db.js

// db.js
const DB_NAME = 'uvcs';
const DB_VERSION = 3;

export function openDb() {
  return new Promise((resolve, reject) => {
    const req = indexedDB.open(DB_NAME, DB_VERSION);
    req.onupgradeneeded = () => {
      const db = req.result;

      if (!db.objectStoreNames.contains('visits')) {
        const v = db.createObjectStore('visits', { keyPath: 'id' });
        v.createIndex('by_ts', 'tsStart');
        v.createIndex('by_tab', 'tabId');
      }
      if (!db.objectStoreNames.contains('edges')) {
        const e = db.createObjectStore('edges', { keyPath: 'id' });
        e.createIndex('by_from', 'fromVisitId');
        e.createIndex('by_to', 'toVisitId');
      }
      // textual snapshots (HTML stored as text)
      if (!db.objectStoreNames.contains('snapshots_html')) {
        const s = db.createObjectStore('snapshots_html', { keyPath: 'id' });
        s.createIndex('by_visit', 'visitId');
      }
      // visual snapshots (JPEG stored as dataURL string)
      if (!db.objectStoreNames.contains('snapshots_img')) {
        const s2 = db.createObjectStore('snapshots_img', { keyPath: 'id' });
        s2.createIndex('by_visit', 'visitId');
      }
      if (!db.objectStoreNames.contains('settings')) {
        db.createObjectStore('settings', { keyPath: 'key' });
      }
    };
    req.onsuccess = () => resolve(req.result);
    req.onerror = () => reject(req.error);
  });
}

// Generic helpers
export async function txGet(store, key) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction(store, 'readonly');
    const r = t.objectStore(store).get(key);
    r.onsuccess = () => resolve(r.result || null);
    r.onerror = () => reject(r.error);
  });
}
export async function txGetAll(store) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction(store, 'readonly');
    const r = t.objectStore(store).getAll();
    r.onsuccess = () => resolve(r.result || []);
    r.onerror = () => reject(r.error);
  });
}
export async function txPut(store, value) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction(store, 'readwrite');
    t.objectStore(store).put(value);
    t.oncomplete = () => resolve();
    t.onerror = () => reject(t.error);
  });
}
export async function txDel(store, key) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction(store, 'readwrite');
    t.objectStore(store).delete(key);
    t.oncomplete = () => resolve();
    t.onerror = () => reject(t.error);
  });
}
export async function txClear(store) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction(store, 'readwrite');
    t.objectStore(store).clear();
    t.oncomplete = () => resolve();
    t.onerror = () => reject(t.error);
  });
}

// Query helpers for snapshots (by visitId)
export async function getHtmlSnapByVisit(visitId) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction('snapshots_html', 'readonly');
    const idx = t.objectStore('snapshots_html').index('by_visit');
    const r = idx.get(visitId);
    r.onsuccess = () => resolve(r.result || null);
    r.onerror = () => reject(r.error);
  });
}
export async function getImgSnapByVisit(visitId) {
  const db = await openDb();
  return new Promise((resolve, reject) => {
    const t = db.transaction('snapshots_img', 'readonly');
    const idx = t.objectStore('snapshots_img').index('by_visit');
    const r = idx.get(visitId);
    r.onsuccess = () => resolve(r.result || null);
    r.onerror = () => reject(r.error);
  });
}