using Google.Protobuf;
using Microsoft.Practices.ServiceLocation;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data.Entity.Validation;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Tango.Core.Commands;
using Tango.Core.Helpers;
using Tango.Integration.Observables;
using Tango.Integration.Services;
using Tango.MachineStudio.Common.Notifications;
using Tango.MachineStudio.Common.StudioApplication;
using Tango.MachineStudio.Synchronization.Navigation;
using Tango.PMR.Integration;
using Tango.SharedUI;
using Tango.Synchronization;
using Tango.Synchronization.Local;
using Tango.Synchronization.Remote;

namespace Tango.MachineStudio.Synchronization.ViewModels
{
    /// <summary>
    /// Represents the 'Direct Synchronization' view model.
    /// </summary>
    /// <seealso cref="Tango.SharedUI.ViewModel" />
    public class DirectSynchronizationViewVM : ViewModel
    {
        private SyncNavigationManager _navigation;
        private String _slaveDBFile;
        private String _masterDBFile;
        private LocalDBComparer _comparer;
        private INotificationProvider _notification;
        private String _comparedSerialNumber;
        private MainViewVM _mainView;

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="DirectSynchronizationViewVM"/> class.
        /// </summary>
        /// <param name="applicationManager">The application manager.</param>
        /// <param name="navigation">The navigation.</param>
        /// <param name="notification">The notification.</param>
        public DirectSynchronizationViewVM(IStudioApplicationManager applicationManager, SyncNavigationManager navigation, INotificationProvider notification)
        {
            ApplicationManager = applicationManager;

            _navigation = navigation;
            _notification = notification;

            BackCommand = new RelayCommand(() => _navigation.NavigateTo(NavigationView.MenuView));

            Differences = new ObservableCollection<Diff>();

            CompareCommand = new RelayCommand(Compare, (x) => !IsWorking && SelectedMachine != null);
            CommitAllCommand = new RelayCommand(Synchronize, (x) => Differences.Count > 0 && !IsWorking && SelectedMachine != null);
        }

        #endregion

        #region Commands

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

        /// <summary>
        /// Gets or sets the browse master database command.
        /// </summary>
        public RelayCommand BrowseMasterDBCommand { get; set; }

        /// <summary>
        /// Gets or sets the browse slave database command.
        /// </summary>
        public RelayCommand BrowseSlaveDBCommand { get; set; }

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

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

        /// <summary>
        /// Gets or sets the commit all command.
        /// </summary>
        public RelayCommand CommitAllCommand { get; set; }

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

        #endregion

        #region Properties

        public IStudioApplicationManager ApplicationManager { get; set; }

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

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

        private ObservableCollection<Diff> _differences;
        /// <summary>
        /// Gets or sets the differences.
        /// </summary>
        public ObservableCollection<Diff> Differences
        {
            get { return _differences; }
            set { _differences = value; RaisePropertyChanged(nameof(Differences)); }
        }

        private Diff _selectedDifference;
        /// <summary>
        /// Gets or sets the selected difference.
        /// </summary>
        public Diff SelectedDifference
        {
            get { return _selectedDifference; }
            set { _selectedDifference = value; RaisePropertyChanged(nameof(SelectedDifference)); InvalidateRelayCommands(); }
        }

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

        #endregion

        #region Event Handlers

        private void Comparer_Progress(object sender, string e)
        {
            if (_mainView == null)
            {
                _mainView = ServiceLocator.Current.GetInstance<MainViewVM>();
                _mainView.Log = String.Empty;
            }

            _mainView.Log += ("[" + DateTime.Now.ToTimeString() + "]  " + e + Environment.NewLine);
        }

        #endregion

        #region Private Methods

        /// <summary>
        /// Compares the selected machine against the remote database.
        /// </summary>
        private void Compare()
        {
            if (SelectedMachine.SerialNumber != ApplicationManager.ConnectedMachine.As<ExternalBridgeTcpClient>().SerialNumber)
            {
                if (!_notification.ShowQuestion("The selected machine serial number does not match the connected machine. Are you sure you want to continue?"))
                {
                    return;
                }
            }

            Task.Factory.StartNew(async () =>
            {
                using (_notification.PushTaskItem("Downloading machine database..."))
                {
                    try
                    {
                        IsWorking = true;
                        InvalidateRelayCommands();
                        Thread.Sleep(1500);

                        ApplicationManager.ConnectedMachine.UseKeepAlive = false;

                        var response = await ApplicationManager.ConnectedMachine.SendRequest<DirectSynchronizationRequest, DirectSynchronizationResponse>(new DirectSynchronizationRequest(), TimeSpan.FromSeconds(60));

                        using (_notification.PushTaskItem("Generating temporary files..."))
                        {
                            String tempFolder = PathHelper.GetTempFolderPath();

                            //File path for the reflected remote data base SQLite.
                            _masterDBFile = Path.Combine(tempFolder, "Remote.db");
                            //File path for the received machine SQLite db.
                            _slaveDBFile = Path.Combine(tempFolder, "Local.db");

