<?php

namespace App\Utils;

class CpuHelper
{
    /**
     * 获取 CPU 核心数
     */
    public static function getCpuCores(): int
    {
        return (int) shell_exec('nproc');
    }

    /**
     * 获取 CPU 使用情况（用户、系统、空闲百分比）
     */
    public static function getCpuUsage(int $interval = 1): array
    {
        $stat1 = self::readStat();
        sleep($interval);
        $stat2 = self::readStat();

        $diff = [];
        foreach ($stat1 as $key => $value) {
            $diff[$key] = $stat2[$key] - $value;
        }

        $total = array_sum($diff);
        if ($total == 0) {
            return [
                'user' => 0,
                'system' => 0,
                'idle' => 100,
            ];
        }

        return [
            'user' => round(($diff['user'] + $diff['nice']) / $total * 100, 2),
            'system' => round($diff['system'] / $total * 100, 2),
            'idle' => round($diff['idle'] / $total * 100, 2),
        ];
    }

    /**
     * 读取 /proc/stat 文件中的 CPU 信息
     */
    private static function readStat(): array
    {
        $fh = fopen('/proc/stat', 'r');
        $line = fgets($fh);
        fclose($fh);

        $parts = preg_split('/\s+/', trim($line));
        // /proc/stat 第一行示例:
        // cpu  3357 0 4313 1362393 0 0 0
        return [
            'user'   => (int) $parts[1],
            'nice'   => (int) $parts[2],
            'system' => (int) $parts[3],
            'idle'   => (int) $parts[4],
            'iowait' => (int) ($parts[5] ?? 0),
            'irq'    => (int) ($parts[6] ?? 0),
            'softirq'=> (int) ($parts[7] ?? 0),
        ];
    }
}