Hi, I'm Pankaj Sangwan

<?php
declare(strict_types=1);

namespace App\Domain\Orders\Services;

use App\Domain\Orders\Repositories\OrderRepositoryInterface;
use App\Domain\Payments\Contracts\PaymentGatewayInterface;
use App\Domain\Orders\DTO\CreateOrderPayload;

/**
 * High-Throughput Order Processing Service (PHP 8.2 Strict Types & DI)
 * Architected by Pankaj Sangwan • Senior Software Engineer
 */
final readonly class OrderProcessingService
{
    public function __construct(
        private OrderRepositoryInterface $orderRepo,
        private PaymentGatewayInterface $payments,
        private \Redis $cache
    ) {}

    public function execute(CreateOrderPayload $payload): OrderResult
    {
        $idempotencyKey = "order:lock:{$payload->customerId}:{$payload->cartHash}";
        
        // Atomic Redis lock to prevent double charges
        if (!$this->cache->set($idempotencyKey, 'locked', ['NX', 'EX' => 30])) {
            throw new DuplicateOrderException('Order is already processing.');
        }

        $charge = $this->payments->capture($payload->paymentToken, $payload->amountCents);
        $order = $this->orderRepo->create($payload, $charge->transactionId);

        return new OrderResult($order->id, $charge->status, $order->total);
    }
}

// hooks/useRealtimeAnalytics.ts - Modern TypeScript React Custom Hook
import { useState, useEffect, useCallback } from 'react';

export interface MetricTelemetry {
  activeUsers: number;
  conversionRate: number;
  latencyMs: number;
}

export function useRealtimeAnalytics(channelId: string) {
  const [metrics, setMetrics] = useState<MetricTelemetry>({ activeUsers: 0, conversionRate: 0, latencyMs: 0 });
  const [isConnected, setIsConnected] = useState<boolean>(false);

  const handlePacket = useCallback((data: MetricTelemetry) => {
    // Optimistic update with moving average dampener
    setMetrics(prev => ({ ...prev, ...data, latencyMs: (prev.latencyMs + data.latencyMs) / 2 }));
  }, []);

  useEffect(() => {
    const ws = new WebSocket(`wss://api.pankajsangwan.com/telemetry/${channelId}`);
    ws.onopen = () => setIsConnected(true);
    ws.onmessage = (event) => handlePacket(JSON.parse(event.data));
    ws.onclose = () => setIsConnected(false);

    return () => ws.close();
  }, [channelId, handlePacket]);

  return { metrics, isConnected };
}

// webhookConsumer.js - Idempotent Stripe Webhook Pipeline with Redis
const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);
const Redis = require('ioredis');
const redis = new Redis(process.env.REDIS_URL);

async function stripeWebhookHandler(req, res) {
  const sig = req.headers['stripe-signature'];
  let event;

  try {
    event = stripe.webhooks.constructEvent(req.rawBody, sig, process.env.STRIPE_ENDPOINT_SECRET);
  } catch (err) {
    return res.status(400).send(`Signature Error: ${err.message}`);
  }

  // Idempotency check: Ignore duplicate delivery within 48 hours
  const seen = await redis.set(`webhook:event:${event.id}`, 'PROCESSED', 'NX', 'EX', 172800);
  if (!seen) {
    return res.status(200).json({ received: true, note: 'Duplicate skipped safely' });
  }

  // Acknowledge HTTP 200 within 20ms and delegate event to async worker queue
  setImmediate(() => dispatchToWorkerQueue(event));
  res.status(200).json({ received: true });
}