using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Data;
using Tango.BL.Entities;
using Tango.Core.Commands;
using Tango.Core.DI;
using Tango.Core.Threading;
using Tango.Emulations.ExternalBridge;
using Tango.FSE.BL;
using Tango.FSE.Common;
using Tango.FSE.Common.FSEApplication;
using Tango.Integration.ExternalBridge;
using Tango.Settings;
using Tango.SharedUI;

namespace Tango.FSE.UI.Panes
{
    /// <summary>
    /// Represents the machine connection pane view model.
    /// </summary>
    /// <seealso cref="Tango.FSE.Common.FSEViewModel" />
    public class MachineConnectionPaneVM : FSEViewModel
    {
        private const string WEB_DEBUG_ADDRESS = "http://localhost:1111";
        private ExternalBridgeScanner _scanner;
        private EmulatorExternalBridge _emulator;
        private List<Machine> _allowedMachines;
        private ICollectionView _tcpMachinesView;
        private ICollectionView _signalRMachinesView;

        private String _filter;
        public String Filter
        {
            get { return _filter; }
            set
            {
                _filter = value; RaisePropertyChangedAuto();
                _tcpMachinesView?.Refresh();
                _signalRMachinesView?.Refresh();
                OnFilterChanged();
            }
        }

        /// <summary>
        /// Occurs when a machine has been selected for connection.
        /// </summary>
        public event EventHandler<IExternalBridgeClient> MachineSelected;

        /// <summary>
        /// Gets or sets the available machines via USB.
        /// </summary>
        public ObservableCollection<ExternalBridgeUsbClient> UsbMachines { get; set; }

        /// <summary>
        /// Gets or sets the available machines via local WiFi network.
        /// </summary>
        public ObservableCollection<ExternalBridgeTcpClient> TcpMachines { get; set; }

        /// <summary>
        /// Gets or sets the available machine via Internet connection (SignalR).
        /// </summary>
        public ObservableCollection<ExternalBridgeSignalRClient> SignalRMachines { get; set; }

        /// <summary>
        /// Gets or sets the available emulated machines.
        /// </summary>
        public ObservableCollection<EmulatorExternalBridge> EmulatorMachines { get; set; }

        /// <summary>
        /// Gets or sets the connect to machine command.
        /// </summary>
        public RelayCommand ConnectToMachineCommand { get; set; }

        private IExternalBridgeClient _selectedMachine;
        /// <summary>
        /// Gets or sets the selected machine.
        /// </summary>
        public IExternalBridgeClient SelectedMachine
        {
            get { return _selectedMachine; }
            set { _selectedMachine = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="MachineConnectionPaneVM"/> class.
        /// </summary>
        public MachineConnectionPaneVM()
        {
            TangoIOC.Default.Inject(this);

            ConnectToMachineCommand = new RelayCommand(ConnectToMachine, () => SelectedMachine != null);

            UsbMachines = new ObservableCollection<ExternalBridgeUsbClient>();
            TcpMachines = new ObservableCollection<ExternalBridgeTcpClient>();
            SignalRMachines = new ObservableCollection<ExternalBridgeSignalRClient>();
            EmulatorMachines = new ObservableCollection<EmulatorExternalBridge>();

            _tcpMachinesView = CollectionViewSource.GetDefaultView(TcpMachines);
            _signalRMachinesView = CollectionViewSource.GetDefaultView(SignalRMachines);

            _tcpMachinesView.Filter = OnFilterMachines;
            _signalRMachinesView.Filter = OnFilterMachines;

            _scanner = new ExternalBridgeScanner();
            _scanner.MachineDiscovered += _scanner_MachineDiscovered;
            _scanner.MachineLost += _scanner_MachineLost;

            ApplicationManager.ApplicationReady += ApplicationManager_ApplicationReady;
        }

        private void ApplicationManager_ApplicationReady(object sender, EventArgs e)
        {
            _allowedMachines = null;
        }

        /// <summary>
        /// Connects to the selected machine.
        /// </summary>
        internal void ConnectToMachine()
        {
            if (SelectedMachine != null)
            {
                Settings.LastSelectedMachine = SelectedMachine.GetUniqueString();
                Settings.Save();

                MachineSelected?.Invoke(this, SelectedMachine);
            }
        }

        /// <summary>
        /// Handles the external bridge scanner machine lost event.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="machine">The machine.</param>
        private void _scanner_MachineLost(object sender, IExternalBridgeClient machine)
        {
            InvokeUI(() =>
            {
                if (machine is ExternalBridgeUsbClient)
                {
                    UsbMachines.Remove(machine as ExternalBridgeUsbClient);
                }
                else if (machine is ExternalBridgeSignalRClient)
                {
                    SignalRMachines.Remove(machine as ExternalBridgeSignalRClient);
                }
                else if (machine is ExternalBridgeTcpClient)
                {
                    TcpMachines.Remove(machine as ExternalBridgeTcpClient);
                }
            });
        }

        /// <summary>
        /// Handles the external bridge scanner machine discovered event.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="machine">The machine.</param>
        private void _scanner_MachineDiscovered(object sender, IExternalBridgeClient machine)
        {
            if (machine is ExternalBridgeTcpClient)
            {
                if (!_allowedMachines.Exists(x => x.SerialNumber == machine.SerialNumber))
                {
                    return;
                }
            }

