<?php

declare(strict_types=1);

namespace App\Services;

use App\Core\Redis;
use App\Core\Database;

final class QueueService
{
    private const REDIS_QUEUE = 'musadaq_jobs';

    public static function push(string $type, array $payload, int $priority = 0, int $delay = 0): void
    {
        $job = [
            'id' => bin2hex(random_bytes(16)),
            'type' => $type,
            'payload' => $payload,
            'priority' => $priority,
            'attempts' => 0,
            'created_at' => time()
        ];

        try {
            $redis = Redis::getInstance();
            $redis->lpush(self::REDIS_QUEUE, json_encode($job));
        } catch (\Throwable $e) {
            // Fallback to MySQL
            self::pushToDatabase($job);
        }
    }

    private static function pushToDatabase(array $job): void
    {
        $db = Database::getInstance();
        $stmt = $db->prepare("INSERT INTO queue_jobs (id, type, payload, priority, status) VALUES (?, ?, ?, ?, 'pending')");
        $stmt->execute([
            $job['id'],
            $job['type'],
            json_encode($job['payload']),
            $job['priority']
        ]);
    }

    public static function pop(): ?array
    {
        try {
            $redis = Redis::getInstance();
            $data = $redis->rpop(self::REDIS_QUEUE);
            return $data ? json_decode($data, true) : null;
        } catch (\Throwable $e) {
            // Fallback to MySQL
            return self::popFromDatabase();
        }
    }

    private static function popFromDatabase(): ?array
    {
        $db = Database::getInstance();
        $db->beginTransaction();
        try {
            $stmt = $db->prepare("SELECT * FROM queue_jobs WHERE status = 'pending' ORDER BY priority DESC, created_at ASC LIMIT 1 FOR UPDATE");
            $stmt->execute();
            $job = $stmt->fetch();

            if ($job) {
                $db->prepare("UPDATE queue_jobs SET status = 'processing', locked_at = NOW() WHERE id = ?")->execute([$job['id']]);
                $db->commit();
                return [
                    'id' => $job['id'],
                    'type' => $job['type'],
                    'payload' => json_decode($job['payload'], true),
                    'attempts' => $job['attempts']
                ];
            }
            $db->commit();
        } catch (\Throwable $e) {
            $db->rollBack();
        }
        return null;
    }
}