import { NextRequest, NextResponse } from 'next/server';
import { createReadStream } from 'node:fs';
import { access, stat } from 'node:fs/promises';
import path from 'node:path';

export const runtime = 'nodejs';

export async function GET(_req: NextRequest, ctx: { params: Promise<{ file: string }> }) {
  try {
    const params = await ctx.params;
    const filename = params?.file;
    if (!filename || !/^[\w.-]+\.onnx$/.test(filename)) {
      return new NextResponse('Not found', { status: 404 });
    }
    const filePath = path.join(process.cwd(), 'models', filename);
    await access(filePath);
    const info = await stat(filePath);
    const stream = createReadStream(filePath);
    return new NextResponse(stream as any, {
      status: 200,
      headers: {
        'Content-Type': 'application/octet-stream',
        'Content-Length': String(info.size),
        'Cache-Control': 'public, max-age=31536000, immutable',
      },
    });
  } catch {
    return new NextResponse('Not found', { status: 404 });
  }
}