/*
 * Copyright & License: :) The Code is very Trivial. If copyright applicable, then (C) 2015 Bsod64 :D
 *
 * Usage:
 * Add it to your project.
 *
 * In your xaml file first add to the xmlns section something along the lines of:
 * xmlns:customwidgets="clr-namespace:Bsod64.CustomWpfControls"
 * (To change this, simple reflect your change in the namespace of this file.)
 *
 * Then use it in your xaml file:
 * <customwidgets:TextboxWithPlaceholder Placeholder="My placeholder text here" />
 *
 */

using Microsoft.Win32;
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace Bsod64.CustomWpfControls
{
        class TextboxWithPlaceholder: TextBox
        {
                private Brush _placeholderColor = Brushes.Gray;

                public string Placeholder
                {
                        get
                        {
                                return (string)GetValue(PlaceholderProperty);
                        }
                        set
                        {
                                SetValue(PlaceholderProperty, value);
                        }
                }

                public static readonly DependencyProperty PlaceholderProperty =
                    DependencyProperty.Register("Placeholder", typeof(string), typeof(TextboxWithPlaceholder), new PropertyMetadata(default(string)));



                protected void Usability_PropertyChanged(object sender, EventArgs e)
                {
                        if(!SystemParameters.HighContrast)
                        {
                                _placeholderColor = Brushes.Gray;
                                if(Text.Equals(Placeholder))
                                        Foreground = _placeholderColor;
                        }
                        else
                        {
                                ClearValue(TextboxWithPlaceholder.ForegroundProperty);
                                _placeholderColor = Foreground;
                        }
                }

                protected override void OnInitialized(EventArgs e)
                {
 	                base.OnInitialized(e);
                        SystemEvents.UserPreferenceChanged += Usability_PropertyChanged; // Starting .NET 4.5 can you can use SystemParameters.StaticPropertyChanged
                        ShowPlaceholder();
                }

                protected override void OnGotKeyboardFocus(System.Windows.Input.KeyboardFocusChangedEventArgs e)
                {
                        base.OnGotKeyboardFocus(e);
                        if(Text.Equals(Placeholder))
                              HidePlaceholder();
                }

                protected override void OnLostKeyboardFocus(System.Windows.Input.KeyboardFocusChangedEventArgs e)
                {
                        base.OnLostKeyboardFocus(e);
                        if(Text.Equals(String.Empty))
                                ShowPlaceholder();
                }

                public void ShowPlaceholder()
                {
                        Text = Placeholder;
                        Foreground = _placeholderColor;
                        FontStyle = FontStyles.Italic;
                }

                public void HidePlaceholder()
                {
                        Text = String.Empty;
                        ClearValue(TextboxWithPlaceholder.ForegroundProperty);
                        FontStyle = FontStyles.Normal;
                }
        }
}