utilities.ts

async function putUser(user:User) {
  await db.users.put(user);
}

async function putGroup(group:Group) {
  await db.groups.put(group);
}

async function putUserInGroup(user:User, group:Group) {
  await db.usersInGroups.put({userId: user.id, groupId: group.id});
}

async function removeUserFromGroup(user, group) {
  await db.table("usersInGroups").delete([user.id, group.id]);
}

async function getUserGroups(user) {
  const groupLinks = await db.usersInGroups.where({userId: user.id}).toArray();
  const groups = await Promise.all(groupLinks.map(link => db.table("groups").get(link.groupId)));
  return groups;
}
async function getGroupUsers(group) {
  const groupLinks = await db.usersInGroups.where({groupId: group.id}).toArray();
  const users = await Promise.all(groupLinks.map(link => db.table("users").get(link.userId)));
  return users;
}

function putUserInGroupC(user, group) {
  return db.transaction('rw', db.users, db.groups, db.usersInGroups, async () => {
    const [validUser, validGroup] = await Promise.all([
      db.users.where({id: user.id}).count(),
      db.groups.where({id: group.id}).count()
    ]);
    if (!validUser) throw new Error('Invalid user');
    if (!validGroup) throw new Error('Invalid group');
    await db.usersInGroups.put({userId: user.id, groupId: group.id});
  });  
}

function getUserGroupsC(user) {
  return db.transaction('r', db.usersInGroups, db.groups, async ()=>{
    const groupLinks = await db.usersInGroups.where({userId: user.id}).toArray();
    const groups = await Promise.all(groupLinks.map(link => db.groups.get(link.groupId)));
    return groups;
  });
}