/BlogEngine/BlogEngine.NET/App_Code/Controls/MonthList.cs

// --------------------------------------------------------------------------------------------------------------------

// <summary>

//   Builds a category list.

// </summary>

// --------------------------------------------------------------------------------------------------------------------



namespace App_Code.Controls

{

	using System;

	using System.Collections.Generic;

	using System.ComponentModel;

	using System.Linq;

	using System.Web;

	using System.Web.Caching;

	using System.Web.UI;



	using Resources;



	using BlogEngine.Core;





	/// <summary>

	/// Displays a list of hyperlinks each of which points at a page

	/// containing blog posts written within a particular month.

	/// </summary>

	public class MonthList : Control

	{

		#region Nested Classes



		/// <summary>

		/// Specifies the way <see cref="App_Code.Controls.MonthList" /> control is displayed.

		/// </summary>

		[Flags]

		public enum MonthListDisplayOptions

		{

			/// <summary>

			/// A convenience constant that corresponds to default <see cref="App_Code.Controls.MonthList" />

			/// behavior where grouping by year is performed.

			/// </summary>

			Grouping_ByYear = 0,



			/// <summary>

			/// When set, the <see cref="App_Code.Controls.MonthList" /> control renders

			/// a flat month list, without grouping by year.

			/// </summary>

			Grouping_Flat = 1,



			/// <summary>

			/// A convenience constant that corresponds to default <see cref="App_Code.Controls.MonthList" />

			/// behavior where more recent dates appear at the bottom of the list.

			/// </summary>

			Sorting_RecentAtBottom = 0,



			/// <summary>

			/// When set, the the <see cref="App_Code.Controls.MonthList" /> control renders

			/// a month list where more recent dates appear at the top of the list.

			/// </summary>

			Sorting_RecentAtTop = 2

		}



		/// <summary>

		/// Represents a <see cref="System.DateTime" /> comparer that performs

		/// direct date comparison.

		/// </summary>

		class DateComparer_Asc : IComparer<DateTime>

		{

			int IComparer<DateTime>.Compare(DateTime x, DateTime y)

			{ return x.CompareTo(y); }

		}



		/// <summary>

		/// Represents a <see cref="System.DateTime" /> comparer that performs

		/// inverse date comparison.

		/// </summary>

		class DateComparer_Desc : IComparer<DateTime>

		{

			int IComparer<DateTime>.Compare(DateTime x, DateTime y)

			{ return -x.CompareTo(y); }

		}

		#endregion



		#region Constants and Fields



		/// <summary>

		/// The cache key.

		/// </summary>

		private const string CacheKey = "BE_MonthListCacheKey";



		/// <summary>

		/// The cache timeout in hours.

		/// </summary>

		private const double CacheTimeoutInHours = 1;



		/// <summary>

		/// The global instance of the direct date comparer.

		/// </summary>

		private static readonly IComparer<DateTime> ourComparer_Asc = new DateComparer_Asc();



		/// <summary>

		/// The global instance of the inverse date comparer.

		/// </summary>

		private static readonly IComparer<DateTime> ourComparer_Desc = new DateComparer_Desc();



		/// <summary>

		/// Stores the current year so that it remains constant while the control is being rendered.

		/// </summary>

		private int myCurrentYear;

		#endregion



		#region Constructors and Destructors



		/// <summary>

		/// Initializes static members of the <see cref="MonthList" /> class.

		/// </summary>

		static MonthList()

		{

			Post.Saved += Handler_Post_Saved;

		}



		/// <summary>

		/// Initializes a new instance of the <see cref="MonthList" /> class.

		/// </summary>

		public MonthList()

		{

			myCurrentYear = DateTime.Now.Year;

		}



		#endregion



		#region Properties



		/// <summary>

		/// Specifies whether the month lit should be render hierarchically, grouped by year.

		/// </summary>

		[DefaultValue(true)]

		public bool GroupByYear

		{

			get

			{

				return (DisplayFlags & (int)MonthListDisplayOptions.Grouping_Flat) == 0;

			}

			set

			{

				if (value) DisplayFlags &= ~(int)MonthListDisplayOptions.Grouping_Flat;

				else DisplayFlags |= (int)MonthListDisplayOptions.Grouping_Flat;

			}

		}



		/// <summary>

		/// Specifies the way months should be sorted: recent dates at top or at bottom.

		/// </summary>

		[DefaultValue(false)]

		public bool RecentDatesAtTop

		{

			get

			{

				return (DisplayFlags & (int)MonthListDisplayOptions.Sorting_RecentAtTop) != 0;

			}

			set

			{

				if (value) DisplayFlags |= (int)MonthListDisplayOptions.Sorting_RecentAtTop;

				else DisplayFlags &= ~(int)MonthListDisplayOptions.Sorting_RecentAtTop;

			}

		}



		/// <summary>

		/// Stores the controls display options in a compact manner.

		/// </summary>

		public virtual int DisplayFlags

		{

			get

			{

				object aVal = ViewState["DisplayFlags"];



				if (aVal == null)

					return 0;

				else

					return (int)aVal;

			}

			set { ViewState["DisplayFlags"] = value; }

		}

		#endregion



		#region Public Methods



		/// <summary>

		/// Outputs server control content to a provided <see cref="T:System.Web.UI.HtmlTextWriter"/>

		/// object and stores tracing information about the control if tracing is enabled.

		/// </summary>

		/// <param name="writer">

		/// The <see cref="T:System.Web.UI.HtmlTextWriter"/> object that receives the control content.