            InvokeUI(() =>
            {
                bool insert = false;

                try
                {
                    if (Settings.LastSelectedMachine != null)
                    {
                        if (machine.GetUniqueString() == Settings.LastSelectedMachine)
                        {
                            insert = true;
                        }
                    }
                }
                catch { }

                if (machine is ExternalBridgeUsbClient && !BuildProvider.IsTwineRSM)
                {
                    if (insert)
                    {
                        UsbMachines.Insert(0, machine as ExternalBridgeUsbClient);
                    }
                    else
                    {
                        UsbMachines.Add(machine as ExternalBridgeUsbClient);
                    }
                }
                else if (machine is ExternalBridgeSignalRClient && !BuildProvider.IsTwineRSM)
                {
                    if (!CurrentUser.PreventRemoteMachineAccess)
                    {
                        if (insert)
                        {
                            SignalRMachines.Insert(0, machine as ExternalBridgeSignalRClient);
                        }
                        else
                        {
                            SignalRMachines.Add(machine as ExternalBridgeSignalRClient);
                        }
                    }
                }
                else if (machine is ExternalBridgeTcpClient)
                {
                    if (insert)
                    {
                        TcpMachines.Insert(0, machine as ExternalBridgeTcpClient);
                    }
                    else
                    {
                        TcpMachines.Add(machine as ExternalBridgeTcpClient);
                    }
                }

                TryAutoSelectMachine();
            });
        }

        /// <summary>
        /// Tries to automatically select a machine by the last connected machine stored on settings.
        /// </summary>
        private void TryAutoSelectMachine()
        {
            if (SelectedMachine == null && Settings.LastSelectedMachine != null)
            {
                SelectedMachine = UsbMachines.Select(x => x.As<IExternalBridgeClient>())
                                  .Concat(TcpMachines.Select(x => x.As<IExternalBridgeClient>()))
                                  .Concat(SignalRMachines.Select(x => x.As<IExternalBridgeClient>()))
                                  .Concat(EmulatorMachines.Select(x => x.As<IExternalBridgeClient>()))
                                  .ToList().SingleOrDefault(x => x.GetUniqueString() == Settings.LastSelectedMachine);

                if (SelectedMachine != null)
                {
                    this.SetFocus(() => ConnectToMachineCommand);
                }
            }
        }

        /// <summary>
        /// Starts scanning for machines.
        /// </summary>
        public async void Start()
        {
            LogManager.Log("Starting machine scanning...");

            if (_allowedMachines == null)
            {
                _allowedMachines = await Services.MachinesService.GetAllMachines();
                _scanner.KnownMachines = _allowedMachines;
            }

            TcpMachines.Clear();
            SignalRMachines.Clear();
            EmulatorMachines.Clear();
            SelectedMachine = null;

            if (Settings.EnableMachineEmulator)
            {
                ThreadFactory.StartNew(() =>
                {
                    try
                    {
                        LogManager.Log("Initializing machine emulator...");

                        if (_emulator != null)
                        {
                            _emulator.Disconnect().Wait();
                        }

                        _emulator = new EmulatorExternalBridge();

                        InvokeUI(() =>
                        {
                            EmulatorMachines.Add(_emulator);
                        });
                    }
                    catch (Exception ex)
                    {
                        LogManager.Log(ex, "Error initializing machine emulator.");
                    }
                });
            }

            TryAutoSelectMachine();

            _scanner.SignalRConfiguration.Enabled = Settings.EnableExternalBridgeSignalR && !BuildProvider.IsTwineRSM;
            if (ApplicationManager.IsWebDebugMode)
            {
                LogManager.Log($"Application is in web debug mode. Scanning for SignalR machine on address '{WEB_DEBUG_ADDRESS}'...");
                _scanner.SignalRConfiguration.Address = WEB_DEBUG_ADDRESS;
            }
            else
            {
                _scanner.SignalRConfiguration.Address = AuthenticationProvider.CurrentEnvironment.MachineServiceAddress;
            }
            _scanner.SignalRConfiguration.Hub = Settings.ExternalBridgeSignalRHub;

            LogManager.Log("Starting external bridge scanner...");
            _scanner.Start();
        }

        /// <summary>
        /// Stops scanning for machines.
        /// </summary>
        public void Stop()
        {
            LogManager.Log("Stopping external bridge scanner...");
            _scanner.Stop();
        }

        private bool OnFilterMachines(object obj)
        {
            var machine = obj as ExternalBridgeTcpClient;

            if (machine != null)
            {
                return machine.SerialNumber.ToLower().Contains(Filter.ToStringOrEmpty().ToLower()) || (machine.GetType() == typeof(ExternalBridgeTcpClient) && machine.IPAddress == Filter);
            }

            return true;
        }

        private void OnFilterChanged()
        {
            if (Filter.IsNotNullOrEmpty())
            {
                Task.Factory.StartNew(() =>
                {
                    _scanner.TryGetMachineByIP(Filter);
                });
            }
        }
    }
}