// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : SplashWindowViewModel.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : GUI view models.
//
// --[ Description ] ----------------------------------------------------------
//
//     View model and code for the splash window.
//
// --[ License ] --------------------------------------------------------------
//
//     This program is free software: you can redistribute it and/or modify
//     it under the terms of the GNU General public License as
//     published by the Free Software Foundation, either version 3 of the
//     License, or (at your option) any later version.
//
//     This program is distributed in the hope that it will be useful,
//     but WITHOUT ANY WARRANTY; without even the implied warranty of
//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//     GNU General public License for more details.
//
//     You should have received a copy of the GNU General public License
//     along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2022 Natalia Portillo
// ****************************************************************************/

using System;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Aaru.Console;
using Aaru.Core;
using Aaru.Database;
using Aaru.Gui.ViewModels.Dialogs;
using Aaru.Gui.Views.Dialogs;
using Aaru.Gui.Views.Windows;
using Aaru.Settings;
using Avalonia.Threading;
using Microsoft.EntityFrameworkCore;
using ReactiveUI;

namespace Aaru.Gui.ViewModels.Windows;

public sealed class SplashWindowViewModel : ViewModelBase
{
    readonly SplashWindow _view;
    double                _currentProgress;
    double                _maxProgress;
    string                _message;

    public SplashWindowViewModel(SplashWindow view) => _view = view;

    public string Message
    {
        get => _message;
        set => this.RaiseAndSetIfChanged(ref _message, value);
    }

    public double MaxProgress
    {
        get => _maxProgress;
        set => this.RaiseAndSetIfChanged(ref _maxProgress, value);
    }

    public double CurrentProgress
    {
        get => _currentProgress;
        set => this.RaiseAndSetIfChanged(ref _currentProgress, value);
    }

    internal void OnOpened()
    {
        Message         = "Welcome to Aaru!";
        MaxProgress     = 9;
        CurrentProgress = 0;

        Dispatcher.UIThread.Post(InitializeConsole);
    }

    void InitializeConsole()
    {
        CurrentProgress++;
        Message = "Initializing console...";

        Task.Run(() =>
        {
            ConsoleHandler.Init();
            AaruConsole.WriteLine("Aaru started!");

            Dispatcher.UIThread.Post(LoadSettings);
        });
    }

    void LoadSettings()
    {
        CurrentProgress++;
        Message = "Loading settings...";
        AaruConsole.WriteLine("Loading settings...");

        Task.Run(() =>
        {
            // TODO: Detect there are no settings yet
            Settings.Settings.LoadSettings();

            Dispatcher.UIThread.Post(MigrateLocalDatabase);
        });
    }

    void MigrateLocalDatabase()
    {
        CurrentProgress++;
        Message = "Migrating local database...";
        AaruConsole.WriteLine("Migrating local database...");

        Task.Run(() =>
        {
            AaruContext ctx = null;

            try
            {
                ctx = AaruContext.Create(Settings.Settings.LocalDbPath, false);
                ctx.Database.Migrate();
            }
            catch(NotSupportedException)
            {
                try
                {
                    ctx?.Database.CloseConnection();
                    ctx?.Dispose();
                }
                catch(Exception)
                {
                    // Should not ever arrive here, but if it does, keep trying to replace it anyway
                }

                File.Delete(Settings.Settings.LocalDbPath);
                ctx = AaruContext.Create(Settings.Settings.LocalDbPath);
                ctx.Database.EnsureCreated();

                ctx.Database.
                    ExecuteSqlRaw("CREATE TABLE IF NOT EXISTS \"__EFMigrationsHistory\" (\"MigrationId\" TEXT PRIMARY KEY, \"ProductVersion\" TEXT)");

                foreach(string migration in ctx.Database.GetPendingMigrations())
                    ctx.Database.
                        ExecuteSqlRaw($"INSERT INTO \"__EFMigrationsHistory\" (MigrationId, ProductVersion) VALUES ('{
                            migration}', '0.0.0')");

                ctx.SaveChanges();
            }

            // Remove duplicates
            foreach(var duplicate in ctx.SeenDevices.AsEnumerable().GroupBy(a => new
                    {
                        a.Manufacturer,
                        a.Model,
                        a.Revision,
                        a.Bus
                    }).Where(a => a.Count() > 1).Distinct().Select(a => a.Key))
                ctx.RemoveRange(ctx.SeenDevices.
                                    Where(d => d.Manufacturer == duplicate.Manufacturer && d.Model == duplicate.Model &&
                                               d.Revision     == duplicate.Revision && d.Bus == duplicate.Bus).Skip(1));

            // Remove nulls
            ctx.RemoveRange(ctx.SeenDevices.Where(d => d.Manufacturer == null && d.Model == null &&
                                                       d.Revision     == null));

            ctx.SaveChanges();

            Dispatcher.UIThread.Post(UpdateMainDatabase);
        });
    }

    void UpdateMainDatabase()
    {
        CurrentProgress++;
        Message = "Updating main database...";
        AaruConsole.WriteLine("Updating main database...");

        Task.Run(() =>
        {
            bool mainDbUpdate = !File.Exists(Settings.Settings.MainDbPath);

            // TODO: Update database

            var mainContext = AaruContext.Create(Settings.Settings.MainDbPath, false);

            if(mainContext.Database.GetPendingMigrations().Any())
            {
                AaruConsole.WriteLine("New database version, updating...");

                try
                {
                    File.Delete(Settings.Settings.MainDbPath);
                }
                catch(Exception)
                {
                    AaruConsole.ErrorWriteLine("Exception trying to remove old database version, cannot continue...");

                    AaruConsole.ErrorWriteLine("Please manually remove file at {0}", Settings.Settings.MainDbPath);

                    return;
                }

                // TODO: Update database
            }

            Dispatcher.UIThread.Post(CheckGdprCompliance);
        });
    }

    [SuppressMessage("ReSharper", "AsyncVoidMethod")]
    async void CheckGdprCompliance()
    {
        CurrentProgress++;
        Message = "Checking GDPR compliance...";
        AaruConsole.WriteLine("Checking GDPR compliance...");

        if(Settings.Settings.Current.GdprCompliance < DicSettings.GDPR_LEVEL)
        {
            var settingsDialog          = new SettingsDialog();
            var settingsDialogViewModel = new SettingsViewModel(settingsDialog, true);
            settingsDialog.DataContext = settingsDialogViewModel;
            await settingsDialog.ShowDialog(_view);
        }

        LoadStatistics();
    }

    void LoadStatistics()
    {
        CurrentProgress++;
        Message = "Loading statistics...";
        AaruConsole.WriteLine("Loading statistics...");

        Task.Run(() =>
        {
            Statistics.LoadStats();

            Dispatcher.UIThread.Post(RegisterEncodings);
        });
    }

    void RegisterEncodings()
    {
        CurrentProgress++;
        Message = "Registering encodings...";
        AaruConsole.WriteLine("Registering encodings...");

        Task.Run(() =>
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

            Dispatcher.UIThread.Post(SaveStatistics);
        });
    }

    void SaveStatistics()
    {
        CurrentProgress++;
        Message = "Saving statistics...";
        AaruConsole.WriteLine("Saving statistics...");

        Task.Run(() =>
        {
            Statistics.SaveStats();

            Dispatcher.UIThread.Post(LoadMainWindow);
        });
    }

    void LoadMainWindow()
    {
        CurrentProgress++;
        Message = "Loading main window...";
        AaruConsole.WriteLine("Loading main window...");
        WorkFinished?.Invoke(this, EventArgs.Empty);
    }

    internal event EventHandler WorkFinished;
}