		/// </param>

		public override void RenderControl(HtmlTextWriter writer)

		{

			SortedDictionary<DateTime, int> months = GetPostsPerMonth(RecentDatesAtTop);



			if (months.Keys.Count == 0)

			{

				writer.RenderBeginTag(HtmlTextWriterTag.P);

				writer.Write(Resources.labels.none);

				writer.RenderEndTag();



				return;

			}



			writer.AddAttribute("id", "monthList");

			writer.RenderBeginTag(HtmlTextWriterTag.Ul);





			if (GroupByYear)

			{

				int current = 0;



				foreach (KeyValuePair<DateTime, int> aIt in months)

				{

					if (current != aIt.Key.Year)

					{

						if (current != 0)

							RenderYearGroupEnd(writer);



						RenderYearGroupBegin(writer, aIt.Key.Year);



						current = aIt.Key.Year;

					}



					RenderMonth(writer, aIt.Key, aIt.Value, false);

				}



				if (current != 0)

					RenderYearGroupEnd(writer);

			}

			else

			{

				foreach (KeyValuePair<DateTime, int> aIt in months)

					RenderMonth(writer, aIt.Key, aIt.Value, true);

			}



			writer.RenderEndTag();

		}



		#endregion



		#region Implementation-Specific Methods



		/// <summary>Obtains a collection of months with a corresponding month post count.</summary>

		/// <returns>

		/// A <see cref="T:System.Collections.Generic.SortedDictionary<DateTime, int>" />

		/// whose keys represent the first day of a month and values contain the month post count.

		/// </returns>

		private static SortedDictionary<DateTime, int> GetPostsPerMonth(bool theSortDesc)

		{

			var months = Blog.CurrentInstance.Cache[CacheKey] as SortedDictionary<DateTime, int>;

			IComparer<DateTime> aComparer = theSortDesc ? ourComparer_Desc : ourComparer_Asc;



			if (months != null)

			{

				if (months.Comparer != aComparer)

				{

                    Blog.CurrentInstance.Cache.Remove(CacheKey);

					months = null;

				}

			}



			if (months == null)

			{

				months = new SortedDictionary<DateTime, int>(aComparer);



				// let dictionary expire after 1 hour

				Blog.CurrentInstance.Cache.Insert(

						CacheKey, months, null, DateTime.Now.AddHours(CacheTimeoutInHours), Cache.NoSlidingExpiration);



				foreach (

					var month in Post.Posts.Where(post => post.IsVisibleToPublic).Select(

						post => new DateTime(post.DateCreated.Year, post.DateCreated.Month, 1)))

				{

					int count;



					// if the date is not in the dictionary, count will be set to 0

					months.TryGetValue(month, out count);

					++count;

					months[month] = count;

				}

			}



			return months;

		}



		/// <summary>

		/// Handles the Saved event of the Post control.

		/// </summary>

		/// <param name="sender">The source of the event.</param>

		/// <param name="e">The <see cref="BlogEngine.Core.SavedEventArgs"/> instance containing the event data.</param>

		private static void Handler_Post_Saved(object sender, SavedEventArgs e)

		{

			// invalidate cache whenever a post is modified

			Blog.CurrentInstance.Cache.Remove(CacheKey);

		}

		

		#region Rendering Methods

		/// <summary>

		/// Renders the beginning of HTML code corresponding to a specific year.

		/// </summary>

		/// <param name="theWriter">The text writer that receives rendered data.</param>

		/// <param name="theYear">The year being rendered</param>

		private void RenderYearGroupBegin(HtmlTextWriter theWriter, int theYear)

		{

			// 1. Year List Item

			string aYearStr = theYear.ToString();



			theWriter.AddAttribute("class", "year");

			theWriter.AddAttribute("onclick", "BlogEngine.toggleMonth('year" + aYearStr + "')");

			theWriter.RenderBeginTag(HtmlTextWriterTag.Li);

			theWriter.Write(aYearStr);



			// 2. Nested Month List

			theWriter.AddAttribute("id", "year" + aYearStr);



			if (theYear == myCurrentYear)

				theWriter.AddAttribute("class", "open");



			theWriter.RenderBeginTag(HtmlTextWriterTag.Ul);

		}



		/// <summary>

		/// Renders the end of HTML code corresponding to a year.

		/// </summary>

		/// <param name="theWriter">The text writer that receives rendered data.</param>

		private void RenderYearGroupEnd(HtmlTextWriter theWriter)

		{

			// 2. Nested Month List

			theWriter.RenderEndTag();





			// 1. Year List Item

			theWriter.RenderEndTag();

		}



		/// <summary>

		/// Renders HTML code corresponding to a specific month/year combination.

		/// </summary>

		/// <param name="theWriter">The text writer that receives rendered data.</param>

		/// <param name="theDate">The date (year and month) being rendered.</param>

		/// <param name="thePostCount">The number of posts published within the specified month.</param>

		/// <param name="theShowYear">True, if the year must be rendered; otherwise, false.</param>

		private void RenderMonth(HtmlTextWriter theWriter, DateTime theDate, int thePostCount, bool theShowYear)

		{

			theWriter.RenderBeginTag(HtmlTextWriterTag.Li);



			{

				string aHref = string.Format

				(

					"{0}{1}/{2}/default{3}",

					Utils.RelativeWebRoot,

					theDate.Year,

					theDate.ToString("MM"),

					BlogConfig.FileExtension

				);

				theWriter.AddAttribute("href", aHref);

				theWriter.RenderBeginTag(HtmlTextWriterTag.A);



				theWriter.Write(theShowYear ? theDate.ToString("MMMM yyyy") : theDate.ToString("MMMM"));



				theWriter.RenderEndTag();

			}



			theWriter.Write(" (");

			theWriter.Write(thePostCount.ToString());

			theWriter.Write(")");



			theWriter.RenderEndTag();

		}

		#endregion

		#endregion

	}

}