// sysfs functions
const fs = require('node:fs');

const LED_PATH = fs.existsSync('/sys/class/leds/ACT') 
    ? '/sys/class/leds/ACT' 
    : '/sys/class/leds/led0';

// detach kernel trigger once at startup
try {
    fs.writeFileSync(`${LED_PATH}/trigger`, 'none');
} catch (err) {
    console.error(`[LED] failed to claim sysfs led:`, err.message);
}

let blinkTimer = null;

function setBrightness(val) {
    try {
        fs.writeFileSync(`${LED_PATH}/brightness`, val.toString());
    } catch (err) {
        console.error(`[LED] error writing brightness:`, err.message);
    }
}

function turnOff() {
    stopBlink();
    setBrightness(0);
}

function turnOn() {
    stopBlink();
    setBrightness(1);
}

function getState() {
    try {
        return parseInt(fs.readFileSync(`${LED_PATH}/brightness`, 'utf8').trim(), 10);
    } catch {
        return null;
    }
}

function toggle() {
    setBrightness(getState() === 1 ? 0 : 1);
}

function startBlink(interval = 500) {
    stopBlink();
    let state = 1;
    setBrightness(state);

    blinkTimer = setInterval(() => {
        state = state === 1 ? 0 : 1;
        setBrightness(state);
    }, interval);
}

function stopBlink() {
    if (blinkTimer) {
        clearInterval(blinkTimer);
        blinkTimer = null;
    }
}

function restoreDefault() {
    stopBlink();
    try {
        fs.writeFileSync(`${LED_PATH}/trigger`, 'mmc0');
    } catch {}
}

module.exports = {
    turnOff,
    turnOn,
    toggle,
    getState,
    startBlink,
    stopBlink,
    restoreDefault
};