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

namespace NW4RTools {
	public class Texture {
		public struct TextureFormatInfo {
			public int TexelWidth, TexelHeight, NybblesPerPixel;

			public const int TexelByteSize = 32;

			private TextureFormatInfo(int tWidth, int tHeight, int npp) {
				TexelWidth = tWidth;
				TexelHeight = tHeight;
				NybblesPerPixel = npp;
			}

			static TextureFormatInfo() {
				I4 = new TextureFormatInfo(8, 8, 1);
				I8 = new TextureFormatInfo(8, 4, 2);
				IA4 = new TextureFormatInfo(8, 4, 2);
				IA8 = new TextureFormatInfo(4, 4, 4);
				RGB565 = new TextureFormatInfo(4, 4, 4);
				RGB5A3 = new TextureFormatInfo(4, 4, 4);
				RGBA8 = new TextureFormatInfo(4, 4, 8);
				C4 = new TextureFormatInfo(8, 8, 1);
				C8 = new TextureFormatInfo(8, 4, 2);
				C14X2 = new TextureFormatInfo(4, 4, 4);
				CMPR = new TextureFormatInfo(8, 8, 1);
			}

			public static TextureFormatInfo GetFormat(TextureFormat format) {
				switch (format) {
				case TextureFormat.I4:
					return I4;
				case TextureFormat.I8:
					return I8;
				case TextureFormat.IA4:
					return IA4;
				case TextureFormat.IA8:
					return IA8;
				case TextureFormat.RGB565:
					return RGB565;
				case TextureFormat.RGB5A3:
					return RGB5A3;
				case TextureFormat.RGBA8:
					return RGBA8;
				case TextureFormat.C4:
					return C4;
				case TextureFormat.C8:
					return C8;
				case TextureFormat.C14X2:
					return C14X2;
				case TextureFormat.CMPR:
					return CMPR;
				default:
					throw new ArgumentOutOfRangeException("unknown texture format");
				}
			}

			public static readonly TextureFormatInfo I4, I8, IA4, IA8, RGB565, RGB5A3, RGBA8, C4, C8, C14X2,
			CMPR;
		}



		public Bitmap BaseImage;

		public TextureFormat Format;
		public UInt32 MipMapCount;
		public float MinLOD, MaxLOD;

		public Texture() {
		}




		public static int GetDataSize(int width, int height, TextureFormat format) {
			var info = TextureFormatInfo.GetFormat(format);
			
			// align width, height up
			width = Misc.AlignUp(width, info.TexelWidth);
			height = Misc.AlignUp(height, info.TexelHeight);
			
			return width * height * info.NybblesPerPixel / 2;
		}

		unsafe public void ImportData(byte[] imgdata, int width, int height, TextureFormat format) {
			var image = new Bitmap(width, height, PixelFormat.Format32bppArgb);
			var bits = image.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, image.PixelFormat);

			var info = TextureFormatInfo.GetFormat(format);
			int blkWidth = info.TexelWidth;
			int blkHeight = info.TexelHeight;

			/*int blkNumY = 0;

			for (int blkY = 0; blkY < height; blkY += blkHeight) {
				byte* pBlkY = (byte*)bits.Scan0 + (blkY * bits.Stride);

				int blkNumX = 0;

				for (int blkX = 0; blkX < width; blkX += blkWidth) {
					byte* pBlk = pBlkY + (blkX * sizeof(uint));

					for (int y = 0; y < blkHeight; y++) {
						if ((blkY + y) >= height)
							break;

						byte* pRow = pBlk + (y * bits.Stride);

						for (int x = 0; x < blkWidth; x++) {
							if ((blkX + x) >= width)
								break;

							uint* pPixel = (uint*)pRow + x;

						}
					}

					blkNumX++;
				}

				blkNumY++;
			}*/

			// What I'm missing overall: IA4, IA8, RGBA8, all the palette ones

			// this thing probably breaks on textures which aren't multiples of the texel width/height, too
			// oh well

			var data = new InputStream(imgdata);

			switch (format) {
			case TextureFormat.RGB565:
			case TextureFormat.RGB5A3:
			case TextureFormat.I4:
			case TextureFormat.I8:
				// I4 is stupid and breaks my parser. I'll keep some state here
				bool alreadyHaveI4Nybble = false;
				byte currentI4Byte = 0;

				for (int y = 0; y < height; y += blkHeight) {
					int yMax = y + blkHeight;
					if (yMax > height)
						yMax = height;

					for (int x = 0; x < width; x += blkWidth) {
						int xMax = x + blkWidth;
						if (xMax > width)
							xMax = width;

						for (int y1 = y; y1 < yMax; y1++) {
							byte *pRow = (byte*)bits.Scan0 + (y1 * bits.Stride);

							for (int x1 = x; x1 < xMax; x1++) {
								uint *pPixel = (uint*)pRow + x1;

								if (format == TextureFormat.RGB565) {
									ushort val = data.ReadUInt16();
									uint r = (uint)(val & 0xF800) >> 8;
									uint g = (uint)(val & 0x7e0) >> 3;
									uint b = (uint)(val & 0x1f) << 3;
									*pPixel = 0xFF000000 | (r << 16) | (g << 8) | b;

