using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using Microsoft.Research.DynamicDataDisplay.Common;
using System.Diagnostics;
using System.Windows.Media;

namespace Microsoft.Research.DynamicDataDisplay
{
	/// <summary>
	/// A central class in 2d coordinate transformation in DynamicDataDisplay.
	/// Provides methods to transform point from one coordinate system to another.
	/// Should be immutable.
	/// </summary>
	public sealed class CoordinateTransform
	{
		private CoordinateTransform(DataRect visibleRect, Rect screenRect)
		{
			this.visibleRect = visibleRect;
			this.screenRect = screenRect;

			rxToScreen = screenRect.Width / visibleRect.Width;
			ryToScreen = screenRect.Height / visibleRect.Height;
			cxToScreen = visibleRect.XMin * rxToScreen - screenRect.Left;
			cyToScreen = screenRect.Height + screenRect.Top + visibleRect.YMin * ryToScreen;

			rxToData = visibleRect.Width / screenRect.Width;
			ryToData = visibleRect.Height / screenRect.Height;
			cxToData = screenRect.Left * rxToData - visibleRect.XMin;
			cyToData = visibleRect.Height + visibleRect.YMin + screenRect.Top * ryToData;
		}

		#region Coeffs
		double rxToScreen;
		double ryToScreen;
		double cxToScreen;
		double cyToScreen;

		double rxToData;
		double ryToData;
		double cxToData;
		double cyToData;
		#endregion

		#region Creation methods

		/// <summary>
		/// Creates CoordinateTransform fro specified rectangles and with Identity transform.
		/// </summary>
		/// <param name="visibleRect">The visible rect.</param>
		/// <param name="screenRect">The screen rect.</param>
		/// <returns></returns>
		public static CoordinateTransform FromRects(DataRect visibleRect, Rect screenRect)
		{
			CoordinateTransform result = new CoordinateTransform(visibleRect, screenRect);
			return result;
		}

		/// <summary>
		/// Closnes transform with current dataTransform and specified rectangles.
		/// </summary>
		/// <param name="visibleRect">The visible rect.</param>
		/// <param name="screenRect">The screen rect.</param>
		/// <returns></returns>
		public CoordinateTransform WithRects(DataRect visibleRect, Rect screenRect)
		{
			CoordinateTransform copy = new CoordinateTransform(visibleRect, screenRect);
			copy.dataTransform = dataTransform;
			return copy;
		}

		/// <summary>
		/// Creates a new instance of CoordinateTransform with the given data transform.
		/// </summary>
		/// <param name="dataTransform">The data transform.</param>
		/// <returns></returns>
		public CoordinateTransform WithDataTransform(DataTransform dataTransform)
		{
			if (dataTransform == null)
				throw new ArgumentNullException("dataTransform");

			CoordinateTransform copy = new CoordinateTransform(visibleRect, screenRect);
			copy.dataTransform = dataTransform;
			return copy;
		}

		internal CoordinateTransform WithScreenOffset(double x, double y)
		{
			Rect screenCopy = screenRect;
			screenCopy.Offset(x, y);
			CoordinateTransform copy = new CoordinateTransform(visibleRect, screenCopy);
			return copy;
		}

		internal static CoordinateTransform CreateDefault()
		{
			CoordinateTransform transform = new CoordinateTransform(new Rect(0, 0, 1, 1), new Rect(0, 0, 1, 1));

			return transform;
		}

		#endregion

		#region Transform methods

		/// <summary>
		/// Transforms point from data coordinates to screen.
		/// </summary>
		/// <param name="dataPoint">The point in data coordinates.</param>
		/// <returns></returns>
		public Point DataToScreen(Point dataPoint)
		{
			Point viewportPoint = dataTransform.DataToViewport(dataPoint);

			Point screenPoint = new Point(viewportPoint.X * rxToScreen - cxToScreen,
				cyToScreen - viewportPoint.Y * ryToScreen);

			return screenPoint;
		}

		/// <summary>
		/// Transforms point from screen coordinates to data coordinates.
		/// </summary>
		/// <param name="screenPoint">The point in screen coordinates.</param>
		/// <returns></returns>
		public Point ScreenToData(Point screenPoint)
		{
			Point viewportPoint = new Point(screenPoint.X * rxToData - cxToData,
				cyToData - screenPoint.Y * ryToData);

			Point dataPoint = dataTransform.ViewportToData(viewportPoint);

			return dataPoint;
		}

		/// <summary>
		/// Transforms point from viewport coordinates to screen coordinates.
		/// </summary>
		/// <param name="viewportPoint">The point in viewport coordinates.</param>
		/// <returns></returns>
		public Point ViewportToScreen(Point viewportPoint)
		{
			Point screenPoint = new Point(viewportPoint.X * rxToScreen - cxToScreen,
				cyToScreen - viewportPoint.Y * ryToScreen);

			return screenPoint;
		}

		/// <summary>
		/// Transforms point from screen coordinates to viewport coordinates.
		/// </summary>
		/// <param name="screenPoint">The point in screen coordinates.</param>
		/// <returns></returns>
		public Point ScreenToViewport(Point screenPoint)
		{
			Point viewportPoint = new Point(screenPoint.X * rxToData - cxToData,
				cyToData - screenPoint.Y * ryToData);

			return viewportPoint;
		}

		#endregion

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private DataRect visibleRect;
		/// <summary>
		/// Gets the viewport rectangle.
		/// </summary>
		/// <value>The viewport rect.</value>
		public DataRect ViewportRect
		{
			get { return visibleRect; }
		}

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private Rect screenRect;
		/// <summary>
		/// Gets the screen rectangle.
		/// </summary>
		/// <value>The screen rect.</value>
		public Rect ScreenRect
		{
			get { return screenRect; }
		}

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private DataTransform dataTransform = DataTransforms.Identity;
		/// <summary>
		/// Gets the data transform.
		/// </summary>
		/// <value>The data transform.</value>
		public DataTransform DataTransform
		{
			get { return dataTransform; }
		}
	}
}