using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Core.Commands;
using Tango.Core.Cryptography;
using Tango.MachineStudio.Common;
using Tango.MachineStudio.Common.Authentication;
using Tango.MachineStudio.Common.EventLogging;
using Tango.MachineStudio.Common.Navigation;
using Tango.MachineStudio.Common.Notifications;
using Tango.Settings;
using Tango.SharedUI;

namespace Tango.MachineStudio.UI.ViewModels
{
    /// <summary>
    /// Represents the Machine Studio login view, view model.
    /// </summary>
    /// <seealso cref="Tango.SharedUI.ViewModel" />
    public class LoginViewVM : ViewModel
    {
        private IAuthenticationProvider _authenticationProvider;
        private INavigationManager _navigationManager;
        private INotificationProvider _notificationProvider;
        private IEventLogger _eventLogger;
        private Rfc2898Cryptographer cryptographer;
        private MachineStudioSettings _settings;

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

        private String _password;
        [Required(ErrorMessage = "Password is required")]
        public String Password
        {
            get { return _password; }
            set { _password = value; RaisePropertyChangedAuto(); }
        }

        private bool _isLogging;
        /// <summary>
        /// Gets or sets a value indicating whether this instance is logging.
        /// </summary>
        public bool IsLogging
        {
            get { return _isLogging; }
            set { _isLogging = value; RaisePropertyChangedAuto(); }
        }

        private bool _rememberMe;
        /// <summary>
        /// Gets or sets a value indicating whether to remember the last user email and password.
        /// </summary>
        public bool RememberMe
        {
            get { return _rememberMe; }
            set { _rememberMe = value; RaisePropertyChangedAuto(); }
        }

        /// <summary>
        /// Gets or sets the login command.
        /// </summary>
        public RelayCommand LoginCommand { get; set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="LoginViewVM"/> class.
        /// </summary>
        /// <param name="authenticationProvider">The authentication provider.</param>
        /// <param name="navigationManager">The navigation manager.</param>
        /// <param name="notificationProvider">The notification provider.</param>
        public LoginViewVM(IAuthenticationProvider authenticationProvider, INavigationManager navigationManager, INotificationProvider notificationProvider, IEventLogger eventLogger)
        {
            _settings = SettingsManager.Default.GetOrCreate<MachineStudioSettings>();

            _notificationProvider = notificationProvider;
            _navigationManager = navigationManager;
            _authenticationProvider = authenticationProvider;
            _eventLogger = eventLogger;
            LoginCommand = new RelayCommand(Login,() => !IsLogging);

            cryptographer = new Rfc2898Cryptographer();
            Email = _settings.LastLoginEmail;
            RememberMe = _settings.RememberMe;

            try
            {
                Password = cryptographer.Decrypt(_settings.LastLoginPassword);
            }
            catch (Exception ex)
            {
                LogManager.Log(ex);
            }
        }

        /// <summary>
        /// Logins the requested user.
        /// </summary>
        private async void Login()
        {
            if (Validate())
            {
                try
                {
                    IsLogging = true;
                    InvalidateRelayCommands();

                    await Task.Factory.StartNew(() =>
                    {
                        _authenticationProvider.Login(Email, Password);
                        _navigationManager.NavigateTo(NavigationView.MainView);
                        _settings.LastLoginEmail = Email;
                        _settings.RememberMe = RememberMe;

                        _settings.LastLoginPassword = RememberMe ? cryptographer.Encrypt(Password) : null;
                        _settings.Save();

                        _eventLogger.Log("User logged in");
                    });
                }
                catch (Exception)
                {

                    _notificationProvider.ShowError("Invalid credentials. Please try again.");
                }
                finally
                {
                    IsLogging = false;
                    InvalidateRelayCommands();
                }
            }
        }
    }
}