path: root/Software/Visual_Studio/FSE/Tango.FSE.UI/ViewModels/LoginViewVM.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.Core.Commands;
using Tango.Core.Cryptography;
using Tango.FSE.Common;
using Tango.FSE.Common.Navigation;
using Tango.FSE.Common.Notifications;
using Tango.MachineService.Gateway;

namespace Tango.FSE.UI.ViewModels
{
    public class LoginViewVM : FSEViewModel, INavigationObjectReceiver<LoginViewVM.NavigationObject>
    {
        #region Navigation

        /// <summary>
        /// Represents the <see cref="LoginViewVM"/> navigation object.
        /// </summary>
        public class NavigationObject
        {
            /// <summary>
            /// Gets or sets a value indicating whether the navigation is due to user logging out from the application.
            /// </summary>
            public bool IsLoggingOut { get; set; }
        }

        #endregion

        public enum LoginViews
        {
            Login,
            Logging
        }

        private Rfc2898Cryptographer _cryptography;

        #region Properties

        private LoginViews _selectedView;
        /// <summary>
        /// Gets or sets the selected navigation view.
        /// </summary>
        public LoginViews SelectedView
        {
            get { return _selectedView; }
            set { _selectedView = value; RaisePropertyChangedAuto(); }
        }

        private String _email;
        /// <summary>
        /// Gets or sets the user email.
        /// </summary>
        [EmailAddress(ErrorMessage = "Please enter a valid email address")]
        public String Email
        {
            get { return _email; }
            set { _email = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        private String _password;
        /// <summary>
        /// Gets or sets the user password.
        /// </summary>
        [Required(ErrorMessage = "Password is required")]
        public String Password
        {
            get { return _password; }
            set { _password = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        private bool _rememberMe;
        /// <summary>
        /// Gets or sets a value indicating whether to remember the user credentials on next restart.
        /// </summary>
        public bool RememberMe
        {
            get { return _rememberMe; }
            set { _rememberMe = value; RaisePropertyChangedAuto(); }
        }

        private EnvironmentConfiguration _selectedEnvironment;
        /// <summary>
        /// Gets or sets the selected environment.
        /// </summary>
        public EnvironmentConfiguration SelectedEnvironment
        {
            get { return _selectedEnvironment; }
            set { _selectedEnvironment = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        private String _status;
        /// <summary>
        /// Gets or sets the current status message.
        /// </summary>
        public String Status
        {
            get { return _status; }
            set { _status = value; RaisePropertyChangedAuto(); }
        }

        #endregion

        #region Commands

        public RelayCommand LoginCommand { get; set; }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="LoginViewVM"/> class.
        /// </summary>
        public LoginViewVM()
        {
            _cryptography = new Rfc2898Cryptographer();
            LoginCommand = new RelayCommand(Login, () => Email.IsNotNullOrEmpty() && Password.IsNotNullOrEmpty() && SelectedEnvironment != null);
        }

        #endregion

        #region Override Methods

        /// <summary>
        /// Called when the application has been started.
        /// </summary>
        public override void OnApplicationStarted()
        {

        }

        /// <summary>
        /// Called before the navigation system has navigated to this VM view.
        /// </summary>
        public override void OnBeforeNavigatedTo()
        {
            base.OnBeforeNavigatedTo();
            SelectedView = LoginViews.Login;
        }

        /// <summary>
        /// Called when the navigation system has navigated to this VM view.
        /// </summary>
        public override void OnNavigatedTo()
        {
            base.OnNavigatedTo();

            SelectedEnvironment = Services.GatewayService.Environments.FirstOrDefault(x => x.MachineServiceAddress == Settings.MachineServiceAddress);

            if (SelectedEnvironment == null)
            {
                SelectedEnvironment = Services.GatewayService.Environments.FirstOrDefault();
            }

            Email = Settings.LastLoginEmail;

            if (Settings.LastLoginPassword.IsNotNullOrEmpty())
            {
                Password = _cryptography.Decrypt(Settings.LastLoginPassword);
            }

            RememberMe = Settings.RememberMe;

            if (!Email.IsNotNullOrEmpty())
            {
                this.SetFocus(() => Email);
            }
            else if (!Password.IsNotNullOrEmpty())
            {
                this.SetFocus(() => Password);
            }
        }

        /// <summary>
        /// Called when navigation system is going to navigate to this instance with the specified object.
        /// </summary>
        /// <param name="obj">The object.</param>
        public void OnNavigatedToWithObject(NavigationObject obj)
        {
            if (obj.IsLoggingOut)
            {
                Password = null;
                RememberMe = false;
                SaveCredentials();
            }
        }

        #endregion

        #region Private Methods

        private async void Login()
        {
            try
            {
                LogManager.Log($"Logging in user '{Email}'...");

                if (!Validate())
                {
                    return;
                }

                IsFree = false;
                SelectedView = LoginViews.Logging;
                var result = await AuthenticationProvider.Login(Email, Password, SelectedEnvironment, (status) => Status = status);

                SaveCredentials();

                Status = "Starting application...";

                if (Settings.WindowMaximizedOnStartup && ApplicationManager.WindowState != System.Windows.WindowState.Maximized)
                {
                    LogManager.Log("Application is configured to maximize the main window post login. Maximizing window...");
                    ApplicationManager.WindowState = System.Windows.WindowState.Maximized;
                }

                await Task.Delay(500);

                if (!result.Response.PasswordChangeRequired)
                {
                    await NavigationManager.NavigateTo(NavigationView.Home);
                }
                else
                {
                    //TODO: Handler password change required!
                    Debugger.Break();
                }
            }
            catch (Exception ex)
            {
                LogManager.Log(ex, $"Error occurred while trying to login user '{Email}'.");
                IsFree = true;
                SelectedView = LoginViews.Login;
                await NotificationProvider.ShowError(GetErrorMessage(ex));
            }
            finally
            {
                IsFree = true;
            }
        }

        private void SaveCredentials()
        {
            Settings.LastLoginEmail = Email;
            Settings.RememberMe = RememberMe;

            if (RememberMe)
            {
                Settings.LastLoginPassword = _cryptography.Encrypt(Password);
            }
            else
            {
                Settings.LastLoginPassword = null;
            }

            Settings.Save();
        }

        private String GetErrorMessage(Exception ex)
        {
            var fullError = ex.FlattenMessage();

            if (fullError.Contains("Invalid column"))
            {
                return "There is a mismatch of data schema between your version of Tango FSE and the remote service.\nPlease check the following:\n\u2022 The remote environment supports this application version.\n\u2022 Try to update your version to the latest.";
            }
            else
            {
                return fullError;
            }
        }

        #endregion
    }
}