#region Copyright & License Information
/*
 * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see COPYING.
 */
#endregion

using System;
using System.Drawing;
using System.Drawing.Imaging;

namespace OpenRA.Graphics
{
	public static class Util
	{
		// yes, our channel order is nuts.
		static readonly int[] ChannelMasks = { 2, 1, 0, 3 };
		static readonly float[] ChannelSelect = { 0.2f, 0.4f, 0.6f, 0.8f };

		public static void FastCreateQuad(Vertex[] vertices, float2 o, Sprite r, float paletteTextureIndex, int nv, float2 size)
		{
			var b = new float2(o.X + size.X, o.Y);
			var c = new float2(o.X + size.X, o.Y + size.Y);
			var d = new float2(o.X, o.Y + size.Y);
			FastCreateQuad(vertices, o, b, c, d, r, paletteTextureIndex, nv);
		}

		public static void FastCreateQuad(Vertex[] vertices, float2 a, float2 b, float2 c, float2 d, Sprite r, float paletteTextureIndex, int nv)
		{
			var attribC = ChannelSelect[(int)r.Channel];
			if (r.Sheet.Type == SheetType.DualIndexed)
				attribC *= -1;

			vertices[nv] = new Vertex(a, r.Left, r.Top, paletteTextureIndex, attribC);
			vertices[nv + 1] = new Vertex(b, r.Right, r.Top, paletteTextureIndex, attribC);
			vertices[nv + 2] = new Vertex(c, r.Right, r.Bottom, paletteTextureIndex, attribC);
			vertices[nv + 3] = new Vertex(c, r.Right, r.Bottom, paletteTextureIndex, attribC);
			vertices[nv + 4] = new Vertex(d, r.Left, r.Bottom, paletteTextureIndex, attribC);
			vertices[nv + 5] = new Vertex(a, r.Left, r.Top, paletteTextureIndex, attribC);
		}

		public static void FastCopyIntoChannel(Sprite dest, byte[] src) { FastCopyIntoChannel(dest, 0, src); }
		public static void FastCopyIntoChannel(Sprite dest, int channelOffset, byte[] src)
		{
			var data = dest.Sheet.GetData();
			var srcStride = dest.Bounds.Width;
			var destStride = dest.Sheet.Size.Width * 4;
			var destOffset = destStride * dest.Bounds.Top + dest.Bounds.Left * 4 + ChannelMasks[(int)dest.Channel + channelOffset];
			var destSkip = destStride - 4 * srcStride;
			var height = dest.Bounds.Height;

			var srcOffset = 0;
			for (var j = 0; j < height; j++)
			{
				for (var i = 0; i < srcStride; i++, srcOffset++)
				{
					data[destOffset] = src[srcOffset];
					destOffset += 4;
				}

				destOffset += destSkip;
			}
		}

		public static void FastCopyIntoSprite(Sprite dest, Bitmap src)
		{
			var createdTempBitmap = false;
			if (src.PixelFormat != PixelFormat.Format32bppArgb)
			{
				src = src.CloneWith32bbpArgbPixelFormat();
				createdTempBitmap = true;
			}

			try
			{
				var destData = dest.Sheet.GetData();
				var destStride = dest.Sheet.Size.Width;
				var width = dest.Bounds.Width;
				var height = dest.Bounds.Height;

				var srcData = src.LockBits(src.Bounds(),
					ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

				unsafe
				{
					var c = (int*)srcData.Scan0;

					// Cast the data to an int array so we can copy the src data directly
					fixed (byte* bd = &destData[0])
					{
						var data = (int*)bd;
						var x = dest.Bounds.Left;
						var y = dest.Bounds.Top;

						for (var j = 0; j < height; j++)
						{
							for (var i = 0; i < width; i++)
							{
								var cc = Color.FromArgb(*(c + (j * srcData.Stride >> 2) + i));
								data[(y + j) * destStride + x + i] = PremultiplyAlpha(cc).ToArgb();
							}
						}
					}
				}

				src.UnlockBits(srcData);
			}
			finally
			{
				if (createdTempBitmap)
					src.Dispose();
			}
		}

		public static Color PremultiplyAlpha(Color c)
		{
			if (c.A == byte.MaxValue)
				return c;
			var a = c.A / 255f;
			return Color.FromArgb(c.A, (byte)(c.R * a + 0.5f), (byte)(c.G * a + 0.5f), (byte)(c.B * a + 0.5f));
		}

