/*
The MIT License

Copyright (c) 2009-2010. Carlos Guzmán Álvarez. http://chronoswpf.codeplex.com/

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using Chronos.Presentation.Core.ViewModel;
using Chronos.Presentation.Core.VirtualDesktops;
using NLog;
using nRoute.Components;
using nRoute.Components.Messaging;

namespace Chronos.Presentation.ViewModel
{
    /// <summary>
    /// Base class for closeable view models
    /// </summary>
    public abstract class ClosableViewModel 
        : ViewModelBase, IClosableViewModel
    {
        #region · NotifyPropertyChanged Cached Instances ·

        private static readonly PropertyChangedEventArgs IdChangedArgs      = CreateArgs<ClosableViewModel>(x => x.Id);
        private static readonly PropertyChangedEventArgs TitleChangedArgs   = CreateArgs<ClosableViewModel>(x => x.Title);

        #endregion

        #region · Logger ·

        private static Logger Logger = LogManager.GetCurrentClassLogger();

        #endregion

        #region · Fields ·

        private Guid                    id;
        private ActionCommand           closeCommand;
        private string                  title;
        private List<IChannelObserver>  observers;

        #endregion

        #region · Commands ·

        /// <summary>
        /// Gets the Close Command
        /// </summary>
        public ActionCommand CloseCommand
        {
            get
            {
                if (this.closeCommand == null)
                {
                    this.closeCommand = new ActionCommand
                    (
                        () => Close(),
                        () => CanClose()
                    );
                }

                return this.closeCommand;
            }
        }

        #endregion

        #region · Properties ·

        /// <summary>
        /// Gets or sets the unique identifier.
        /// </summary>
        /// <value>The id.</value>
        public Guid Id
        {
            get { return this.id; }
            set
            {
                if (this.id != value)
                {
                    this.id = value;
                    this.NotifyPropertyChanged(IdChangedArgs);
                }
            }
        }

        /// <summary>
        /// Returns the user-friendly name of this object.
        /// Child classes can set this property to a new value,
        /// or override it to determine the value on-demand.
        /// </summary>
        public virtual string Title
        {
            get { return this.title; }
            set
            {
                if (this.title != value)
                {
                    this.title = value;
                    this.NotifyPropertyChanged(TitleChangedArgs);
                }
            }
        }

        #endregion

        #region · Constructors ·

        /// <summary>
        /// Initializes a new instance of the <see cref="ClosableViewModel"/> class.
        /// </summary>
        protected ClosableViewModel()
            : base()
        {
            this.Id         = Guid.NewGuid();
            this.observers  = new List<IChannelObserver>();
        }

        #endregion

        #region · Messaging Methods ·

        protected void Subscribe<T>(Action<T> payloadHandler)
            where T: class
        {
            this.Subscribe<T>(payloadHandler, ThreadOption.BackgroundThread);
        }

        protected void Subscribe<T>(Action<T> payloadHandler, ThreadOption threadOption)
            where T: class
        {
            ChannelObserver<T> observer = new ChannelObserver<T>((l) => payloadHandler(l));

            observer.Subscribe(threadOption);

            this.observers.Add(observer);
        }

        protected void Publish<T>(T message)
            where T: class
        {
            Channel<T>.Publish(message, true);
        }

        protected void Publish<T>(T message, bool async)
            where T: class
        {
            Channel<T>.Publish(message, async);
        }

        #endregion

        #region · Command Actions ·

        /// <summary>
        /// Determines whether the view related to this view model can be closed.
        /// </summary>
        /// <returns>
        /// 	<c>true</c> if the related view can be closed; otherwise, <c>false</c>.
        /// </returns>
        public virtual bool CanClose()
        {
            return true;
        }

        /// <summary>
        /// Called when the related view is being closed.
        /// </summary>
        public virtual void Close()
        {
            if (this.observers != null)
            {
                this.observers.ForEach(o => o.Unsubscribe());
                this.observers.Clear();
                this.observers = null;
            }

            this.GetService<IVirtualDesktopManager>().Close(this.Id);

            this.id             = Guid.Empty;
            this.title          = null;
            this.closeCommand   = null;
        }

        #endregion
    }
}