):
            with p.open("r", encoding="utf-8") as f:
                reader = csv.DictReader(f)
                for row in reader:
                    n0_col = next((k for k in row if "N0" in k or k == "N0"), None)
                    if n0_col and row.get(n0_col):
                        try:
                            n0_values.append(int(row[n0_col]))
                        except ValueError:
                            pass
    return n0_values


def main() -> None:
    parser = argparse.ArgumentParser(
        description="Compute N* = max of all N0 from certificat JSON files"
    )
    parser.add_argument("--certificats-dir", required=True, help="Directory containing certificat_*.json")
    parser.add_argument("--output", required=True, help="Output markdown path")
    args = parser.parse_args()

    cert_dir = Path(args.certificats_dir)
    if not cert_dir.is_dir():
        raise SystemExit(f"Not a directory: {cert_dir}")

    n0_values = scan_n0_values(cert_dir)
    nstar = max(n0_values) if n0_values else 0

    out_path = Path(args.output)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    out_path.write_text(f"N* = {nstar}\n", encoding="utf-8")


if __name__ == "__main__":
    main()