// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
 
using System.Windows.Controls.Primitives;
 
namespace System.Windows.Controls
{
    /// <summary>
    /// The separator used to indicate drop location during column header drag-drop
    /// </summary>
    internal class DataGridColumnDropSeparator : Separator
    {
        #region Constructors
 
        static DataGridColumnDropSeparator()
        {
            DefaultStyleKeyProperty.OverrideMetadata(
                typeof(DataGridColumnDropSeparator), 
                new FrameworkPropertyMetadata(DataGridColumnHeader.ColumnHeaderDropSeparatorStyleKey));
 
            WidthProperty.OverrideMetadata(
                typeof(DataGridColumnDropSeparator), 
                new FrameworkPropertyMetadata(null, new CoerceValueCallback(OnCoerceWidth)));
            
            HeightProperty.OverrideMetadata(
                typeof(DataGridColumnDropSeparator), 
                new FrameworkPropertyMetadata(null, new CoerceValueCallback(OnCoerceHeight)));
        }
 
        #endregion
 
        #region Static Methods
 
        private static object OnCoerceWidth(DependencyObject d, object baseValue)
        {
            double width = (double)baseValue;
            if (double.IsNaN(width))
            {
                return 2.0;
            }
 
            return baseValue;
        }
 
        private static object OnCoerceHeight(DependencyObject d, object baseValue)
        {
            double height = (double)baseValue;
            DataGridColumnDropSeparator separator = (DataGridColumnDropSeparator)d;
            if (separator._referenceHeader != null && double.IsNaN(height))
            {
                return separator._referenceHeader.ActualHeight;
            }
 
            return baseValue;
        }
 
        #endregion
 
        #region Properties
 
        internal DataGridColumnHeader ReferenceHeader
        {
            get
            {
                return _referenceHeader;
            }
 
            set
            {
                _referenceHeader = value;
            }
        }
 
        #endregion
 
        #region Data
 
        private DataGridColumnHeader _referenceHeader;
 
        #endregion
    }
}