extensions/brainly/background.js

chrome.runtime.onInstalled.addListener(() => {
  chrome.storage.sync.set({ blockedSites: [] });
  updateDeclarativeNetRequestRules();
});

chrome.storage.onChanged.addListener((changes, namespace) => {
  if (namespace === 'sync' && changes.blockedSites) {
    updateDeclarativeNetRequestRules();
  }
});

async function updateDeclarativeNetRequestRules() {
  const { blockedSites } = await chrome.storage.sync.get('blockedSites');
  const rules = blockedSites.map((site, index) => ({
    id: index + 1,
    priority: 1,
    action: { type: 'block' },
    condition: {
      urlFilter: `||${site}^`,
      resourceTypes: ['script']
    }
  }));

  await chrome.declarativeNetRequest.updateDynamicRules({
    removeRuleIds: rules.map(rule => rule.id),
    addRules: rules
  });
}