import { NextResponse } from 'next/server';
import { mkdir, writeFile } from 'node:fs/promises';
import { extname, join } from 'node:path';
import { randomUUID } from 'node:crypto';
import { UPLOADS_DIR } from '@/lib/db/store';

export const runtime = 'nodejs';

const ALLOWED = new Set(['.png', '.jpg', '.jpeg', '.webp', '.gif', '.svg', '.avif']);
const MAX_BYTES = 8 * 1024 * 1024; // 8 MB

export async function POST(req: Request) {
  let form: FormData;
  try {
    form = await req.formData();
  } catch {
    return NextResponse.json({ error: 'expected multipart form' }, { status: 400 });
  }

  const file = form.get('file');
  if (!(file instanceof File)) {
    return NextResponse.json({ error: 'no file' }, { status: 400 });
  }
  if (file.size > MAX_BYTES) {
    return NextResponse.json({ error: 'file too large (max 8MB)' }, { status: 413 });
  }

  const ext = extname(file.name).toLowerCase();
  if (!ALLOWED.has(ext)) {
    return NextResponse.json({ error: `unsupported type ${ext}` }, { status: 415 });
  }

  const name = `${Date.now()}-${randomUUID().slice(0, 8)}${ext}`;
  const buffer = Buffer.from(await file.arrayBuffer());

  try {
    await mkdir(UPLOADS_DIR, { recursive: true });
    await writeFile(join(UPLOADS_DIR, name), buffer);
  } catch {
    return NextResponse.json({ error: 'write failed' }, { status: 500 });
  }

  return NextResponse.json({ url: `/api/uploads/${name}`, name });
}