namespace GongSolutions.Wpf.DragDrop.Utilities
{
    using System.Diagnostics.CodeAnalysis;
    using System.Reflection;
    using System.Windows;
    using System.Windows.Media;

    /// <summary>
    /// A helper class for Dpi logicm cause Microsoft hides this with the internal flag.
    /// </summary>
    public static class DpiHelper
    {
        private static Matrix _transformToDevice;
        private static Matrix _transformToLogical;

        public static double DpiX = 0d;
        public static double DpiY = 0d;

        [SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline")]
        static DpiHelper()
        {
            var dpiXProperty = typeof(SystemParameters).GetProperty("DpiX", BindingFlags.NonPublic | BindingFlags.Static);
            var dpiYProperty = typeof(SystemParameters).GetProperty("Dpi", BindingFlags.NonPublic | BindingFlags.Static);

            var pixelsPerInchX = (int)dpiXProperty.GetValue(null, null); //SystemParameters.DpiX;
            DpiX = (double)pixelsPerInchX;
            var pixelsPerInchY = (int)dpiYProperty.GetValue(null, null); //SystemParameters.Dpi;
            DpiY = (double)pixelsPerInchY;

            _transformToLogical = Matrix.Identity;
            _transformToLogical.Scale(96d / (double)pixelsPerInchX, 96d / (double)pixelsPerInchY);
            _transformToDevice = Matrix.Identity;
            _transformToDevice.Scale((double)pixelsPerInchX / 96d, (double)pixelsPerInchY / 96d);
        }

        /// <summary>
        /// Convert a point in device independent pixels (1/96") to a point in the system coordinates.
        /// </summary>
        /// <param name="logicalPoint">A point in the logical coordinate system.</param>
        /// <returns>Returns the point converted to the system's coordinates.</returns>
        public static Point LogicalPixelsToDevice(Point logicalPoint)
        {
            return _transformToDevice.Transform(logicalPoint);
        }

        /// <summary>
        /// Convert a point in system coordinates to a point in device independent pixels (1/96").
        /// </summary>
        /// <param name="devicePoint">A point in the physical coordinate system.</param>
        /// <returns>Returns the point converted to the device independent coordinate system.</returns>
        public static Point DevicePixelsToLogical(Point devicePoint)
        {
            return _transformToLogical.Transform(devicePoint);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static Rect LogicalRectToDevice(Rect logicalRectangle)
        {
            Point topLeft = LogicalPixelsToDevice(new Point(logicalRectangle.Left, logicalRectangle.Top));
            Point bottomRight = LogicalPixelsToDevice(new Point(logicalRectangle.Right, logicalRectangle.Bottom));

            return new Rect(topLeft, bottomRight);
        }

        public static Rect DeviceRectToLogical(Rect deviceRectangle)
        {
            Point topLeft = DevicePixelsToLogical(new Point(deviceRectangle.Left, deviceRectangle.Top));
            Point bottomRight = DevicePixelsToLogical(new Point(deviceRectangle.Right, deviceRectangle.Bottom));

            return new Rect(topLeft, bottomRight);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static Size LogicalSizeToDevice(Size logicalSize)
        {
            Point pt = LogicalPixelsToDevice(new Point(logicalSize.Width, logicalSize.Height));

            return new Size { Width = pt.X, Height = pt.Y };
        }

        public static Size DeviceSizeToLogical(Size deviceSize)
        {
            Point pt = DevicePixelsToLogical(new Point(deviceSize.Width, deviceSize.Height));

            return new Size(pt.X, pt.Y);
        }

        public static Thickness LogicalThicknessToDevice(Thickness logicalThickness)
        {
            Point topLeft = LogicalPixelsToDevice(new Point(logicalThickness.Left, logicalThickness.Top));
            Point bottomRight = LogicalPixelsToDevice(new Point(logicalThickness.Right, logicalThickness.Bottom));

            return new Thickness(topLeft.X, topLeft.Y, bottomRight.X, bottomRight.Y);
        }
    }
}