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

Generate base validation report (trajectories 1 to N*). Outputs Markdown; for PDF use pandoc.

Usage: python collatz_generate_base_validation.py --Nstar N --output PATH
"""

from __future__ import annotations
import argparse
from pathlib import Path

from collatz_k_core import U_step


def collatz_steps(n: int) -> int:
    """Number of steps to reach 1 (accelerated on odds)."""
    steps = 0
    x = n
    while x > 1:
        if x % 2 == 0:
            x //= 2
        else:
            x, _ = U_step(x)
        steps += 1
    return steps


def main() -> None:
    ap = argparse.ArgumentParser(description="Generate base validation (1 to N*)")
    ap.add_argument("--Nstar", type=int, required=True, help="Upper bound N*")
    ap.add_argument("--output", required=True, help="Output path (.md or .pdf)")
    args = ap.parse_args()

    lines = [
        "# Validation de base",
        "",
        "## Introduction",
        "",
        f"Vérification des trajectoires pour n = 1 à {args.Nstar}.",
        "",
        "## Résultats",
        "",
    ]

    ok_count = 0
    for n in range(1, args.Nstar + 1):
        try:
            collatz_steps(n)
            ok_count += 1
        except Exception:
            pass

    lines.extend([
        f"- Entiers vérifiés : {ok_count} / {args.Nstar}",
        "",
    ])

    out_path = Path(args.output)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    md_content = "\n".join(lines)

    if out_path.suffix.lower() == ".pdf":
        out_md = out_path.with_suffix(".md")
        out_md.write_text(md_content, encoding="utf-8")
        try:
            import subprocess
            subprocess.run(["pandoc", str(out_md), "-o", str(out_path)], check=True)
        except (FileNotFoundError, subprocess.CalledProcessError):
            out_path.write_text(md_content, encoding="utf-8")
    else:
        out_path.write_text(md_content, encoding="utf-8")

    print(f"Wrote {out_path}")


if __name__ == "__main__":
    main()