using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL.Entities;
using Tango.Core.Commands;
using Tango.Core.DI;
using Tango.Core.ExtensionMethods;
using Tango.Integration.ExternalBridge;
using Tango.PMR.Integration;
using Tango.PPC.Common;
using Tango.PPC.Common.ExternalBridge;
using Tango.PPC.Common.Navigation;
using Tango.PPC.UI.Dialogs;

namespace Tango.PPC.UI.ViewModels
{
    /// <summary>
    /// Represents the external bridge view ViewModel.
    /// </summary>
    /// <seealso cref="Tango.PPC.Common.PPCViewModel" />
    [TangoCreateWhenRegistered]
    public class ExternalBridgeViewVM : PPCViewModel
    {
        private bool _disconnecting;

        private const int KEEP_SAFETY_AUTHENTICATION_MINUTES = 5;

        #region Properties

        private ExternalBridgeClientConnectedEventArgs _connection;
        /// <summary>
        /// Gets or sets the last client connection event arguments.
        /// </summary>
        public ExternalBridgeClientConnectedEventArgs Connection
        {
            get { return _connection; }
            set { _connection = value; RaisePropertyChangedAuto(); }
        }

        private User _user;
        /// <summary>
        /// Gets or sets the user connected user.
        /// </summary>
        public User User
        {
            get { return _user; }
            set { _user = value; RaisePropertyChangedAuto(); }
        }

        #endregion

        #region Commands

        /// <summary>
        /// Gets or sets the close session command.
        /// </summary>
        public RelayCommand CloseSessionCommand { get; set; }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="ExternalBridgeViewVM"/> class.
        /// </summary>
        public ExternalBridgeViewVM()
        {
            CloseSessionCommand = new RelayCommand(CloseSession, () => !_disconnecting);
        }

        #endregion

        #region Private Methods

        /// <summary>
        /// Closes the current session.
        /// </summary>
        private void CloseSession()
        {
            LogManager.Log("Disconnecting current external bridge session.");
            _disconnecting = true;
            InvalidateRelayCommands();
            ExternalBridgeService.DisconnectFullControlSession();
        }

        #endregion

        #region Override Methods

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

            _disconnecting = false;
            InvalidateRelayCommands();
        }

        /// <summary>
        /// Called when the application has been started.
        /// </summary>
        public override void OnApplicationStarted()
        {
            ExternalBridgeService.ConnectionRequest += ExternalBridgeService_ConnectionRequest;
            ExternalBridgeService.FullControlSessionDisconnected += ExternalBridgeService_FullControlSessionDisconnected;
        }

        #endregion

        #region Event Handlers

        /// <summary>
        /// Handles the <see cref="ExternalBridgeService.FullControlSessionDisconnected"/> event.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
        private void ExternalBridgeService_FullControlSessionDisconnected(object sender, EventArgs e)
        {
            if (IsVisible)
            {
                LogManager.Log("External bridge client disconnected. Navigating to home module...");

                InvokeUI(() =>
                {
                    NavigationManager.NavigateTo(NavigationView.HomeModule);
                });
            }
        }

        /// <summary>
        /// Handles the <see cref="ExternalBridgeService.ConnectionRequest"/> event.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="ExternalBridgeClientConnectedEventArgs"/> instance containing the event data.</param>
        private async void ExternalBridgeService_ConnectionRequest(object sender, ExternalBridgeClientConnectedEventArgs e)
        {
            LogManager.Log($"External bridge connection request received.\n{e.ToJsonString()}");

            if (!e.Request.Intent.RequiresPassword() || e.Request.Password == Settings.ExternalBridgePassword)
            {
                e.ApplicationInformation.Version = ApplicationManager.VersionAndTag;
                e.ApplicationInformation.StartupDate = ApplicationManager.StartUpDate.ToUniversalTime().ToString();

                Connection = e;

                User = Adapter.Users.SingleOrDefault(x => x.Guid == e.Request.UserGuid);

                if (User != null)
                {
                    LogManager.Log($"External bridge connection user has been identified as {User.Contact.FullName}");
                }

                if (e.Request.RequireSafetyLevelOperations)
                {
                    DateTime lastAuthenticationTime;
                    bool bypassSafetyConfirmation = false;

                    if (ExternalBridgeReceiver.LastSafetyLevelContactsTimes.TryGetValue(e.Request.UserName, out lastAuthenticationTime))
                    {
                        if (DateTime.Now < lastAuthenticationTime.AddMinutes(KEEP_SAFETY_AUTHENTICATION_MINUTES))
                        {
                            bypassSafetyConfirmation = true;
                            e.Confirm();
                        }
                    }

                    if (!bypassSafetyConfirmation)
                    {
                        SafetyLevelOperationsConfirmationViewVM vm = new SafetyLevelOperationsConfirmationViewVM(e);
                        await NotificationProvider.ShowDialog(vm);

                        if (vm.DialogResult)
                        {
                            e.Confirm();
                        }
                        else
                        {
                            e.Decline("Safety level connection refused by the remote user.");
                            return;
                        }
                    }
                }
                else
                {
                    e.Confirm();
                }

                if (e.Request.Intent == ExternalBridgeLoginIntent.FullControl)
                {
                    LogManager.Log("Navigating to external bridge view...");
                    InvokeUI(() =>
                    {
                        NavigationManager.NavigateTo(NavigationView.ExternalBridgeView, false);
                    });
                }
            }
            else
            {
                e.Decline("Connection password did not match the machine external bridge password.");
                LogManager.Log("Connection password did not match the machine external bridge password.");
            }
        }

        #endregion
    }
}