#!/usr/bin/env python3
"""Ensure dtoverlay=spi1-3cs is under [all] for Pi 5 Model B."""

from __future__ import annotations

import sys
from pathlib import Path

CONFIG = Path("/boot/firmware/config.txt")
OVERLAY = "dtoverlay=spi1-3cs"


def main() -> int:
    if not CONFIG.exists():
        print(f"Error: {CONFIG} not found", file=sys.stderr)
        return 1

    lines = CONFIG.read_text().splitlines()
    out: list[str] = []
    in_cm5 = False
    has_overlay = False
    inserted = False

    for line in lines:
        stripped = line.strip()
        if stripped == "[cm5]":
            in_cm5 = True
        elif stripped.startswith("[") and stripped.endswith("]"):
            if in_cm5 and not inserted and not has_overlay:
                out.append(OVERLAY)
                inserted = True
            in_cm5 = False

        if stripped == "dtparam=spi1=on":
            continue
        if stripped == OVERLAY:
            has_overlay = True
            if in_cm5:
                continue
            out.append(line)
            continue
        out.append(line)

    if not has_overlay and not inserted:
        if out and out[-1].strip():
            out.append("")
        out.append(OVERLAY)

    new_text = "\n".join(out) + "\n"
    if new_text == CONFIG.read_text():
        print("config.txt already correct.")
    else:
        CONFIG.write_text(new_text)
        print("Updated /boot/firmware/config.txt:")
        print(f"  - removed dtparam=spi1=on (ignored on Pi 5)")
        print(f"  - moved {OVERLAY} out of [cm5] into [all]")
        print("Reboot for the change to take effect on boot.")

    print(
        "\nWiring:\n"
        "  strip 0 DIN → GPIO 10 (SPI0 MOSI)  /dev/spidev0.0\n"
        "  strip 1 DIN → GPIO 20 (SPI1 MOSI)  /dev/spidev1.0"
    )
    return 0


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