Template Based Multiple Control Validator

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing.Design;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel.Design;
using ValidationAggregator;

namespace ValidationAggregator
{
	[
		AspNetHostingPermission(SecurityAction.Demand,
			Level = AspNetHostingPermissionLevel.Minimal),
		AspNetHostingPermission(SecurityAction.InheritanceDemand,
			Level = AspNetHostingPermissionLevel.Minimal),
		Designer(typeof(ValidationTemplateDesigner)),
		DefaultProperty("Validators"),
		ToolboxData("<{0}:ValidationTemplate runat=\"server\"></{0}:ValidationTemplate>")
	]
	public class ValidationTemplate : CompositeControl
	{

		#region Fields

		private ITemplate _validators;
		private List<ControlDesc> _controlsToValidate;
		private string _defaultValidationGroup;
		private bool _forceValidationGroup;

		#endregion

		#region Properties

		[
			Browsable(false),
			PersistenceMode(PersistenceMode.InnerProperty),
			DefaultValue(typeof(ITemplate), ""),
			Description("Control template"),
			TemplateContainer(typeof(ValidationTemplate))
		]
		public virtual ITemplate Validators
		{
			get
			{
				return _validators;
			}
			set
			{
				_validators = value;
			}
		}


		[
			Category("Behavior"),
			Description("The controls collection"),
			DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
			Editor(typeof (CollectionEditor), typeof (UITypeEditor)),
			PersistenceMode(PersistenceMode.InnerProperty)
		]
		public List<ControlDesc> ControlsToValidate
		{
			get
			{
				if (_controlsToValidate == null)
					_controlsToValidate = new List<ControlDesc>();

				return _controlsToValidate;
			}
		}



		[
			Category("Behavior"),
			DefaultValue(""),
			Description("Use this validation group if the control didn't specify")
		]
		public string DefaultValidationGroup
		{
			get { return _defaultValidationGroup; }
			set { _defaultValidationGroup = value; }
		}

		[
			Category("Behavior"),
			DefaultValue("false"),
			Description("Override the validation group of all controls. If Default validation is empty this will clean the validatin group.")
		]
		public bool ForceValidationGroup
		{
			get { return _forceValidationGroup; }
			set { _forceValidationGroup = value; }
		}


		#endregion

		protected override void OnInit(EventArgs e)
		{
			base.OnInit(e);
			Page.InitComplete += OnPageInitComplete;
		}

		private class CtrlsContainer : WebControl
		{
			
		}

		protected void OnPageInitComplete(object sender, EventArgs args)
		{
			if (_validators == null || _controlsToValidate == null)
				return;

			foreach (ControlDesc ctrlDesc in _controlsToValidate)
			{
				Control ctrl = NamingContainer.FindControl(ctrlDesc.CID);

				int idx = ctrl.Parent.Controls.IndexOf(ctrl);

				CtrlsContainer cnt = new CtrlsContainer();

				_validators.InstantiateIn(cnt);

				PrepareValidators(cnt, ctrlDesc, null);

				ctrl.Parent.Controls.AddAt(idx + 1, cnt);
			}
		}

		/// <summary>
		/// 
		/// </summary>
		/// <param name="control"></param>
		/// <param name="desc"></param>
		/// <param name="validationGroup">It take precedence if is not null</param>
		private void PrepareValidators(Control control, ControlDesc desc, string validationGroup)
		{
			foreach (Control ctrl in control.Controls)
			{
				if (ctrl is BaseValidator)
				{
					BaseValidator val = (BaseValidator)ctrl;

					val.ID = "";	// we let the container generate the ids
					val.ControlToValidate = desc.CID;
					val.Text = string.Format(val.Text, desc.Label);
					val.ErrorMessage = string.Format(val.ErrorMessage, desc.Label);

					if (string.IsNullOrEmpty(val.ValidationGroup) || _forceValidationGroup) 
						val.ValidationGroup = _defaultValidationGroup;

					if (validationGroup != null)
						val.ValidationGroup = validationGroup;
				}

				PrepareValidators(ctrl, desc, validationGroup);
			}
		}
		
		/// <summary>
		/// Used by the validator
		/// </summary>
		public Control GetValidators(ControlDesc ctrlDesc, string validationGroup)
		{
			CtrlsContainer cnt = new CtrlsContainer();

			_validators.InstantiateIn(cnt);

			PrepareValidators(cnt, ctrlDesc, validationGroup);

			return cnt;
		}
	}
}