Build a Pandora clone with Silverlight 4

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.ComponentModel;
using JudahHimango.Chavah.MessianicMusicService;
using System.Diagnostics.Contracts;
using JudahHimango.Chavah.Infrastructure;
using JudahHimango.Chavah.Infrastructure.Messages;

namespace JudahHimango.Chavah.ViewModels
{
    public class SongViewModel : INotifyPropertyChanged
    {
        private readonly Song song;
        private readonly IMessageBus messageBus;
        private int rank;
        private string rankDescription;

        public event PropertyChangedEventHandler PropertyChanged;

        public SongViewModel()
        {
            // For design-time purposes only.
            if (!System.ComponentModel.DesignerProperties.IsInDesignTool)
            {
                throw new NotSupportedException("The default constructor is for designer aid only.");
            }
        }

        public SongViewModel(Song song, IMessageBus messageBus)
        {
            Contract.Requires(song != null);
            Contract.Requires(messageBus != null);

            this.song = song;
            this.messageBus = messageBus;
            this.Name = song.Name;
            this.Artist = song.Artist;
            this.Album = song.Album;
            this.LikeStatus = song.SongLike;
            this.Rank = song.CommunityRank;
            this.RankDescription = GetRankDescription();
        }

        public string Name { get; set; }
        public string Artist { get; set; }
        public string Album { get; set; }
        public SongLike LikeStatus { get; set; }
        public int Rank
        {
            get { return this.rank; }
            set
            {
                if (this.rank != value)
                {
                    this.rank = value;
                    OnPropertyChanged("Rank");
                    this.RankDescription = GetRankDescription();
                }
            }
        }

        private string GetRankDescription()
        {
            if (rank >= 10)
            {
                return "Oh yes! A minyan of Messianics love this tune.";
            }
            if (rank >= 5)
            {
                return string.Format("Great song! {0} Messianics love it!", rank);
            }
            if (rank == 1)
            {
                return string.Format("At least one Messianic music maestro likes this song.");
            }
            if (rank > 0)
            {
                return string.Format("{0} Messianics agree - this song is a great tune for the Lord!", rank);
            }
            if (rank < 0)
            {
                return string.Format("{0} Messianics don't care for this song.", Math.Abs(rank));
            }
            return "The Messianic community doesn't have much to say about this song. Give it a thumb up if you like it.";
        }

        public string RankDescription
        {
            get { return this.rankDescription; }
            set
            {
                if (this.rankDescription != value)
                {
                    this.rankDescription = value;
                    OnPropertyChanged("RankDescription");
                }
            }
        }

        public ICommand ThumbUpCommand
        {
            get
            {
                return new DelegateCommand(ThumbUp);
            }
        }

        public ICommand ThumbDownCommand
        {
            get
            {
                return new DelegateCommand(ThumbDown);
            }
        }

        private void ThumbUp()
        {
            if (song != null)
            {
                if (song.SongLike != SongLike.Like)
                {
                    this.messageBus.Publish(new LikeSongEventArgs(song));
                }

                var incrementAmount = song.SongLike != SongLike.Like ? 1 : 0;
                this.Rank += incrementAmount;

                song.SongLike = SongLike.Like;
            }
        }

        private void ThumbDown()
        {
            if (song != null)
            {
                if (song.SongLike != SongLike.Dislike)
                {
                    this.messageBus.Publish(new DislikeSongEventArgs(song));
                }

                var decrementAmount = song.SongLike != SongLike.Dislike ? 1 : 0;
                this.Rank -= decrementAmount;

                song.SongLike = SongLike.Dislike;
            }
        }

        private void OnPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                var args = new PropertyChangedEventArgs(propertyName);
                this.PropertyChanged(this, args);
            }
        }
    }
}