Advanced Route Handler Patterns

// app/api/stream/route.ts
export async function GET() {
  const encoder = new TextEncoder();

  const stream = new ReadableStream({
    async start(controller) {
      for (let i = 0; i < 10; i++) {
        await new Promise((r) => setTimeout(r, 1000));
        controller.enqueue(encoder.encode(`data: ${i}\n\n`));
      }
      controller.close();
    },
  });

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
    },
  });
}

// app/api/upload/route.ts
import { writeFile } from 'fs/promises';
import { join } from 'path';

export async function POST(request: Request) {
  const formData = await request.formData();
  const file = formData.get('file') as File;

  const bytes = await file.arrayBuffer();
  const buffer = Buffer.from(bytes);

  const path = join(process.cwd(), 'uploads', file.name);
  await writeFile(path, buffer);

  return Response.json({ success: true });
}

import { headers } from 'next/headers';

const rateLimit = new Map();

export async function GET() {
  const headersList = headers();
  const ip = headersList.get('x-forwarded-for') || 'anonymous';

  const now = Date.now();
  const windowMs = 60000; // 1 minute
  const maxRequests = 10;

  const requests = rateLimit.get(ip) || [];
  const recentRequests = requests.filter((t: number) => now - t < windowMs);

  if (recentRequests.length >= maxRequests) {
    return Response.json(
      { error: 'Too many requests' },
      { status: 429 }
    );
  }

  rateLimit.set(ip, [...recentRequests, now]);

  return Response.json({ data: 'success' });
}