		public static Color PremultipliedColorLerp(float t, Color c1, Color c2)
		{
			// Colors must be lerped in a non-multiplied color space
			var a1 = 255f / c1.A;
			var a2 = 255f / c2.A;
			return PremultiplyAlpha(Color.FromArgb(
				(int)(t * c2.A + (1 - t) * c1.A),
				(int)((byte)(t * a2 * c2.R + 0.5f) + (1 - t) * (byte)(a1 * c1.R + 0.5f)),
				(int)((byte)(t * a2 * c2.G + 0.5f) + (1 - t) * (byte)(a1 * c1.G + 0.5f)),
				(int)((byte)(t * a2 * c2.B + 0.5f) + (1 - t) * (byte)(a1 * c1.B + 0.5f))));
		}

		public static float[] IdentityMatrix()
		{
			return Exts.MakeArray(16, j => (j % 5 == 0) ? 1.0f : 0);
		}

		public static float[] ScaleMatrix(float sx, float sy, float sz)
		{
			var mtx = IdentityMatrix();
			mtx[0] = sx;
			mtx[5] = sy;
			mtx[10] = sz;
			return mtx;
		}

		public static float[] TranslationMatrix(float x, float y, float z)
		{
			var mtx = IdentityMatrix();
			mtx[12] = x;
			mtx[13] = y;
			mtx[14] = z;
			return mtx;
		}

		public static float[] MatrixMultiply(float[] lhs, float[] rhs)
		{
			var mtx = new float[16];
			for (var i = 0; i < 4; i++)
				for (var j = 0; j < 4; j++)
				{
					mtx[4 * i + j] = 0;
					for (var k = 0; k < 4; k++)
						mtx[4 * i + j] += lhs[4 * k + j] * rhs[4 * i + k];
				}

			return mtx;
		}

		public static float[] MatrixVectorMultiply(float[] mtx, float[] vec)
		{
			var ret = new float[4];
			for (var j = 0; j < 4; j++)
			{
				ret[j] = 0;
				for (var k = 0; k < 4; k++)
					ret[j] += mtx[4 * k + j] * vec[k];
			}

			return ret;
		}

		public static float[] MatrixInverse(float[] m)
		{
			var mtx = new float[16];

			mtx[0] = m[5] * m[10] * m[15] -
				m[5] * m[11] * m[14] -
				m[9] * m[6] * m[15] +
				m[9] * m[7] * m[14] +
				m[13] * m[6] * m[11] -
				m[13] * m[7] * m[10];

			mtx[4] = -m[4] * m[10] * m[15] +
				m[4] * m[11] * m[14] +
				m[8] * m[6] * m[15] -
				m[8] * m[7] * m[14] -
				m[12] * m[6] * m[11] +
				m[12] * m[7] * m[10];

			mtx[8] = m[4] * m[9] * m[15] -
				m[4] * m[11] * m[13] -
				m[8] * m[5] * m[15] +
				m[8] * m[7] * m[13] +
				m[12] * m[5] * m[11] -
				m[12] * m[7] * m[9];

			mtx[12] = -m[4] * m[9] * m[14] +
				m[4] * m[10] * m[13] +
				m[8] * m[5] * m[14] -
				m[8] * m[6] * m[13] -
				m[12] * m[5] * m[10] +
				m[12] * m[6] * m[9];

			mtx[1] = -m[1] * m[10] * m[15] +
				m[1] * m[11] * m[14] +
				m[9] * m[2] * m[15] -
				m[9] * m[3] * m[14] -
				m[13] * m[2] * m[11] +
				m[13] * m[3] * m[10];

			mtx[5] = m[0] * m[10] * m[15] -
				m[0] * m[11] * m[14] -
				m[8] * m[2] * m[15] +
				m[8] * m[3] * m[14] +
				m[12] * m[2] * m[11] -
				m[12] * m[3] * m[10];

			mtx[9] = -m[0] * m[9] * m[15] +
				m[0] * m[11] * m[13] +
				m[8] * m[1] * m[15] -
				m[8] * m[3] * m[13] -
				m[12] * m[1] * m[11] +
				m[12] * m[3] * m[9];

