Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="TipOfTheDayData.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Class that shows a tip of the day.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Xml.Serialization;
using Catel.Runtime.Serialization;

namespace Catel.Windows.Data
{
    /// <summary>
    /// Class that shows a tip of the day.
    /// </summary>
    [XmlRoot("TipOfTheDay", Namespace = "http://schemas.catel.com/winfx/2010/TipOfTheDay")]
    public class TipOfTheDayData
    {
        #region Variables
        private ObservableCollection<TipOfTheDayItem> _tips = new ObservableCollection<TipOfTheDayItem>();
        private List<int> _tipsToShow = new List<int>();
        #endregion

        #region Constructor & destructor
        /// <summary>
        /// Initializes a new instance of the <see cref="TipOfTheDayData"/> class.
        /// </summary>
        public TipOfTheDayData()
        {
        }
        #endregion

        #region Properties
        /// <summary>
        /// Gets the list of tips.
        /// </summary>
        [XmlElement("Tip", typeof(TipOfTheDayItem))]
        public ObservableCollection<TipOfTheDayItem> Tips
        {
            get { return _tips; }
        }
        #endregion

        #region Methods
        /// <summary>
        /// Loads a TipOfTheDay from a file.
        /// </summary>
        /// <returns>TipOfTheDay object.</returns>
        public static TipOfTheDayData Load()
        {
            TipOfTheDayData result = SerializationHelper.DeserializeXml<TipOfTheDayData>(PathHelper.FullTipOfTheDayPath, PathHelper.RelativeTipOfTheDayPath);
            result.UpdateToShowList();
            return result;
        }

        /// <summary>
        /// Saves the current instance of this data object.
        /// </summary>
        /// <returns>True if save was successful, otherwise false.</returns>
        public bool Save()
        {
            return SerializationHelper.SerializeXml(PathHelper.FullTipOfTheDayPath, this);
        }

        /// <summary>
        /// Updates the list that contains the to show tips.
        /// </summary>
        private void UpdateToShowList()
        {
            _tipsToShow.Clear();
            for (int i = 0; i < _tips.Count; i++)
            {
                _tipsToShow.Add(i);
            }
        }

        /// <summary>
        /// Gets the next tip index when the tips should occur randomly.
        /// </summary>
        /// <returns>Index of the next tip or -1 if there are no tips.</returns>
        public int GetNextTip()
        {
            if (_tipsToShow.Count <= 0)
            {
                UpdateToShowList();

                if (_tipsToShow.Count <= 0)
                {
                    return -1;
                }
            }

            // Get a random tip that is still in the tips to show
            Random random = new Random(DateTime.Now.Millisecond);
            int indexToShow = random.Next(_tipsToShow.Count - 1);
            int result = _tipsToShow[indexToShow];
            _tipsToShow.Remove(_tipsToShow[indexToShow]);
            return result;
        }
        #endregion
    }

    /// <summary>
    /// Class that represents a single TipOfTheDay element.
    /// </summary>
    public class TipOfTheDayItem : ICloneable, INotifyPropertyChanged
    {
        #region Variables
        private string _title = string.Empty;
        private string _description = string.Empty;
        #endregion

        #region Constructor & destructor
        /// <summary>
        /// Initializes a new instance of the <see cref="TipOfTheDayItem"/> class.
        /// </summary>
        public TipOfTheDayItem()
        {
        }
        #endregion

        #region Properties
        /// <summary>
        /// Gets or sets the title.
        /// </summary>
        [XmlElement("Title")]
        public string Title
        {
            get { return _title; }
            set
            {
                _title = value;
                OnPropertyChanged("Title");
            }
        }

        /// <summary>
        /// Gets or sets the description.
        /// </summary>
        [XmlElement("Description")]
        public string Description
        {
            get { return _description; }
            set
            {
                _description = value;
                OnPropertyChanged("Description");
            }
        }
        #endregion

        #region Methods
        /// <summary>
        /// Clones the object
        /// </summary>
        /// <returns>New object</returns>
        public object Clone()
        {
            TipOfTheDayItem newObject = new TipOfTheDayItem();
            newObject.Title = Title;
            newObject.Description = Description;

            return newObject;
        }

        /// <summary>
        /// Called when a property has changed.
        /// </summary>
        /// <param name="propertyName">Name of the property.</param>
        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion

        #region INotifyPropertyChanged Members
        /// <summary>
        /// Occurs when a property value changes.
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
    }
}