								} else if (format == TextureFormat.RGB5A3) {
									ushort val = data.ReadUInt16();
									if ((val & 0x8000) == 0) {
										uint a = (uint)(val & 0x7000) >> 3;
										uint r = (uint)(val & 0xF00) >> 4;
										uint g = (uint)(val & 0xF0);
										uint b = (uint)(val & 0xF) << 4;
										*pPixel = (a << 24) | (r << 16) | (g << 8) | b;
									} else {
										uint r = (uint)(val & 0x7c00) >> 7;
										uint g = (uint)(val & 0x3e0) >> 2;
										uint b = (uint)(val & 0x1f) << 3;
										*pPixel = 0xFF000000 | (r << 16) | (g << 8) | b;
									}

								} else if (format == TextureFormat.I4) {
									if (!alreadyHaveI4Nybble) {
										currentI4Byte = data.ReadByte();
										uint val = (uint)currentI4Byte & 0xF0;
										*pPixel = 0xFF000000 | (val << 16) | (val << 8) | val;
									} else {
										uint val = (uint)(currentI4Byte & 0xF) << 4;
										*pPixel = 0xFF000000 | (val << 16) | (val << 8) | val;
									}

									alreadyHaveI4Nybble = !alreadyHaveI4Nybble;

								} else if (format == TextureFormat.I8) {
									byte val = data.ReadByte();
									*pPixel = 0xFF000000 | (uint)(val << 16) | (uint)(val << 8) | val;
								}
							}
						}
					}
				}

				break;

			case TextureFormat.CMPR:
				// this code is messy

				ushort[] rawClrArray = new ushort[4];
				uint[] clrArray = new uint[4];

				for (int y = 0; y < height; y += 8) {
					for (int x = 0; x < width; x += 8) {
						for (int iBlockY = 0; iBlockY < 2; iBlockY++) {
							for (int iBlockX = 0; iBlockX < 2; iBlockX++) {
								// decode a block
								rawClrArray[0] = data.ReadUInt16();
								rawClrArray[1] = data.ReadUInt16();

								bool hasAlpha = false;
								if (rawClrArray[0] > rawClrArray[1]) {
									rawClrArray[2] = CMPRAvgColor(2, 1, rawClrArray[0], rawClrArray[1]);
									rawClrArray[3] = CMPRAvgColor(1, 2, rawClrArray[0], rawClrArray[1]);
								} else {
									rawClrArray[2] = CMPRAvgColor(1, 1, rawClrArray[0], rawClrArray[1]);
									rawClrArray[3] = rawClrArray[1];
									hasAlpha = true;
								}

								for (int i = 0; i < 4; i++) {
									byte r = (byte)(((rawClrArray[i] >> 11) & 0x1F) << 3);
									byte g = (byte)(((rawClrArray[i] >> 5) & 0x3F) << 2);
									byte b = (byte)((rawClrArray[i] & 0x1F) << 3);
									byte a = (byte)(((i == 3) && hasAlpha) ? 0 : 255);

									clrArray[i] = (uint)(a << 24) | (uint)(r << 16) | (uint)(g << 8) | b;
								}

								for (int inY = 0; inY < 4; inY++) {
									byte* pRow = (byte*)bits.Scan0 + ((y + (iBlockY * 4) + inY) * bits.Stride);
									byte val = data.ReadByte();

									for (int inX = 0; inX < 4; inX++) {
										uint *pPixel = (uint*)pRow + x + (iBlockX * 4) + inX;
										*pPixel = clrArray[(val >> 6) & 3];
										val <<= 2;
									}
								}
							}
						}
					}
				}

				break;

			default:
				Console.WriteLine("Unsupported texture format: {0}", format);
				break;
			}

			
			image.UnlockBits(bits);
			
			BaseImage = image;
			Format = format;
		}

		private static ushort CMPRAvgColor(ushort w0, ushort w1, ushort c0, ushort c1) {
			uint result;

			ushort a0 = (ushort)(c0 >> 11);
			ushort a1 = (ushort)(c1 >> 11);
			uint a = (uint)((w0*a0 + w1*a1) / (w0+w1));
			result = (a << 11) & 0xffff;

			a0 = (ushort)((c0 >> 5) & 63);
			a1 = (ushort)((c1 >> 5) & 63);
			a = (uint)((w0 * a0 + w1 * a1) / (w0 + w1));
			result |= ((a << 5) & 0xffff);

			a0 = (ushort)(c0 & 31);
			a1 = (ushort)(c1 & 31);
			a = (uint)((w0 * a0 + w1 * a1) / (w0 + w1));
			result |= a;

			return (ushort)result;
		}
	}
}