/*
 * Util.ExtendedDisplayIdentificationData.cs
 * Authors: Adam Nabinger
 * Copyright (c) 2007-2008 Cornell University

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

using System;
using System.Collections.Generic;
using Microsoft.Win32;
using Microsoft.Xna.Framework.Graphics;

namespace Util
{
	/// <summary>
	/// Attempt to pull the device information from the windows registry. This is /very/ hardware dependent and not guaranteed to work.
	/// It does, however, work on the development dell laptops.
	/// See the DeviceInfo class for more options.
	/// </summary>
	public static class ExtendedDisplayIdentificationData
	{
		#region Fields

		// Array for storing all the arrays of information of the various graphics devices
		private static readonly byte[][] data;
		
		// Array for storing all the information for the current graphics device
		private static byte[] bytes;

		#endregion

		#region Properties

		/// <summary>
		/// Check if there is a profile available to read information from.
		/// </summary>
		public static bool HasProfile { get { return bytes != null; } }

		/// <summary>
		/// The reported Physical Horizontal Width of the Monitor, in Millimeters.
		/// </summary>
		public static int HorizontalSize
		{
			get
			{
#if DEBUG
				if (!HasProfile)
				{
					throw new InvalidOperationException("This is not guaranteed to work. Check if the EDID Has Profile first!");
				}
#endif
				return getHorizontalSize(bytes);
			}
		}

		/// <summary>
		/// The reported Physical Vertical Height of the Monitor, in Millimeters.
		/// </summary>
		public static int VerticalSize
		{
			get
			{
#if DEBUG
				if (!HasProfile)
				{
					throw new InvalidOperationException("This is not guaranteed to work. Check if the EDID Has Profile first!");
				}
#endif
				return getVerticalSize(bytes);
			}
		}

		/// <summary>
		/// The reported Horizontal Resolution of the Monitor, in Pixels.
		/// </summary>
		public static int HorizontalResolution
		{
			get
			{
#if DEBUG
				if (!HasProfile)
				{
					throw new InvalidOperationException("This is not guaranteed to work. Check if the EDID Has Profile first!");
				}
#endif
				return getHorizontalResolution(bytes);
			}
		}

		/// <summary>
		/// The reported Vertical Resolution of the Monitor, in Pixels.
		/// </summary>
		public static int VerticalResolution
		{
			get
			{
#if DEBUG
				if (!HasProfile)
				{
					throw new InvalidOperationException("This is not guaranteed to work. Check if the EDID Has Profile first!");
				}
#endif
				return getVerticalResolution(bytes);
			}
		}

		#endregion

		#region Creation

		/// <summary>
		/// Constructor
		/// </summary>
		static ExtendedDisplayIdentificationData()
		{
			List<byte[]> list = new List<byte[]>();
			try
			{
				RegistryKey DisplayKey = Registry.LocalMachine.OpenSubKey("SYSTEM").OpenSubKey("CurrentControlSet").OpenSubKey("Enum").OpenSubKey("DISPLAY");
				foreach (string s in DisplayKey.GetSubKeyNames())
				{
					RegistryKey MonitorKey = DisplayKey.OpenSubKey(s);
					foreach (string x in MonitorKey.GetSubKeyNames())
					{
						list.Add((byte[])MonitorKey.OpenSubKey(x).OpenSubKey("Device Parameters").GetValue("EDID"));
					}
				}
			} catch(NullReferenceException)
			{
				// Error reading from registry, stop and use what we've got so far.
			}
			data = list.ToArray();
		}

		#endregion

		#region Getters

		/// <summary>
		/// Gets the horizontal resolution of the current graphics device
		/// </summary>
		/// <param name="p_bytes">The array of information for the current graphics device</param>
		/// <returns>The horizontal resolution of the current graphics device</returns>
		private static int getHorizontalResolution(byte[] p_bytes)
		{
			return ((((240 & (p_bytes[58])) >> 4) << 8) | p_bytes[56]);
		}

		/// <summary>
		/// Gets the verticle resolution of the current graphics device
		/// </summary>
		/// <param name="p_bytes">The array of information for the current graphics device</param>
		/// <returns>The verticle resolution of the current graphics device</returns>
		private static int getVerticalResolution(byte[] p_bytes)
		{
			return ((((240 & (p_bytes[61])) >> 4) << 8) | p_bytes[59]);
		}

		/// <summary>
		/// Gets the horizontal size of the current graphics device
		/// </summary>
		/// <param name="p_bytes">The array of information for the current graphics device</param>
		/// <returns>The horizontal size of the current graphics device</returns>
		private static int getHorizontalSize(byte[] p_bytes)
		{
			return ((((240 & (p_bytes[68])) >> 4) << 8) | p_bytes[66]);
		}

		/// <summary>
		/// Gets the verticle size of the current graphics device
		/// </summary>
		/// <param name="p_bytes">The array of information for the current graphics device</param>
		/// <returns>The verticle size of the current graphics device</returns>
		private static int getVerticalSize(byte[] p_bytes)
		{
			return (((15 & (p_bytes[68])) << 4) | p_bytes[67]);
		}

		#endregion

		#region Setters

		/// <summary>
		/// The EDID data may contain multiple devices, such as for example, on a dual-monitor machine.
		/// We pick a dataset that matches the known information about the graphics device we're being displayed on.
		/// </summary>
		/// <param name="device">The graphics device to set as active</param>
		public static void SetActiveDevice(GraphicsDevice device)
		{
			bytes = null;
			foreach (byte[] b in data)
			{
				if (b == null)
				{
					continue;
				}
				if (getHorizontalResolution(b) != device.DisplayMode.Width || getVerticalResolution(b) != device.DisplayMode.Height)
				{
					continue;
				}
#if DEBUG
				if (bytes != null)
				{
					Console.WriteLine("Debug: More than one possible matching display device EDID");
				}
#endif
				bytes = b;
#if !DEBUG
				return;
#endif
			}
		}

		#endregion
	}
}