using System;
using System.Data;
using System.Collections;

namespace Rss
{
	/// <summary>
	/// Summary description for RssChannelBuilder.
	/// </summary>
	public class RssChannelBuilder : RssChannel
	{
		private DataTable dataTable;

		private string itemTitleField;
		private string itemDescriptionField;
		private string itemPubDateField;
		private string itemLinkField;
		private string itemLinkFormat;

		/// <summary>
		/// This object will assist in the building of the channel by 
		/// obtaining the channel's items from the set DataSource.
		/// </summary>
		public RssChannelBuilder()
		{
		}

		/// <summary>
		/// The DataTable which holds the channel's items.
		/// </summary>
		public DataTable DataSource
		{
			set { this.dataTable = value ; }
		}

		/// <summary>
		/// The column name for the item's title.
		/// </summary>
		public string ItemTitleField
		{
			set { this.itemTitleField = value ; }
		}

		/// <summary>
		/// The column name for the item's description.
		/// </summary>
		public string ItemDescriptionField
		{
			set { this.itemDescriptionField = value ; }
		}

		/// <summary>
		/// The column name for the item's publish date.
		/// </summary>
		public string ItemPubDateField
		{
			set { this.itemPubDateField = value ; }
		}

		/// <summary>
		/// The column name that contains the unique ID of the item.
		/// </summary>
		public string ItemLinkField
		{
			set { this.itemLinkField = value ; }
		}

		/// <summary>
		/// The formatted string (ala RSSMaster style) of the item's link.
		/// Example: "http://www.centralchristianev.com/weekend/CurrentSeries.aspx?id={0}";
		/// The {0} is replaced with the value found in the ItemLinkField.
		/// </summary>
		public string ItemLinkFormat
		{
			set { this.itemLinkFormat = value ; }
		}

		/// <summary>
		/// Call this method to bind the DataSource to the RssChannel.
		/// </summary>
		public void DataBind()
		{
			foreach ( DataRow row in dataTable.Rows )
			{
				RssItem item = new RssItem();
				if ( row[ this.itemTitleField ] != null )
					item.Title = LoadStringData( row[ this.itemTitleField ] );

				if ( row[ this.itemLinkField ] != null )
					item.Link = new Uri( itemLinkFormat.Replace("{0}", LoadIntData( row[ this.itemLinkField ] ).ToString() ) );

				if ( row[ this.itemDescriptionField ] != null )
					item.Description = LoadStringData( row[ this.itemDescriptionField ] );

				if ( row[ this.itemPubDateField ] != null )
					item.PubDate = LoadDateTimeData( row[ this.itemPubDateField ] );

				Items.Add( item );
			}
		}

		/// <summary>
		/// used to check for a DbNull value and return the default Null
		/// </summary>
		/// <param name="dataToLoad">date to be checked for DbNull</param>
		/// <returns>The original value or the default Null value if DbNull</returns>
		private int LoadIntData( object dataToLoad )
		{
			if ( dataToLoad == DBNull.Value )
				return -1;
			else
				return (int)dataToLoad;
		}

		/// <summary>
		/// used to check for a DbNull value and return the default Null
		/// </summary>
		/// <param name="dataToLoad">date to be checked for DbNull</param>
		/// <returns>The original value or the default Null value if DbNull</returns>
		private string LoadStringData( object dataToLoad )
		{
			if ( dataToLoad == DBNull.Value )
				return "";
			else
				return (string)dataToLoad;
		}

		/// <summary>
		/// used to check for a DbNull value and return the default Null
		/// </summary>
		/// <param name="dataToLoad">date to be checked for DbNull</param>
		/// <returns>The original value or the default Null value if DbNull</returns>
		private DateTime LoadDateTimeData(object dataToLoad)
		{
			if (dataToLoad == DBNull.Value)
				return DateTime.MinValue;
			else
				return (DateTime)dataToLoad;
		}
	}
}