/******************************************************************************
// RomRepoMgr - ROM repository manager
// ----------------------------------------------------------------------------
//
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// --[ 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 © 2020 Natalia Portillo
*******************************************************************************/

using System;
using System.IO;
using System.Linq;
using System.Reactive;
using System.Threading.Tasks;
using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Threading;
using Microsoft.EntityFrameworkCore;
using ReactiveUI;
using RomRepoMgr.Core.EventArgs;
using RomRepoMgr.Core.Models;
using RomRepoMgr.Database;

namespace RomRepoMgr.ViewModels
{
    public sealed class SplashWindowViewModel : ViewModelBase
    {
        string _exitButtonText;
        bool   _exitVisible;
        bool   _loadingDatabaseError;
        bool   _loadingDatabaseOk;
        string _loadingDatabaseText;
        bool   _loadingDatabaseUnknown;
        bool   _loadingRomSetsError;

        bool   _loadingRomSetsOk;
        string _loadingRomSetsText;
        bool   _loadingRomSetsUnknown;
        bool   _loadingSettingsError;
        bool   _loadingSettingsOk;
        string _loadingSettingsText;
        bool   _loadingSettingsUnknown;
        string _loadingText;
        bool   _migratingDatabaseError;
        bool   _migratingDatabaseOk;
        string _migratingDatabaseText;
        bool   _migratingDatabaseUnknown;

        public SplashWindowViewModel()
        {
            ExitCommand = ReactiveCommand.Create(ExecuteExitCommand);

            LoadStrings();

            LoadingSettingsOk        = false;
            LoadingSettingsError     = false;
            LoadingSettingsUnknown   = true;
            LoadingDatabaseOk        = false;
            LoadingDatabaseError     = false;
            LoadingDatabaseUnknown   = true;
            MigratingDatabaseOk      = false;
            MigratingDatabaseError   = false;
            MigratingDatabaseUnknown = true;
            LoadingRomSetsOk         = false;
            LoadingRomSetsError      = false;
            LoadingRomSetsUnknown    = true;
            ExitVisible              = false;
        }

        public ReactiveCommand<Unit, Unit> ExitCommand { get; }

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

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

        public bool LoadingSettingsOk
        {
            get => _loadingSettingsOk;
            set => this.RaiseAndSetIfChanged(ref _loadingSettingsOk, value);
        }

        public bool LoadingSettingsError
        {
            get => _loadingSettingsError;
            set => this.RaiseAndSetIfChanged(ref _loadingSettingsError, value);
        }

        public bool LoadingSettingsUnknown
        {
            get => _loadingSettingsUnknown;
            set => this.RaiseAndSetIfChanged(ref _loadingSettingsUnknown, value);
        }

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

        public bool LoadingDatabaseOk
        {
            get => _loadingDatabaseOk;
            set => this.RaiseAndSetIfChanged(ref _loadingDatabaseOk, value);
        }

        public bool LoadingDatabaseError
        {
            get => _loadingDatabaseError;
            set => this.RaiseAndSetIfChanged(ref _loadingDatabaseError, value);
        }

        public bool LoadingDatabaseUnknown
        {
            get => _loadingDatabaseUnknown;
            set => this.RaiseAndSetIfChanged(ref _loadingDatabaseUnknown, value);
        }

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

        public bool MigratingDatabaseOk
        {
            get => _migratingDatabaseOk;
            set => this.RaiseAndSetIfChanged(ref _migratingDatabaseOk, value);
        }

        public bool MigratingDatabaseError
        {
            get => _migratingDatabaseError;
            set => this.RaiseAndSetIfChanged(ref _migratingDatabaseError, value);
        }

        public bool MigratingDatabaseUnknown
        {
            get => _migratingDatabaseUnknown;
            set => this.RaiseAndSetIfChanged(ref _migratingDatabaseUnknown, value);
        }

        public bool ExitVisible
        {
            get => _exitVisible;
            set => this.RaiseAndSetIfChanged(ref _exitVisible, value);
        }

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

        public bool LoadingRomSetsOk
        {
            get => _loadingRomSetsOk;
            set => this.RaiseAndSetIfChanged(ref _loadingRomSetsOk, value);
        }

        public bool LoadingRomSetsError
        {
            get => _loadingRomSetsError;
            set => this.RaiseAndSetIfChanged(ref _loadingRomSetsError, value);
        }

        public bool LoadingRomSetsUnknown
        {
            get => _loadingRomSetsUnknown;
            set => this.RaiseAndSetIfChanged(ref _loadingRomSetsUnknown, value);
        }

