<?php

namespace App\Services;

use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Redis;

/**
 * Sammelt System-Stats aus /proc, Disk, Ollama API, Redis Queue.
 * Ein einziger Producer (Artisan-Command) ruft das auf und broadcastet
 * per Reverb an alle Browser.
 */
class SystemStatsService
{
    /**
     * @return array{cpu:int, memory: array, disk: array, load: array, ollama: array, queue: int}
     */
    public function collect(): array
    {
        return [
            'cpu' => $this->cpuUsage(),
            'memory' => $this->memoryUsage(),
            'disk' => $this->diskUsage(),
            'load' => $this->loadAverage(),
            'ollama' => $this->ollamaStatus(),
            'openai' => $this->openaiStatus(),
            'queue' => $this->queueLength(),
        ];
    }

    protected function cpuUsage(): int
    {
        $sample = function (): array {
            $line = explode("\n", (string) @file_get_contents('/proc/stat'))[0] ?? '';
            $parts = preg_split('/\s+/', trim($line));
            array_shift($parts);
            $parts = array_map('intval', $parts);

            return [
                'idle' => ($parts[3] ?? 0) + ($parts[4] ?? 0),
                'total' => array_sum($parts),
            ];
        };

        $a = $sample();
        usleep(100_000);
        $b = $sample();

        $totalDiff = $b['total'] - $a['total'];
        $idleDiff = $b['idle'] - $a['idle'];

        return $totalDiff > 0 ? (int) round((1 - $idleDiff / $totalDiff) * 100) : 0;
    }

    protected function memoryUsage(): array
    {
        $info = (string) @file_get_contents('/proc/meminfo');
        preg_match('/MemTotal:\s+(\d+)/', $info, $totalMatch);
        preg_match('/MemAvailable:\s+(\d+)/', $info, $availMatch);

        $total = (int) ($totalMatch[1] ?? 0);
        $available = (int) ($availMatch[1] ?? 0);
        $used = max(0, $total - $available);

        return [
            'percent' => $total > 0 ? (int) round(($used / $total) * 100) : 0,
            'used_mb' => (int) round($used / 1024),
            'total_mb' => (int) round($total / 1024),
        ];
    }

    protected function diskUsage(): array
    {
        $total = (int) @disk_total_space('/var/www');
        $free = (int) @disk_free_space('/var/www');
        $used = max(0, $total - $free);

        return [
            'percent' => $total > 0 ? (int) round(($used / $total) * 100) : 0,
            'used_gb' => round($used / 1024 / 1024 / 1024, 1),
            'total_gb' => round($total / 1024 / 1024 / 1024, 1),
        ];
    }

    protected function loadAverage(): array
    {
        $line = (string) @file_get_contents('/proc/loadavg');
        $parts = preg_split('/\s+/', trim($line));

        return [
            '1m' => (float) ($parts[0] ?? 0),
            '5m' => (float) ($parts[1] ?? 0),
            '15m' => (float) ($parts[2] ?? 0),
        ];
    }

    protected function ollamaStatus(): array
    {
        try {
            $r = Http::timeout(2)->get(rtrim((string) config('services.ollama.url'), '/').'/api/tags');
            if ($r->successful()) {
                return ['online' => true, 'models' => count($r->json('models', []))];
            }
        } catch (\Throwable) {
            // ignore
        }

        return ['online' => false, 'models' => 0];
    }

    /**
     * OpenAI ist "online" wenn ein Key gesetzt ist - kein Live-Ping (kostet Geld).
     * Der echte Health-Check passiert beim ersten realen Request, im LLM-Fallback.
     */
    protected function openaiStatus(): array
    {
        return ['online' => ! empty(config('services.openai.key'))];
    }

    protected function queueLength(): int
    {
        try {
            return (int) Redis::connection()->llen(config('cache.prefix', '').'queues:default');
        } catch (\Throwable) {
            return 0;
        }
    }
}