#!/usr/bin/env python3
import os
import re
import subprocess
import time
from pathlib import Path


CACHE_FILE = Path("/run/control-rpi-disk-temp")
DISK = "/dev/sda"
INTERVAL_SECONDS = 5
SMARTCTL = "/usr/sbin/smartctl"


def parse_temp(output):
    for line in output.splitlines():
        stripped = line.strip()
        if stripped.startswith("Temperature:"):
            match = re.search(r"([0-9]+(?:\.[0-9]+)?)", stripped)
            if match:
                return float(match.group(1))
        if "Temperature_Celsius" in stripped or "Airflow_Temperature_Cel" in stripped:
            parts = stripped.split()
            for part in reversed(parts):
                if part.isdigit():
                    return float(part)
    return None


def read_temp():
    result = subprocess.run(
        [SMARTCTL, "-A", "-d", "sntasmedia", DISK],
        stdout=subprocess.PIPE,
        stderr=subprocess.DEVNULL,
        text=True,
        timeout=4,
        check=False,
    )
    if result.returncode not in (0, 4, 64):
        return None
    return parse_temp(result.stdout)


def write_cache(temp):
    tmp = CACHE_FILE.with_suffix(".tmp")
    if temp is None:
        content = f"UPDATED={time.time():.3f}\nTEMP=\nOK=0\n"
    else:
        content = f"UPDATED={time.time():.3f}\nTEMP={temp:.1f}\nOK=1\n"
    tmp.write_text(content, encoding="utf-8")
    os.replace(tmp, CACHE_FILE)
    os.chmod(CACHE_FILE, 0o644)


def main():
    while True:
        try:
            write_cache(read_temp())
        except Exception:
            write_cache(None)
        time.sleep(INTERVAL_SECONDS)


if __name__ == "__main__":
    main()