			mtx[13] = m[0] * m[9] * m[14] -
				m[0] * m[10] * m[13] -
				m[8] * m[1] * m[14] +
				m[8] * m[2] * m[13] +
				m[12] * m[1] * m[10] -
				m[12] * m[2] * m[9];

			mtx[2] = m[1] * m[6] * m[15] -
				m[1] * m[7] * m[14] -
				m[5] * m[2] * m[15] +
				m[5] * m[3] * m[14] +
				m[13] * m[2] * m[7] -
				m[13] * m[3] * m[6];

			mtx[6] = -m[0] * m[6] * m[15] +
				m[0] * m[7] * m[14] +
				m[4] * m[2] * m[15] -
				m[4] * m[3] * m[14] -
				m[12] * m[2] * m[7] +
				m[12] * m[3] * m[6];

			mtx[10] = m[0] * m[5] * m[15] -
				m[0] * m[7] * m[13] -
				m[4] * m[1] * m[15] +
				m[4] * m[3] * m[13] +
				m[12] * m[1] * m[7] -
				m[12] * m[3] * m[5];

			mtx[14] = -m[0] * m[5] * m[14] +
				m[0] * m[6] * m[13] +
				m[4] * m[1] * m[14] -
				m[4] * m[2] * m[13] -
				m[12] * m[1] * m[6] +
				m[12] * m[2] * m[5];

			mtx[3] = -m[1] * m[6] * m[11] +
				m[1] * m[7] * m[10] +
				m[5] * m[2] * m[11] -
				m[5] * m[3] * m[10] -
				m[9] * m[2] * m[7] +
				m[9] * m[3] * m[6];

			mtx[7] = m[0] * m[6] * m[11] -
				m[0] * m[7] * m[10] -
				m[4] * m[2] * m[11] +
				m[4] * m[3] * m[10] +
				m[8] * m[2] * m[7] -
				m[8] * m[3] * m[6];

			mtx[11] = -m[0] * m[5] * m[11] +
				m[0] * m[7] * m[9] +
				m[4] * m[1] * m[11] -
				m[4] * m[3] * m[9] -
				m[8] * m[1] * m[7] +
				m[8] * m[3] * m[5];

			mtx[15] = m[0] * m[5] * m[10] -
				m[0] * m[6] * m[9] -
				m[4] * m[1] * m[10] +
				m[4] * m[2] * m[9] +
				m[8] * m[1] * m[6] -
				m[8] * m[2] * m[5];

			var det = m[0] * mtx[0] + m[1] * mtx[4] + m[2] * mtx[8] + m[3] * mtx[12];
			if (det == 0)
				return null;

			for (var i = 0; i < 16; i++)
				mtx[i] *= 1 / det;

			return mtx;
		}

		public static float[] MakeFloatMatrix(int[] imtx)
		{
			var fmtx = new float[16];
			for (var i = 0; i < 16; i++)
				fmtx[i] = imtx[i] * 1f / imtx[15];
			return fmtx;
		}

		public static float[] MatrixAABBMultiply(float[] mtx, float[] bounds)
		{
			// Corner offsets
			var ix = new uint[] { 0, 0, 0, 0, 3, 3, 3, 3 };
			var iy = new uint[] { 1, 1, 4, 4, 1, 1, 4, 4 };
			var iz = new uint[] { 2, 5, 2, 5, 2, 5, 2, 5 };

			// Vectors to opposing corner
			var ret = new float[] { float.MaxValue, float.MaxValue, float.MaxValue,
				float.MinValue, float.MinValue, float.MinValue };

			// Transform vectors and find new bounding box
			for (var i = 0; i < 8; i++)
			{
				var vec = new float[] { bounds[ix[i]], bounds[iy[i]], bounds[iz[i]], 1 };
				var tvec = MatrixVectorMultiply(mtx, vec);

				ret[0] = Math.Min(ret[0], tvec[0] / tvec[3]);
				ret[1] = Math.Min(ret[1], tvec[1] / tvec[3]);
				ret[2] = Math.Min(ret[2], tvec[2] / tvec[3]);
				ret[3] = Math.Max(ret[3], tvec[0] / tvec[3]);
				ret[4] = Math.Max(ret[4], tvec[1] / tvec[3]);
				ret[5] = Math.Max(ret[5], tvec[2] / tvec[3]);
			}

			return ret;
		}
	}
}