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

        internal void ExecuteExitCommand() =>
            (Application.Current.ApplicationLifetime as ClassicDesktopStyleApplicationLifetime)?.Shutdown();

        void LoadStrings()
        {
            LoadingText           = "ROM Repository Manager";
            LoadingSettingsText   = "Loading settings...";
            LoadingDatabaseText   = "Loading database...";
            MigratingDatabaseText = "Migrating database...";
            LoadingRomSetsText    = "Loading ROM sets...";
            ExitButtonText        = "Exit";
        }

        internal void OnOpened() => Dispatcher.UIThread.Post(LoadSettings);

        void LoadSettings() => Task.Run(() =>
        {
            try
            {
                Settings.Settings.LoadSettings();

                Dispatcher.UIThread.Post(LoadDatabase);
            }
            catch(Exception e)
            {
                // TODO: Log error
                Dispatcher.UIThread.Post(FailedLoadingSettings);
            }
        });

        void FailedLoadingSettings()
        {
            LoadingSettingsUnknown = false;
            LoadingSettingsError   = true;
            ExitVisible            = true;
        }

        void LoadDatabase()
        {
            LoadingSettingsUnknown = false;
            LoadingSettingsOk      = true;

            Task.Run(() =>
            {
                try
                {
                    string dbPathFolder = Path.GetDirectoryName(Settings.Settings.Current.DatabasePath);

                    if(!Directory.Exists(dbPathFolder))
                        Directory.CreateDirectory(dbPathFolder);

                    _ = Context.Singleton;

                    Dispatcher.UIThread.Post(MigrateDatabase);
                }
                catch(Exception e)
                {
                    // TODO: Log error
                    Dispatcher.UIThread.Post(FailedLoadingDatabase);
                }
            });
        }

        void FailedLoadingDatabase()
        {
            LoadingDatabaseUnknown = false;
            LoadingDatabaseError   = true;
            ExitVisible            = true;
        }

        void MigrateDatabase()
        {
            LoadingDatabaseUnknown = false;
            LoadingDatabaseOk      = true;

            Task.Run(() =>
            {
                try
                {
                    Context.Singleton.Database.Migrate();

                    Dispatcher.UIThread.Post(LoadRomSets);
                }
                catch(Exception e)
                {
                    // TODO: Log error
                    Dispatcher.UIThread.Post(FailedMigratingDatabase);
                }
            });
        }

        void FailedMigratingDatabase()
        {
            MigratingDatabaseUnknown = false;
            MigratingDatabaseError   = true;
            ExitVisible              = true;
        }

        void LoadRomSets()
        {
            MigratingDatabaseUnknown = false;
            MigratingDatabaseOk      = true;

            Task.Run(() =>
            {
                try
                {
                    GotRomSets?.Invoke(this, new RomSetEventArgs
                    {
                        RomSets = Context.Singleton.RomSets.OrderBy(r => r.Name).ThenBy(r => r.Version).
                                          ThenBy(r => r.Date).ThenBy(r => r.Description).ThenBy(r => r.Comment).
                                          ThenBy(r => r.Filename).Select(r => new RomSetModel
                                          {
                                              Author      = r.Author,
                                              Comment     = r.Comment,
                                              Date        = r.Date,
                                              Description = r.Description,
                                              Filename    = r.Filename,
                                              Homepage    = r.Homepage,
                                              Name        = r.Name,
                                              Sha384      = r.Sha384,
                                              Version     = r.Version
                                          }).ToList()
                    });

                    Dispatcher.UIThread.Post(LoadMainWindow);
                }
                catch(Exception e)
                {
                    // TODO: Log error
                    Dispatcher.UIThread.Post(FailedLoadingRomSets);
                }
            });
        }

        void FailedLoadingRomSets()
        {
            LoadingRomSetsUnknown = false;
            LoadingRomSetsError   = true;
            ExitVisible           = true;
        }

        void LoadMainWindow()
        {
            LoadingRomSetsUnknown = false;
            LoadingRomSetsOk      = true;

            WorkFinished?.Invoke(this, EventArgs.Empty);
        }

        internal event EventHandler WorkFinished;

        internal event EventHandler<RomSetEventArgs> GotRomSets;
    }
}