using System;
using System.Collections.Generic;
using NW4RTools;
using NW4RTools.Models;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;

namespace NW4RTools.Models.OpenGL {
	public class GLModel {
		public ResFile SourceFile {
			get; private set;
		}

		public Model SourceModel {
			get; private set;
		}

		public GLModel(ResFile rf, string modelName) {
			SourceFile = rf;
			SourceModel = rf.GetGroup<Model>("3DModels(NW4R)")[modelName];

			// cache some stuff
			m_textureGroup = rf.GetGroup<Texture>("Textures(NW4R)");
		}




		private ResDict<Texture> m_textureGroup;
		private Dictionary<string, GLTexture> m_glTextures;
		private Dictionary<Material, GLDisplayList> m_glMaterials;
		private Dictionary<Shape, GLDisplayList> m_glShapes;

		public void Prepare(IGraphicsContext context) {
			// convert every texture
			m_glTextures = new Dictionary<string, GLTexture>();

			foreach (var material in SourceModel.Materials) {
				foreach (var texInfo in material.Value.TextureInfos) {
					if (!m_glTextures.ContainsKey(texInfo.TextureName)) {
						var newTex = new GLTexture();
						newTex.Load(m_textureGroup[texInfo.TextureName]);
						m_glTextures.Add(texInfo.TextureName, newTex);
					}
				}
			}

			// convert every material
			m_glMaterials = new Dictionary<Material, GLDisplayList>();

			foreach (var material in SourceModel.Materials.Values) {
				m_glMaterials.Add(material, MakeMaterialDisplayList(material));
			}

			// convert every shape
			m_glShapes = new Dictionary<Shape, GLDisplayList>();

			foreach (var shape in SourceModel.Shapes.Values) {
				m_glShapes.Add(shape, MakeShapeDisplayList(shape));
			}
		}



		private static readonly TextureUnit[] TextureUnits = new TextureUnit[] {
			TextureUnit.Texture0, TextureUnit.Texture1, TextureUnit.Texture2, TextureUnit.Texture3,
			TextureUnit.Texture4, TextureUnit.Texture5, TextureUnit.Texture6, TextureUnit.Texture7,
			TextureUnit.Texture8, TextureUnit.Texture9, TextureUnit.Texture10, TextureUnit.Texture11,
			TextureUnit.Texture12, TextureUnit.Texture13, TextureUnit.Texture14, TextureUnit.Texture15
		};

		private Material m_currentMaterial;

		private void ClearCache() {
			m_currentMaterial = null;
		}

		private void LoadMaterial(Material m) {
			if (m == m_currentMaterial)
				return;

			m_currentMaterial = m;
			m_glMaterials[m].Execute();
		}

		private void DrawShape(ByteCode.DrawShapeInstruction insn) {
			LoadMaterial(SourceModel.Materials[insn.MaterialID]);

			var shape = SourceModel.Shapes[insn.ShapeID];
			m_glShapes[shape].Execute();
		}

		public void Render(IGraphicsContext context) {
			// This'll be fun.

			ClearCache();
			
			foreach (var insn in SourceModel.Bytecode["DrawOpa"].Instructions) {
				if (insn is ByteCode.DrawShapeInstruction) {
					DrawShape(insn as ByteCode.DrawShapeInstruction);
				}
			}

			if (SourceModel.Bytecode.ContainsKey("DrawXlu")) {
				foreach (var insn in SourceModel.Bytecode["DrawXlu"].Instructions) {
					if (insn is ByteCode.DrawShapeInstruction) {
						DrawShape(insn as ByteCode.DrawShapeInstruction);
					}
				}
			}
		}



		#region Display Lists
		private GLDisplayList MakeMaterialDisplayList(Material m) {
			var displayList = new GLDisplayList();
			displayList.Begin();
			
			if (m.TextureInfos.Count > 0) {
				GL.Enable(EnableCap.Texture2D);
				
