using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Core.Commands;
using Tango.DAL.Observables;
using Tango.MachineStudio.Common.Notifications;
using Tango.MachineStudio.DB.Managers;
using Tango.SharedUI;
using Tango.MachineStudio.DB.ExtensionMethods;

namespace Tango.MachineStudio.DB.ViewModels
{
    public abstract class DbTableViewModel<T> : ViewModel where T : class, IObservableEntity
    {
        private INotificationProvider _notification;

        /// <summary>
        /// Initializes a new instance of the <see cref="DbTableViewModel"/> class.
        /// </summary>
        public DbTableViewModel(INotificationProvider notification) : base()
        {
            _notification = notification;
            Adapter = ObservablesEntitiesAdapter.Instance;

            AddCommand = new RelayCommand(OnAdd);
            EditCommand = new RelayCommand(OnEdit,(x) => SelectedEntity != null);
            DeleteCommand = new RelayCommand(OnDelete, (x) => SelectedEntity != null);
            DialogOKCommand = new RelayCommand(() => OnDialogOKPressed(DialogOpenMode, EditEntity));
            DialogCancelCommand = new RelayCommand(() => OnDialogCancelPressed(DialogOpenMode, EditEntity));

            IsDialogOpen = false;
        }

        private T _editEntity;
        /// <summary>
        /// Gets or sets the edit entity.
        /// </summary>
        public T EditEntity
        {
            get { return _editEntity; }
            set { _editEntity = value; RaisePropertyChangedAuto(); }
        }

        private DialogOpenMode _dialogOpenMode;
        /// <summary>
        /// Gets or sets the dialog open mode.
        /// </summary>
        public DialogOpenMode DialogOpenMode
        {
            get { return _dialogOpenMode; }
            set { _dialogOpenMode = value; RaisePropertyChangedAuto(); }
        }

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

        private ObservablesEntitiesAdapter _adapter;
        /// <summary>
        /// Gets or sets the DB adapter.
        /// </summary>
        public ObservablesEntitiesAdapter Adapter
        {
            get { return _adapter; }
            set { _adapter = value; RaisePropertyChangedAuto(); }
        }

        private T _selectedEntity;
        /// <summary>
        /// Gets or sets the selected entity.
        /// </summary>
        public T SelectedEntity
        {
            get { return _selectedEntity; }
            set { _selectedEntity = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

        private String _filter;
        /// <summary>
        /// Gets or sets the search filter.
        /// </summary>
        public String Filter
        {
            get { return _filter; }
            set { _filter = value; RaisePropertyChangedAuto(); OnFilterChanged(value); }
        }

        /// <summary>
        /// Gets or sets the dialog OK command.
        /// </summary>
        public RelayCommand DialogOKCommand { get; set; }

        /// <summary>
        /// Gets or sets the dialog cancel command.
        /// </summary>
        public RelayCommand DialogCancelCommand { get; set; }

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

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

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

        /// <summary>
        /// Called when delete command invoked.
        /// </summary>
        protected virtual void OnDelete()
        {
            SelectedEntity.Deleted = true;
            SelectedEntity.Save();
        }

        /// <summary>
        /// Called when edit command invoked.
        /// </summary>
        protected virtual void OnEdit()
        {
            DialogOpenMode = DialogOpenMode.Editing;
            EditEntity = GetEditableEntity(DialogOpenMode);
            _notification.ShowDialog(DialogOpenMode, this);
            IsDialogOpen = true;
        }

        /// <summary>
        /// Called when add command invoked.
        /// </summary>
        protected virtual void OnAdd()
        {
            DialogOpenMode = DialogOpenMode.Adding;
            EditEntity = GetEditableEntity(DialogOpenMode);
            _notification.ShowDialog(DialogOpenMode, this);
            IsDialogOpen = true;
        }

        /// <summary>
        /// Called when dialog closes with OK button.
        /// </summary>
        /// <param name="mode">The mode.</param>
        protected virtual void OnDialogOKPressed(DialogOpenMode mode, T entity)
        {
            if (mode == DialogOpenMode.Editing)
            {
                entity.ShallowCopyTo(SelectedEntity);
                entity = SelectedEntity;
            }

            OnBeforeEntitySave(mode, entity);

            entity.Save();
            IsDialogOpen = false;
            SelectedEntity = EditEntity;
            SelectedEntity = null;
        }

        /// <summary>
        /// Called when [before entity save].
        /// </summary>
        /// <param name="mode">The mode.</param>
        /// <param name="entity">The entity.</param>
        protected virtual void OnBeforeEntitySave(DialogOpenMode mode,T entity)
        {

        }

        /// <summary>
        /// Called when dialog closes with cancel button.
        /// </summary>
        /// <param name="mode">The mode.</param>
        protected virtual void OnDialogCancelPressed(DialogOpenMode mode, T entity)
        {
            IsDialogOpen = false;
        }

        /// <summary>
        /// Gets the editable entity.
        /// </summary>
        /// <param name="mode">The mode.</param>
        /// <returns></returns>
        private T GetEditableEntity(DialogOpenMode mode)
        {
            if (mode == DialogOpenMode.Adding)
            {
                var newEntity = Activator.CreateInstance<T>();
                InitializeEntity(newEntity);
                return newEntity;
            }
            else
            {
                return SelectedEntity.ShallowClone();
            }
        }

        protected virtual void OnFilterChanged(String filter)
        {

        }

        protected virtual void InitializeEntity(T entity)
        {

        }
    }
}