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

namespace Tango.SharedUI
{
    /// <summary>
    /// Represents a dialog view model base class.
    /// </summary>
    /// <seealso cref="Tango.SharedUI.ViewModel" />
    public abstract class DialogViewVM : ViewModel
    {
        public event Action Accepted;
        public event Action Canceled;

        /// <summary>
        /// Initializes a new instance of the <see cref="DialogViewVM"/> class.
        /// </summary>
        public DialogViewVM()
        {
            CanClose = true;
            CloseCommand = new RelayCommand(Cancel, (x) => CanClose);
            OKCommand = new RelayCommand(Accept, (x) => CanOK());
        }

        private bool _canClose;
        /// <summary>
        /// Gets or sets a value indicating whether this dialog can be closed.
        /// </summary>
        public bool CanClose
        {
            get { return _canClose; }
            set { _canClose = value; RaisePropertyChangedAuto(); InvalidateRelayCommands(); }
        }

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


        /// <summary>
        /// Determines whether this instance can invoke the OK command.
        /// </summary>
        protected virtual bool CanOK()
        {
            return true;
        }

        /// <summary>
        /// Gets a value indicating whether the dialog has been confirmed.
        /// </summary>
        public bool DialogResult { get; private set; }

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

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

        /// <summary>
        /// Called when the dialog has been shown.
        /// </summary>
        public virtual void OnShow()
        {
            IsVisible = true;
        }

        /// <summary>
        /// Invokes the <see cref="Accepted"/> event.
        /// </summary>
        protected virtual void Accept()
        {
            IsVisible = false;
            DialogResult = true;
            Accepted?.Invoke();
        }

        /// <summary>
        /// Invokes the <see cref="Canceled"/> event.
        /// </summary>
        protected virtual void Cancel()
        {
            IsVisible = false;
            Canceled?.Invoke();
        }

        /// <summary>
        /// Closes the dialog with the specified result.
        /// </summary>
        /// <param name="result">if set to <c>true</c> accepted.</param>
        public void Close(bool result)
        {
            DialogResult = result;
            if (result)
            {
                Accept();
            }
            else
            {
                Cancel();
            }
        }
    }
}