/**
 * Namespace: System.Web.UI.WebControls
 * Class:     LinkButton
 *
 * Author:  Gaurav Vaish
 * Maintainer: gvaish@iitk.ac.in
 * Contact: <my_scripts2001@yahoo.com>, <gvaish@iitk.ac.in>
 * Implementation: yes
 * Status:  100%
 *
 * (C) Gaurav Vaish (2001)
 */

using System;
using System.Web;
using System.Web.UI;
using System.ComponentModel;

namespace System.Web.UI.WebControls
{
	[DefaultEvent("Click")]
	[DefaultProperty("Text")]
	//[Designer("??")]
	[ControlBuilder(typeof(LinkButtonControlBuilder))]
	//[DataBindingHandler("??")]
	[ParseChildren(false)]
	[ToolboxData("<{0}:LinkButton runat=\"server\">LinkButton</{0}:LinkButton>")]
	public class LinkButton : WebControl, IPostBackEventHandler
	{
		private static readonly object ClickEvent   = new object();
		private static readonly object CommandEvent = new object();

		public LinkButton () : base (HtmlTextWriterTag.A)
		{
		}

		public bool CausesValidation
		{
			get {
				object o = ViewState ["CausesValidation"];
				return (o == null) ? true : (bool) o;
			}

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

		public string CommandArgument
		{
			get {
				object o = ViewState ["CommandArgument"];
				return (o == null) ? String.Empty : (string) o;
			}

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

		public string CommandName
		{
			get {
				object o = ViewState ["CommandName"];
				return (o == null) ? String.Empty : (string) o;
			}

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

		public virtual string Text
		{
			get {
				object o = ViewState ["Text"];
				return (o == null) ? String.Empty : (string) o;
			}

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

		public event EventHandler Click
		{
			add { Events.AddHandler(ClickEvent, value); }
			remove { Events.RemoveHandler(ClickEvent, value); }
		}

		public event CommandEventHandler Command
		{
			add { Events.AddHandler(CommandEvent, value); }
			remove { Events.RemoveHandler(CommandEvent, value); }
		}

		protected virtual void OnClick (EventArgs e)
		{
			if(Events != null){
				EventHandler eh = (EventHandler) (Events [ClickEvent]);
				if (eh != null)
					eh (this, e);
			}
		}

		protected virtual void OnCommand (CommandEventArgs e)
		{
			if(Events != null){
				CommandEventHandler ceh = (CommandEventHandler) (Events [CommandEvent]);
				if (ceh != null)
					ceh (this, e);
			}
		}

		protected virtual void OnPreRender (EventArgs e)
		{
			base.OnPreRender(e);
		}

		void IPostBackEventHandler.RaisePostBackEvent (string eventArgument)
		{
			if (CausesValidation)
				Page.Validate ();
			OnClick (EventArgs.Empty);
			OnCommand (new CommandEventArgs (CommandName, CommandArgument));
		}

		protected override void AddAttributesToRender (HtmlTextWriter writer)
		{
			base.AddAttributesToRender (writer);
			if (Enabled && Page != null){
				if (CausesValidation && Page.Validators.Count > 0){
					writer.AddAttribute (HtmlTextWriterAttribute.Href,
							     "javascript:" + 
							     Utils.GetClientValidatedPostBack (this));
					return;
				}
				writer.AddAttribute (HtmlTextWriterAttribute.Href,
						     Page.GetPostBackClientHyperlink (this, ""));
			}
		}

		protected override void AddParsedSubObject (object obj)
		{
			if (HasControls ()){
				base.AddParsedSubObject (obj);
				return;
			}

			if (obj is LiteralControl){
				Text = ((LiteralControl) obj).Text;
				return;
			}

			if (Text.Length > 0){
				base.AddParsedSubObject (new LiteralControl (Text));
				Text = String.Empty;
			}

			base.AddParsedSubObject (obj);
		}

		protected override void LoadViewState (object savedState)
		{
			if (savedState != null){
				base.LoadViewState (savedState);
				string savedText = (string) ViewState ["Text"];
				if (savedText != null)
					Text = savedText;
			}
		}

		protected override void RenderContents (HtmlTextWriter writer)
		{
			if (HasControls ()){
				base.RenderContents (writer);
				return;
			}
			writer.Write (Text);
		}
	}
}