Modeling M-V-VM

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.ObjectModel;
using System.Windows.Input;
using System.ComponentModel;

using WorldDataLib.Model;

namespace TestTreeViewWithRightBarView.ViewModel
{
    public class ContinentViewModel : ITreeViewWithChildrenNode, IContinentViewModel, ISelectionSectionPresenter, INotifyPropertyChanged
    {
        #region Members

        IViewModel m_Parent;
        Continent m_Continent;

        ObservableCollection<ITreeViewNode> m_Children;

        #endregion

        #region Properties
        
        #region ITreeViewWithChildrenNode Members

        public ObservableCollection<ITreeViewNode> Children
        {
            get 
            {
                return m_Children; 
            }
        }

        #endregion

        #region ITreeViewNode Members

        public string Caption
        {
            get 
            {
                string str = string.Empty;
                if (m_Continent != null)
                {
                    str = m_Continent.Name;
                }
                return str;
            }
        }

        #endregion

        #region IViewModel Members

        public IViewModel VMParent
        {
            get 
            { 
                return m_Parent; 
            }
        }

        #endregion

        #region ISelectionSectionPresenter Members

        public string Title
        {
            get;
            set;
        }

        #endregion

        public double Size
        {
            get;
            set;
        }

        #endregion

        #region Methods

        #region Ctor

        public ContinentViewModel(IViewModel parent, Continent continent)
        {
            m_Parent = parent;
            m_Continent = continent;
            m_Children = new ObservableCollection<ITreeViewNode>();
            if ((m_Continent != null) && (m_Continent.Countries != null))
            {
                for (int iter = 0; iter < m_Continent.Countries.Count; iter++)
                {
                    m_Children.Add(new CountryViewModel(this, m_Continent.Countries[iter]));
                }
            }
        }

        #endregion

        #region IViewModel Members

        public void HandleEvent(IViewModel sender, object param, ViewModelOperationsEnum viewModelEvent)
        {
            if (m_Parent != null)
            {
                m_Parent.HandleEvent(sender, param, viewModelEvent);
            }
        }

        #endregion

        #region GotFocus

        public ICommand GotFocus
        {
            get
            {
                return new DelegateCommand(this.ControlGotFocus);
            }
        }

        /// <summary>
        /// When the control gets focus, an event is fired for external handling
        /// </summary>
        public void ControlGotFocus()
        {
            if (VMParent != null)
            {
                VMParent.HandleEvent(this, null, ViewModelOperationsEnum.GotFocus);
                VMParent.HandleEvent(this, Caption, ViewModelOperationsEnum.GetContinentSize);
            }
        }

        #endregion

        #region IContinentViewModel Members

        public void SetSize(double fSize)
        {
            Size = fSize;
            Title = string.Format("Continent {0} size is {1}sq miles",Caption, Size);
            OnPropertyChanged("Title");
        }

        #endregion

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string str)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(str));
            }
        }

        #endregion

        #endregion        
    
       
    }
}