#!/usr/bin/env python3
"""Raise spidev bufsiz so full WS2812 SPI frames fit (405 LEDs ≈ 10 KiB)."""

from __future__ import annotations

import argparse
import subprocess
import sys
from pathlib import Path

from leds.backends.spi import _DEFAULT_BUFSIZ, spidev_bufsize

MODPROBE_D = Path("/etc/modprobe.d/spidev-bufsiz.conf")
MARKER = "# portal spidev bufsiz"


def main() -> int:
    parser = argparse.ArgumentParser(
        description="Configure spidev bufsiz for long WS2812 SPI strips"
    )
    parser.add_argument(
        "--bufsiz",
        type=int,
        default=_DEFAULT_BUFSIZ,
        help=f"Kernel SPI buffer size (default {_DEFAULT_BUFSIZ})",
    )
    parser.add_argument(
        "--install",
        action="store_true",
        help="Write /etc/modprobe.d/spidev-bufsiz.conf and reload spidev (sudo)",
    )
    args = parser.parse_args()

    current = spidev_bufsize()
    print(f"spidev bufsiz: {current}")
    print(f"405 LEDs need ~9762 bytes per frame.\n")

    line = f"options spidev bufsiz={args.bufsiz}"
    print("Add to /etc/modprobe.d/spidev-bufsiz.conf:\n")
    print(f"{MARKER}")
    print(line)
    print("\nThen reload:\n  sudo modprobe -r spidev && sudo modprobe spidev")

    if not args.install:
        return 0

    try:
        existing = MODPROBE_D.read_text() if MODPROBE_D.exists() else ""
        if MARKER in existing:
            print(f"\n{MODPROBE_D} already configured.")
        else:
            MODPROBE_D.write_text(f"{MARKER}\n{line}\n")
            print(f"\nWrote {MODPROBE_D}.")

        subprocess.run(["modprobe", "-r", "spidev"], check=False)
        subprocess.run(["modprobe", "spidev", f"bufsiz={args.bufsiz}"], check=True)
        print(f"Reloaded spidev (bufsiz={spidev_bufsize()}).")
    except OSError as exc:
        print(f"Error: {exc}", file=sys.stderr)
        print("Re-run with sudo.", file=sys.stderr)
        return 1
    except subprocess.CalledProcessError as exc:
        print(f"modprobe failed: {exc}", file=sys.stderr)
        return 1
    return 0


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