using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace FWindSoft.Wpf.Controls
{
    public class TextWatermark
    {
        public static readonly DependencyProperty ShowInfoProperty = DependencyProperty.RegisterAttached("ShowInfo",
            typeof(string), typeof(TextWatermark), new PropertyMetadata(string.Empty, OnShowChanged));
        public static readonly DependencyProperty UseWatermarkProperty = DependencyProperty.RegisterAttached("UseWatermark",
           typeof(bool), typeof(TextWatermark), new PropertyMetadata(false, OnShowChanged));
        private static readonly DependencyProperty RefTriggerProperty = DependencyProperty.RegisterAttached("RefTrigger",
          typeof(MultiTrigger), typeof(TextWatermark));

        [AttachedPropertyBrowsableForType(typeof(TextBox))]
        public static string GetShowInfo(DependencyObject obj)
        {
            return (string)obj.GetValue(ShowInfoProperty);
        }
        [AttachedPropertyBrowsableForType(typeof(TextBox))]
        public static void SetShowInfo(DependencyObject obj, string value)
        {
            obj.SetValue(ShowInfoProperty, value);
        }
        [AttachedPropertyBrowsableForType(typeof(TextBox))]
        public static bool GetUseWatermark(DependencyObject obj)
        {
            return (bool)obj.GetValue(UseWatermarkProperty);
        }
        [AttachedPropertyBrowsableForType(typeof(TextBox))]
        public static void SetUseWatermark(DependencyObject obj, bool value)
        {
            obj.SetValue(UseWatermarkProperty, value);
        }
        /*
        可以使用蒙版的形式
        */
        public static void OnShowChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            TextBox textBox = d as TextBox;
            if (textBox == null)
                return;

            //创建触发器
            Style style = null;
            try
            {
                style = new Style() {TargetType=typeof(TextBox)};
                if (textBox.Style != null)
                {
                    #region 复制style
                    style.BasedOn = textBox.Style;
                    #endregion
                }
                //else
                //{
                //    style = new Style();
                //}
                var oldTrigger = (MultiTrigger)textBox.GetValue(TextWatermark.RefTriggerProperty);
                if (oldTrigger != null)
                {
                    style.Triggers.Remove(oldTrigger);
                }

                if (!GetUseWatermark(textBox))
                {
                    return;
                }

                MultiTrigger multiTrigger = new MultiTrigger();
                //暂时不需要交点控制
                //multiTrigger.Conditions.Add(new Condition(TextBox.IsFocusedProperty, false));
                multiTrigger.Conditions.Add(new Condition(TextBox.TextProperty, string.Empty));
                Setter setter = new Setter();
                setter.Property = TextBox.BackgroundProperty;
                setter.Value = new VisualBrush()
                {
                    AlignmentX = AlignmentX.Left,
                    AlignmentY = AlignmentY.Top,
                    Stretch = Stretch.None,
                    Visual = new TextBlock()
                    {
                        Text = GetShowInfo(textBox),
                        Background = (Brush)textBox.GetValue(TextBox.BackgroundProperty), //Brushes.Transparent,
                        Foreground = Brushes.Gray,
                        FontSize = textBox.FontSize,
                    }
                };
                multiTrigger.Setters.Add(setter);
                textBox.SetValue(TextWatermark.RefTriggerProperty, multiTrigger);

                style.Triggers.Add(multiTrigger);
                textBox.Style = style;
            }
            catch (Exception ex)
            {

                throw;
            }
          

        }
    }
}