                            //Save the machine db to file.
                            File.WriteAllBytes(_slaveDBFile, response.Message.LocalDB.ToByteArray());

                            //Copy the SQLite db template.
                            File.Copy(Path.Combine(PathHelper.GetStartupPath(), "Tango.db"), _masterDBFile);

                            //Synchronize the SQL Server db with the new SQLite template. (Overwrite basically)
                            RemoteDBSynchronizer.Synchronize(_masterDBFile, SelectedMachine.SerialNumber, true);

                            _comparedSerialNumber = SelectedMachine.SerialNumber;

                            using (_notification.PushTaskItem("Comparing database..."))
                            {
                                _comparer = new LocalDBComparer(new SQLiteDataBase(_masterDBFile), new SQLiteDataBase(_slaveDBFile));
                                _comparer.Progress += Comparer_Progress;

                                var diffs = _comparer.Compare();
                                Differences = new ObservableCollection<Diff>(diffs);

                                if (diffs.Where(x => x.Action != DiffAction.ReplaceTableDataInSlave).Count() > 0)
                                {
                                    ShowInfo("Found " + Differences.Where(x => x.Action != DiffAction.ReplaceTableDataInSlave).Count() + " differences.");
                                }
                                else
                                {
                                    ShowInfo("The machine database is synchronized.");
                                }
                            }
                        }
                    }
                    catch (DbEntityValidationException ex)
                    {
                        String message = "The following validation errors occurred." + Environment.NewLine + Environment.NewLine;

                        foreach (var error in ex.EntityValidationErrors.SelectMany(x => x.ValidationErrors).ToList())
                        {
                            message += error.ErrorMessage + Environment.NewLine;
                        }

                        ShowError(message);
                    }
                    catch (Exception ex)
                    {
                        ShowError(ex.Message);
                    }
                    finally
                    {
                        IsWorking = false;
                        SelectedDifference = null;
                        InvalidateRelayCommands();
                        ApplicationManager.ConnectedMachine.UseKeepAlive = true;
                    }
                }
            });
        }


        /// <summary>
        /// Synchronizes the selected machine with the remote database.
        /// </summary>
        private void Synchronize()
        {
            if (IsClearMachine)
            {
                if (!_notification.ShowQuestion("This will erase and override the existing machine database. Do you want to proceed?"))
                {
                    return;
                }
            }

            if (SelectedMachine.SerialNumber != _comparedSerialNumber)
            {
                _notification.ShowError("You have selected a different machine serial number after comparing. Please compare again if you wish to synchronize a different machine.");
                return;
            }

            Task.Factory.StartNew(async () =>
            {
                using (_notification.PushTaskItem("Synchronizing..."))
                {
                    try
                    {
                        ApplicationManager.ConnectedMachine.UseKeepAlive = false;

                        IsWorking = true;
                        InvalidateRelayCommands();
                        Thread.Sleep(1500);

                        for (int i = 0; i < Differences.Count; i++)
                        {
                            var diff = Differences[i];

                            diff.Commit();
                            InvokeUINow(() => Differences.Remove(diff));
                            i--;
                        }

                        _comparer.Dispose();

                        byte[] remoteDbBytes = IsClearMachine ? File.ReadAllBytes(_masterDBFile) : File.ReadAllBytes(_slaveDBFile);

                        var response = await ApplicationManager.ConnectedMachine.SendRequest<OverrideDataBaseRequest, OverrideDataBaseResponse>(new OverrideDataBaseRequest()
                        {
                            RemoteDB = ByteString.CopyFrom(remoteDbBytes)
                        }, TimeSpan.FromSeconds(30));

                        if (!response.Message.Successful)
                        {
                            ShowError("The remote machine has reported some error while trying to override the database.");
                        }
                        else
                        {
                            //Synchronize the SQL Server db with the synchronized master DB.
                            RemoteDBSynchronizer.Synchronize(_masterDBFile, _comparedSerialNumber, false);

                            PathHelper.TryDeleteFile(_slaveDBFile);
                            PathHelper.TryDeleteFile(_masterDBFile);
                            _slaveDBFile = null;
                            _masterDBFile = null;
                            InvalidateRelayCommands();
                        }
                    }
                    catch (Exception ex)
                    {
                        ShowError(ex.Message);
                    }
                    finally
                    {
                        IsWorking = false;
                        SelectedDifference = null;
                        InvalidateRelayCommands();
                        ApplicationManager.ConnectedMachine.UseKeepAlive = true;
                    }
                }
            });
        }

        /// <summary>
        /// Displays an error message.
        /// </summary>
        /// <param name="message">The message.</param>
        private void ShowError(String message)
        {
            InvokeUINow(() => _notification.ShowError(message));
        }

        /// <summary>
        /// Displays an information message.
        /// </summary>
        /// <param name="message">The message.</param>
        private void ShowInfo(String message)
        {
            InvokeUINow(() => _notification.ShowInfo(message));
        }

        #endregion
    }
}