using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Core.DI;
using Tango.SharedUI;

namespace Tango.MachineStudio.Common
{
    /// <summary>
    /// Represents a Machine Studio view model
    /// </summary>
    /// <seealso cref="Tango.SharedUI.ViewModel" />
    /// <seealso cref="Tango.MachineStudio.Common.IStudioViewModel" />
    public abstract class StudioViewModel : ViewModel, IStudioViewModel
    {
        private bool _isVisible;
        /// <summary>
        /// Gets or sets a value indicating whether this view model view's is visible.
        /// </summary>
        public bool IsVisible
        {
            get { return _isVisible; }
            set { _isVisible = value; RaisePropertyChangedAuto(); }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="StudioViewModel{Module}"/> class.
        /// </summary>
        public StudioViewModel() : base()
        {

        }

        /// <summary>
        /// Called when the user has navigated out of this view model.
        /// </summary>
        public virtual void OnNavigatedFrom()
        {
            IsVisible = false;
        }

        /// <summary>
        /// Called when the user has navigated in to this view model.
        /// </summary>
        public virtual void OnNavigatedTo()
        {
            IsVisible = true;
        }

        /// <summary>
        /// Called before the application is shutting down.
        /// Return false to cancel the shutdown in case an important process is in progress.
        /// </summary>
        /// <returns></returns>
        public virtual Task<bool> OnShutdownRequest()
        {
            return Task.FromResult(true);
        }

        /// <summary>
        /// Called when application is shutting down.
        /// </summary>
        public virtual void OnShuttingDown()
        {

        }

        /// <summary>
        /// Called when the application has been started
        /// </summary>
        public virtual void OnApplicationStarted()
        {

        }

        /// <summary>
        /// Called when the application is ready and all modules are loaded.
        /// </summary>
        public abstract void OnApplicationReady();
    }

    /// <summary>
    /// Represents a Machine Studio view model with a support for a view contract.
    /// </summary>
    /// <typeparam name="TView"></typeparam>
    /// <seealso cref="Tango.SharedUI.ViewModel" />
    public abstract class StudioViewModel<TView> : StudioViewModel where TView : IView
    {
        /// <summary>
        /// Gets the view model's view.
        /// </summary>
        public TView View { get; private set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="StudioViewModel{TView}"/> class.
        /// </summary>
        public StudioViewModel() : base()
        {
            TangoIOC.Default.GetInstanceWhenAvailable<TView>((view) => 
            {
                View = view;
                OnViewAttached(view);
            });
        }

        /// <summary>
        /// Called when the view has been attached
        /// </summary>
        /// <param name="view">The view.</param>
        protected virtual void OnViewAttached(TView view)
        {
            //Do Nothing.
        }
    }
}