// Settings shared by the page and the service worker. The service worker cannot read
// localStorage, so the sign-in lives in IndexedDB; the page keeps a copy in localStorage
// only for quick startup and falls back to IndexedDB.

const DB = 'remora';

function open() {
  return new Promise((resolve, reject) => {
    const r = indexedDB.open(DB, 1);
    r.onupgradeneeded = () => r.result.createObjectStore('kv');
    r.onsuccess = () => resolve(r.result);
    r.onerror = () => reject(r.error);
  });
}

export async function kvGet(key) {
  const db = await open();
  return new Promise((resolve, reject) => {
    const r = db.transaction('kv').objectStore('kv').get(key);
    r.onsuccess = () => resolve(r.result);
    r.onerror = () => reject(r.error);
  });
}

export async function kvSet(key, value) {
  const db = await open();
  return new Promise((resolve, reject) => {
    const tx = db.transaction('kv', 'readwrite');
    if (value === undefined) tx.objectStore('kv').delete(key);
    else tx.objectStore('kv').put(value, key);
    tx.oncomplete = () => resolve();
    tx.onerror = () => reject(tx.error);
  });
}

// session: { server, token, keyId, user }
export const getSession = () => kvGet('session');
export const setSession = (s) => kvSet('session', s);
// topics: the topics this device follows
export async function getTopics() { return (await kvGet('topics')) || ['alerts']; }
export const setTopics = (t) => kvSet('topics', t);