using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.BL.Entities;
using Tango.MachineStudio.Common;
using System.Data.Entity;
using Tango.MachineStudio.Common.Notifications;
using Tango.MachineStudio.Dispensers.Contracts;
using Tango.Core.Commands;
using Tango.Core.Threading;

namespace Tango.MachineStudio.Dispensers.ViewModels
{
    public class MainViewVM : StudioViewModel<IMainView>
    {
        private ObservablesContext _dbContext;
        private ObservablesContext _activeContext;
        private INotificationProvider _notification;
        private ActionTimer _filter_timer;

        private ObservableCollection<Dispenser> _dispensers;
        public ObservableCollection<Dispenser> Dispensers
        {
            get { return _dispensers; }
            set { _dispensers = value; RaisePropertyChangedAuto(); }
        }

        private Dispenser _selectedDispenser;
        public Dispenser SelectedDispenser
        {
            get { return _selectedDispenser; }
            set { _selectedDispenser = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        private Dispenser _activeDispenser;
        public Dispenser ActiveDispenser
        {
            get { return _activeDispenser; }
            set { _activeDispenser = value; RaisePropertyChangedAuto(); }
        }

        private ObservableCollection<DispenserType> _dispenserTypes;
        public ObservableCollection<DispenserType> DispenserTypes
        {
            get { return _dispenserTypes; }
            set { _dispenserTypes = value; RaisePropertyChangedAuto(); }
        }

        private String _filter;
        public String Filter
        {
            get { return _filter; }
            set { _filter = value; RaisePropertyChangedAuto(); OnFilterChanged(); }
        }

        public RelayCommand AddDispenserCommand { get; set; }

        public RelayCommand RemoveDispenserCommand { get; set; }

        public RelayCommand ManageDispenserCommand { get; set; }

        public RelayCommand BackToDispensersCommand { get; set; }

        public RelayCommand SaveCommand { get; set; }

        public MainViewVM(INotificationProvider notificationProvider)
        {
            _notification = notificationProvider;
            _filter_timer = new ActionTimer(TimeSpan.FromMilliseconds(200));

            ManageDispenserCommand = new RelayCommand(() => LoadSelectedDispenser(), () => SelectedDispenser != null);
            BackToDispensersCommand = new RelayCommand(() => { View.NavigateTo(DispensersNavigationView.DispensersView); });
            SaveCommand = new RelayCommand(SaveActiveDispenser);
            AddDispenserCommand = new RelayCommand(AddNewDispenser);
            RemoveDispenserCommand = new RelayCommand(RemoveSelectedDispenser, () => SelectedDispenser != null);
        }

        private void OnFilterChanged()
        {
            if (Filter != null)
            {
                _filter_timer.ResetReplace(() =>
                {
                    IsFree = false;
                    Dispensers = _dbContext.Dispensers.Where(x => x.SerialNumber.ToLower().StartsWith(Filter.ToLower())).Include(x => x.DispenserType).Include(x => x.IdsPacks).ToList().ToObservableCollection();
                    IsFree = true;
                });
            }
        }

        private async void LoadSelectedDispenser(bool isNew = false)
        {
            if (_activeContext != null)
            {
                _activeContext.Dispose();
            }

            using (_notification.PushTaskItem("Loading dispenser data..."))
            {
                try
                {
                    IsFree = false;
                    _activeContext = ObservablesContext.CreateDefault();
                    DispenserTypes = (await _activeContext.DispenserTypes.ToListAsync()).ToObservableCollection();

                    if (!isNew)
                    {
                        ActiveDispenser = await _activeContext.Dispensers.Include(x => x.DispenserType).Include(x => x.IdsPacks).SingleOrDefaultAsync(x => x.Guid == SelectedDispenser.Guid);
                        ActiveDispenser.InitMachine(_activeContext);
                    }
                    else
                    {
                        ActiveDispenser = new Dispenser();
                        _activeContext.Dispensers.Add(ActiveDispenser);
                    }
                    View.NavigateTo(DispensersNavigationView.DispenserView);
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, $"Error loading dispenser {SelectedDispenser.SerialNumber}.");
                    _notification.ShowError($"An error occurred while trying to load the selected dispenser data.\n{ex.Message}");
                }
                finally
                {
                    IsFree = true;
                    InvalidateRelayCommands();
                }
            }
        }


        private void AddNewDispenser()
        {
            LoadSelectedDispenser(true);
        }

        private async void RemoveSelectedDispenser()
        {
            if (_notification.ShowQuestion("Are you sure you want to delete the selected dispenser?"))
            {
                try
                {
                    IsFree = false;

                    if (SelectedDispenser.IsInstalled)
                    {
                        _notification.ShowError("Cannot delete an installed dispenser. Please detach it first from it's machine and try again.");
                        return;
                    }

                    _dbContext.Dispensers.Remove(SelectedDispenser);
                    await _dbContext.SaveChangesAsync();
                    Dispensers.Remove(SelectedDispenser);
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, $"Error removing dispenser {SelectedDispenser.SerialNumber}.");
                    _notification.ShowError($"An error occurred while trying to remove the selected dispenser.\n{ex.FlattenMessage()}");
                }
                finally
                {
                    IsFree = true;
                }
            }
        }

        private async void SaveActiveDispenser()
        {
            using (_notification.PushTaskItem("Saving dispenser data..."))
            {
                try
                {
                    IsFree = false;
                    await _activeContext.SaveChangesAsync();
                    if (SelectedDispenser != null)
                    {
                        await SelectedDispenser.Reload(_dbContext);
                    }

                    View.NavigateTo(DispensersNavigationView.DispensersView);
                }
                catch (Exception ex)
                {
                    LogManager.Log(ex, $"Error saving dispenser {ActiveDispenser.SerialNumber}.");
                    _notification.ShowError($"An error occurred while trying to save the dispenser data.\n{ex.Message}");
                }
                finally
                {
                    IsFree = true;
                    InvalidateRelayCommands();
                }
            }
        }

        public async override void OnApplicationReady()
        {
            _dbContext = ObservablesContext.CreateDefault();
            await _dbContext.DispenserTypes.LoadAsync();
        }
    }
}