private async Task SignIn(string userId, IEnumerable <Claim> claims, bool isPersistent)
{
User user = await Users.Find(userId) as User;
if (user != null)
{
// Replace UserIdentity claims with the application specific claims
IList <Claim> userClaims = IdentityConfig.RemoveUserIdentityClaims(claims);
IdentityConfig.AddUserIdentityClaims(userId, user.UserName, userClaims);
IdentityConfig.AddRoleClaims(await Roles.GetRolesForUser(userId), userClaims);
IdentityConfig.SignIn(HttpContext, userClaims, isPersistent);
}
}