Next.js API Development

You are an expert in building APIs with Next.js App Router.

## API Route Structure
```typescript
// app/api/posts/route.ts
import { NextRequest, NextResponse } from 'next/server';
import { z } from 'zod';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth';

// Validation schema
const createPostSchema = z.object({
  title: z.string().min(1).max(200),
  content: z.string().min(1),
  published: z.boolean().default(false),
});

export async function POST(request: NextRequest) {
  try {
    // 1. Authentication
    const session = await getServerSession(authOptions);
    if (!session) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      );
    }

    // 2. Parse and validate body
    const body = await request.json();
    const validatedData = createPostSchema.parse(body);

    // 3. Business logic
    const post = await prisma.post.create({
      data: {
        ...validatedData,
        authorId: session.user.id,
      },
    });

    // 4. Return response
    return NextResponse.json({ post }, { status: 201 });
    
  } catch (error) {
    if (error instanceof z.ZodError) {
      return NextResponse.json(
        { error: 'Validation failed', details: error.errors },
        { status: 400 }
      );
    }
    
    console.error('POST /api/posts error:', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}
```

## Dynamic API Routes
```typescript
// app/api/posts/[id]/route.ts
import { NextRequest, NextResponse } from 'next/server';

interface RouteParams {
  params: { id: string };
}

export async function GET(request: NextRequest, { params }: RouteParams) {
  const { id } = params;
  
  const post = await prisma.post.findUnique({
    where: { id },
    include: { author: true },
  });
  
  if (!post) {
    return NextResponse.json(
      { error: 'Post not found' },
      { status: 404 }
    );
  }
  
  return NextResponse.json({ post });
}

export async function PATCH(request: NextRequest, { params }: RouteParams) {
  // Update logic
}

export async function DELETE(request: NextRequest, { params }: RouteParams) {
  // Delete logic
}
```

## Response Helpers
```typescript
// lib/api-response.ts
export function successResponse<T>(data: T, status = 200) {
  return NextResponse.json({ success: true, data }, { status });
}

export function errorResponse(message: string, status = 400) {
  return NextResponse.json({ success: false, error: message }, { status });
}

export function paginatedResponse<T>(
  data: T[],
  page: number,
  total: number,
  limit: number
) {
  return NextResponse.json({
    success: true,
    data,
    pagination: {
      page,
      limit,
      total,
      totalPages: Math.ceil(total / limit),
    },
  });
}
```