				TextureInfo[] texInfoArray = new TextureInfo[8];
				
				foreach (var texInfo in m.TextureInfos) {
					texInfoArray[texInfo.TexMapID] = texInfo;
				}
				
				for (int i = 0; i < 8; i++) {
					GL.ActiveTexture(TextureUnits[i]);
					GL.TexEnv(TextureEnvTarget.TextureEnv, TextureEnvParameter.TextureEnvMode, (int)TextureEnvMode.Decal);
					
					if (texInfoArray[i] == null) {
						GL.BindTexture(TextureTarget.Texture2D, 0);
					} else {
						m_glTextures[texInfoArray[i].TextureName].Bind(TextureTarget.Texture2D);
					}
				}
				
			} else {
				GL.Disable(EnableCap.Texture2D);
			}
			
			displayList.End();
			return displayList;
		}

		private GLDisplayList MakeShapeDisplayList(Shape shape) {
			var displayList = new GLDisplayList();
			displayList.Begin();
			
			var firstDL = new InputStream(shape.DisplayList1);
			firstDL.Seek(0x0C);
			UInt32 vtxDesc1 = firstDL.ReadUInt32();
			firstDL.Seek(0x12);
			UInt32 vtxDesc2 = firstDL.ReadUInt32();
			firstDL.Seek(0x22);
			UInt32 vtxAttr1 = firstDL.ReadUInt32();
			firstDL.Seek(0x28);
			UInt32 vtxAttr2 = firstDL.ReadUInt32();
			firstDL.Seek(0x2E);
			UInt32 vtxAttr3 = firstDL.ReadUInt32();
			
			var vs = new VertexSettings();
			vs.SetDesc(vtxDesc1, vtxDesc2);
			vs.SetAttrFmt(vtxAttr1, vtxAttr2, vtxAttr3);
			
			
			InputStream dl = new InputStream(shape.DisplayList2);
			
			while (true) {
				if (dl.AtEnd)
					break;
				
				byte cmd = dl.ReadByte();
				if (cmd == 0)
					break;
				
				PrimitiveType prim = (PrimitiveType)((cmd >> 3) & 7);
				int vtxCount = dl.ReadUInt16();
				
				// first, parse it into a list of vertices
				GXIndexedVertex[] vtxs = new GXIndexedVertex[vtxCount];
				for (int i = 0; i < vtxCount; i++) {
					vtxs[i].LoadFrom(dl, vs);
				}
				
				switch (prim) {
				case PrimitiveType.Quads:
					GL.Begin(BeginMode.Quads);
					break;
				case PrimitiveType.Triangles:
					GL.Begin(BeginMode.Triangles);
					break;
				case PrimitiveType.TriangleStrip:
					GL.Begin(BeginMode.TriangleStrip);
					break;
				case PrimitiveType.TriangleFan:
					GL.Begin(BeginMode.TriangleFan);
					break;
				case PrimitiveType.Lines:
					GL.Begin(BeginMode.Lines);
					break;
				case PrimitiveType.LineStrip:
					GL.Begin(BeginMode.LineStrip);
					break;
				case PrimitiveType.Points:
					GL.Begin(BeginMode.Points);
					break;
				default:
					Console.WriteLine("UNIMPLEMENTED PRIMITIVE TYPE {0}", prim);
					throw new NotImplementedException();
				}
				
				for (int i = 0; i < vtxCount; i++) {
					for (int j = 0; j < 8; j++) {
						if (vs.TexCoordDesc[j] != VertexSettings.DescType.None)
							GL.MultiTexCoord2(TextureUnits[j], shape.TexCoordData[j].Data[vtxs[i].TexCoords[j]]);
					}
					
					GL.Vertex3(shape.PosData.Data[vtxs[i].Position]);
				}
				
				GL.End();
			}
			
			displayList.End();
			return displayList;
		}

		#endregion
	}
}