using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.BL.Builders;
using Tango.BL.Entities;
using Tango.Core;
using Tango.Core.DI;
using Tango.PPC.Common.Authentication;
using Tango.PPC.Common.Navigation;

namespace Tango.PPC.UI.Authentication
{
    /// <summary>
    /// Represents the default PPC authentication provider.
    /// </summary>
    /// <seealso cref="Tango.Core.ExtendedObject" />
    /// <seealso cref="Tango.PPC.Common.Authentication.IAuthenticationProvider" />
    public class DefaultAuthenticationProvider : ExtendedObject, IAuthenticationProvider
    {
        /// <summary>
        /// Gets or sets the navigation manager.
        /// </summary>
        [TangoInject(TangoInjectMode.WhenAvailable)]
        public INavigationManager NavigationManager { get; set; }

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

        private User _currentUser;
        /// <summary>
        /// Gets the current logged-in user.
        /// </summary>
        public User CurrentUser
        {
            get { return _currentUser; }
            private set
            {
                _currentUser = value;
                RaisePropertyChangedAuto();
            }
        }

        /// <summary>
        /// Gets a value indicating whether the authentication provider is using a null user.
        /// </summary>
        public bool AuthenticationRequired { get; private set; }

        /// <summary>
        /// Performs a user login by the specified email and password.
        /// </summary>
        /// <param name="email">The email.</param>
        /// <param name="password">The password.</param>
        /// <param name="encrypt">Determines whether to encrypt the provided password before attempting to login</param>
        /// <returns></returns>
        public Task<User> Login(string email, string password, bool encrypt = true)
        {
            return Task.Factory.StartNew<User>(() =>
            {

                AuthenticationRequired = true;

                String hash = encrypt ? User.GetPasswordHash(password) : password;

                LogManager.Log($"Logging in user {email}...");

                using (var db = ObservablesContext.CreateDefault())
                {
                    CurrentUser = new UserBuilder(db).Set(x => x.Email.ToLower() == email && x.Password == hash)
                    .WithOrganization()
                    .WithRolesAndPermissions()
                    .Build();
                }

                if (CurrentUser != null)
                {
                    LogManager.Log($"Current user is now: {CurrentUser.Contact.FullName}.");
                }
                else
                {
                    LogManager.Log("Login failed!");
                }

                CurrentUserChanged?.Invoke(this, CurrentUser);
                return CurrentUser;
            });
        }

        public Task Login()
        {
            return Task.Factory.StartNew(() => 
            {
                AuthenticationRequired = false;
                CurrentUser = null;
                CurrentUserChanged?.Invoke(this, CurrentUser);
            });
        }

        /// <summary>
        /// Logs-out the current logged-in user.
        /// </summary>
        public void LogOut()
        {
            LogManager.Log("Logging out current user.");
            CurrentUser = null;
            CurrentUserChanged?.Invoke(this, CurrentUser);
            NavigationManager.NavigateTo(NavigationView.LoginView);
        }
    }
}