// Background Service Worker - 唯一出网口（绕 CORS 取图）
export default defineBackground(() => {
  console.log('Seller Helper background started');

  // 点击扩展图标 → 打开 Side Panel
  chrome.sidePanel.setPanelBehavior({ openPanelOnActionClick: true });

  // 代理图片 fetch（CORS 绕过）
  chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
    if (msg.action === 'fetchImage') {
      fetchImageAsBlob(msg.url)
        .then(blob => sendResponse({ ok: true, blob }))
        .catch(err => sendResponse({ ok: false, error: err.message }));
      return true;  // 保持异步通道
    }
  });
});

async function fetchImageAsBlob(url: string): Promise<Blob> {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`HTTP ${res.status}`);
  return res.blob();
}