OAuthProvider.cs

using System;
using System.Linq;
using System.Web;
using DevExpress.Data.Filtering;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Security;
using DevExpress.ExpressApp.Utils;
using DevExpress.ExpressApp.Web;

using Microsoft.Owin.Security;
using MySolution.Module.BusinessObjects;
using MySolution.Module.Web.Security;

namespace MySolution.Web.Security {
    public class OAuthProvider : IAuthenticationProvider {
        private readonly Type userType;
        private readonly SecurityStrategyComplex security;
        public bool CreateUserAutomatically { get; set; }
        public OAuthProvider(Type userType, SecurityStrategyComplex security) {
            Guard.ArgumentNotNull(userType, "userType");
            this.userType = userType;
            this.security = security;
        }
        public object Authenticate(IObjectSpace objectSpace) {
            ApplicationUser user = null;
            string userEmail = GetUserEmail();
            if(!string.IsNullOrEmpty(userEmail)) {
                user = (ApplicationUser)objectSpace.FindObject(userType, CriteriaOperator.Parse("OAuthAuthenticationEmails[Email = ?]", userEmail));
                if(user == null && CreateUserAutomatically) {
                    user = (ApplicationUser)objectSpace.CreateObject(userType);
                    user.UserName = userEmail;
                    EmailEntity email = objectSpace.CreateObject<EmailEntity>();
                    email.Email = userEmail;
                    user.OAuthAuthenticationEmails.Add(email);
                    ((CustomSecurityStrategyComplex)security).InitializeNewUser(objectSpace, user);
                    objectSpace.CommitChanges();
                }
            }
            else {
                WebApplication.Redirect(WebApplication.LogonPage);
            }
            if(user == null) {
                throw new Exception("Login failed");
            }
            return user;
        }
        private string GetUserEmail() {
            var authentication = HttpContext.Current.GetOwinContext().Authentication;
            var externalLoginInfo = authentication.GetExternalLoginInfo();
            if(externalLoginInfo != null) {
                return externalLoginInfo.Email;
            }
            var email = authentication.User.Claims.Where(c => c.Type == Microsoft.Identity.Web.ClaimConstants.PreferredUserName).Select(c => c.Value).FirstOrDefault();
            return email;
        }
        public void Setup(params object[] args) {
        }
    }
}