<?php

namespace App\Command;

/** What a running server writes every second (status.json in its data folder), for the status command. */
final class StatusFile
{
    public function __construct(private readonly string $file)
    {
    }

    public function write(array $stats): void
    {
        $stats['pid'] = getmypid();
        $stats['at'] = time();
        @file_put_contents($this->file, json_encode($stats, JSON_UNESCAPED_UNICODE) . "\n");
    }

    /** @return array<string, mixed>|null null when no server wrote it lately */
    public function read(int $maxAge = 10): ?array
    {
        $data = is_file($this->file) ? json_decode((string)file_get_contents($this->file), true) : null;
        if (!is_array($data) || (time() - (int)($data['at'] ?? 0)) > $maxAge) {
            return null;
        }
        return $data;
    }

    public function remove(): void
    {
        @unlink($this->file);
    }
}