<?php

namespace App\Services\Monitoring;

use App\Support\Monitoring\ErrorReportScrubber;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Artisan;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;
use Throwable;

/**
 * Daten für die Monitoring-Seite im Admin (09.10.2026): dieselben Prüfungen wie `/health`, dazu
 * Version, geplante Aufgaben, fehlgeschlagene Jobs und die letzten Fehler und Alarme aus den
 * Logs. Liest nur, ändert nichts; Logs nur das Ende der Datei, damit die Seite schnell bleibt.
 */
class SystemStatus
{
    /** Zeitzone für die Anzeige – die App rechnet in UTC. */
    public const DisplayTimezone = 'Europe/Berlin';

    private const LogTailBytes = 262144;

    private const LogLinePattern = '/^\[(\d{4}-\d{2}-\d{2}[ T]\d{2}:\d{2}:\d{2})[^\]]*\] \w+\.(\w+): (.*)$/';

    public function __construct(private readonly HealthProbe $probe) {}

    /**
     * @return array{status: string, checks: list<array{key: string, label: string, status: string, detail: string}>}
     */
    public function health(): array
    {
        $checks = $this->probe->checks();

        return ['status' => HealthProbe::worstStatus($checks), 'checks' => $checks];
    }

    /**
     * @return array{version: string, environment: string, debug: bool, php: string, laravel: string, deployed_at: ?Carbon}
     */
    public function application(): array
    {
        $release = base_path('RELEASE');

        return [
            'version' => (string) (config('app.version') ?? '—'),
            'environment' => app()->environment(),
            'debug' => (bool) config('app.debug'),
            'php' => PHP_VERSION,
            'laravel' => app()->version(),
            'deployed_at' => is_file($release) ? Carbon::createFromTimestamp((int) filemtime($release))->timezone(self::DisplayTimezone) : null,
        ];
    }

    /**
     * Geplante Aufgaben mit nächstem Lauf (über `schedule:list`, das die Konsolen-Routen lädt).
     *
     * @return list<array{command: string, expression: string, next: ?Carbon, description: string}>
     */
    public function scheduledTasks(): array
    {
        try {
            Artisan::call('schedule:list', ['--json' => true]);
            $tasks = json_decode(Artisan::output(), true);
        } catch (Throwable) {
            return [];
        }

        return collect(is_array($tasks) ? $tasks : [])
            ->map(fn (array $task): array => [
                'command' => trim((string) preg_replace('/^.*?artisan\s+/', '', (string) ($task['command'] ?? ''))),
                'expression' => (string) ($task['expression'] ?? ''),
                'next' => filled($task['next_due_date'] ?? null) ? Carbon::parse($task['next_due_date'])->timezone(self::DisplayTimezone) : null,
                'description' => (string) ($task['description'] ?? ''),
            ])
            ->values()
            ->all();
    }

    /**
     * @return array{count: int, latest: list<array{job: string, queue: string, failed_at: Carbon, error: string}>}
     */
    public function failedJobs(int $limit = 5): array
    {
        try {
            $table = DB::table((string) config('queue.failed.table', 'failed_jobs'));

            return [
                'count' => $table->count(),
                'latest' => $table->orderByDesc('failed_at')->limit($limit)->get()
                    ->map(fn (object $job): array => [
                        'job' => (string) (json_decode((string) $job->payload, true)['displayName'] ?? 'Job'),
                        'queue' => (string) $job->queue,
                        'failed_at' => Carbon::parse($job->failed_at)->timezone(self::DisplayTimezone),
                        'error' => ErrorReportScrubber::scrubText(Str::limit(strtok((string) $job->exception, "\n") ?: '', 180)),
                    ])
                    ->all(),
            ];
        } catch (Throwable) {
            return ['count' => 0, 'latest' => []];
        }
    }

    /**
     * Letzte Einträge ab einer Stufe aus dem jüngsten Log einer Art (`laravel`, `monitoring`).
     *
     * @param  list<string>  $levels
     * @return list<array{at: Carbon, level: string, message: string}>
     */
    public function recentLogEntries(string $prefix, array $levels, int $limit = 10): array
    {
        $files = glob(storage_path("logs/{$prefix}*.log")) ?: [];
        usort($files, fn (string $a, string $b): int => filemtime($b) <=> filemtime($a));
        $file = $files[0] ?? null;

        if ($file === null) {
            return [];
        }

        $handle = @fopen($file, 'rb');

        if ($handle === false) {
            return [];
        }

        $size = (int) filesize($file);
        fseek($handle, max(0, $size - self::LogTailBytes));
        $tail = (string) stream_get_contents($handle);
        fclose($handle);

        $entries = [];

        foreach (preg_split('/\R/', $tail) ?: [] as $line) {
            if (preg_match(self::LogLinePattern, $line, $match) !== 1 || ! in_array(strtoupper($match[2]), $levels, true)) {
                continue;
            }

            $message = (string) preg_replace('/\s*\{"(exception|userId)".*$/s', '', $match[3]);

            $entries[] = [
                'at' => Carbon::parse($match[1])->timezone(self::DisplayTimezone),
                'level' => strtolower($match[2]),
                'message' => ErrorReportScrubber::scrubText(Str::limit($message, 220)),
            ];
        }

        return array_slice(array_reverse($entries), 0, $limit);
    }

    /**
     * Links zu den Diensten außerhalb der App, soweit konfiguriert.
     *
     * @return array<string, string>
     */
    public function links(): array
    {
        $links = [];
        $dsn = (string) config('sentry.dsn');

        if (preg_match('#^https?://[^@]+@([^/]+)/(\d+)#', $dsn, $match) === 1) {
            $links['GlitchTip'] = "https://{$match[1]}/";
        }

        if (filled(config('monitoring.status_url'))) {
            $links['Uptime Kuma'] = (string) config('monitoring.status_url');
        }

        return $links;
    }
}