using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Authentication;
using System.Text;
using System.Threading.Tasks;
using Tango.Core;
using Tango.BL.Entities;
using Tango.MachineStudio.Common.Authentication;
using Tango.BL;
using Tango.BL.Enumerations;
using System.Data.Entity;

namespace Tango.MachineStudio.UI.Authentication
{
    /// <summary>
    /// Represents the default Machine Studio <see cref="IAuthenticationProvider">Authentication provider</see>
    /// </summary>
    /// <seealso cref="Tango.Core.ExtendedObject" />
    /// <seealso cref="Tango.MachineStudio.Common.Authentication.IAuthenticationProvider" />
    public class DefaultAuthenticationProvider : ExtendedObject, IAuthenticationProvider
    {
        private User _currentUser;
        /// <summary>
        /// Gets the current logged-in user.
        /// </summary>
        public User CurrentUser
        {
            get { return _currentUser; }
            set
            {
                _currentUser = value;
                CurrentUserChanged?.Invoke(this, _currentUser);
                RaisePropertyChangedAuto();
            }
        }

        /// <summary>
        /// Occurs when the current logged-in user has changed.
        /// </summary>
        public event EventHandler<User> CurrentUserChanged;

        /// <summary>
        /// Performs a user login by the specified email and password.
        /// </summary>
        /// <param name="email">The email.</param>
        /// <param name="password">The password.</param>
        /// <returns></returns>
        /// <exception cref="AuthenticationException">Login failed for user " + email</exception>
        public User Login(string email, string password)
        {
            using (ObservablesContext db = ObservablesContext.CreateDefault())
            {

                String hash = User.GetPasswordHash(password);

                db.Roles.Load();
                db.Permissions.Load();
                db.RolesPermissions.Load();

                User user = db.Users
                    .Include(x => x.UsersRoles)
                    .Include(x => x.Contact)
                    .Include(x => x.Address)
                    .Include(x => x.Organization).SingleOrDefault(x => x.Email.ToLower() == email.ToLower() && x.Password == hash);

                if (user == null)
                {
                    throw new AuthenticationException("Invalid credentials for " + email);
                }

                if (!user.HasPermission(Permissions.RunMachineStudio))
                {
                    throw new AuthenticationException("It seems like you do not have sufficient privileges to run Machine Studio. Please contact your administrator.");
                }

                if (user != null)
                {
                    user.LastLogin = DateTime.UtcNow;
                    db.SaveChanges();
                }

                CurrentUser = user;
                return user;
            }
        }

        /// <summary>
        /// Logs-out the current logged-in user.
        /// </summary>
        public void Logout()
        {
            CurrentUser = null;
        }
    }
}