using Delta.Utilities.Datatypes;



namespace Delta.Rendering.Basics.Drawing

{

	/// <summary>

	/// Helper class to draw a coordinate system grid and gizmo, mostly used

	/// for debugging or some tools that display simple 3D data like the mesh

	/// viewer in the ContentManager tool.

	/// </summary>

	public static class Grid

	{

		#region Draw (Static)

		/// <summary>

		/// Draw a 3D grid, default values are 20m x 20m with the Color Grey.

		/// </summary>

		public static void Draw()

		{

			Draw(20, 20, 20, 20, Color.Grey);

		}



		/// <summary>

		/// Draws a grid with the given positions/sizes and colors.

		/// </summary>

		/// <param name="width">Grid width</param>

		/// <param name="depth">Grid depth</param>

		/// <param name="widthFaceCount">Number of faces in width</param>

		/// <param name="depthFaceCount">Number of faces in depth</param>

		/// <param name="gridColor">The color for the inner grid lines</param>

		/// <param name="lineColor">The color for the marker lines</param>

		/// <param name="drawCoordinateSystemGizmo">If tue, a coordinate

		/// system gizmo will be drawn at (0f,0f,0.1f)</param>

		public static void Draw(float width, float depth, int widthFaceCount,

			int depthFaceCount, Color gridColor, Color lineColor,

			bool drawCoordinateSystemGizmo = true)

		{

			int numberOfWidthLines = widthFaceCount;

			if (numberOfWidthLines % 2 != 0)

			{

				numberOfWidthLines++;

			}

			int numberOfDepthLines = depthFaceCount;

			if (numberOfDepthLines % 2 != 0)

			{

				numberOfDepthLines++;

			}

			float faceWidth = width / widthFaceCount;

			float faceDepth = depth / depthFaceCount;



			// Draw everything 1cm off the ground (needs pretty good depth buffer)

			float offset = 0.01f; //0.0001f; 0.01cm is not enough!



			#region WidthLines

			Vector startPos = new Vector(0, -(depth * 0.5f), offset);

			Vector endPos = new Vector(0, (depth * 0.5f), offset);



			// Draw the middle line.

			DrawManager drawInstance = DrawManager.Instance;

			drawInstance.Draw3DLine(ref startPos, ref endPos, ref lineColor);



			// Add the width lines.

			for (int index = 0; index < numberOfWidthLines / 2; index++)

			{

				startPos += new Vector(faceWidth, 0, 0);

				endPos += new Vector(faceWidth, 0, 0);



				drawInstance.Draw3DLine(startPos, endPos,

					(index + 1) % 5 == 0

						? lineColor

						: gridColor);

			}



			// Reset the position.

			startPos = new Vector(0, -(depth * 0.5f), offset);

			endPos = new Vector(0, (depth * 0.5f), offset);



			for (int index = 0; index < numberOfWidthLines / 2; index++)

			{

				startPos -= new Vector(faceWidth, 0, 0);

				endPos -= new Vector(faceWidth, 0, 0);



				drawInstance.Draw3DLine(startPos, endPos,

					(index + 1) % 5 == 0

						? lineColor

						: gridColor);

			}

			#endregion



			#region DepthLines

			startPos = new Vector(-(width * 0.5f), 0, offset);

			endPos = new Vector((width * 0.5f), 0, offset);

			drawInstance.Draw3DLine(ref startPos, ref endPos, ref lineColor);



			// Add the depth lines.

			for (int index = 0; index < numberOfDepthLines / 2; index++)

			{

				startPos += new Vector(0, faceDepth, 0);

				endPos += new Vector(0, faceDepth, 0);



				drawInstance.Draw3DLine(startPos, endPos,

					(index + 1) % 5 == 0

						? lineColor

						: gridColor);

			}



			startPos = new Vector(-(width * 0.5f), 0, offset);

			endPos = new Vector((width * 0.5f), 0, offset);



			for (int index = 0; index < numberOfDepthLines / 2; index++)

			{

				startPos -= new Vector(0, faceDepth, 0);

				endPos -= new Vector(0, faceDepth, 0);



				drawInstance.Draw3DLine(startPos, endPos,

					(index + 1) % 5 == 0

						? lineColor

						: gridColor);

			}

			#endregion



			if (drawCoordinateSystemGizmo)

			{

				DrawCoordinateSystemGizmo(offset);

			}

		}



		/// <summary>

		/// Draws a 3-dimensional grid using "LineColor" as ambient color.

		/// </summary>

		/// <param name="width">Grid width.</param>

		/// <param name="depth">Grid depth.</param>

		/// <param name="widthFaceCount">Count of faces in width.</param>

		/// <param name="depthFaceCount">Count of faces in depth.</param>

		/// <param name="color">Grid color.</param>

		public static void Draw(float width, float depth, int widthFaceCount,

			int depthFaceCount, Color color)

		{

			Draw(width, depth, widthFaceCount, depthFaceCount, color, Color.White);

		}

		#endregion



		#region DrawCoordinateSystemGizmo (Static)

		/// <summary>

		/// Draw gizmo with offset of 0.01f

		/// </summary>

		public static void DrawCoordinateSystemGizmo()

		{

			DrawCoordinateSystemGizmo(0.01f);

		}



		/// <summary>

		/// DrawCoordinateSystemGizmo with given offset

		/// </summary>

		/// <param name="offset">The offset.</param>

		public static void DrawCoordinateSystemGizmo(float offset)

		{

			// Draw the coordinate system gizmo

			Vector vOffset = new Vector(0, 0, offset + 0.0025f);

			DrawManager drawInstance = DrawManager.Instance;

			drawInstance.Draw3DLine(vOffset,

				Vector.UnitX + vOffset, Color.Red);

			drawInstance.Draw3DLine(vOffset,

				Vector.UnitY + vOffset, Color.Green);

			drawInstance.Draw3DLine(vOffset,

				Vector.UnitZ + vOffset, Color.Blue);

		}

		#endregion

	}

}