import type { VercelRequest, VercelResponse } from '@vercel/node';

const FILE_URLS: Record<string, string> = {
  deals: "https://www.dropbox.com/scl/fi/3mm5m4e04myhqt59piefs/Deals-Amazon-2025.xlsx?rlkey=6llr0xhs6di0c3d8o96ashzmv&st=ggu0z7hu&dl=1",
  promos: "https://www.dropbox.com/scl/fi/ufhej9do9w839oyyfrpk3/Promos_Amazon_2025_all-countries.xlsx?rlkey=4foano9dt5h3sl58l35vqg89d&st=wu0t56wh&dl=1",
  chargebacks: "https://www.dropbox.com/scl/fi/m2qr2cxhtgkc48acjrrgx/Amazon-Operational-Chargebacks-2025.xlsx?rlkey=vlrz4qfydsjtikgh0ylivocjq&st=zdhmjvaz&dl=1",
};

export default async function handler(req: VercelRequest, res: VercelResponse) {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (req.method === 'OPTIONS') {
    return res.status(200).end();
  }

  const file = req.query.file as string;
  const url = FILE_URLS[file];

  if (!url) {
    return res.status(400).json({ error: `Unknown file: "${file}". Valid options: deals, promos, chargebacks` });
  }

  try {
    console.log(`[fetch-mkt-data] Fetching ${file} from Dropbox...`);
    const response = await fetch(url, {
      cache: 'no-store',
      headers: { 'Pragma': 'no-cache', 'Cache-Control': 'no-cache' }
    });

    if (!response.ok) {
      throw new Error(`Dropbox responded with ${response.status}`);
    }

    const buffer = await response.arrayBuffer();
    console.log(`[fetch-mkt-data] Successfully fetched ${file}, size:`, buffer.byteLength);

    res.setHeader('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
    res.status(200).send(Buffer.from(buffer));
  } catch (error: any) {
    console.error(`[fetch-mkt-data] Error fetching ${file}:`, error);
    res.status(500).json({ error: error.message });
  }
}