using System;

using System.Diagnostics;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

namespace VisualValidation

{

/// <summary>

/// ValidationContainer is a light weight validation framework which only takes care displaying visaul effect of validation results for each validation field.

/// Don't use it to control Navigation. View Model should control it.

/// </summary>

public class ValidationContainer : ContentControl, IValidationContainer

{

/// <summary>

/// used internally by valiation framework.

/// </summary>

public static readonly DependencyProperty ValidationFieldHandlerProperty =

DependencyProperty.RegisterAttached("ValidationFieldHandler",

typeof(ValidationFieldHandler),

typeof(ValidationContainer),

new FrameworkPropertyMetadata(null));

/// <summary>

/// The name of a property of the IValidationSource. When this IValidationSource notifies this property changed,

/// ValidationContainer will validate this field with IValiationSource and set ValidationResult to the binded UI control.

/// </summary>

public static readonly DependencyProperty ValidationFieldProperty =

DependencyProperty.RegisterAttached("ValidationField", typeof(string), typeof(ValidationContainer),

new PropertyMetadata(string.Empty, OnValidateFieldSet));

/// <summary>

/// Can be used to display validation result for the binded UI control.

/// </summary>

public static readonly DependencyProperty ValidationResultProperty =

DependencyProperty.RegisterAttached("ValidationResult",

typeof(ValidationResult),

typeof(ValidationContainer),

new PropertyMetadata(null, OnValidationResultSet));

/// <summary>

/// An object of IValidationSource which provide vilidation and normally is View Model.

/// </summary>

public static readonly DependencyProperty ValidationSourceProperty =

DependencyProperty.Register("ValidationSource", typeof(IValidationSource),

typeof(ValidationContainer),

new FrameworkPropertyMetadata(null, OnValidationSourcePropertySet));

public static readonly DependencyProperty ValidationEnabledProperty =

DependencyProperty.Register("ValidationEnabled", typeof(bool),

typeof(ValidationContainer),

new PropertyMetadata(false, OnValidationEnabledSet));

public static readonly DependencyProperty ValidationTemplateProperty = DependencyProperty.RegisterAttached("ValidationTemplate",

typeof(ControlTemplate), typeof(ValidationContainer), new PropertyMetadata(null));

public static ControlTemplate GetValidationTemplate(DependencyObject obj)

{

return (ControlTemplate)obj.GetValue(ValidationTemplateProperty);

}

public static void SetValidationTemplate(DependencyObject obj, ControlTemplate value)

{

obj.SetValue(ValidationTemplateProperty, value);

}

internal static readonly DependencyProperty ValidationErrorAdornerProperty = DependencyProperty.RegisterAttached("ValidationErrorAdorner",

typeof(Adorner), typeof(ValidationContainer), new UIPropertyMetadata(null));

#region IValidationContainer Members

//not strong type it as IValidationSource, in order to avoid exception when binding is not ready.

public IValidationSource ValidationSource

{

get { return GetValue(ValidationSourceProperty) as IValidationSource; }

set

{

SetValue(ValidationSourceProperty, value);

ValidationSourceChanged.Invoke(this, null);

}

}

public event EventHandler ValidationSourceChanged = delegate { };

public event EventHandler ValidationEnabledChanged = delegate { };

public bool ValidationEnabled

{

get { return (bool)GetValue(ValidationEnabledProperty); }

set

{

SetValue(ValidationEnabledProperty, value);

ValidationEnabledChanged.Invoke(this, null);

}

}

#endregion

public static string GetValidationField(DependencyObject d)

{

return (string)d.GetValue(ValidationFieldProperty);

}

public static void SetValidationField(DependencyObject d, string value)

{

d.SetValue(ValidationFieldProperty, value);

}

public static ValidationResult GetValidationResult(DependencyObject d)

{

return (ValidationResult)d.GetValue(ValidationResultProperty);

}

public static void SetValidationResult(DependencyObject d, ValidationResult value)

{

d.SetValue(ValidationResultProperty, value);

}

private static void OnValidationSourcePropertySet(DependencyObject d, DependencyPropertyChangedEventArgs e)

{

var container = d as ValidationContainer;

if (container != null)

{

container.NotifyValidationSourceChanged();

Debug.WriteLine(string.Format("Validation source {0} set on {1}", e.NewValue, container));

}

}

private static void OnValidateFieldSet(DependencyObject d, DependencyPropertyChangedEventArgs e)

{

var uiElement = d as FrameworkElement;

if (uiElement == null) throw new ApplicationException("ValidationField property should be set on a FrameworkElement.");

if (uiElement.IsLoaded) throw new ApplicationException("ValidationField property should not be set after it is loaded.");

var filed = e.NewValue as string;

var oldValidationFieldHandler = uiElement.GetValue(ValidationFieldHandlerProperty) as ValidationFieldHandler;

if (oldValidationFieldHandler != null)

{

oldValidationFieldHandler.UnRegisterEventFromValidationSource();

uiElement.SetValue(ValidationFieldHandlerProperty, null);

}

uiElement.Loaded += (s, arg) => SetValidationHandler(uiElement, filed);

}

private static void OnValidationEnabledSet(DependencyObject d, DependencyPropertyChangedEventArgs e)

{

var container = d as ValidationContainer;

if (container != null)

{

container.NotifyValidationEnabledChanged();

Debug.WriteLine(string.Format("ValidationEnabled {0} set on {1}", e.NewValue, container));

}

}

private static void SetValidationHandler(FrameworkElement uiElement, string filed)

{

var oldValidationFieldHandler = uiElement.GetValue(ValidationFieldHandlerProperty) as ValidationFieldHandler;

if (oldValidationFieldHandler == null) //only need set once

{

IValidationContainer validationContainer = new UiTreeHelper().FindValidationContainer(uiElement);

var validationFieldHandler = new ValidationFieldHandler(new UIElementWrapper(uiElement), filed, validationContainer);

uiElement.SetValue(ValidationFieldHandlerProperty, validationFieldHandler);

}

}

private static void OnValidationResultSet(DependencyObject d, DependencyPropertyChangedEventArgs e)

{

var uiElement = d as FrameworkElement;

if (uiElement == null) throw new ApplicationException("ValidationResult property should be set on a FrameworkElement.");

ReoveAdorner(uiElement);

var validationResult = e.NewValue as ValidationResult;

if (validationResult != null)

{

if (!validationResult.IsValid)

AddAdorner(uiElement, e.NewValue);

}

}

private static void AddAdorner(FrameworkElement element, object dataContext)

{

ControlTemplate template = GetValidationTemplate(element);

if (template == null) return;

AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(element);

if (adornerLayer != null)

{

var adorner = new TemplatedAdorner(element, dataContext, template);

adornerLayer.Add(adorner);

element.SetValue(ValidationErrorAdornerProperty, adorner);

}

}

private static void ReoveAdorner(FrameworkElement element)

{

AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(element);

if (adornerLayer != null)

{

var oldAdorner = element.GetValue(ValidationErrorAdornerProperty) as Adorner;

if (oldAdorner != null)

{

adornerLayer.Remove(oldAdorner);

}

}

}

private void NotifyValidationEnabledChanged()

{

ValidationEnabledChanged.Invoke(this, null);

}

private void NotifyValidationSourceChanged()

{

ValidationSourceChanged.Invoke(this, null);

}

}

}